MXPA01000105A - Microparticle formulation for inhalation - Google Patents

Abstract

Microparticles, obtainable by spray-drying a substantially pure solution of a therapeutic agent, consist essentially of the agent having its therapeutic activity when administered to the lung. In a preferred embodiment the agent is insulin.

Description

FORMULATION OF MICROPARTICLES FOR INHALATION FIELD OF THE INVENTION This invention relates to a formulation of a therapeutic agent such as insulin, which is suitable for administration to the lungs, and which has good stability.

BACKGROUND OF THE INVENTION At present, there is a very broad interest in the formulation of therapeutic agents for inhalation. In particular, many efforts have been made to formulate suitable therapeutic agents, such as dry powders, to deliver them by means of inhalers. Typically, the formulations are produced by drying the active agent in the presence of certain excipients, such as polysaccharides or citrate, to improve the stability during the drying or storage process. Insulin is a typical example of a therapeutic agent that can be administered to the lung, by inhalation. As a commercial product, insulin is usually provided in the form of a suspension or a low concentration solution, such as a hexamer in complex with zinc. Refrigeration is necessary to maintain the stability of said formulation.

The crystalline Zn insulin is stable at a neutral pH. Dry powder also requires refrigeration. CA-A-2136704 describes a product that is obtained by spray drying a medicinal substance such as insulin (among many others) and a vehicle. Example 4 describes the action of spray drying a clear solution of human insulin, soy lecithin and lactose. WO-A-9735562 also describes the action of spray drying a solution of insulin and a polysaccharide. The objective of this combination is to achieve the preferred size scale of the spray dried microparticles, for a good deposition in the lung. In Examples 1 and 3, the insulin solution for spray drying, before the combination with polysaccharides, is prepared by dissolving zinc insulin in HCl, and then adding NaOH, at a pH of 7.2. The spray-drying solutions contain respectively 25 and 6 mg / ml of insulin and at least 5.5 / 7.2% of NaCl, based on the combined weight of insulin plus salt. WO-A-9524183 is directed primarily to a dry powder comprising insulin and a carrier material, typically a saccharide, in the form of an amorphous powder of microparticles obtained by spray drying. In addition, the experimental section compares the properties of said microparticles with and without saccharide excipients. The insulin solution for spray drying is prepared by dissolving Zn insulin in a citrate pH regulator, at a pH of 6.7 ± 0.3, at a solids content of 7.5 mg / ml. The powder is kept in a container at a RH of 10%. The formulation without saccharide has a considerably lower bioavailability than that with saccharides. For several reasons, this experiment can not be reproduced: citrate is a pH regulator at a pH of 3.0 / 6.2, and not at a pH of 6.7; crystalline insulin will not dissolve in a citrate pH regulator at a pH of 6.2 before or after adjustment to a pH of 7.4 with NaOH; in any case, no addition of alkali is specified. It was believed that the presence of citrate in dry powder formulations was necessary to improve the stability of the final product (Drug Development and Industrial Pharmacy 1984; 10 (3): 425-451). However, in many cases, the high concentration of citrate dilutes the amount of active agent in the initial supply material, resulting in small amounts of active material for drying. Pikal and Rigsbee, Pharm. Rev. 14 (10): 1379-87 (1997), report that freeze dried amorphous insulin was significantly more stable than crystalline insulin at corresponding water contents of 0 to 15% w / w. The mechanism was not clear, but it could be due to the configuration differences between the amorphous and crystalline states, the reactive parts of the protein being in close proximity to the latter. The formulation reported by Pikal and Rigsbee does not contain salt, since low concentrations of insulin are used (c 0.5% w / v) such that pH manipulation is not necessary. WO95 / 23613 discloses a spray dried DNase formulation. The spray dried product is in a crystalline form, mainly due to a high salt concentration. It is established that high salt concentrations increase the dispersibility quality of the final product. In Example 1, the final product contains 60% salt compared to 30% DNase. In summary, the prior art describes several results of interest but of uncertain commercial importance. None of the methods described above give a pure insulin product that is stable, or use a sufficiently concentrated solution for spray drying, which is suitable as a commercial process. The most effective procedures invariably suggest that co-drying by insulin and a saccharide is necessary for better results.

BRIEF DESCRIPTION OF THE INVENTION The present invention is based on the surprising discovery that it is possible to spray-dry a therapeutic agent at higher (and therefore commercially useful) concentrations than those previously used, without the concomitant production of an undesirable high salt concentration. or other excipients. Said formulations do not show a substantial loss of activity after the drying process and have a broad stability, as compared to the pre-sprayed preparations. This discovery is of value for all the therapeutic agents, in particular proteins and peptides that are to be administered by means of the lung. In accordance with the present invention, the microparticles, which are obtained by spray drying a substantially pure solution of a therapeutic agent, consist essentially only of the agent. In a preferred embodiment, the microparticles consist essentially only of insulin and NaCl salt. Said microparticles can be kept in a container at a HR greater than 10%, and thus essentially at ambient humidity. Insulin microparticles are obtained by dissolving Zn insulin in acid, adding alkali to give an insulin solution, for example at a pH above 7, and by spray drying the insulin solution (which also contains a salt formed as a result of the dissolution process, or a pH regulator). Preferably the microparticles are not crystalline / amorphous.

DESCRIPTION OF THE INVENTION As indicated above, the microparticles of the invention "consist essentially" of the therapeutic agent. This term is used herein to indicate that they are substantially free of polysaccharides, or pH regulating salts, eg citrate, since none is necessary. In general, there will be no polysaccharide present at all, although an amount greater than 10% by weight can be tolerated. The absence of polysaccharides has the advantage that a given unit dose, for example a particle, essentially contains only the desired active component. This is an important consideration, for a drug that is required in large quantities. Another advantage is that the provision of unnecessary material to a subject is avoided. A further advantage is that a consistent dosage of the therapeutic agent is facilitated; This is especially important where there is a narrow therapeutic margin. The absence of a pH regulating salt is preferred since it allows a more concentrated supply material solution of the active agent to be spray dried, resulting in significant cost savings and provides a more commercial scale process that is can adopt. The term "substantially pure" is used herein to mean that the solution of supply material that is to be spray dried comprises primarily only one therapeutic agent and one solvent. Again, as described above, there may be a lower amount of solids than in the active agent, but this does not have a significant effect on the eventual stability of the product. The insulin microparticles of the invention may include components that are produced during the successive addition of acid and an alkali, in preparation of the supply material, for example, a salt. For example, NaCl is formed if the acid and alkali are HCl and NaOH respectively. It has been found that the presence of NaCl apparently does not have a stabilizing effect. In fact, the stability can be greater with reduced amounts of salt, again allowing more concentrated supply material to be used. Typically, the solution for spray drying may contain less than 4% by weight of salt, by weight of the total solids. The salt content is based on theoretical considerations, by titration at a pH of 7. More particularly, this value is calculated by considering the molar amounts of the ions added during the dissolution. The solution may contain any desired amount of the therapeutic agent, for example more than 20, 30 or 50 mg / ml, often up to 100 or 200 mg / ml. As indicated above, the successive addition of acid and alkali apparently destroys the crystalline form of Zn insulin. Zn can be dissociated from the hexameric complex but does not need to be removed. Likewise, Zn may be present in the microparticles. If desired, this and any other component, other than the therapeutic agent, can be removed, using any suitable technique, known to those skilled in the art. In a preferred embodiment for insulin, Zn is removed from the solution before it is spray dried. This can be achieved by dialysis of the solution, in accordance with methods known in the art. The Zn-free insulin may have greater stability than the Zn-containing product. It can also be present in moisture. As described in more detail in WO-A-9218164, WO-A-9408627 and other Andaris publications, spray drying conditions can be controlled so that microparticles having a scale of defined size, for example 0.1 to 50 μm, can be obtained. The average particle size of the mass, preferably is 1 to 10 μm, when the product is intended to be administered by inhalation. The microparticles (microcapsules) obtained by spray drying can be solid or hollow. In addition, the surface can be smooth or "rough"; a rough surface may be beneficial for inhalation. The microparticles have good stability and can be maintained in such a manner, i.e., as a dry powder, in a container. During storage or in formulation, they can be mixed with any suitable pharmaceutical agent, carriers, bulking agents, etc., and can be processed by any desired technique to give a product having properties that are reserved for the ultimate therapeutic use. In particular, the formulation of particles for formulations that can be delivered to the lung, for example, using a metered dose or dry powder inhaler, is known to those skilled in the art. The nature of the container is not critical. For example, it can be a glass jar or a plastic box. This only defines a storage environment within which, in a manner different from the prior art and as shown below, there is no need to remove the moisture or otherwise control the conditions. The therapeutic agent can be any protein or peptide having a desired therapeutic effect. Functional derivatives, such as glycoproteins, are included within the definition of proteins and peptides.

Typical examples of proteins that can be used include enzymes, hormones and blood plasma products. DNase and trypsin are specific examples. Others include growth hormone, calcitonins, interferons, interferon-1 receptor, and low molecular weight heparin. The therapeutic agent can be, in particular, any of those described in WO-A-9632149. The insulin that is used in the invention can be in any suitable form. It can be, for example, bovine or human insulin. The results that have been obtained, in relation to the stability of bovine insulin, apparently also apply to human insulin. The following examples illustrate the invention.

EXAMPLE 1 A solution of bovine or human insulin for spray drying is typically prepared in the following manner: 5 g of insulin are dissolved in 70 ml of 0.05 m HCl, after which the solution is again titrated with 1 M NaOH sufficient to reform a solution from the isoelectric point precipitate. According to the final concentration required, water is added to carry a volume. Approximately 4.8 ml of 1 M NaOH is required in this example. The solution is then spray dried using a Mini Spray dryer with an outlet temperature of about 87 ° C and a solution feed rate of about 0.75 g / min.

High performance reverse phase liquid chromatography (CLAR-FI) was used to evaluate the stability of insulin, under the following conditions: Column: Vydac C-18, 5 μm, 30 nm Mobile phase: A- 0.1% TFA in water B- 0.1% TFA in acetonitrile (95%) and water (5%) Elution with gradient Flow rate: 1.5 ml / min Detection: UV at 220 nm Injection volume: 100 μL Under these conditions, bovine insulin has a retention time of approximately 7.4 minutes. A peak that can be attributed to deamidate insulin is located at the posterior border of the main peak. The degree of deamidation is used to indicate stability and is calculated by expressing the peak area of deamidation as a percentage of the total peak area. The total degradation is expressed as the area of all the degrading peaks as a percentage of the total peak area.

TABLE 1 Percentage of total degradation and deamidation of bovine crystalline insulin not spray dried TABLE 2 Percentage of total degradation and deamidation of insulin microparticles The results indicate that the degree of deamidation as of total degradation increases with time, for all the batches evaluated. Also, the data suggest that spray drying confers additional stability to the protein, and that the control of bovine crystalline insulin suffers from . JA * ztn. increased degradation compared to the microparticle formulations at comparable time points after storage at 30 ° C / 60% RH. To investigate whether this was also observed with human insulin, the human insulin microparticles were prepared (by the same general procedure as described above) and placed in accelerated stability at 40 ° C / 75% RH. All samples were analyzed by CLAR-FI at the initial time point, and also after 1 week, 2 weeks and 5 weeks.

TABLE 3 Storage effect at 40 ° C / 75% RH on deamidation and total degradation levels of human insulin recombinant from E. Coli TABLE 4 Effect of storage at 40 ° C / 75% RH on deamidation and total degradation levels of human insulin microparticles Comparing tables 3 and 4, the microparticle formulation of human insulin is less prone to degradation, showing only 3.32% of the total degradation after 5 weeks at 40 ° C / 75% RH compared to 8.40% the total degradation for the stored material as received under the same conditions.

EXAMPLE 2 A solution of bovine DNase (molecular mass 31 kD) for spray drying was prepared by dissolving the source material in water containing 1 mm of phenylmethylsulfonyl fluoride (PMSF). PMSF is present to inhibit proteolytic degradation. The resulting supply material solution comprised 50 mg / ml DNase.

Subsequently, the solution was spray-dried using a Mini-spray dryer with an inlet temperature of 130 ° C, an outlet temperature of 85 ° C and a feed rate of the solution of approximately 0.8 ml / minute. The activity was measured by the rate of increase of the spectrophotometric absorbance at 260 nm of DNA (hyperchromicity test), and CLAR-gel penetration chromatography was used to evaluate the physical stability. The spray-dried DNase retained approximately 90% of its initial activity and showed no change in physical stability. For the spray-dried material stored at 40 ° C / 75 /%? of HR and 25 ° C / 60% RH, and a source material stored at 25 ° C / 60% RH, there was comparable activity and physical stability in the fourth and eighth weeks.

EXAMPLE 3 A solution of bovine trypsin (molecular mass 23.3 kD) for spray drying was prepared to dissolve the source material (crystallized) in water. The resulting supply material solution comprised 50 mg / ml trypsin. Subsequently the solution was spray-dried as described in Example 2. The activity was measured against azocasein substrate, and CLAR-gel penetration chromatography was used to evaluate the physical stability.

• • * "- - ~ - •" • '-' 'Spray-dried trypsin retained approximately 100% of its initial activity and showed no change in physical stability. A comparison of the spray dried material stored at 4 ° C, 25 ° C / 60% RH and 40 ° C / 75% RH, and a source material stored at 25 ° C / 60% RH, showed no loss substantial activity or physical stability in the twelfth week.

EXAMPLE 4 A solution of reduced glutathione (a 307D molecular mass peptide) to be spray dried was prepared by dissolving the crystalline source material in water. The resulting supply material solution comprised 100 mg / ml of reduced glutathione. The solution was spray-dried using a Buchi Mini B-191 spray dryer with an inlet temperature of 100 ° C, and an outlet temperature of 74 ° C, and a feed rate of the solution of approximately 1 ml / min. . Spray drying using either compressed air or nitrogen for atomization of the fluid stream did not result in a significant increase in the level of oxidized glutathione (initially present at 0.8% w / w, increasing to 0.9% w / w ).

Claims (19)

NOVELTY OF THE INVENTION CLAIMS

1. Microparticles, which are obtained by spray drying a substantially pure solution of a therapeutic agent, characterized in that the microcapsules consist essentially only of the therapeutic agent that has its therapeutic activity when administered to the lungs.

2. The microparticles according to claim 1, further characterized in that the agent is not crystalline / amorphous.

3. The microparticles according to claim 1 or claim 2, further characterized in that the therapeutic agent is a protein or peptide.

4. The microparticles according to any of the preceding claims, further characterized in that the agent is insulin.

5. The microparticles according to any of claims 1 to 3, further characterized in that the agent is DNase.

6. The microparticles according to any of claims 1 to 3, further characterized in that the agent is trypsin.

7. The microparticles according to any of the preceding claims, further characterized in that they consist essentially of the agent and a salt formed in solution of the agent.

8. The microparticles according to claim 7, further characterized in that the salt is formed from an alkali and a mineral acid.

9. The microparticles according to any of the preceding claims, further characterized in that the microparticles comprise less than 4% by weight of the total solids.

10. A closed container containing, at ambient humidity, microparticles according to any of the preceding claims.

11. An inhaler device comprising microparticles according to any of claims 1 to 9.

12. A process for the preparation of microparticles according to any of claims 1 to 9, comprising spray-drying a substantially pure solution. of a therapeutic agent.

13. The method according to claim 12, further characterized in that the solution contains more than 10 mg / ml of agent.

14. The method according to claim 13, further characterized in that the solution contains 20 to 200 mg / ml of agent.

15. The process according to claim 13, further characterized in that the solution contains 50 to 100 mg / ml of agent.

16. The process according to any of claims 12 to 15, further characterized in that the solution contains less than 4% salt.

17. The process according to any of claims 12 to 16, further characterized in that the solution is free of pH regulating salt.

18. The method according to any of claims 12 to 17, further characterized in that the agent is insulin and the solution is obtained by dissolving Zn insulin in acid, and then adding an alkali.

19. The process according to claim 18, further characterized in that the Zn is removed from the solution before being spray dried. ^^^ M-MM