Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Peptide containing doai
Reexamination Certificate
1998-03-20
2001-10-30
Russel, Jeffrey E. (Department: 1653)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Peptide containing doai
C514S003100, C530S303000, C530S305000
Reexamination Certificate
active
06310038
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to zinc free insulin crystals having a diameter below 10 &mgr;m and to therapeutic powder formulations suitable for pulmonary administration comprising such insulin crystals.
BACKGROUND OF THE INVENTION
Diabetes is a general term for disorders in man having excessive urine excretion as in diabetes mellitus and diabetes insipidus. Diabetes mellitus is a metabolic disorder in which the ability to utilize glucose is more or less completely lost. About 2% of all people suffer from diabetes.
Since the introduction of insulin in the 1920's, continuous strides have been made to improve the treatment of diabetes mellitus. To help avoid extreme glycemia levels, diabetic patients often practice multiple injection therapy, whereby insulin is administered with each meal.
Insulin is usually administrated by s.c. or i.m. injections. However, due to the adherent discomfort of injections alternative ways of administration such as nasal and pulmonary has been extensively investigated. For a review on alternative routes of administration of insulin, see Danielsen et al. New routes and means of insulin delivery, in: Childhood and Adolescent Diabetes (Ed. Kelnar), Chapman & Hall Medical, London 1994, pp. 571-584.
In order to circumvent injections, administration of insulin via the pulmonary route could be an alternative way to provide absorption profiles which mimic the endogenous insulin without the need to inject the insulin.
DESCRIPTION OF THE BACKGROUND ART
Administration of insulin via the pulmonary route can be accomplished by either an aqueous solution or a powder preparation. A description of the details can be found in several references, one of the latest being by Niven, Crit. Rev. Ther. Drug Carrier Sys, 12(2&3):151-231 (1995). One aspect covered in said review is the stability issue of protein formulations, aqueous solutions being less stable than powder formulation. So far, all powder formulations have been described as mainly amorphous.
A review of the permeation enhancers useful for the promotion of trans-mucosal absorption is found in Sayani et al., Crit. Rev. Ther. Drug Carrier Sys, 13(1&2): 85-184 (1996).
Patton et al., Inhale Therapeutic Systems, PCT WO 95/24183, claim a method for aerosolising a dose of insulin comprising providing the insulin as a dry powder dispersing an amount of the dry powder in a gas stream to form an aerosol capturing the aerosol in a chamber for subsequent inhalation.
It has been found that when insulin is combined with an appropriate absorption enhancer and is introduced into the lower respiratory tract in the form of a powder of appropriate particle size, it readily enters the systemic circulation by absorption through the layer of epithelial cells in the lower respiratory tract as described in U.S. Pat. No. 5,506,203. The manufacturing process described in said patent, comprising dissolution of insulin at acid pH followed by a pH adjustment to pH 7.4 and addition of sodium taurocholate before drying the solution by vacuum concentration, open drying, spray drying, or freeze drying, results in a powder composed of human insulin and absorption enhancer. The powder is characterized as mainly amorphous determined under a polarized light microscope. The desired particle size distribution is achieved by micronizing in a suitable mill, such as a jet mill, and the components may be mixed before or after micronizing. The biological effect of the powder obtained according to the methods described in this patent is only seen in the presence of a substantial amount of enhancer.
Platz et al., Inhale Therapeutic Systems, PCT WO 96/32149, describes spray drying of zinc insulin from a solution containing mannitol and a citrate buffer, pH 6.7. The inlet temperature is 120 to 122° C., the outlet temperature 80-81° C. The mass median aerodynamic diameter, MMAd, of the obtained insulin particles was determined to 1.3 to 1.5 &mgr;m.
In his thesis, “Insulin Crystals”, Munksgaard Publisher 1958, p. 54-55, Schlichtkrull describes crystallization of zinc free, recrystallized porcine insulin from a solution comprising 0.01 M sodium acetate and 0.7%~0.12 M sodium chloride and 0.1% methylparahydroxybenzoate and using a pH of 7.0. The crystals obtained were 10-50 &mgr;m rhombic dodecahedral crystals showing no birefringence.
Jackson, U.S. Pat. No. 3,719,655 describes a method of purification of crude porcine and bovine insulin by crystallization. Zinc free crystals of insulin are obtained by crystallization at pH 8.2 (range 7.2-10) in the presence of 0.5 M (range 0.2 M-1 M) of a sodium, potassium, lithium or ammonium salt. Crystallization is achieved by addition of 1 N alkali metal hydroxide or 1 N ammonia to a solution of crude insulin in 0.5 N acetic acid to a pH of 8.2 is obtained. Alternatively, crystallization is achieved in an aqueous solution of impure insulin at pH 8.2 by addition of solid sodium chloride to a concentration of sodium ions of 0.45 M. The crystals appear in the octadecahedral or dodecahedral forms, i.e. crystals belonging to the cubic crystal system.
Baker et al., Lilly, EP 0 709 395 A2 (filed Oct. 31, 1994) describe a zinc free crystallization process for LyS
B28
-Pro
B29
human insulin characterized by adjustment of the pH of a strongly buffered acid solution containing metal cations or ammonium ions and a preservative with metal hydroxide or ammonia to a value between 8.5 and 9.5.
The known methods for the manufacture of insulin particles of the desired size for pulmonary administration are cumbersome, generate problems with insulin dust and the investments in equipment are large. Furthermore, insulin is exposed to conditions where some denaturation is likely to take place. Thus WO 96/32149 discloses spray drying in a temperature range of 50° C. to 100° C., followed by milling of the particles to achieve to desired particle size.
Furthermore, the known powder formulations for pulmonary administration which have been described as mainly amorphous have a tendency to associate into aggregates in the dry powder.
DESCRIPTION OF THE INVENTION
Definitions
The expression “enhancer” as used herein refers to a substance enhancing the absorption of insulin, insulin analogue or insulin derivative through the layer of epithelial cells lining the alveoli of the lung into the adjacent pulmonary vasculature, i.e. the amount of insulin absorbed into the systemic system is higher than the amount absorbed in the absence of enhancer.
In the present context the expression “powder” refers to a collection of essentially dry particles, i.e. the moisture content being below about 10% by weight, preferably below 6 % by weight, and most preferably below 4% by weight.
The diameter of the crystals is defined as the Martin's diameter. It is measured as the length of the line, parallel to the ocular scale, that divides the randomly oriented crystals into two equal projected areas.
BRIEF DESCRIPTION OF THE INVENTION
It is an object of the present invention to provide an insulin powder suitable for pulmonary delivery which has a reduced tendency to associate into aggregates in the dry powder compared to the pulmonary insulin particles described in the prior art.
According to the present invention this object has been accomplished by providing zinc free insulin crystals having a diameter below 10 &mgr;m.
The crystals of the present invention furthermore exhibit a better stability profile than powders of essentially the same composition prepared by spray drying, freeze-drying, vacuum drying and open drying. This is probably due to the amorphous state of powders prepared by the other methods described. By this means it is possible to store the powder formulations based on the crystals of the present invention at room temperature in contrary to human insulin preparations for injections and some amorphous insulin powders without stabilizing agent which have to be stored between 2° C. to 8° C.
Furthermore, therapeutical powder formulations comprising the insulin crystals of the invention elucidates better flowing properties than
Green, Esq. Reza
Novo Nordisk A S
Russel Jeffrey E.
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