Stabilization of interferons in aqueous solution for manufacture of sublingually administered tablets.

STABILISATION OF INTERFERONS IN AQUEOUS SOLUTION FOR MANUFACTURE OF SUBLINGUALLY ADMINISTERED TABLETS

The invention concerns the stabilisation of interferons in aqueous solution for application in the manufacturing of sublingually administered tablets in low dosage for the preventing and treating of interferon sensitive viral infections in humans and for functioning as an immunomodulator.

interferons belong to a group of glycoprotein and proteins and are derived from leukocytes, lymphoblastoid and fibroblast cells during the activation of immune responses in humans and other vertebrate animals or by recombinant DNA methods. Interferon is classified into alfa, beta and gamma designations which correspond to leukocyte, fibroblast and type II interferons, respectively.

For the sake of clarity, the various kinds of interferon would simply be referred to as interferon in the following description.

PCT Patent Application WO 88/03441 is dealing with interferon therapy 15 and may be considered as a good reference text to which one could report to become familiar with interferon and its use. In this PCT Application, interferon may be used in contact with oral or pharyngeal mucosa, for instance in a lozenge as a solid unitary dosage adapted to be dissolved in saliva when placed in the mouth.

However, interferon which is commonly available in lyophilised form for 20 application are highly hydrophobic and have to be stabilised in order to be kept, and used in low dosages. This is a key feature that seems to have been overlooked in the PCT Application cited above.

An object of the present invention is therefore to provide stabilised interferon for allopathic use and a method to stabilise interferon in order for this substance to be used in low dosages.

Another object of the invention is to use a viscous molecule having the general formula (C5H₁₀O₅)n as a stabilising agent for stabilising interferon in tablets. The method comprises adding a compound of the general formula (C5Hio0₅)_n., to an aqueous solution of lyophilised interferons.

Among the compounds having the general formula (C₅Hio0₅)_n, arabic gum is a preferred compound.

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Another object of the invention is a pre-stabilised interferon and a method to pre-stabilise interferon by using albumin. This method comprises adding albumin as a previous pre-stabilising agent to an aqueous solution of lyophilised interferons.

Another object of the invention is to use such stabilised interferons in low dosages in a tablet or a pastille or granules which will be made in contact with saliva in a patient's mouth in order to enter the oral submucous lymphatic plexi.

The present invention thus relates to a method of stabilising interferons in aqueous solution with a compound of the general formula (C5H₁₀O₅)_n such as arabic gum for the manufacture of sublingually administrated tablets in low concentrations.

In this case (C5H10O5),,, for instance arabic gum, will be used together with albumine as a pre-stabilisation agent and, in a preferred embodiment, various phosphates.

Such stabilised interferon may be kept in solution under room temperature without the use of refrigeration up to 6 months to treat interferon sensitive viral infections and cancers.

Said compound has to be used when preparing the tablets from the base material, and can be used as well earlier when preparing the base material to be transformed subsequently into tablets. In other words, this compound may be utilised twice successively during the manufacturing of the drug in its final form.

This method of stabilisation can be applied to any kind of interferon like alfa, beta or gamma interferons derived from bovine and humans, or by recombinant DNA methods. Among interferons, human alfa-interferon is preferred.

The invention relates also to a method for the preparation of an drug comprising an low amount of interferons , for instance from 1 I.U. to 2000 I.U. per 100 mg tablet, in which said tablet contains an excipient comprising a compound of general formula (θ5Η₁₀Ο₅)_η, such as arabic gum.

This tablet may also contain lactose and starch and is used to stimulate the therapeutic response in human patients by making contact with saliva in the patient's mouth.

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Interferon is a macromolecule which cannot pass through mucosae in general and mouth mucosa in particular. It will act by stimulating the immune system, by oral contact. Therefore, interferon contained in the tablets are likely not to enter the blood or lymphatic system of the patient. The tablets should preferably not be swallow as the interferon is likely to be destroyed in the stomach or the intestines and to become of no use.

This tablet can be administrated sublingually for the prevention and treatment of various diseases such as hepatitis B+C, viral tumours and cancers, aids (HIV) and other viral infections sensitive to interferon treatment For example a tablet of 100 mg comprising between 100 to 300 l.U. of stabilised human alfainterferon will be administrated one to four times a day.

The optimum results are obtained when the interferon used has been put into contact with albumin and already compound of general formula (C₅Hio0₅)n, especially arabic gum.

For the foregoing, it is clear that the compound of the general formula (C5H₁₀O₅)n provides an adhesive surface for the interferon molecules.

The preparation of tablets containing interferons in allopathic low dose may be divided in two steps. In a first step, a base material is prepared by dissolving lyophilised interferon in bidistiiled water in the presence of lactose and by adding successively lyophilised albumin, sodium monohydrophosphate, sodium dihydrosuifate and (CsHwOsL, for instance arabic gum..

In a second step, the solution of base material obtained is then sprayed on granules of excipient containing (C₅Hio0₅)_n, for instance arabic gum, lactose and starch, and the mixture is vacuum dried and finally compressed into tablets.

A typical method of preparing tablets is given on the enclosed Table, which is an example with corresponding typical weights, volumes and proportions to be used.

This example is given for illustrative purpose only. The clinical trial results of the invention are based on the application of human alfa-interferon in low concentration of 200 l.U. per 100 mg tablet, as expressed before dilution steps.

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Example 1

The invention is carried out in two stages which are as follows :

I - Stabilisation of Interferon :

Base stock of 30 million I.U. of lyophilised high purity human alfa5 interferon is thoroughly mixed with 20 ml of double distilled water, 20 g of lactose, 600 pg of lyophilised HP albumin, 150 pg of sodium monohydrophosphate, 150 pg of sodium dihydrophosphate and 20 g of arabic gum to form the base material. The base material must be free of alcohol, and all ingredients are either of high purity or pharmaceutical grade.

II - Preparation of the Excipient and Application

The excipient is prepared by mixing thoroughly 3000 g of arabic gum (20%); 4500 g of lactose (30%); and 7500g of wheat or rice starch, all pharmaceutical grade which become granular in texture.

The final stock solution (base material) is then sprayed on the granules 15 of the excipient with a regular spray nozzle with sterilised, filtered air under one atmosphere pressure during less than 60 minutes while the entire mixture is being stirred by standard mixing procedures. Losses of stock solution vary between 5% and 50% depending on the equipment used. Tablets of 100 mg each containing 200 I.U. of stabilised human alfa-interferon are made by standard methods and vacuum dried at temperatures between 8^SC and 20^aC before packaging into blister packs.

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The entire process must be carried out in strict conformity to the pharmaceutical norms.

The tablets are to be used by patients sublingually to promote and enhance the immune response of the body for the treatment of viral infections sensitive to interferon.

Example 2 g of lactose, 600 μg of lyophilised high purity (HP) albumin, 150 μg of sodium monohydrophosphate, 150 pg of sodium dihydrophosphate are added to 30 million I.U. lyophilised high purity human alfa-interferon of natural origin dissolved in

20 ml of distilled water.

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This material in then dissolved in three times under stirring in an aqueous solution containing propylene glycol to make an overall 25 % albumin solution, with careful rinsing with distilled water between each disolution and recovery of the rinsing products. Stirring is continued at 60 RPM for 30 minutes to give the final solution.

The excipient is prepared by mixing thoroughly 3000 g of arabic gum (20%); 4500 g of lactose (30%); and 7500g of mais starch, ail pharmaceutical grade which become granular in texture.

The final stock solution is then sprayed on the granules of the excipient 10 with a regular spray nozzle with sterilised, filtered air under one atmosphere pressure during less than 60 minutes while the entire mixture is being stirred by standard mixing procedures. Losses of stock solution vary between 5% and 50% depending on the equipment used.

Tablets of 100 mg each containing 200 I.U. of stabilised human alfa15 interferon are made by standard methods and vacuum dried at temperatures between 8^SC and 20^BC before packaging into blister packs.

The entire process must be carried out in strict conformity to the pharmaceutical norms.

The tablets are to be used by patients sublingually to promote and 20 enhance the immune response of the body for the treatment of viral infections sensitive to interferon.

A treatment using the tablets of example 2 was given sublingally for 10 weeks at a daily dose of 200 I.U. to patients seropositive to HIV-1, 8 % of them being asymptomatic.

All clinical symptoms commonly linked to HIV-1 infection scaled down radically after the 10 weeks of therapy, down to 0 for some patients. Karnofsky performance scores of the patients increased from an average of 60 at start of study to 100 at the end of treatment.

% of the patients had seroconversion as measured by clinical trials.

CD4+ and CD8+ lymphocytes counts showed significant increase after 10 weeks of therapy.

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These results suggest that the low dose oral alfa-interferon is of benefit to seropositive patients.

By contrast, and as published in AIDS (1992), 6, 563-569, a traditional low-dose oral interferon with no arabic gum in its formulation and with no pre5 stabilisation step during its preparation showed no significant change in a group of patients, in no aspect; and ail patients remained HIV-1-antibody-positive.

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Table

STARTING MATERIAL x 10⁶1.U. lyophilised HP human alfa-lnterferon 4· to 25 ml bidistilled water + to 25 g pharmaceutical grade lactose

400 to 800 pg lyophilised HP albumin +

100 to 200 pg Na₂HPO₄+

100 to 200 pg NAH2PO4 + to 25 g (C₅H₁₀O₅)n 4

BASE MATERIAL I

Spray onto granules of 10 to 20 kg of excipient to compress 150 000 tablets of 10 mg each Excipient: arabic gum, lactose, and starch for instance 20% arabic gum, 30% lactose, and 50% starch

Vacuum dry at temperatures between +8^aC and +25^eC 4

Compress tablets under pressure TABLETS

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