Method of and compositions and sets of agents for enhancing oral biological availability of pharmaceutic agents

The present invention relates to the use of an agent to increase oral bioavailability, a pharmaceutical kit and a pharmaceutical composition from oral administration. More particularly, the invention relates to the use of an agent to increase the oral bioavailability, compositions and kits for improving the oral bioavailability of pharmaceutical agents that are poorly absorbed from the gastrointestinal system and that allow treatment of patients by oral administration of such agents.

Many valuable pharmacologically active compounds cannot be effectively administered by the oral route due to poor systemic absorption from the gastrointestinal tract. All these pharmaceutical agents are therefore administered by the intravenous or intramuscular route requiring the intervention of a physician or other healthcare professional, presenting severe discomfort and potential local shock to the patient, even requiring hospital administration and surgery for certain intravenous infusions.

It has been contemplated that, in some instances, the poor oral bioavailability of drugs is due to the activity of a multidrug transporter - membrane-bound P-glycoprotein, which acts as an energy-dependent transport or efflux pump to reduce intracellular drug accumulation by forcing foreign substances out of the cell. This P-glycoprotein has been identified in normal tissues of the secretory endothelium, such as those that line the biliary tract, the brush border of the proximal tubule in the kidney and the lumen surface, and the vascular endothelial cells that line the blood-brain barrier, placenta, and testes.

The P-glycoprotein efflux pump is believed to prevent certain pharmaceutical compounds from crossing the cells of the mucosa of the small intestine and, therefore, from being absorbed into the circulation. Numerous known non-toxic pharmacological agents have been shown to inhibit P-glycoprotein, including, but not limited to, cyclosporin A (also known as cyclosporin), verapamil, tamoxifen, quinidine, and phenothiazines. Many of these studies have been aimed at achieving greater accumulation of cytotoxic drugs inside tumor cells. In fact, clinical experiments were conducted to investigate the effects of cyclosporin on the pharmacokinetics and toxicity of paclitaxel (Fisher et al., Proc. Am. Soc. Clin. Oncol., 13: 143, 1994); doxorubicin (Bartlett et al., J. Clin. One., 12: 835-842,1994); and etoposide (Lum et al., J.Clin.Onc., 10: 1635-42, 1992), all of which are anti-neoplastic agents known to be susceptible to multiple drug resistance (MDR). For a general discussion of the pharmacological implications of the clinical use of P-gp inhibitors, see Lum et al., Drug Resist.Clin.One. Hemat., 9: 319-336, (1995); Schinkel et al., Eur. J. Cancer, 31A: 1295-1298 (1995).

It is not suggested in these publications that cyclosporine and other substances that inhibit the P-gp efflux pump could be administered orally to significantly increase the bioavailability of orally administered anti-cancer drugs and other pharmaceutical agents that are themselves poorly absorbed from the gut without producing highly toxic effects. side effects. Indeed, in 1995 the review publication cited above, Lum et al., Showed that co-administration of MDR inhibitors and chemotherapeutic agents subject to MDR with the simultaneous administration of MDR increases the level of toxicity and worsens the severe side effects in patients. Schinkel et al. Briefly noted that MDR1 and P-glycoprotein are abundant in the intestinal mucosa and that this may affect the oral bioavailability of P-glycoprotein substrate drugs, but does not suggest or imply that oral administration of MDR inhibitors could improve the bioavailability of agents not available orally. Moreover, like Lum et al., Schinkel et al., Recalled that P-glycoprotein inhibitors can dramatically increase the toxicity of chemotherapy in patients and should therefore be used with caution.

In earlier publications, Schinkel et al. Showed that the absorption of orally ingested ivermectin was increased in mice homozygous for disruption of the MDR1 gene, compared to normal mice, showing that P-glycoprotein plays a major role in reducing the bioavailability of this agent (Cell, 77 : 491-502,1994). In addition, these studies also showed that penetration of vinblastine into various tissues was enhanced in mutant mice.

None of the published studies has foreseen a procedure that would allow for effective oral administration of otherwise poorly bioavailable drugs, e.g. by determining appropriate dosage amounts and timing the timing of specific target drugs and bioavailability enhancers, i.e. by demonstrating which agents

MDR inhibitors are most suitable for promoting the oral absorption of any target drug or class of drugs.

The methods disclosed in the art to increase the intestinal absorption of drugs that have until now been administered only parenterally generally focus on the use of penetration and solubility enhancers as stimulants, or the co-administration of P-gp inhibitors by perfusion into the lumen. the small intestine or by the intravenous route, e.g. Leu et al., Cancer Chemother. Pharmacol., 35: 432-436, 1995 (quinidine perfusion or IV infusion inhibits the efflux of etoposide from the blood into the lumen of the gastrointestinal tract). However, these methods suffer from numerous disadvantages. Solubility and permeation enhancers are often either impractical or ineffective when administered orally at the required dosages, and may impair the pharmacological activity of the target drug. Parenteral administration of P-gp inhibitors to humans at therapeutic (or near-therapeutic) doses may result in numerous clinical consequences. In the case of quinidine, e.g., IV administration can cause arrhythmias, peripheral vasodilation, gastrointestinal upset, and the like.

In PCT Application Publication WO 95/20980 (published August 10, 1995), Benet et al. Discloses a significant method of increasing the bioavailability of orally administered hydrophobic pharmaceutical compounds. The method includes orally administering such compounds to a patient concurrently with a biamplifier, including an inhibitor of the cytochrome P450 3A enzyme, or a P-glycoprotein mediated membrane transport inhibitor. However, Benet et al., Did not provide a true means of identifying which bioavailability enhancers would improve the availability of specific "target pharmaceutical compounds, nor would they provide a specific dosage amount, schedule or regimen for the administration of the enhancers or target agents." In fact, although the Benet application lists dozens of potential enhancers (P450 3A inhibitors) and target drugs (P450 3A substrates), the only combination of enhancer and target supported by any experimental fact in the application is ketoconazole as the enhancer and cyclosporin A as the target drug.

Describing the general characteristics of compounds that can be used as bio-enhancers by reducing the transport activity of P-glycoprotein, Benet et al. Indicate that they are hydrophobic compounds which generally, but not necessarily, contain two common-plane aromatic rings, positively charged group. , containing nitrogen or a carbonyl group - a class that includes a huge number of compounds, most of which would not provide the desired activity. absorption enhancer in the case of specific target agents. In addition, the classes of target agents described by Benet et al. Include the vast majority of pharmaceutical agents listed in the Physicians' Desk Reference. These classifying criteria are of no value to practicing physicians seeking safe, practical, and effective means of orally administering specific pharmaceutical agents.

A further deficiency in Benet et al. Is the standard used to determine whether the bioavailability of a drug that is poorly absorbed when orally administered has improved. Benet et al. Indicate that any P-glycoprotein inhibitory agent which, when present in the intestine at a given concentration, reduces the transmembrane transport of rhodamine 123 by P-glycoprotein in the membrane of brush border vesicles or cells containing P-glycoprotein by 10% or more, can be considered a biostrengthening agent at this concentration and can be used in the practice of their invention. But increasing the absorption of only 10% from the intestine, an otherwise nonabsorbable agent, is inadequate to render the agent therapeutically valuable for any purpose. Indeed, according to the Federal Food and Drug Administration, two pharmaceutical preparations containing the same ingredient, differing in their bioavailability levels in the range of -20% / + 25%, are still considered bioequivalent, because for most drugs the difference in the concentration of the active ingredient in the blood within -20% / + 25% is not clinically significant. Approved Drug Products with Therapeutic Equiyalence Eyaluations (Dept. HHS, 14th Ed. 1994). When the FDA decides that two pharmaceutical preparations are bioequivalent, doctors and pharmacists consider them to be freely substitutable with one another.

In general, Benet et al. Do not provide the knowledge that could be proceeded by a medical or pharmaceutical professional to identify an appropriate bio-enhancer / target drug combination, or to specifically design treatment regimens and plans that would make target agents therapeutically effective when administered. by mouth.

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Thus, a safe, yet effective, method of increasing the systemic availability of orally administered drugs is desired, which is currently only administered parenterally, since these are not absorbed sufficiently or properly when administered orally and has not been provided in the prior art. .

Surprisingly, it has now been discovered and experimentally confirmed that certain agents that apparently inhibit P-glycoprotein drug transport activity can be used to substantially increase the oral bioavailability of otherwise poorly or unavailable pharmaceutical agents, e.g. anti-cancer drugs such as paclitaxel (formerly known as taxol ), as well as its analogs and derivatives, and etoposide.

The present invention relates to the use of an oral bioavailability enhancer in the manufacture of a medicament for the treatment of mammalian patients with taxane sensitive disease conditions, wherein the oral bioavailability enhancer is selected from the group consisting of ketoconazole, verapamil, and dipyridamole, whereby after simultaneous oral administration of the taxane and the enhancer, therapeutic blood and serum taxane levels are achieved.

Preferably, a metabolite of paclitaxel is selected as the taxane. More preferably, a paclitaxel metabolite of the formula is selected as the taxane:

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wherein R1 is hydrogen or hydroxy and R2 is hydrogen or hydroxy, wherein if R1 is hydrogen, R2 is hydroxy.

Paclitaxel is also preferably selected as the taxane.

In another preferred embodiment, docetaxel is selected as the taxane. In another preferred embodiment, the dosage form of the taxane, bioavailability enhancer, or combinations thereof are administered in a form selected from the group consisting of tablets, capsules, caplets, pills, lozenges, and liquid solutions, suspensions or elixirs.

In a further preferred embodiment of the invention, the taxane dosage form comprises paclitaxel as taxane and polyoxyethylene castor oil, alcohol or polyoxyethylene sorbitan monooleate.

In a preferred use of the bioavailability enhancer, the neoplastic disease is cancer, neoplastic tumor, neoplastic proliferation, or uncontrolled tissue or cellular proliferation secondary to damaged tissue. Optionally, the neoplastic disease is one selected from the group consisting of ovarian cancer, breast cancer, lung cancer, head and neck cancers, liver cell cancer, hepatic metastases, urogenital and gastrointestinal carcinomas, Kaposi's sarcoma, polycystic kidney disease. and malaria. It can also be breast cancer, lung cancer, ovarian cancer, gastrointestinal cancer, and hepatocellular carcinoma.

Preferably, the medicament comprises about 20-1000 mg / m2² of the taxane based on the patient's body surface area.

Also preferably, the medicament comprises about 2-30 mg / kg taxane based on the patient's body weight.

The invention also relates to a pharmaceutical kit which comprises an oral dosage form of an agent to increase the oral bioavailability and an oral dosage form of ketoconazole,

Verapamil or dipyridamole and an oral taxane dosage form, or a combination of an oral dosage form containing both a bioavailability enhancer and a taxane, wherein, upon simultaneous oral administration of the taxane and the enhancer, therapeutic blood and serum levels of the taxane are achieved.

Preferably, the kit of the invention further comprises, as an attachment, printed dosage information for the simultaneous administration of the enhancement and target agents.

Also preferably, in the kit of the invention, the bioavailability enhancer and the taxane are contained in separate pharmaceutical oral dosage forms.

Also preferably, the kit may contain a combination of oral pharmaceutical dosage forms.

In another preferred embodiment, the kit of the invention is characterized in that the oral dosage form containing the taxane and the oral dosage form containing the bioavailability enhancer or the combination of these oral dosage forms is selected from the group consisting of tablets, capsules, caplets, pills, lozenges, liquid solutions. , suspensions or elixirs.

The invention also relates to a pharmaceutical composition for oral administration, characterized in that it comprises a taxane effective in the treatment of taxane-sensitive diseases and an oral bioavailability-enhancing agent selected from the group consisting of ketoconazole, verapamil and dipyridamole, which when administered orally results in the achievement of a therapeutic concentration of the taxane in the blood or serum.

In the composition of the invention, the taxane may be selected from the group consisting of paclitaxel, docetaxel, and pharmaceutically acceptable salts, metabolites, analogs, derivatives and prodrugs thereof.

In a more preferred embodiment of the composition of the invention, the taxane comprises paclitaxel.

More preferably the composition comprises docetaxel as a taxane.

Brief description of the drawings

Figure 1 is a graph reflecting the levels of radioactivity detected in total blood samples collected from three groups of rats over a period of 24 hours: one group was given 10 mg / kg orally verapamil as a booster, the other group was given oral progesterone as a booster, and a third group was given oral dipyridamole as a booster, each group receiving an oral dose of the same booster one hour later immediately after the oral dose of radiographically paclitaxel.

Figure 2 is a graph reflecting the levels of radioactivity detected in total blood samples collected over a period of 24 hours from rats in the first group defined with reference to Figure 1 (which were orally dosed with 10 mg / kg verapamil) dosed orally with radiolabeled paclitaxel. alone and from the group of rats administered orally ciclosporin one hour before and again immediately after radiolabeled oral paclitaxel.

Figure 3 is a graph reflecting the levels of radioactivity detected in total blood samples collected over a period of 24 hours from the rats in the second group defined with reference to Figure 1 (which was administered orally progesterone), the group of rats administered orally radiolabelled paclitaxel, and the group of rats. who was administered orally ciclosporin one hour before, and again immediately after, radiolabeled oral paclitaxel.

Figure 4 is a graph reflecting the levels of radioactivity detected in total blood samples collected over a period of 24 hours from the rats of the third group defined with reference to Figure 1 (which was administered orally with dipyridamole), the group of rats treated with radiolabeled oral paclitaxel alone and from the group of rats. receiving oral ciclosporin one hour before and again immediately after radiolabeled oral paclitaxel.

Figure 5 is a graph reflecting the levels of radioactivity detected in total blood samples collected from three groups of rats over a period of 24 hours: one group was orally administered 100 mg / kg verapamil¹ as a booster, the second group was given orally megestrol acetate (commercialized as Megace® by Bristol-Myers Squibb Oncology) as a booster, and a third group was given oral ketoconazole as a booster, each group receiving the same oral dose of the same booster, one one hour later, immediately after an oral dose of radiolabeled paclitaxel.

₁

As shown in Figure 5, the rats in the high dose verapamil group did not survive for more than 8 hours.

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Figure 6 is a graph reflecting the levels of radioactivity detected in total blood samples collected over a period of 24 hours from rats in the first group defined with reference to Figure 5 (who were orally dosed with 100 mg / kg verapamil) treated with oral radiolabeled paclitaxel alone and a group of rats administered orally ciclosporin one hour before and again immediately after radiolabeled oral paclitaxel.

Figure 7 is a graph reflecting the levels of radioactivity detected in total blood samples collected over a 24 hour period from rats in the second group defined with reference to Figure 5 (orally dosed with megestrol acetate), the orally radiolabeled paclitaxel alone group and the rats group. who was administered orally ciclosporin one hour before and again immediately after radiolabeled oral paclitaxel.

Figure 8 is a graph reflecting the levels of radioactivity detected in total blood samples collected over a period of 24 hours from the rats in the third group defined with reference to Figure 5 (who received oral ketoconazole), the orally radiolabeled paclitaxel alone group and the rats group that received oral cyclosporin one hour before and again immediately after radiolabeled oral paclitaxel.

Figure 9 is a graph reflecting the levels of radioactivity detected in total blood samples collected over a period of 24 hours from rats in the first group defined with reference to Figure 1 (which was orally administered 10 mg / kg verapamil), the first group defined with reference to Figure 1. 12 (dosed orally with 100 mg / kg verapamil), the group of rats receiving radiolabeled oral paclitaxel alone, and the group of rats receiving oral ciclosporin one hour before and again immediately after radiolabeled oral paclitaxel.

Figure 10 is a graph reflecting the levels of radioactivity detected in total blood samples taken over a 24 hour period from the rats of the second group identified with reference to Figure 1 (which was administered orally progesterone), the second group identified with 5 (orally dosed with megestrol acetate), the rats group that received radiolabeled oral paclitaxel alone, and the rats group that received oral ciclosporin one hour before and again immediately after radiolabeled oral paclitaxel.

Figure 10A is a graph reflecting a comparison of the dose response curves of the group of rats receiving oral cyclosporin one hour before and again immediately after radiolabeled oral paclitaxel with the group of rats receiving oral ketoconazole one hour before and again immediately after radiolabeled oral paclitaxel. Figure 10B is a comparison of AUC0-24 values ​​determined in relation to the same two groups of rats.

Figure 11 is a graph reflecting the levels of radioactivity detected in total blood samples collected from three groups of rats over a period of 24 hours: one group was given oral ketoconazole both one hour before and immediately after the oral dose of radiolabeled paclitaxel, the other group was given a combined oral dose of cyclosporin A and ketoconazole both one hour before and immediately after the oral dose of radiolabeled paclitaxel, and the third group was given both cyclosporin A and both one hour before and immediately after an oral dose of radiolabeled paclitaxel.

Figure 12 is a graph reflecting the levels of radioactivity detected in total blood samples collected from three groups of rats over a period of 24 hours: one group was administered oral captopril both two hours before and immediately after the oral dose of radiolabeled paclitaxel, the other group was administered cyclosporin A both one hour before and immediately after the oral dose of radiolabeled paclitaxel, and the third group was administered orally with radiolabeled paclitaxel alone.

Figure 13 is a graph reflecting the levels of radioactivity detected in total blood samples collected from three groups of rats over a 24 hour period: one (group A) was given only radiolabeled docetaxel ("Taxotere") IV, the other (group B) was given orally only radiolabeled docetaxel and the third group (group C) was given orally radiolabeled docetaxel with oral doses of cyclosporin one hour before and immediately after dose of docetaxel, with the ordinate of said plot running from 0-12.0 mean decetaxel equivalents in ppm.

Figure 14 is a graph reflecting the levels of radioactivity detected in total blood samples collected from the three groups of rats defined in Figure 13 but with the ordinate of said plot ranging from 0-2.0 mean docetaxel equivalents in ppm.

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Figure 15 is a graph reflecting the levels of radioactivity detected in total blood samples collected from three groups of rats over a 24 hour period: one (group A) was administered only radiolabeled paclitaxel intravenously, the other (group B) was administered orally only radiolabeled paclitaxel, and a third group ( group C) orally administered radiolabeled paclitaxel with oral doses of cyclosporin one hour before and immediately after the dose of paclitaxel.

Figure 16 is a graph reflecting the levels of unchanged radiolabeled paclitaxel detected in total blood samples collected from three groups of rats identified with reference to Figure 15 from 1-24 hours post-dose.

Figure 17 is a graph reflecting the levels of unchanged radiolabeled paclitaxel detected in total blood samples taken from 0-12 hours post-dose from the rats in group A defined with reference to Figure 15 and from the fourth group of rats (group D) administered with radiolabeled paclitaxel. IV with oral doses of cyclosporin one hour before and immediately after the paclitaxel dose, with the ordinate of said plot running from 0-30 ppm paclitaxel.

Figure 18 is a graph reflecting the levels of unchanged radiolabeled paclitaxel detected in total blood samples drawn from 1-12 hours post-dose from Group A rats as defined with reference to Figure 15 and from Group D as defined with respect to Figure 17, wherein the ordinate of said plot is from 0.000-5.000 ppm paclitaxel.

Figure 19-24 are schematic diagrams of the process of extracting and distributing radioactivity from a composite (homogenate) of various tissues of rats in groups A and C, respectively, as determined with reference to Figure 15.

Figure 25 is a graph reflecting the paclitaxel levels detected in the plasma samples collected at the specified intervals in a group of ten rats on the third and fourth days of a regimen in which they were administered twice daily an oral dose (5 mg / kg) of cyclosporin and, one hour later , a combination of the same dose of oral cyclosporin plus oral paclitaxel (3 mg / kg).

The present invention generally relates to increasing the oral absorption and bioavailability of orally administered pharmacologically active agents, especially agents that are poorly or not absorbed at all from the gastrointestinal tract or the intestine. The preferred embodiments of the invention relate to (a) a method of increasing the oral bioavailability of anti-cancer agents, in particular paclitaxel (currently commercialized as Taxol® by the BristolMyers Quibb Oncology Division) and its derivatives; other taxanes; the semisynthetic paclitaxel analog docetaxel (N-debenzoyl-N-tert-butoxycarbonyl-10-deacetyl paclitaxel), manufactured under the trade name Taxotere® by Rhone-Poulenc Rorer SA; and etoposide; (b) into dosage forms and kits for oral administration of anti-cancer agents and other drugs previously administered only parenterally; and (c) methods of treating cancer patients using such oral dosage forms or combinations thereof.

The expressions "oral bioavailability and" oral bioavailability as used herein refer to the systemic availability (ie, blood / plasma levels) of an administered amount of drug administered orally to a patient.

Paclitaxel is a natural diterpene product isolated from Pacific yew (Taxus brevifolia). It is a member of the taxane family of terpenes. It was first isolated in 1971 by Wani et al. (J.Am.Soc., 93: 2325, 1971), who characterized its structure by chemical methods and X-ray crystallography. One mechanism of its activity relates to the ability of paclitaxel to bind tubulin, and thus inhibit cancer cell growth. Schiff et al., Proc. Natl. Acad. Sci USA, 77: 1561-1565 (1980); Schiff et al., Nature, 277: 665-667 (1979); Kumar, J. Biol. Chem., 256: 10435-10441 (1981).

Paclitaxel has been approved for clinical use in the treatment of refractory ovarian cancer in the United States (Markman et al., Yale Journal of Biology and Medicine, 64: 583, 1991; McGuire et al., Ann. Intern. Med., 11: 273). , 1989). It is effective in chemotherapy for several types of cancer, including breast cancer (Holmes et al., J.Nat. Cancer Inst., 83: 1797, 1991) and has also been approved for the treatment of breast cancer. It is a potential candidate for the treatment of skin cancers (Einzig et al., Proc. Am.Soc. Clin. Oncol., 20:46) and head and neck cancers (Forastire et al., Sem. Oncol., 20:56, 1990). ). This compound is also potent in the treatment of polycystic kidney disease (Woo et al., Nature, 368: 750, 1994), lung cancer and malaria.

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Paclitaxel is only slightly soluble in water and this poses problems in the development of suitable injectable and infusion formulations useful in anti-cancer chemotherapy. Some IV infusion formulations of paclitaxel have been developed using Cremophor El^TM(polyethoxylated castor oil) as a drug carrier, due to the water-insolubility of paclitaxel. For example, paclitaxel used in clinical trials under the aegis of NCI was formulated in 50% Cremophor El^TM and 50% dehydrated alcohol. However, Cremophor El^TM if administered intravenously, it is itself toxic and causes vasodilation, gasping, lethargy, hypotension and death in dogs. It is also thought to be responsible for the allergic-type reactions seen with paclitaxel administration.

In an attempt to increase the solubility of paclitaxel and develop safer clinical formulations, research was directed to synthesizing paclitaxel analogues where the 2 'and / or 7 positions were derivatized with groups that enhance water solubility. These efforts resulted in pro-drug compounds that are more water-soluble than the original compound, and that exhibit cytotoxic properties upon activation. One important group of such prodrugs includes the 2'-onium salts of paclitaxel and docetaxel, in particular the salts of 2'-methylpyridinium mesylate (2'-MPM).

Paclitaxel is very poorly absorbed orally (less than 1%); see Eiseman et al., Second NCI Workshop on Taxol and Taxus (September 1992); Suffness et al., In Taxol Science and Appliccations (CRC Press 1995). Eiseman et al. Indicate that paclitaxel has a bioavailability of 0% when administered orally, and Suffness et al. Report that oral dosing with paclitaxel does not seem possible because no antitumor activity was found when orally administered up to 160 mg / kg / day. Moreover, an effective method of effectively administering paclitaxel orally (ie, a method of increasing the oral bioavailability of paclitaxel) or other oral taxanes or analogs of paclitaxel such as docetaxel, which have anti-tumor activity, has not been achieved. For this reason, paclitaxel has not yet been administered orally to humans, and certainly not in the treatment of paclitaxel responsive diseases.

Docetaxel becomes commercially available as Taxotere® parenterally for the treatment of breast cancer. To date, there is no mention in the scientific literature of the oral absorption of docetaxel in animals or patients.

Etoposide is a semi-synthetic derivative of podophyllotoxin and is used to treat certain neoplastic diseases, especially gamete cancers (e.g. nuclear carcinomas) and small cell lung cancers (Loehrer, Sem. Onc., 19 No. 6 supp.14, pp. 48-52, 1992). It is available as an oral dosage form (Vepesid® capsules, Bristol-Myers Squibb Oncology) but is not adequately well absorbed orally (mean value for oral bioavailability for etoposide capsules is close to 50%).

Ketoconazole is a widely used antifungal imidazole derivative that has also been used in some areas of prostate cancer treatment. Ketoconazole, as one of its forms of action, has been shown to reverse MDR in highly resistant human KB cancer cells (Siegsmund et al., J. Urology, 151: 485-491, 1994), but can also inhibit cytochrome P-450 enzymes. metabolizing drugs.

It has now been found that many pharmaceutical agents with a poor oral absorption profile can be effectively administered orally with systemic absorption sufficient to exhibit therapeutic activity levels when said agents are administered orally concurrently with an oral dose of certain cyclosporins or other agents known to inhibit multi-resistance. drugs, drug transport activity, intracellular P-glycoprotein pump, as well as certain enhancers, whose ability to inhibit P-glycoprotein transport has not yet been determined. A further surprising discovery of our invention is that under certain conditions, oral administration leads to a more favorable pharmacokinetic profile, better tissue penetration and a higher volume of distribution of the target therapeutic agent.

We have observed in animal studies that certain multi-drug resistance inhibitors, such as cyclosporine and ketoconazole, when administered orally immediately after and / or before a drug such as paclitaxel and etoposide, increase the absorption of the latter drugs in an unexpected and unexpected manner. an astonishing degree that results in the achieved therapeutic levels. However, it is not at all obvious that these observed results are due to suppression of the P-gp pump.

Another possible explanation for the observed increase in the bioavailability of paclitaxel and etoposide is that there may be an interaction at the level of drug metabolising enzymes for cyclosporin and paclitaxel. Both agents are known to be highly metabolized by the cytochrome system

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P-450 (e.g. P-450 3A), which is concentrated in the liver and also in the small intestine. It is not excluded that the cyclosporin that was administered first might inhibit these enzymes so that paclitaxel, which is non-polar and lipophilic, might be absorbed. In the absence of this local inhibition, paclitaxel would be metabolized to more polar metabolites which would not pass through the mucosal cells. The inability to show the pharmacokinetic interaction between cyclosporin and paclitaxel when cyclosporin was administered 3 hours before paclitaxel TV administration suggested that the site of interaction was the lumen. Even this theoretical explanation does not explain our surprising finding that certain P-gp inhibitors (e.g. cyclosporins and ketoconazole) greatly increase the oral bioavailability of specific target drugs, while other agents known as active P-glycoprotein inhibitors show little activity as oral absorption enhancers for the same target drugs.

This theoretical inhibition of intestinal metabolism of the target agents would be less or not at all effective in increasing systemic blood levels when the target agent is administered intravenously. Moreover, since the primary effect of oral absorption of the enhancer may be a local effect in the lumen of the gut, sub-therapeutic doses should be effective in achieving the desired effect.

Increasing the oral bioavailability of target therapeutic agents with poor oral bioavailability (average or mean bioavailability less than 50%), includes the oral administration of an agent that enhances oral absorption or bioavailability to mammalian patients (human or animal) concurrently, or before, or simultaneously, and before by oral administration to increase the amount and duration of absorption of the intact target into the bloodstream.

Agents that enhance oral bioavailability in the manufacture of a medicament for the treatment of taxane sensitive disease states include, but are not limited to, the following:

Antifungal agents - ketoconazole.

Cardiovascular drugs - MS-209 (from BASF), amiodarone, nifedipine, reserpine, quinidine, nicardipine, ethacrynic acid, propafenone, reserpine, amiloride.

Natural anti-migraine products - ergot alkaloids.

Antibiotics - cefoperazone, tetracycline, chloroquine, fosfomycin.

Antiparasitic agents - ivermectin.

Multidrug resistance reversal agents - VX-710 and VX-853 (Vertex Pharmaceutical Incorporated).

Tyrosine kinase inhibitors - genistein and the corresponding isoflavonoids, quercetin.

Protein kinase C inhibitors - calphostin.

Agents inducing apoptosis - ceramides.

Endorphin receptor active agents - morphine, morphine related compounds, other opioids and opioid antagonists including (but not limited to naloxone, naltrexone and nalmefene).

The class of orally administered target therapeutic agents whose oral absorption is enhanced by enhancing agents includes, but is not limited to, the following agents:

Paclitaxel, other taxanes, docetaxel and derivatives and prodrugs of all in use, especially their salts, 2'-MPM and other 2'-methylpyridinium salts.

Other chemotherapeutic agents that have low or highly variable oral bioavailability, including etoposide, camptothecin, CPT-11 (Pharmacia and Upjohn), topetecan (SmithKline Beecham), doxorubicin, vincristine, daunorubicin, mitoxantrone, and colchicine, all of which are considered to be affected by P-glycoprotein efflux

Other drugs that have not been shown to be translocated by P-glycoprotein, but that can be made absorbable in the presence of a P-glycoprotein inhibitor in the gut, include ganciclovir, foscarnet, camptothecin, and camptothecin derivatives.

The dosage amount of the enhancer co-administered with the target drug, in accordance with the invention, is about 0.1 to about 15 mg / kg of patient body weight. By "co-administration" of an enhancing agent is meant administration substantially co-administration with the target agent (or less than 0.5 hours before, less than 0.5 hours thereafter, or together) from about 0.5 to about 24 hours prior to administration of the target agent. or in both ways, i.e. with one or more doses of the same or different boosting agents, given at least 0.5 hours prior to, and one dose given substantially simultaneously with (or together with, either immediately before or after) of the target agent. Additionally, by "co-administration is meant the administration of more than one dose of the target agent within 24 hours after the dose of the enhancer agent, in other words,

The enhancer (s) need not be re-administered prior to or with each administration of the target, but may be administered intermittently during the treatment period.

The dosage amount of orally administered target agents will vary from drug to drug based on its therapeutic index, the requirements of the condition being treated, the status of the subject, and so on. The method according to the invention enables the oral administration of paclitaxel in an amount of about 20 mg / m2² up to about 1000 mg / m² (based on patient body surface area) or about 2-30 mg / kg (based on patient weight) in a single or divided daily dose (2-3), maintains plasma paclitaxel levels in humans in the range of 50-500 ng / ml for extended periods (e.g. 8-12 hours) after each oral dose. These levels are at least comparable to those achieved with 96-hour therapy with IV taxol infusion (which causes great inconvenience to the patient, discomfort, waste of time, possible infection, etc.). Moreover, such plasma levels of paclitaxel are more than sufficient to provide the desired pharmacological activities of the target drug, e.g. inhibition of tubulin degradation (which occurs at levels of about 0.1 mM or about 85 ng / ml) and inhibition of protein isoprenylation (which occurs at levels of about 0.03 mM or about 25 ng / ml), which is directly related to with its anti-tumor activity, by inhibiting the function of the oncogene and other signaling proteins which play a crucial role in the regulation of cell growth.

It may be appropriate in some cases to administer to a subject a higher aggravating starting dose of a target agent in order to achieve a peak blood level followed by lower maintenance doses.

Two or more different enhancers and / or two or more different target agents may be administered together, sequentially or intermittently, in all various aspects of the method of the invention.

The drugs obtained by the use of the invention can treat mammalian patients suffering from neoplastic tumors, tumors, Kaposi's sarcoma, malignant conditions, uncontrolled tissue or cellular proliferation secondary to damaged tissue, and any other disease state responsive to paclitaxel, taxanes, docetaxel, etoposide, prodrugs and derivatives of all the former, paclitaxel 2'-MPM and docetaxel 2'-MPM, with orally administered dosage forms, containing one or more of these agents. The types of cancer that can be treated particularly effectively with oral paclitaxel, docetaxel, other taxanes, and their prodrugs and derivatives are hepatocellular carcinomas and hepatic metastases, and cancers of the gastrointestinal tract, pancreas and lungs. Examples of non-cancerous disease states that can be effectively treated with these orally administered active agents in accordance with the present invention are uncontrolled tissue and cell proliferation secondary to damaged tissue, polycystic kidney disease and malaria, including chloroquine and pyrimethamine resistant malaria parasites (Pouvelle et al., J.Clin. Invest., 44: 413-417,1994).

Antitumor agents, which have so far been administered only parenterally, can now be administered according to the invention by the oral route with sufficient bioavailability to ensure pharmacologically active blood concentrations, particularly effective in the treatment of patients with primary tumors and metastases. The active ingredients will penetrate the intestinal wall as a result of prior and / or simultaneous administration of MDR inhibitors or other enhancers, and will be rapidly taken up by the portal circulation, providing a higher local initial concentration of chemotherapeutic agents in the liver (much higher local concentration than currently achieved with infusion therapy) IV) than the general circulatory system or most other organs for seven days. Furthermore, it should be noted that the higher hepatic levels of paclitaxel after oral administration may not reflect the increased plasma levels due to the high first hepatic pass-through effect. The method of the invention, in selectively producing high blood concentrations of anti-tumor agents, is particularly valuable in the treatment of liver cancers (e.g., liver cell cancer and liver metastases), gastrointestinal (e.g., colon, rectal) and lung cancers.

Similarly, after oral administration in accordance with the present invention, higher levels of paclitaxel are found after twenty four hours (using tissue separation analysis) in the gastrointestinal tract, pancreas and lungs, compared to systemic circulation and most other organs. This fact makes orally administered paclitaxel of great value in the treatment of gastrointestinal, pancreatic and lung cancers.

In addition to a higher hepatic concentration of the active ingredients than previously achieved, the plasma and tissue distribution of the active target agent when administered orally

The formulation with suitable enhancing agents as envisaged in the present invention is visibly and surprisingly similar to that seen with intravenous administration. A series of experimental animal studies showed that a stabilized state of plasma levels of paclitaxel was achieved with oral co-administration with CsA by the third day of the regimen. Target agent levels obtained at steady state were comparable to those obtained in patients with 96-hour IV infusion of paclitaxel. A 27% response rate was found in non-taxane metastatic breast cancer patients treated with a continuous 96-hour infusion every three weeks (Seidman et al., J.Clin.Oncol., 14: 1877, 1996). It is believed that similar results can be obtained with the treatment methods of the present invention without the discomfort, inconvenience, and risk of prolonged intravenous infusion.

Besides, and quite significantly, the blood concentration during the clearance phase of paclitaxel and other anti-tumor agents mentioned above when administered orally as provided herein is approximately equal to that obtained with intravenous administration, and these higher, therapeutically effective levels can be maintained. -12 hours after each administration. The increase in urinary drug excretion after oral administration in the presence of CsA not only supports the enhanced oral absorption of paclitaxel, but also provides more drug delivery to the urogenital tract in the treatment of cancers.

Oral dosage forms of the target agents whose bioavailability is enhanced by co-administration of the enhancing agents may be in the form of conventional tablets, capsules, caplets, gelatin capsules, pills, liquids (e.g., solutions, suspensions, or elixirs), lozenges, and either. other oral dosage form known in the pharmaceutical art. Liquid preparations may include, e.g. paclitaxel or other taxane on a vehicle containing Cremophor EI or other polyoxyethylene castor oil, alcohol, and / or polyoxyethylated sorbitan monoelate (e.g., Tween® 80, ICI Americas, Inc.). Each dosage form comprises an effective amount of a target agent (e.g., effective amounts of anti-tumor or anti-tumor, anti-tumor or anti-tumor agent) and inert pharmaceutically inert ingredients, e.g. conventional excipients, vehicles, fillers, binders, disintegrating agents, solvents, dissolving agents, sweetening agents, coloring agents and all other inactive ingredients that are regularly incorporated into a pharmaceutical dosage form for oral administration. Many such dosage forms and oral vehicles are listed in Remington's Pharmaceutical Sciences, 17th edition (1985), right after the list of inactive ingredients. Each dosage form also contains a pharmacologically effective amount, e.g., an antitumor or tumor reducing effective amount of one of the target drugs.

The exact amounts of each of the target drugs in oral dosage forms will vary with the age, weight, disease, and condition of the patient. For example, paclitaxel dosage forms may contain sufficient amounts of paclitaxel to provide a daily dose of about₂

20-1000 mg / m² (based on patient body surface area) or 2-30 mg / kg (based on patient body weight) as single or divided (2-3) daily doses. Oral etoposide dosage forms may contain sufficient amounts of etoposide to provide a daily dose of about 20-200 mg / m2²(based on the average or mean body surface area of ​​the patient), as single or divided (2-3) daily doses.

As already indicated, some target agents are commercially available in oral dosage forms despite their relatively poor or inappropriate oral bioavailability. For example, Vepesid® capsules are available containing 50 mg of etoposide each.

Dosage schedules for the treatment of diseases such as, e.g., paclitaxel responsive diseases, oral paclitaxel dosage forms co-administered with enhancing agents, can also be adjusted with respect to the patient characteristics and the disease state. The recommended dosing schedules for oral administration of paclitaxel are (a) daily dosing, to a patient in need of it, of 1-3 equally divided doses, providing about 20-1000 mg / m2² (based on body surface area), with said daily dosing being continued for 1-4 consecutive days, every 2-3 weeks, or (b) administration for about one day each week. The usual schedule equates to a 96-hour infusion of paclitaxel every 2-3 weeks, which some consider the recommended IV treatment regimen. The recommended dosing schedule for the oral administration of etoposide when co-administered with a boosting agent is the daily administration of 1-3 equally divided doses to a patient in need thereof, providing about 50-100 mg / m2.²(based on body surface area) for the treatment of testicular cancer patients and approximately 35-50 mg / m2² as

The daily dose in the treatment of small cell lung cancer, with the daily administration being continued for 5-21 days in each case and with a period of 2-3 weeks between each treatment cycle.

Oral administration of the potent chemotherapeutic agents described in the invention can now reduce toxic side effects in many cases, compared to current intravenous therapy. Absorption of the active agent through the intestinal wall (stimulated by enhancers), rather than the generation of sudden and rapid high levels in blood levels, as is usually the case with an intravenous infusion, ensures that blood levels appear more gradually and keep these levels constantly stabilized. levels at or near ideal size over a long period of time.

According to another aspect of the invention, a combination of an oral dosage form is envisaged containing fixed amounts of at least one enhancer and at least one target agent. For example such dosage forms may include tablets, capsules, caplets, gelatin capsules, pills, liquids, lozenges, and any other conventional oral dosage form containing as active ingredients an effective amount to enhance the oral bioavailability of an anti-tumor or anti-cancer agent as well as suitable inactive ingredients. .

Co-administration of enhancers with target drugs promotes not only the oral bioavailability of these agents, but also allows their use in the treatment of neoplastic tumors at sites highly protected by MDR, e.g. in the testes and brain. Another aspect of the present invention is therefore a method of delivering MDR-protected anti-tumor drugs to tumor sites by oral administration concurrently with enhancers and anti-tumor agents, which allows the treatment of brain tumors such as glioblastoma.

Yet another aspect of the present invention is a method of delivering an active metabolite of paclitaxel to diseased sites at therapeutic levels for the treatment of paclitaxel responsive diseases. In vivo major metabolites of paclitaxel have been identified, in particular the following metabolites of hydroxylated paclitaxel A, B and C:

<img file="PL192544B1_D0002.tif" />

A: R1 = H, R2 = OH; B: R1 = OH, R2 = H; C: R1 = OH, R2 = OH (Paclitaxel: R1 = H, R2 = H) It has been observed in some in vivo tests that the metabolite B shown above (also reported in the literature as metabolite M4) has a higher therapeutic index (ratio of toxic concentration level to an effective concentration level) than paclitaxel in some human tumor cell lines. The invention likely allows the delivery of enhancers of metabolite B and other active metabolites of paclitaxel to the tumor sites, since when orally administered all paclitaxel administered will pass through the liver and be metabolized by liver microsomes, delivering more of each metabolite to the circulation than is achieved with IV administration.

An additional aspect of the invention relates to kits for use in the treatment of mammalian patients suffering from conditions responsive to each active target agent for which

Oral absorption and bioavailability are enhanced by the enhancing agent. These kits include one or more oral dosage forms of at least one enhancer and one or more oral dosage forms of at least one target agent, or one or more dosage forms which are both.

By way of illustration, the kit of the invention may comprise one or more tablets, capsules, caplets, gelatin capsules or liquid formulations containing cyclosporin or ketoconazole, and one or more tablets, capsules, caplets, gelatin capsules or liquid formulations, containing paclitaxel or etoposide, in the dosage amounts within the ranges described above. Such kits may be used in hospitals, clinics, physicians' offices, or at home to facilitate the simultaneous administration of enhancement and target agents. The kits should also include attached printed information regarding the simultaneous administration of the enhancement and target agents.

The subject kits can also include combinations of different enhancers and / or combinations of target agents. For example, the kit can contain oral dosage forms containing cyclosporin and ketoconazole as enhancers, respectively, with paclitaxel alone as the target or with a combination of paclitaxel and another anti-tumor drug. The second target should be a drug (such as paclitaxel) that exhibits poor oral bioavailability, but which, with co-administered enhancers, can achieve therapeutically effective blood levels when administered orally. The target agent can coexist with the enhancer in the same dosage form or it can be in a separate dosage form.

The following examples illustrate various aspects of the invention and demonstrate the unexpected, very significant increases in oral absorption of the target agents obtained.

Example 1

Three groups of rats were administered as enhancers, respectively, 10 mg / kg verapamil orally, 5 mg / kg progesterone orally and 10 mg / kg dipyridamole, orally, both singly and with an oral dose of paclitaxel, one hour thereafter. A graphical comparison of the concentration profile in total blood over time (measured as concentration equivalents over time) determined for the three groups is shown in Figure 1. The data reflect roughly similar results using verapamil and dipyridamole as enhancers, with much lower bioavailability obtained with progesterone.

Figure 2 shows a graphical comparison between the concentration time profile of paclitaxel determined for the group of rats treated with verapamil (10 mg / kg) as a booster, with the values ​​determined in the previous study for animals treated with oral paclitaxel alone (9 mg / kg) and another group to whom oral ciclosporin (5 mg / kg) was administered both one hour before and immediately after an oral dose of paclitaxel (9 mg / kg). The cyclosporine group achieved significantly higher blood levels than the other groups during almost the entire 24-hour period.

Figures 3 and 4 show graphical comparisons analogous to Figure 9 but with the values ​​for the progesterone administered group shown in Figure 3 and the dipyridamole group shown in Figure 4 in place of the verapamil group shown in Figure 4. 2.

Example 2

Three groups of rats were administered as enhancers, respectively, 100 mg / kg verapamil orally, 5 mg / kg megestrol acetate orally and 50 mg / kg ketoconazole orally, both singly and with an oral dose of radiolabeled paclitaxel, one hour thereafter. Figure 5 shows a graphical comparison of the concentration profile in total blood over time (measured as concentration equivalents over time) determined for the three groups. The data reflect roughly similar results for verapamil and megestrol acetate as enhancers, with much higher bioavailability obtained with ketoconazole in the first 12 hours.

Figure 6 shows a graphical comparison between the concentration time profile of radioactivity determined for a group of rats that were administered verapamil (100 mg / kg) as a booster with the values ​​determined in a previous study for animals that were administered oral paclitaxel alone (9 mg / kg). and for another group of animals administered oral cyclosporin (5 mg / kg) both one hour before and immediately after the dose of oral radiolabeled paclitaxel (9 mg / kg).

PL 192 544 B1

Figures 7 and 8 show graphical comparisons analogous to Figure 6 but with the values ​​for the megestrol acetate administered group shown in Figure 7 and the ketoconazole group shown in Figure 8 in place of the verapamil group in Figure 6.

Figure 9 shows graphical comparisons between the concentration-time profiles of radioactivity determined for the group of rats dosed with 10 mg / kg verapamil in Example 1 and the group dosed with 100 mg / kg verapamil in Example 2.

Figure 10 shows a graphical comparison between the radioactivity concentration over time profiles determined for the group of rats treated with 5 mg / kg progesterone in Example 1 and the group treated with 5 mg / kg megestrol acetate in Example 2.

Both Figures 9 and 10 also show the same profiles reflected in Figures 6-8 for the study groups receiving radio-labeled oral paclitaxel alone and radio-labeled oral paclitaxel immediately after, and one hour at 5 mg / kg cyclosporin.

A dose-response data study was performed for ciclosporin. Increasing the dose to 10 mg / kg and 20 mg / kg one hour before and simultaneously with paclitaxel resulted in an oral absorption of radioactivity of about 45%. This can be contrasted with the findings for ketoconazole where doses up to 50 mg / kg were administered one hour prior to and concurrently with paclitaxel, and did not result in a further increase in oral radioactivity absorption (see Figures 10A and 10B).

The mean pharmacokinetic parameters for the study groups of animals discussed in Examples 1 and 2 are shown in Table 1^{* 2}.

The data generated from the studies of Examples 1 and 2 and reflected in Table 1 and Figures 1-10B clearly demonstrate the efficacy of cyclosporin as an oral bioavailability enhancer and its superiority over high or low dose verapamil, progesterone or megestrol acetate, especially in the first 12 hours after treatment. paclitaxel dose. They also indicate that ketoconazole, although not as effective as cyclosporine, also has significant activity in promoting the oral absorption of paclitaxel.

T ab elal

Mean pharmacokinetic parameters for NP951202 and NP960101

<td>Protocol research</td><td>Treatment</td><td>Dose / route (mg / kg)</td><td>AUC0-24 (M.Sc.- nxh / ml)</td><td>F%</td><td>t1 / 2 (hours)</td><td>Cmax (mg * eq / ml)</td>

<td> 1</td><td> 2</td><td> 3</td><td> 4</td><td> 5</td><td> 6</td><td> 7</td>

<td>NP951001</td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td>Only paclitaxel</td><td>9 / IV</td><td> 32,04</td><td></td><td> 20,15</td><td> 37,00</td>

<td></td><td>Only paclitaxel</td><td>9 / PO</td><td> 3,24</td><td> 10,1</td><td> 18,86</td><td> 0,21</td>

<td></td><td>Cyclosporine</td><td>5 / PO (c), 9 / PO (P) 5 / PO (C)</td><td> 12,02</td><td> 37,5</td><td> 14,51</td><td> 0,82</td>

<td>NP951202</td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td>Verapamil</td><td>10 / PO (W) 9 / PO (P) 10 / PO (W)</td><td> 6,34</td><td> 19,8</td><td> 24,40</td><td> 0,78</td>

₂²The study of example 1 is referred to in table 1 as protocol NP951202 and the study of example 5 is designated as protocol NP960101.

PL 192 544 B1

cd of table I

<td> 1</td><td> 2</td><td> 3</td><td> 4</td><td> 5</td><td> 6</td><td> 7</td>

<td></td><td>Progesterone</td><td>5 / PO (pro), 9 / PO (P) 5 / PO (pro)</td><td> 3,78</td><td> 11,8</td><td> 20,00</td><td> 0,26</td>

<td></td><td>Dipyridamole</td><td>10 / PO (D), 9 / PO (P) 10 / PO (D)</td><td> 6,18</td><td> 19,3</td><td> 26,60</td><td> 0,46</td>

<td>NP960101</td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td>* Verapamil (animals died)</td><td>100 / PO (W), 9 / PO (P) 100 / PO (W)</td><td>ON</td><td>ON</td><td>ON</td><td> 0,44</td>

<td></td><td>Megace</td><td>5 / PO (M), 9 / PO (P) 5 / PO (M)</td><td> 5,19</td><td> 16,2</td><td> 23,10</td><td> 0,44</td>

<td></td><td>Ketoconazole</td><td>50 / PO (K), 9 / PO (P) 50 / PO (K)</td><td> 8,03</td><td> 25,1</td><td> 9,23</td><td> 0,69</td>

Example 3

In another series of studies, three groups of three male rats each were fasted 16-18 hours prior to dosing. At the end of the fasting period, an oral dose of ketoconazole (2 mg / kg) was administered to one group of rats. One hour later, this group was orally administered 2 mg / kg ketoconazole with 1 mg / kg radiolabeled etoposide³H orally. The other two groups were treated in the same way except they were administered 10 and 50 mg / kg of ketoconazole, respectively, after the fasting period, before and immediately after oral administration.³H-etoposide. The procedures for collecting blood and determining total radioactivity were the same as in Examples 4 and 5. The data obtained is shown in Table 7A. Thus, in contrast to the effect of cyclosporine, which had a nearly doubled oral absorption of paclitaxel-derived radioactivity, ketoconazole administered over a wide dose range did not enhance the oral absorption of etoposide compared to etoposide alone.

<img file="PL192544B1_D0003.tif" />

PL 192 544 B1

Example 4

The procedure of Examples 1 and 2 was followed, but three groups of three male rats each were dosed with 5 mg / kg cyclosporin A, 50 mg / kg ketoconazole and 5 mg / kg cyclosporin A plus 50 mg / kg ketoconazole, both alone and alone. and one hour later, immediately after an oral dose of 9 mg / kg of radiolabeled paclitaxel. A graphical comparison of the obtained results is shown in Fig. 11. The group receiving the combination of ketoconazole and cyclosporin A unexpectedly showed significantly higher levels of radioactivity in the blood over almost the entire 24 hour period than the groups receiving only one of these enhancers.

Example 5

The procedure of Examples 4 and 5 was followed, but three groups of three male rats each were dosed with 100 mg / kg captopril, both alone and two hours later, immediately following an oral dose of 9 mg / kg radiolabeled paclitaxel at 5 mg. / kg ciclosporin alone and again one hour later, immediately after an oral dose of 9 mg / kg of radiolabeled paclitaxel, and an oral dose of 9 mg / kg of radiolabeled paclitaxel alone. A graphical comparison of the obtained results is shown in Fig. 12.

The studies described so far have provided several previously unknown and unexpected discoveries, all of which are of great importance in the clinical management of many diseases, especially different types of cancers:

1. Certain MDR (P-glycoprotein) inhibitors, as well as other agents not known as MDR inhibitors, can be administered orally to effectively enhance the oral bioavailability of drugs that have so far been administered only parenterally because therapeutic blood levels cannot be achieved when administered oral.

2. Co-administration of the enhancers of the invention with target drugs having poor oral bioavailability may result in sustained blood levels of the target drugs comparable to those obtained with IV infusions, but with less sudden initial increase in blood levels and therefore less likely toxic side effects.

3. Oral co-administration of enhancers and target drugs increases the proportional concentrations of the target agent in the liver, lung and gastrointestinal tract as compared to IV administration, making the new method of administration particularly useful in the treatment of liver tumors and metastases.

4. Administration of the enhancer orally prior to the administration of simultaneous oral doses of the enhancer and the target drug increases the oral bioavailability of the target drug to a significantly greater degree than the simultaneous administration of the enhancer and target without administration of the enhancer first. This results in plasma levels of the target drug reaching therapeutic levels.

5. Cyclosporins, especially cyclosporins A, D and F, are agents much more effective at enhancing the bioavailability of agents against neoplastic tumors than MDR inhibitors such as verapamil and progesterone. Ketoconazole has clinically significant bioavailability-enhancing activity, but less than that of cyclosporin.

In general, the various aspects of the invention enable and are practical for the first time administration of an oral dosage form of widely used pharmaceuticals, particularly anti-cancer drugs such as paclitaxel related taxanes and etoposide, which until now could only be efficiently or reliably administered by IV infusion. The use of such oral dosage forms in the clinical management of cancer will increase patient comfort, convenience, consideration of wishes and safety, and result in savings for patients, hospitals and government and private medical insurers.

In addition, the knowledge of the invention presented herein will provide information regarding target and enhancer selection as well as timing, scheduling, and dosing. This information and the methods and compositions of the invention will provide clinicians with procedures for determining therapeutic drug levels that require a narrow drug concentration window while avoiding unnecessary and often deleterious peaks and drops in blood concentration levels. In addition, the increased volume of separation of paclitaxel in the presence of cyclosporin suggests that more drug will be available for eliciting anti-tumor activity.

In addition to multi-drug resistance caused by the P-glycoprotein encoded by the MDR1 gene, there is another gene that has recently been discovered to confer a multi-drug resistance phenotype in some

In laboratory systems: the multi-drug resistance protein gene, MRP (e.g., Zaman et al., Proc. Natl. Acad. Sci. USA, 91: 8822-8826, 1994).

Less is known about this new gene and its 190 kd membrane-bound glycoprotein protein product. Although both the MRP and MDR1 genes encode membrane glycoproteins that can act as transporters for many drugs, there are differences in function, possibly substrates, and prognostic importance between the two genes. For example, expression of the MRP gene, but not of MDR1, is a good marker with a poor clinical outcome in patients with neuroblastoma. The purported function of MRP-related proteins is to serve as the efflux pump for glutathione S junctions. Thus, molecules that bind glutathione would be susceptible to the effects of the MRP-related system.

The oral bioavailability of pharmacologically active agents (or tumor exposure to such agents), which are resistant to MRP-associated proteins, may be enhanced by co-administered orally MRP inhibitors. A preferred embodiment for this method of increasing bioavailability is orally administering one or more MRP inhibitors prior to the simultaneous oral administration of the one or more MRP inhibitors and one or more target agents subject to MRP associated resistance.

Examples of this type of target include, but are not limited to, vinca alkaloids (e.g., vincristine), anthracyclines, epipodophyllotoxins (e.g., etoposide), and various taxanes. Examples of inhibitors that can increase the oral bioavailability of target agents include, but are not limited to, cyclosporins, ketoconazole, and the experimental drugs VX-710 and VX-853 (Vertex Pharmaceuticals, Inc., Cambridge, MA). The structures of VX-710 and VX853, as well as many related compounds, are disclosed in US Patent No. 5,192,773.

Another way to improve the oral bioavailability of agents subject to MRP-associated resistance is the co-administration of glutathione or substances that form glutathione conjugate products that may interfere with the functioning of the MRP system and enhance intestinal absorption of the target or increase the systemic exposure of agents that are transported by MRP.

Yet another system capable of conferring multi-drug resistance is the so-called pulmonary resistance associated protein (LRP), as it was first identified in a multi-drug resistant lung cancer cell line. This protein is the main structural protein of the so-called vault apparatus, a particle with a great abundance of cytoplasmic ribonucleins that got into humans from slimy molds. Inhibition of this system may also positively affect the oral bioavailability of certain agents. LRP is highly expressed in secretory and excretory epithelial cells as well as in cells chronically exposed to foreign substances such as cells lining the bronchi and intestines (Scheffer et al., Nature Medicine, 1: 578-582, 1955). Therefore, this system could also serve as a target for enhancing bioavailability.