Alkylene oxide polymer compositions

Details Alkylene oxide polymer compositions Alkylene oxide polymer compositions

2000-09-25

2001-11-27

Acquah, Samuel A. (Department: 1711)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Capsules

C428S402000, C428S402210, C424S464000, C424S485000, C424S486000, C424S488000, C424S489000

Reexamination Certificate

active

06322811

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to alkylene oxide polymer compositions. More specifically, the present invention relates to alkylene oxide polymer compositions having molecular weight distributions suitable for the manufacture of films, e.g., water soluble, flexible films for use as soft gel capsules.
BACKGROUND OF THE INVENTION
Gelatin is a protein material produced by hydrolysis of collagen from animal bones and connective tissues. Gelatin has served as an encapsulating material, a coating for pills, an emulsifying agent, a coating for photographic materials, a bacterial culture medium, a component of printers' rollers and hectograph plates, an ingredient of popular desserts, and for many other widely varied uses.
One common use for gelatin is in the manufacture of soft gel capsules for the delivery of active ingredients. Although gelatin is generally strong and tough, its extensibility and flexibility are generally low. In addition, since gelatin is derived from animal sources, there are often inconsistencies in product quality from batch to batch. The physical and chemical properties of gelatin are a function of the source of the collagen, method of manufacturing, conditions during extraction and concentration, thermal history, pH and the chemical nature of impurities and additives. Moreover, during storage, gelatin often undergoes a crosslinking reaction which in turn changes the dissolution character and the drug bio-availability characteristics. This shortens the useful life of the gelatin. Thus, mechanical failures of gelatin soft gel capsules are often encountered. Additionally, the use of animal derived materials, such as gelatin, has come under regulatory review due to concerns regarding the transmission of animal based illness.
Accordingly, new materials are desired which can function as replacements for gelatin, particularly gelatin based films useful for manufacturing soft gel capsules and the like.
SUMMARY OF THE INVENTION
By the present invention, problems commonly associated with the use of gelatin in manufacturing films, used for example in manufacturing soft gel capsules, have been solved. More specifically, films manufactured using the polymer compositions of the present invention can have enhanced stability, processability and physical and chemical properties as compared to films made from gelatin.
In accordance with the present invention, alkylene oxide polymer compositions having certain molecular weight distributions are provided. Advantageously, the polymer compositions of the present invention are water soluble. However, quite surprisingly, films made from the compositions of the present invention are substantially insoluble in aqueous polyethylene glycol solutions, a liquid often used as a physiologically acceptable carrier, when such solutions contain about 25 wt. % water or less. As a result of the high water tolerance of the films, capsules made from these films can accommodate increased amounts of active ingredients, e.g., acetaminophen, in the capsule. In accordance with the present invention, enhancements in the concentration of the active ingredients in the fill can often be up to 30 percent or more as compared to a comparable gelatin capsule.
DETAILED DESCRIPTION OF THE INVENTION
The alkylene oxide polymers of the present invention are prepared from alkylene oxide monomers containing from about 1 to 5 carbon atoms per molecule, e.g., ethylene oxide or propylene oxide, as well as copolymers and derivatives thereof. Alkylene oxide monomers suitable for use as starting materials are commercially available.
Preferably, the alkylene oxide polymers of the present invention comprise ethylene oxide polymers. The ethylene oxide polymers include, for example, homopolymers of ethylene oxide and copolymers of ethylene oxide with one or more polymerizable comonomers. The particular comonomer is not critical to the present invention and may contain hydrocarbon substituents, such as, for example, alkyl, cycloalkyl, aromatic, alkene (also referred to as alkylene) or branched alkyl or alkene groups; provided, however, that the water solubility or water-dispersibility is maintained. Further details concerning the preparation of ethylene oxide polymers is known in the art. See for example, U.S. Pat. No. 2,969,403 issued to Helmut et al., U.S. Pat. No. 3,037,943 issued to Bailey et al., U.S. Pat. No. 3,167,519 issued to Bailey et al., U.S. Pat. No. 4,193,892, issued to Goeke et al. and U.S. Pat. No. 4,267,309 issued to Goeke et al.
The desired molecular weight distribution of the alkylene oxide polymers of the present invention can be obtained by polymerizing the alkylene oxide monomers directly or by blending alkylene oxide polymers having different molecular weight ranges. For polymers having a molecular weight of less than 50,000 grams per gram mole (“g/gmol”), as used herein, the term “molecular weight” means number average molecular weight (sometimes referred to herein as “M
n
”). For polymers having a molecular weight of 50,000 g/gmol or higher, as used herein, the term “molecular weight” means weight average molecular weight (sometimes referred to as “M
w
”). Techniques for determining the average molecular weight are known to those skilled in the art. A suitable technique to determine number average molecular weight is by end group titration and a suitable technique to determine the weight average molecular weight is by light scattering.
Often in the art, alkylene oxide polymers having molecular weights of about 50,000 and higher are referred to as polyalkylene oxides, e.g., polyethylene oxide, and alkylene oxide polymers having molecular weights of less than about 50,000 are referred to as polyalkylene glycols, e.g., polyethylene glycol. Polyalkylene oxides and polyalkylene glycols are commercially available, for example, from Union Carbide Corporation, Danbury, Conn., under the tradenames POLYOX® Water Soluble Resins and CARBOWAX® polyethylene glycols (PEG), respectively. Preferably, various polyalkylene glycols and polyalkylene oxides are blended in appropriate proportions to achieve the desired molecular weight distribution of the alkylene oxide polymer compositions of the present invention.
In accordance with the present invention, the alkylene oxide polymer compositions typically comprise from 1 to about 25 wt. %, more typically from 1 to about 19 wt. %, preferably from about 2 to 19 wt. %, and more preferably from about 3 to 18 wt. % of alkylene oxide polymer having a molecular weight of about 100 to 2,000 g/gmol, typically 100 to 1,000 g/gmol.
The alkylene oxide polymer compositions further typically comprise from about 10 to 60 wt. %, more typically from about 10 to 50 wt. %, preferably from about 20 to 45 wt. % and more preferably from about 25 to 35 wt. % of alkylene oxide polymer having a molecular weight of from about 1,000 to 50,000 g/gmol, typically about 2000 to 50,000 g/gmol and preferably from about 1,000 to 25,000 g/gmol.
Additionally, the alkylene oxide polymer compositions of the present invention typically comprise from about 25 to 89 wt. %, preferably from about 30 to 75 wt. %, more preferably from about 35 to 70 wt. % and most preferably from about 45 to 65 wt. % of alkylene oxide polymer having a molecular weight of from about 50,000 to 10,000,000 g/gmol, preferably from about 100,000 to 4,000,000 g/gmol.
Unless otherwise indicated, the weight percentages of the various molecular weight fractions are based on the total weight of the alkylene oxide polymer composition, e.g., including water, other polymers and additives as hereinafter described. The alkylene oxide polymer compositions of the present invention may comprise one or more alkylene oxide polymers within each molecular weight range. For instance, in one aspect of the invention, the alkylene oxide polymer composition comprises an alkylene oxide polymer having a molecular weight of 1,450 g/gmol and an alkylene oxide polymer having a molecular weight of about 8,000 g/gmol, both of which are within the more broadly stated range of about 1,000 to 50

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