Nasal formulations comprising phospholipids and their preparation

Nasal formulations comprising phospholipids and their preparation

NOVO NORDISK A/S

C: 73559

WA/VMN, 1987-12-02, 3u, IL

3125.200

The present invention relates to novel pharmaceutical preparations adapted for intranasal administration and to a process for preparing such preparations.

BACKGROUND OF THE INVENTION

While non-invasive medication, such as oral or rectal administration of a drug is undoubtedly most convenient to the patient, parenteral drug delivery is usually regarded as being the most effective. In particular, drugs which are inactivated in or poorly absorbed by the gastrointestinal tract and drugs which are subject to extensive first pass hepatic metabolism following oral administration are usually administered parenterally.

There are obvious inconveniences associated with parenteral drug administration, such as the need for sterile delivery devices, pain and irritation caused by reiterated injections and the potential risk of infection. Therefore, alternative means of drug delivery, equalling parenteral administration in the sense that first pass metabolism is circumvented, have been sought. One such potentially promising alternative is drug administration via the nasal route. However, just as is the case with other methods for noninvasive medication, the bioavailability of a drug after intranasal administration is largely unpredictable, depending inter alia on the chemical nature of the drug.

Thus it is known that progesterone and propranolol are absorbed from the nasal cavity in a manner providing blood levels almost equal to intraveneous administration.

Other examples of intranasal formulations of pharmaceutically active agents with molecular weights up to about 1 kD are known, for example compositions containing ergopeptide alkaloids dissolved in aqueous ethanol administered as aerosols (Swiss Patent No. 636,011), salts of pharmaceutically active amines with fatty acids (Canadian

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3125.200

Patent No. 988,852) and catecholamine suspended in a fatty acid (or ester) emulsified with polyoxyethylene (European Patent Publication No. 0 160 501 A).

Over the last decades a variety of (mainly synthetic) polypetide drugs have been developed. In general, polypeptides have been administered parenterally due to incomplete absorption from and digestive instability in the alimentary canal. This is probably the reason why in particular studies of the nasal delivery of polypeptides have been intensified during recent years. It has been found that while some smaller polypeptides (up to about 10 amino acid residues) may be reasonably well absorbed intranasally from simple aqueous formulations, generally the nasal bioavailability of larger polypeptides becomes both incomplete and variable, and increasingly so with increasing molecular weight (for review, see L. Ilium: Archiv for Pharmaci og Chemi 94 (1987), 127-135).

With a view to overcoming the disadvantages encountered particularly with nasal delivery compositions containing larger polypeptides, the additional incorporation of a variety of biocompatible absorption promoting agents or socalled enhancers has been devised.

In this respect reference is made to European Patent Publication No. 0 111 841 A, disclosing the absorption enhancing effect of a bile acid and to U.S. Patent No. 4,476,116, using chelating agents such as EDTA.

Nasal formulations adapted to insulin delivery would naturally be highly preferred by the insulin dependent diabetic patient to the presently available preparations for parenteral administration provided that the insulin is absorbed to a reasonably effective and constant extent from the nasal cavity. A variety of absorption enhancing agents, mainly surfactants, have been devised for such formulations.

Ionic as well as non-ionic surfactant enhancers, such as bile acid salts and polyoxyethylene higher alcohol ethers are disclosed in British Patent No. 1,527,605 while the use of a specific polyoxyethylene higher alcohol ether, namely polyoxyethylene-9 lauryl ether is described in: R. Salzman et al. , New England J. of Med. 312 (1985), 1078-1084. Other enhancers, for example salts of taurodihydrofusidic acid, are disclosed in U.S. Patent No. 4,548,922.

The chemical structure of enhancers known heretofore deviate considerably from those of known constituents of cellul ar.-a^mbranes, including those of the nasal cavity. This feature could possibly explain their general proneness to cause nasal, irritation or even permanent damage to the nasal membrane, particularly during chronic administration. On this background enhancers more akin to other physiologically occurring surfactants, such as phospholipids could be contemplated. However, according to the data disclosed in British Patent No. 1,527,605 (supra) the phospholipids in a commonly supplied long chain lecithin mixture have no detectable absorption promoting effect in insulin containing nasal formulations. It is actually shown in this publication (Table 1) that a composition containing no surface-active agent has a better effect than the composition containing lecithin. Lecithin is a mixture of phosphatidylcholines containing C-^θ, C^g and higher fatty acid residues. The fatty acid residues of the phosphatidylcholines according to the present invention contain not more than 14 carbon atoms. Therefore, this publication does not make the present invention obvious but rather teaches away from it.

The use of lecithin for stabilizing the particle size of aqueous aerosols to be inspired into the lungs is described in US patent No. 3,594,476. Lecithin is outside the scope of the claims of the present application and since furthermore the problem solved by the present invention is quite remote from

3a the problem solved by the invention described in the US patent cited, this publication does not anticipate the present invention, nor does it make it obvious.

The use of lecithin for effecting dissolution of drug substances in chlorofluorocarbons is described in patent application No. WO 86/04233. Lecithin is outside the scope of the claims of the present patent application and since furthermore the problem solved by. the present invention is quite remote from the problem solved by the invention described in the US patent cited, this publication does not anticipate the preset invention,״.nor does it make it obvious.

In Euorpean Patent application having the publication No. 200,383 lecithin is mentioned as a natural emulsifying agent. In column 5, line 9, reference is made to certain emulsifiers being capable of enhancing intranasal absorption, with lines 12 to 19 of column 5 specifying what these certain emulsifiers are (note the use of therefore in line 13). Lecithin is not mentioned in this place. Thus the present invention is neither anticipated nor made obvious by this publication.

DE 3,323,389 discloses the use of certain surfactants for enhancing the nasal absorption of heparin. The absorption of heparin from a composition containing lecithin turnedout to be very poor. This publication thus teaches away from the use of lecithin and the present invention is neither anticipated nor made obvious by it.

It has now surprisingly been found that medium chain length phosphatidylcholines and phosphatidylethanolamines substantially promote the intranasal absorption of pharmaceutically active compounds, in particular of polypeptides, without damaging or irritating the nasal mucosa. The intranasal absorption is further enhanced from formulations wherein a fatty oil, for example a vegetable oil, is admixed with the phospolipid.

SUMMARY OF THE INVENTION

According to its first aspect the present invention provides a preparation for intranasal administration comprising a pharmaceuticaly active agent and an absorption enhancing system comprising at least one phospholipid of the general formula I

H-CH-OR'

־. CH-OR (I)

H-CH-O-P(O)(OH)-OR' wherein R' and R are identical, or different, each selected from the group consisting, of hydrogen, alkyl, alkenyl, alkylcarbonyl, alkenylcarbonyl and alkadienyl-, alkatrienyl- or alkatetraenylcarbonyl containing up to a total of 14 carbon atoms, provided that both R' and R are not hydrogen, and R' represents a hydrophilic moiety selected from the group consisting of 2-(trimethylammonio)ethyl, 2-aminoethyl, 2carboxy-2-aminoethyl, 2,3-dihydroxypropyl and 2,3,4,5,6pentahydroxycyclohexyl, thus comprising phosphatidyl derivatives of choline (lecithins), ethanolamine, glycerol, serine and inositols, respectively. Optionally, but preferably, the absorption enhancing system also comprises a fatty oil in admixture with the phospholipid(s).

According to a second aspect of the present invention there is provided a process for making a preparation for intranasal administration, which method comprises dispersing at ].east one phospholipid of the general formula I, optionally, but preferably admixed with a fatty oil, in a liquid or solid diluent together with the pharmaceutically active agent either in solution or in a powdery state, which diluent may optionally comprise ancillary pH-buffering, preserving and osmotic pressure controlling agents.

WA/VMN, 1987-12-02, 3u, IL

3125.200 compounds being known as lecithins. A still further preference is for compounds of formula I, wherein R' and R each represent alkylcarbonyl or alkyl with from about 4 carbon atoms, preferably not more than 12 carbon atoms. The most preferred subclass of compounds of formula I is compounds wherein R' and R each represent nonylcarbonyl.

A preferred .preparation of this invention is one containing a mixture of two phospholipids of formula I, preferably in proportions by weight of from 1:10 to 10:1, more preferred from 1:2 to 2:1. One of these two phospholipids may conveniently be a compound wherein R' and R both are octanoyl, decanoyl or lauroyl. The other of these two phosphollipids may conveniently be a compound wherein one of the two substituents R' and R is hydrogen and the other of the two substituents R' and R is octanoyl, decanoyl or lauroyl (dodecanoyl).

Examples of preferred compounds of formula I are:

dioctanoyl L-a-phosphatidylcholine, dioctyl-O-L-a-phosphatidylcholine, didecanoy1 L-a-phosphatidylcholine, didecyl-O-L-a-phosphatidylcholine, decyl-O-L-a-lysophatidylcholine di lauroyl L-a-phosphatidylcholine, lauroyl L-a-lysophosphatidylcholine.

The compounds of formula I, of which some are known, can be prepared by methods known per se.

The fatty oil optionally incorporated into the absorption enhancing system of this invention is preferably a vegetable oil, more preferably soybean oil, peanut oil, coconut oil, maize oil, olive oil, sunflower oil, or mixtures thereof.

In another preferred embodiment of this invention the pharmaceutically active agent is a polypeptide. One group of preferred polypeptides is insulin and insulin derivatives, e.g. insulin modified by chemical or enzymatic methods or by recombinant DNA technology, or mixtures of such insulins.

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3125.200 proinsulin and glucagon. Other preferred polypeptides are parathyroid hormone, parathyroid hormone antagonist, calcitonin, vasopressin, renin, prolactin, growth hormone, thyroid stimulating hormone, corticotropin, corticotropinreleasing factor, follicle stimulating hormone, luteinizing hormone, chorionic gonadotropin, atrial peptides, interferon, tissue plasminogen activator, gammaglobulins, Factor VII, Factor VIII, growth hormone releasing hormone, luteinizing hormone releasing hormone, somatostatin and cholecystokinins.

The preparation of this invention may be liquid, e.g. adapted for administration as a spray or a solid, e.g. a powder acceptable for snuffing. Liquid preparations, such as those based on aqueous formulations, will usually include ancillary agents, for example a pH-buffering system, preferably a buffer such as phosphate, citrate or acetate buffers, a preservative and an osmotic pressure controlling agent, e.g. glycerol or sodium chloride. Powder formulations may contain the pharmaceutically active agent and the absorption enhancing system in admixture with nasally acceptable powdery diluents or mixtures thereof, e.g. cellulose or derivatives thereof, for example cellulose ethers or sodium carboxymethylcellulose, starch, a long chain fatty acid or a salt thereof, e.g. aluminum stearate, an organic polymer, e.g. of an acrylic acid derivative or inorganic vehicles, such as talc or diatomaceous earth. Supplementary addition of water-absorbing polymers, for example polyethylene glycol or polyvinyl pyrrolidone may be desirable to improve adhesion of the powder formulation to the nasal mucosa.

Preferred liquid preparations are those in which the diluent is water. Such preparations may be prepared by dispersing the absorption enhancing system in the aqueous medium containing the pharmaceutically active agent and ancillary agents, the dispersion being conducted by any method usually employed for suspension or emulsification, e.g. ultrasonic treatment. Adjustment of the aqueous phase to neutrality (i.e. to pH in the range from about 6.5 to about 8)

ר

WA/VMN, 1987-12-02, 3u, IL

3125.200 may be accomplished in any of the preparatory steps. Preferably, microemulsions are prepared in which the size of the dispersed particles or droplets is of the order of 10 nm, thereby facilitating their passage across the nasal mucosa.

Such microemulsions may be sterilized by filtration. The content of phospholipid of formula I and of fatty oil in preferred formulations of the present invention is in the range of from 0.01 to 10%, preferably from 0.5 to 5% (w/v), and 0.01 - 50%, preferably from 0.1 to 10% (w/v), respectively, of the 10 preparation.- Due to the fact that proteases and peptidases are associated with the nasal mucosa (see R.E. Stratford and V.H.L. Lee: Int.Journ.Pharmaceutics 30 (1986), 73-82) it may be desirable to incorporate biocompatible protease and peptidase inhibitors into polypeptide containing formulations.

The concentration of the pharmaceutically active agent in the preparations of this invention will of course depend on the particular agent chosen, on its efficacy, on a comparison of its bioavailability by nasal administration and by other routes of administration, for example parenteral 20 injection, and on the desired frequency of administration combined with the desired single dosage of the formulation. Such pharmacological data can routinely be obtained by the skilled artisan from animal experiments, for example in terms of index values, such as those estimated for insulin 25 preparations in the examples hereinafter provided.

Taking insulin as an example, its concentration in the preparation of this invention may be in the range of from about 5 to 1000 international units (I.U.) per ml, preferably from 50 to 500 I.U. per ml.

The insulin preparations of this invention preferably contain bovine, porcine or human insulin.

An exemplary mode of.preparing the insulin preparations of this invention wherein the diluent is water comprises dissolving insulin, for example crystalline zinc 35 insulin, for example the highly purified grade of insulin disclosed in British Patent No. 1,285,023, in water in the

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3125.200 presence of an acid, for example hydrochloric acid. An aqueous .solution of a preservative, for example phenol, an alkyl phenol, such as cresol, or methyl p-hydroxybenzoate, is prepared separately, optionally also containing an agent rendering the solution isotonic, such as sodium chloride or glycerol. Furthermore, the preservative solution may contain a buffering agent, such as sodium phosphate, sodium citrate, sodium acetate or TRIS (tris(hydroxymethyl)aminomethane) and a protease inhibitor. The resulting preservative solution is then admixed with the acid insulin solution followed by addition of a base, for example a sodium hydroxide solution, to adjust the pH value to neutrality. The phospholipid of formula I, optionally in admixture with the fatty oil, may be added to the insulin solution as a solution or an emulsion which is prepared by dissolving or suspending the phospholipid of formula I in water and and, if necessary, subjecting any suspension to an ultrasonic treatment before mixing with the insulin solution. Alternatively the phospholipid solution or emulsion may, if desired, contain the buffering agent and preservative. After mixing, the pH value of the insulin preparation may be readjusted to neutrality. Finally, the resulting insulin solution is made up to the calculated volume by addition of water.

The preparations of this invention may be used in any dosage dispensing device adapted for intranasal administration. The device should be constructed with a view to ascertaining optimum metering accuracy and compatibility of its constructive elements, such as container, valve and actuator with the nasal formulation and could be based on a mechanical pump system, e.g. that of a metered-dose nebulizer, or on a pressurized aerosol system. The aerosol system requires the propellant to be inert towards the formulation. Suitable propellants may be selected among such gases as fluorocarbons, hydrocarbons, nitrogen and dinitrogen oxide or mixtures thereof.

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Further details of practising this invention are furnished by way of the following examples which, however, should not be construed so as to imposes any kind of limitation to the scope of this invention.

The insulin starting material used in Examples 1-12 contained about 20 to 30 pg zinc per mg nitrogen.

Soybean oil and peanut oil were purified grades corresponding to those of U.S.P. χχι and N.F. XVI, respectively.