WO2007033427A1

WO2007033427A1 - Stabilisation of peptides with basic amino acids

Info

Publication number: WO2007033427A1
Application number: PCT/AU2006/001391
Authority: WO
Inventors: Frieder K. Hofmann
Original assignee: Metabolic Pharmaceuticals Limited
Priority date: 2005-09-23
Filing date: 2006-09-22
Publication date: 2007-03-29

Abstract

The present invention provides a pharmaceutical or veterinary formulation comprising as an active ingredient a peptide susceptible to degradation by acid hydrolysis and amount of free base basic amino acid sufficient to reduce the acid hydrolysis of the peptide. Also provided is a method of increasing the shelf life of peptide formulations by adding a free base basic amino acid.

Description

Stabilisation of peptides with basic amino acids

This invention relates to pharmaceutical or veterinary formulations comprising a peptide as an active ingredient and methods for improving the stability of peptides in formulations, particularly where said peptides are orally available .

BACKGROUND

Peptides are susceptible to aggregation and/or chemical degradation when stored in an aqueous solution for extended periods of time. This tendency of peptides to aggregate or degrade is generally characterized as "instability" . To extend the long term storage of peptides are often dried (for example by spray-drying or freeze-drying) for long-term storage.

Even dried peptide formulations tend to be unstable at room temperature. Degradation products formed from deamidation, oxidation and cleavage are often generated, limiting the room temperature shelf life. For this reason, a stable formulation is highly desirable for a peptide drug to enable distribution and storage without refrigeration, particularly where large market indications with oral formulations are concerned.

It is an aim of a preferred embodiment of the present invention to improve the storage stability of peptides for pharmaceutical or veterinary use and to provide peptide formulations with improved stability.

SUMMARY

The present invention in a first aspect provides a pharmaceutical or veterinary formulation comprising as an active ingredient a peptide susceptible to degradation by acid hydrolysis and amount of free base basic amino acid sufficient to reduce the acid hydrolysis of the peptide.

In a second aspect the invention provides a method of increasing the shelf-life of a pharmaceutical or veterinary formulation comprising as an active ingredient a peptide susceptible to degradation by acid hydrolysis comprising the step of adding a free base basic amino acid to the formulation.

Preferably the peptide and the amino acid are present in a dry form and particularly as a dry powder.

The applicant has studied the storage stability of their orally available peptide, AOD9604, described in International Patent application PCT/AU98/00724 and published as WO99/12969 (herein incorporated by reference) . Lyophilised pharmaceutical formulations of AOD9604, Tyr-hGH 177-191, amino acid sequence NH₂-Tyr-Leu- Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Gln-Gly-Ser-Cys-Gly-Phe- COOH (SEQ ID NO: 1) are unstable at room temperature in dry form after three months .

For clinical development AOD9604 is manufactured using conventional solid phase chemical synthesis and its final form is as a lyophilized hydrochloride salt. On further investigation the applicant determined, that when formulated in a PEG/Pearlitol capsule, HCl is present in the peptide formulation and that this HCl causes the AOD9604 to degrade, via acid hydrolysis. The applicant determined that the main degradation pathway is initiated by the deamidation of the glutamine residue of the peptide .

The applicant then determined that the addition of a free base basic amino acid to the formulation of AOD9604 increased the stability of the formulation against acid hydrolysis, extending the room temperature stability from 3 months to more than 12 months.

The applicant envisages that the stabilising effect of the basic amino acid can be used to stabilise other peptide formulations which are susceptible to acid hydrolysis. Such peptides include the applicant's orally available conotoxin peptide ACV-3 as described in their PCT application PCT/AU2006/001098 and having the amino acid sequence provided as SEQ ID NO: 2.

ACV-3 : Ac-Tyr-Leu-Arg-Ile-Val-Gly-Cys-Cys-Ser-Asp-Pro-Arg- Cys-Asn-Tyr-Asp-His-Pro-Glu-Ile-Cys-NH₂ (SEQ ID NO: 2)

In one embodiment, the formulation is a solid dosage form, in particular for oral use, such as a tablet or a capsule and the peptide is AOD9604 or ACV-3. The solid dosage form may also be for administration to the respiratory tract .

In a third aspect the present invention provides a tablet comprising AOD9604 or ACV-3 as active ingredient and a free base basic amino acid.

In the fourth aspect the present invention provides a capsule comprising AOD9604 or ACV-3 as active ingredient and a free base basic amino acid.

In a fifth aspect the present invention provides a method of making a pharmaceutical or veterinary formulation comprising the step of adding to a peptide susceptible to degradation by acid hydrolysis a suitable amount of a free base basic amino acid to reduce the acid hydrolysis of the peptide .

Preferably the peptide and amino acid are provided in dry form. Preferably the peptide and amino acid are dry blended to homogeneity to form the formulation.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows the four formulations used to assess the effect of arginine on stability in capsule formulations.

Figure 2 shows a graph plotting the 6 month stability of various formulations containing Arginine, stored at 25 degrees Celsius and 60% relative humidity.

Figure 3 shows a graph plotting the 6 month stability of various formulations containing Arginine, stored at 40 degrees Celsius and 75% relative humidity.

Figure 4 shows a graph plotting the 6 month stability of various formulations containing Arginine, stored at 60 degrees Celsius.

Figure 5 shows the percentage of total related substances present in each formulation initially, and at 1, 3, and 6 month time points.

Figure 6 shows a graph plotting the 12 month stability of various capsule formulations containing Arginine, stored at 25 degrees Celsius and 60% relative humidity.

Figure 7 shows a graph plotting the 12 month stability of various capsule formulations containing Arginine, stored at 40 degrees Celsius and 75% relative humidity. Figure 8 shows a graph plotting the 12 month stability of various capsule formulations containing Arginine, stored at 60 degrees Celsius.

Figure 9 shows the formulations used to assess the effect of Arginine on stability in tablet formulations.

Figure 10 shows a graph plotting the 9 month stability of various tablet formulations containing Arginine, stored at 4, 25 and 40 degrees Celsius (TEAP method) .

Figure 11 shows a graph plotting the 9 month stability of various tablet formulations containing Arginine, stored at 4, 25 and 40 degrees Celsius (TFA method) .

DETAILED DESCRIPTION

In a study of the stability of the dried formulations of AOD9604, four different formulations of capsules containing AOD9604 were manufactured containing varying amounts of free base Arginine as basic amino acid. Stability analysis on the capsule formulations were performed to determine the optimum level of Arginine that improves the stability characteristics of the formulation.

Comparison of the stability data shows that the formulations containing the most Arginine were the most stable, achieving a loss in potency of only approximately 20% with respect to initial value even after storage at elevated temperatures over a 6 month period. Physical decomposition of the formulations stored at 60°C was also observed in formulations without Arginine, or with low levels of Arginine, with no physical decomposition detected in the formulation containing the highest level of Arginine . Assay results indicate a degeneration of AOD9604 over time at elevated temperature and humidity conditions, with less degradation occurring in the formulations containing higher levels of Arginine . Similarly, the levels of related substances increased over time with decreasing Arginine levels, with the formulation containing no Arginine totally degrading within 3 months at 6O⁰C.

Therefore, it is evident that there is a direct correlation between levels of Arginine and stability of AOD9604 in capsule formulations of AOD9604, with the optimum level being 40 - 80 mg per capsule (11.5 - 23%w/w or a ratio of 8:1 Arginine to peptide (w/w) ) . Arginine appears to contribute both to overall stability and initial release of the active ingredient into solution with higher levels demonstrating rapid release of the drug.

Further experiments showed that there is a direct correlation between levels of Arginine and stability of AOD9604 in tablet formulations of AOD9604.

Whilst all the examples have been carried out using Arginine as free base basic amino acid it would be immediately apparent to those skilled in the art of pharmaceutical peptide formulation that other basic amino acids could be used.

The free base basic amino acid may be Arginine, Lysine or Histidine or corresponding non-conventional amino acids, for example 5-Hydroxylysine, Homoarginine, Ornithine or Citrulline. A D-amino acid may be used instead of the corresponding L-amino acid, any amino acid may be N- methylated, or the N-terminus may be acetylated.

Free-base Arginine is the preferred basic amino acid as it has the highest pKa and accordingly is proposed to be the most effective at reducing the acid hydrolysis of the peptide. Additionally L-Arginine is readily available, has no adverse biological activity and is non-toxic.

Preferably the basic amino acid is in the L-form. Preferably the basic amino acid is L-Arginine in free base form.

Preferably the formulation is formulated for oral administration. Administration to the respiratory tract is also contemplated.

Preferably, the formulation is in a capsule or formed into a tablet or is provided as a dry powder for use in a dry powder inhaler.

The peptide and the amino acid are preferably in dry form. The formulation may also further comprise one or more dry excipients .

Dry form as used herein means ingredients that are in solid form, including flowable solids which have some liquid-like properties. These generally contain less than 6% moisture. Dry form peptide formulations include freeze dried, lyophilised or desiccated peptide formulations.

The active peptide may be any peptide which is susceptible to acid hydrolysis. The present invention is particularly suited to peptides provided in acid salt form. It is more particularly suited to peptides that are for oral administration, particularly those peptides that are orally bioavailable, such as AOD9604, ACV-3 and certain cyclosporins .

The invention may be particularly applicable to peptides that are less than 50 amino acids long, and more particularly applicable to peptides that are less than 25 amino acids long.

In a preferred embodiment, the peptide is an analogue of the C terminus of human growth hormone of between 8 and 30 amino acids in length.

Preferably, the peptide is active to increase lipolysis and/or decrease lipogenesis in adipocytes.

Preferably, the active peptide is AOD9604 or a lipid metabolising subfragment or analogue thereof.

In another embodiment the active peptide is ACV-3 or an active subfragment or analogue thereof.

It will be appreciated that the active peptide may be in the form of a pharmaceutically acceptable derivative, preferably a pharmaceutically acceptable salt. Examples of pharmaceutically acceptable salts include salts of pharmaceutically acceptable cations such as sodium, potassium, lithium, calcium, magnesium, ammonium and alkylammonium; acid addition salts of pharmaceutically acceptable inorganic acids such as hydrochloric, orthophosphoric, sulphuric, phosphoric, nitric, carbonic, boric, sulfamic and hydrobromic acids; or salts of pharmaceutically acceptable organic acids such as acetic, propionic, butyric, tartaric, maleic, hydroxymaleic, fumaric, citric, lactic, mucic, gluconic, benzoic, succinic, oxalic, phenylacetic, methanesulphonic, trihalomethanesulphonic , toluenesulphonic , benzenesulphonic, salicylic, sulphanilic, aspartic, glutamic, edetic, stearic, palmitic, oleic, lauric, pantothenic, tannic, ascorbic and valeric acids. Salts of amine groups may also comprise quaternary ammonium salts in which the amino nitrogen atom carries a suitable organic group such as an alkyl, alkenyl, alkynyl or aralkyl moiety.

Preferably, the ratio of basic amino acid to peptide in the formulation is more than 2:1 by weight.

More preferably, the ratio of basic amino acid to peptide in the formulation is more than 4:1 by weight.

Most preferably, the ratio of basic amino acid to peptide in the formulation is more than 8:1 by weight.

Excess basic amino acid may be used in the formulation (as high as a ratio of 20:1 or more by weight) provided the basic amino acid is well tolerated.

The pharmaceutical composition described in this invention could be used to treat any mammal . The animal may be a human, or may be a domestic or companion animal. While it is particularly contemplated that the present invention is used in medical treatment of humans, it is also applicable to veterinary treatment, including treatment of companion animals such as dogs and cats, and domestic animals such as horses, cattle and sheep, or zoo animals such as non- human primates, felids, canids, bovids, and ungulates.

Preferably the mammal is a human. The human may be a child or an adult.

Use of the term "peptide" in this specification includes polypeptides of any amino acid length, including proteins, unless specifically restricted.

As referred to herein "oral delivery" or "oral administration" are intended to encompass any administration or delivery to the GI tract and includes administration directly to the oropharyngeal cavity, and administration via the mouth in which the actual absorption of the peptide or polypeptide takes place in the gastrointestinal tract, including the stomach, small intestine, or large intestine. Oral administration as used herein encompasses sublingual administration

(administration by application under the tongue of the recipient, representing one form of administration via the oropharyngeal cavity) and buccal administration

(administration of a dosage form between the teeth and the cheek of the recipient) .

An orally available peptide as defined herein is a peptide that is suitable for oral administration.

Oral delivery and oral administration may be used interchangeably herein.

Formulations for oral use include tablets containing the active compound in a mixture with non-toxic pharmaceutically acceptable excipients. These- excipients may be, for example, inert diluents or fillers {e.g., sucrose, sorbitol, sugar, mannitol, mirocrystalline cellulose, starches including potato starch, calcium carbonate, sodium chloride, lactose, calcium phosphate, calcium sulfate or sodium phosphate) ; granulating and disintegrating agents {e.g., cellulose derivatives including microcrystalline cellulose, starches including potato starch, croscarmellose sodium, alginates or alginic acid); binding agents [e.g. , sucrose, glucose, sorbitol, acacia, alginic acid, sodium alginate, gelatin, starch, pregelatinized starch, microcrystalline cellulose, magnesium aluminium silicate, carboxymethylcellulose sodium, methylcellulose, hydroxypropyl methylcellulose, ethylcellulose, polyvinylpyrrolidone or polyethylene glycol) ; and lubricating agents, glidants, and antiadhesives {e.g., magnesium stearate, zinc stearate, stearic acid, silicas, hydrogenated vegetable oils or talc) . Other pharmaceutically acceptable excipients can be colourants, flavouring agents, plasticisers, humectants, buffering agents and the like.

The tablets may be uncoated or they may be coated by known techniques, optionally to delay disintegration and absorption in the gastrointestinal tract and thereby providing a sustained action over a longer period. The coating may be adapted to release the active compound in a predetermined pattern (e.g., in order to achieve a controlled release formulation) or it may be adapted not to release the active compound until after passage of the stomach (enteric coating) . The coating may be a sugar coating, a film coating (e.g., based on hydroxypropyl methylcellulose, methylcellulose, methyl hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, acrylate copolymers, polyethylene glycols and/or polyvinylpyrrolidone) , or an enteric coating (e.g., based on methacrylic acid copolymer, cellulose acetate phthalate, hydroxypropyl methylcellulose phthalate, hydroxypropyl methylcellulose acetate succinate, polyvinyl acetate phthalate, shellac and/or ethylcellulose) . Furthermore, a time delay material such as, glyceryl monostearate or glyceryl distearate may be employed.

The solid tablet compositions may include a coating adapted to protect the composition from unwanted chemical changes, (e.g., chemical degradation prior to the release of the active compound) .

Formulations for oral use may also be presented as chewing tablets or as hard gelatin capsules wherein the active compound is mixed with an inert solid diluent (e.g., potato starch, lactose, microcrystalline cellulose, calcium carbonate, calcium phosphate or kaolin) . Powders and granulates may be prepared using the ingredients mentioned above under tablets and capsules in a conventional manner using, e.g, a mixer, a fluid bed apparatus or a spray drying equipment .

The peptide may also be administered to the respiratory tract, for example by intranasal administration, by methods and formulations employed in the art for administration to the respiratory tract.

Thus in general the peptide may be administered to the respiratory tract in the form of a dry powder . Administration to the respiratory tract may be achieved by means of a dry powder inhaler (DPI) . The powder composition may be presented in unit dose form, for example in capsules or cartridges of eg. gelatin, or blister packs from which the powder may be administered by means of an inhaler.

In formulations intended for administration to the respiratory tract, including intranasal formulations, the active compound will generally have a small particle size, for example of the order of 5 microns or less . Such a particle size may be obtained by means known in the art, for example by micronisation.

When desired, formulations adapted to give sustained release of the active compound may be employed.

The active compound may be administered by oral inhalation as a free-flow powder via a "Diskhaler" (trade mark of Glaxo Wellcome pic or a meter dose aerosol inhaler.

As used herein "free base" is intended to mean the free amino acid, not in the form of a salt.

The formulation may comprise pharmaceutically acceptable carrier and, or excipients. Methods and pharmaceutical carriers for preparation of pharmaceutical compositions are well known in the art, as set out in textbooks such as Remington's Pharmaceutical Sciences, 20th Edition, Williams and Williams, Pennsylvania, USA (2000) .

The formulation may further contain or be used in conjunction with other pharmaceutical preparations.

As used herein, a "pharmaceutically acceptable carrier" is a pharmaceutically acceptable solvent, a diluent, a suspending agent, excipient or vehicle for delivering the peptide to the subject.

The formulation preferably comprises a bulking agent (which acts as a diluent and disintegrant , for example ProSolv HD90™) , if necessary a flow enhancer, such as fumed silica (for example Cab-O-sil™) , and if necessary a lubricant, for example magnesium sterate, in addition to the peptide and free base amino acid.

Preferred AOD tablet formulations are provided in Figure 9. In a capsule formulation the lubricant need not be present. The components of the formulations will depend upon which peptide is included. However it is envisaged that the presence of free base amino acid in a ratio of 2:1 to 10:1 and possibly up to 20:1 or more will reduce acid hydrolysis of the peptide.

The formulations are preferably prepared and administered in dosage units. Solid dosage units include tablets, capsules and suppositories. For treatment of a subject, depending on activity of the compound, manner of administration, nature and severity of the disorder, age and body weight of the subject, different daily doses can be used. Under certain circumstances, however, higher or lower daily doses may be appropriate. The administration of the daily dose can be carried out both by single administration in the form of an individual dose unit or else several smaller dose units and also by multiple administration of subdivided doses at specific intervals.

The formulations according to the invention may be administered in a therapeutically effective dose. Amounts effective for this use will, of course, depend on the severity of the disease and the weight and general state of the subject. Typically, dosages used in vitro may provide useful guidance in the amounts useful for in situ administration of the pharmaceutical composition, and animal models may be used to determine effective dosages for treatment of the cytotoxic side effects. Various considerations are described, e.g. in Langer, Science, 249: 1527, (1990) .

It will be understood, however, that the specific dose level for any particular patient will depend upon a variety of factors including the activity of the specific compound employed, the age, body weight, general health, sex, diet, time of administration, route of administration, rate of excretion, drug combination and the severity of the particular disease undergoing therapy.

In the description of the invention and in the claims which follow, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

As used herein, the singular forms "a" , "an" , and "the" include the corresponding plural reference unless the context clearly dictates otherwise. Thus, for example, a reference to "a peptide" includes a plurality of such peptides, and a reference to "an amino acid" is a reference to one or more amino acids.

Where a range of values is expressed, it will be clearly understood that this range encompasses the upper and lower limits of the range, and all values in between these limits .

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any materials and methods similar or equivalent to those described herein can be used to practice or test the present invention, the preferred materials and methods are described.

It is to be clearly understood that this invention is not limited to the particular materials and methods described herein, as these may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and it is not intended to limit the scope of the present invention, which will be limited only by the appended claims.

Unless otherwise indicated, the present invention employs conventional chemistry and protein chemistry within the capacity of those skilled in the art. Such techniques are well known to the skilled worker, and are explained fully in the literature. See, for example, Coligan, Dunn, Ploegh, Speicher and Wingfield: "Current protocols in Protein Science" (1999) Volumes I and II (John Wiley & Sons Inc . ) .

The invention will now be described in detail by way of reference only to the following non-limiting examples.

EXAMPLES SYNTHESIS OF HEXADECAPEPTIDE OF AMINO ACID RESIDUES 177-191 OF NATIVE HUMAN GROWTH HORONE, DESIGNATED HGH (177-191) WITH AN N-TERMINAL TYROSINE ELONGATION (REF NO: AOD9604)

AOD9604 has the sequence provided as SEQ ID NO" 1.

NHa-Tyr-Leu-Arg-Ile-Val-Gln-Cys-Arg-Ser-Val-Gln-Gly-Ser- Cys-GIy-Phe-COOH (SEQ ID NO: 1)

The following procedure was employed in preparing the hexadecapeptide, as previously described in WO99/12969.

Step 1.

Wang resin (0.625 g, 0.5 mmol) was placed in a 10 ml reaction vessel .

DCM (4 ml) was added to the reaction vessel. The Wang resin was washed with vigorous stirring for 2 minutes. The

DCM solution was then drained from the reaction vessel .

This washing was repeated twice.

Step 2.

Fmoc-L-phenylalanine (Fmoc-Phe, 0.388 g, 1.0 mmol) in 2.4 ml NMP-DCM (1:5, v/v) and DIC (0.135 g, 1.0 mmol) in 1.0 ml NMP were mixed in a reaction vessel for 10 minutes. To the mixture, 4-dimethylaminopyridine (DMAP, 0.074g, 0.06 mmol) in 0.6 ml DMF was added. The reaction in the solution was allowed to continue for 68 minutes at room temperature. The solution was then drained, the resin was washed thoroughly with NMP (4 ml x 3) and OCM (4 ml x 3) . The Fmoc-Phe-Wang Resin complex was dried in vacuo overnight to yield 0.781 g of material. The coupling level of amino acid to resin was determined to be 0.80 mmol/g resin by using spectrophotometry measurement of the Fmoc- piperidine adduct . Step 3.

Fmoc-Phe-Wang Resin (0.263 g, 0.20 tnmol) was placed in the 10 ml reaction vessel. DMF (8 ml) was added to wash and swell the resin by stirring for 2 minutes. The solution was then drained from the reaction vessel.

Step 4.

A 25% piperidine/DMF solution (4 ml) was added to the reaction vessel . The resulting mixture was stirred for 2 minutes. The solution was drained from the reaction vessel. This deprotection procedure was repeated once but with prolonged stirring time (18 mm) . The solution was drained from the reaction vessel .

Step 5.

DMF (8 ml) was added to the reaction vessel. The resulting solution was stirred for 2 minutes. The solution was drained from the resin in the reaction vessel . This washing procedure was repeated twice. DMF (2 ml) was added to the reaction vessel to keep the resin swollen.

Step 6.

Fmoc-glycine (Fmoc-Gly, 0.238 g, 0.8 mmol) , HOBt (108 mg; 0.8 mmol) and DIC (128 μl ; 0.8 mmol) were added to a 10 ml test tube containing 2 ml DMF. The mixture was stirred for 10 minutes to start the activation of amino acid. The solution was then added to the resin which originally was placed in the reaction vessel . The resulting mixture was stirred for 1.5 hours or until a negative ninhydrin test was obtained. The solution was then drained from the reaction vessel . Step 7 .

DMF (8 ml) was added to the reaction vessel. The resulting solution was vigorously stirred for 2 minutes. The solution was then drained from the reaction vessel . The washing procedure was repeated twice.

Steps 4 through 7 were then repeated employing the following order of amino acid:

Fmoc-Cys (Acm) Fmoc-Ser (t-Bu) Fmoc-Gly Fmoc-Glu (O-tBu) Fmoc-Val Fmoc-Ser (t-Bu) Fmoc-Arg (Pmc) Fmoc-Cys (Acm) Emoc-Gln Fmoc-Val Fmoc-lle Fmoc-Arg (Pmc) Fmoc-Leu Fmoc-Tyr (t-Bu)

After completion of the synthesis of the desired peptide- resin, the reaction vessel containing the peptide-resin was then placed in a desiccator and dried overnight under vacuum. The yield of peptide-resin was 0.635 g. The dried peptide-resin was removed from the reaction vessel and placed in a 50 ml round-bottom flask containing a magnetic stirring bar. The cleavage of the peptide from the resin with TFA was carried out with the following procedure: A scavenger solution, containing 0.75 g phenol, 0.5 ml H20, 0.5 ml thioanisole, and 0.25 ml ethanedithio, was added to the round-bottom flask. The resulting mixture was stirred for 5 minutes. 10 ml TFA was added drop by drop into the flask while kept stirring vigorously. The resulting mixture was stirred for 2.5 hours at room temperature .

The mixture was filtered through a medium-porosity filter, fritted glass funnel . The TFA-peptide solution was sucked into another 500 ml round-bottom flask containing 200 ml cold diethyl ether by applying vacuum. Peptide was allowed to be precipitated in the ether solution at 4OC overnight, then collected by filtering the mixture through a fine- porosity, fritted glass funnel. The peptide pellet on the filter was washed with cold ether (10 ml x 3) to remove the scavenger. The peptide pellet was then dissolved with 25% aqueous acetic acid and then lyophilized to yield the crude peptide (about 400 mg dry weight, purity -80%) .

The crude peptide was purified by reversed-phase high performance liquid chromatography (RP-HPLC) . Purification was carried out on a preparative 21.2 x 250mm Supelcosil PLC-18 (octadecyl, C18) column (120 Angstrom pore size, 12 μm particle size, 190 m2/g surface area; Supelco, Beliefonte, PA, U.S.A.) at 5.0 ml/mm flow rate at room temperature. A linear gradient program was utilized , where solvent A was water with 0.1 % TEA, and solvent B was acetonitrile-water (50/50: v/v, containing 0.1% TEA). The gradient was developed from 20 to 100% over 80mm. Separation profiles were recorded and analysed using a Perkin-Elmer LO-IQO integrator. The desired peptide component was eluted and collected with the Pharmacia Model PRAC-IQO automatic fraction collector (Uppsala, Sweden) . The fractions of identical component were combined and lyophilized. The purified peptide (275 mg dry weight, purity >98%) , Cys(Acm)7-14 hexadecapeptide, was kept frozen at -20 OC.

For cyclisation of the disulfide bridge of the peptides, iodine oxidation in 80% aqueous acetic acid was used to remove the cysteine-protecting groups, Acm, and furnished the intramolecular disulfide bridge simultaneously. Cys (Acm) 7-14 pentadecapeptide (275 mg, 0.155 mmole) was dissolved in 50 ml 80% aqueous acetic acid. This solution was slowly added to a 250 ml round-bottom flask containing iodine (378 mg, 1.4 mmole) in 100 ml 80% aqueous acetic acid by stirring vigorously. Reaction was allowed to continue for 2 hours at room temperature and terminated by adding the ascorbic acid (Vitamin C) to the resulting solution. Liquid volume was then reduced by rotary evaporation and peptide recovered by lyophilization. The cyclised peptide was then purified by RP-HPLC as described in the purification of linear peptide. After lyophilization, 165 mg cyclic pentadecapeptide with 96% purity was yielded. The total yield of synthesis of AOD9604 was about 46%.

For formulation the AOD9604 acetate salt was dissolved in 1OmM HCl and relyophilised to yield AOD9604 Hydrochloride salt .

Capsule Formulations

Four different formulations of AOD9604 capsules containing varying amounts of Arginine were made. Stability analysis on the capsule formulations were performed to determine the optimum level of Arginine that improves the stability characteristics of the formulation.

Four formulations were manufactured, each containing different amounts of free base Arginine as indicated in Figure 1 below.

All four formulations were prepared as follows:

1. All excipients were screened through a 40 mesh sieve

2. AOD9604 , PEG3350 and an equivalent amount of Pearlitol were added to the cube blender and mixed for 10 minutes

3. Resultant powder blend was screened through a 40 mesh screen and returned to the cube mixer

4. Arginine was added to the blend and mixed for a further 10 minutes

5. Resultant powder blend was again screened though a 40 mesh sieve and returned to the cube mixer

6. Remaining quantity of Pearlitol was added to the blend and mixed for 10 minutes

7.5 x 1 gram samples were taken to be tested for blend homogeneity 8. Balance of blend collected and stored at -20⁰C awaiting homogeneity results.

Following receipt of satisfactory homogeneity results, the final powder blend was encapsulated using the Dott Bonopace encapsulator fitted with size 0 change parts.

Following homogeneity results, the four formulations were placed on a 6 month stability study to ascertain the correlation between Arginine levels and the stability of AOD9604 with respect to dissolution and drug release profiles. Capsules were stored at 25°C/60% relative humidity (RH) , 40°C/75%RH and 60°C with sampling points of 1 month, 3 months and 6 months. The results obtained for the assay of each formulation at each stability time point and storage condition are presented in Figures 2 to 4 below.

Note: Formulation 4 was hazy and did not fully dissolve in solution at initial testing point. Solution remained hazy despite additional sonication/shaking and remained cloudy for up to 5 days after preparation. This probably accounts for the lower levels of AOD9604 detected at the initial timepoint .

Comparison of the stability suggests a correlation between Arginine levels and product stability, with Formulation 3 and Formulation 4 achieving a loss in potency of only approximately 20% with respect to initial value even after storage at elevated temperatures over a 6 month period.

Physical decomposition of the formulations stored at 60°G was also observed in Formulations 1 and 2 within 3 months of storage and to a lesser extent in Formulation 3, with 20% of capsule contents examined showing discolouration. No discolouration was observed in the contents of capsules containing Formulation 4.

Assay results indicate a degeneration of AOD9604 over time at elevated temperature and humidity conditions, with less degradation occurring in the formulations containing higher levels of Arginine. Similarly, related substances levels increased over time with decreasing Arginine levels, with Formulation 1 totally degrading within 3 months at 60°C. Formulation 4 appeared to be the most stable with respect to assay degradation and formation of related substances, see Figure 5.

From this experiment it is evident that there is a direct correlation between levels of Arginine and stability of AOD9604 in capsule formulations, with the optimum level being 40 - 80 mg per capsule (4:1 - 8:1 Arginine to AOD9604 w/w) .

The stability study was continued for 12 months and the further results shown in Figures 6-8. The trend of reduction in stability of the AOD formulation is continued. After 12 months under 75% relative humidity and 60 degrees centigrade, the formulation comprising AOD9604 and 12% or 24% Arginine is shown to be stable.

Tablet Formulations

Tablets comprising ltng, 0.5 mg, 0.25 mg and 0 mg of AOD9604 were formulated with varying amounts of Arginine were made. Stability analysis on the tablet formulations were performed to determine the optimum level of Arginine that improves the stability characteristics of the formulation.

Four formulations were manufactured, each containing different amounts of free base Arginine as indicated in Figure 9 below.

Direct Compression Tablets: The ProSolv, L-Arginine, Cab- O-sil and AOD9604 were accurately weighed and placed in a V-blender and blended for between 5 and 20 minutes. The Mg Stearate was added to the shell and blended for a further 5 - 20 minutes. The total blend time was 25 minutes . The blend was placed in the tablet press hopper and adjusted for weight and thickness settings to yield 100 mg tablets with thickness of approximately 4.2mm.

The formulations were placed on a 24 month stability study. Tablets were stored at 4, 25 and 4O⁰C. So far sampling points of 1 month, 3 months, 6 months and 9 months have been taken.

The graphs show the results of HPLC methods used to determine the purity of AOD . Two methods are required in case an impurity is eluting at the same time as the main peak, this would be less likely to occur under two differenent sets of conditions. TFA refers to Trifluoro acetic acid, and TEAP refers to Triethylammonium phosphate .

The results obtained for the assay of each formulation at each stability time point and storage condition are presented in Figures 10 and 11 below.

From this experiment it is evident that there is a direct correlation between levels of Arginine and stability of AOD9604 in tablet formulations. It is anticipated that this correlation would also be seen with other basic amino acids .

Additionally it is also envisaged that the stabilizing effect of the basic amino acids would extend to other dried peptide formulations susceptible to acid hydrolysis.

Claims

Claims .

1. A pharmaceutical or veterinary formulation comprising as an active ingredient a peptide susceptible to degradation by acid hydrolysis and amount of free base basic amino acid sufficient to reduce the acid hydrolysis of the peptide.

2. A formulation according to claim 1 in dry form.

3. A formulation according to claim 1 as a solid dosage unit .

4. A formulation according to claim 1 in which the basic amino acid is Arginine, Lysine, Histidine, Ornithine, or Citrulline .

5. A formulation according to claim 1 in which the basic amino acid is Arginine .

6. A formulation according to claim 1 in which the basic amino acid is an L amino acid.

7. A formulation according to any preceding claim formulated for oral administration.

8. A formulation according to any preceding claim in tablet form.

9. A formulation according to any one of claims 1 to 7 in capsule form.

10. A formulation according to any preceding claim in which the peptide is a peptide that is susceptible to acid hydrolysis .

11. A formulation according to claim 10 in which the peptide is in acid salt form.

12. A formulation according to claim 10 in which the peptide is less than 50 amino acids in length.

13. A formulation according to claim 10 in which the peptide is an analogue of the C terminus of human growth hormone of between 8 and 30 amino acids in length.

14. A formulation according to claim 13 in which the peptide is active to increase lipolysis and/or decrease lipogenesis in adipocytes.

15. A formulation according to claim 13 in which the peptide is AOD9604 or a lipid metabolising subfragment or analogue thereof .

16. A formulation according to claim 10 in which the peptide is ACV-3 or an active subfragment or analogue thereof .

17. A formulation according to claim 1 in which the ratio of free base basic amino acid to peptide is more than 2:1 by weight .

18. A formulation according to claim 1 in which the ratio of free base basic amino acid to peptide is more than 4:1 by weight .

19. A formulation according to claim 1 in which the ratio of free base basic amino acid to peptide is more than 8:1 by weight .

20. A method of increasing the shelf-life of a pharmaceutical or veterinary formulation comprising as an active ingredient a peptide susceptible to degradation by acid hydrolysis comprising the step of adding a free base basic amino acid to the formulation.

21. A method according to claim 20 in which the basic amino acid is Arginine, Lysine, Histidine, Ornthine, or Citrulline .

22. A method according to claim 20 in which the peptide is AOD9604 or a lipid metabolising subfragment or analogue thereof .

23. A formulation according to claim 20 in which the peptide is ACV-3 or an active subfragment or analogue thereof .

24. A method according to claim 20 in which the formulation is for oral administration.

25. A tablet comprising AOD9604 or a lipid metabolising subfragment or analogue thereof as active ingredient and a free base basic amino acid.

26. A capsule comprising AOD9604 or a lipid metabolising subfragment or analogue thereof as active ingredient and a free base basic amino acid.

27. A tablet comprising ACV-3 or an active subfragment or analogue thereof as active ingredient and a free base basic amino acid.

28. A capsule comprising ACV-3 or an active subfragment or analogue thereof as active ingredient and a free base basic amino acid.

29. A method of making a pharmaceutical or veterinary formulation comprising the step of adding to a peptide susceptible to acid hydrolysis a suitable amount of a free base basic amino acid to reduce the acid hydrolysis of the peptide .

30. A method according to claim 25 in which the peptide and amino acid are dry mixed.