Polyesters

Details Polyesters Polyesters

1994-09-26

1998-12-15

Truong, Duc

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From carboxylic acid or derivative thereof

528272, 5282955, 528302, 4242781, 4242791, 4242801, 114 2, 114 23, 114 54, C08G 6300

Patent

active

058498591

DESCRIPTION:

BRIEF SUMMARY
The invention relates to biodegradable and biocompatible polyesters and to pharmaceutical compositions containing them.
The function of the polyesters in the pharmaceutical compositions is to control the rate of the release of pharmacologically active compounds from the compositions and the duration of the activity in the animal body to which the compositions are administered.
Although we do not wish to be bound by any theory, it is believed that when administered to the body the polyesters can initially screen off the pharmacologically active compounds from the aqueous media, present in the body, whereafter due to biodegradation of the polyesters or to diffusion of the drug compounds through the polyesters, the drug releases and becomes medically active. This may be an interesting mechanism e.g. when the polyesters are water-insoluble.
In the compositions the drug compound may also be chemically bound to the polyesters, whereafter due to biodegradation of the polyester molecule part, the drug releases from the compositions. This may be an interesting mechanism e.g. when the polyesters are water-soluble and the polyester-drug compound combination functions as a water-soluble pro-drug.
Dependent on the type of release mechanism the drug compound can be set free e.g. within one or more hours or days if chemically bound to polyesters or within one or more days, weeks or months if screened off by the polyesters.
The invention provides biodegradable, biocompatible polyesters comprising (C.sub.3-10) alkylene carbonic acid ester units, each alkylene group being a C.sub.3 -alkylene group having 1 oxy substituent or a (C.sub.4-10) alkylene group having 2-8 oxy substituents, each of the oxy substituents occurring independently as a hydroxyl group, or as a moiety independently comprising an ester or an ortho ester or an acetal group.
Thus the polymers may contain e.g. mixtures of different oxy substitutents. Preferably the oxy substituents are the same. Representative compounds may contain however a hydroxyl group and an oxy substituent, e.g. up to 30 or 20% hydroxyl groups.
The polyesters of carbonic acid are in principle biodegradable since their backbone chains contain carbonic acid esters bonds --O--C(.dbd.O)--O-- which are hydrolysable in the human body's aqueous media, at suitable pH, e.g. in the presence of hydrolytic enzymes, e.g. esterases. Polyesters containing carbonic acid ester groups are generally known as rather stable polymeric materials. Exceptions reported so far are poly(ethylene carbonate)s, which decompose within approximately 2-4 weeks in vivo.
The next higher homologue, namely poly(trimethylenecarbonate), is not completely decomposed in vivo even after 6 months. Both poly(ethylenecarbonate) and poly(trimethylene carbonate) are polymers in which the alkylene group is unsubstituted.
The polyesters of the invention comprise preferably C.sub.3 -alkylene groups or (C.sub.4-10) alkylene groups situated between the carbonic acid ester groups, each having 2 terminal --CH.sub.2 -- groups. (C.sub.4-10)alkylene groups have a (C.sub.2-8) alkylene central part carrying at least 2 and at most 8 hydroxyl groups in free form or in a form in which at least one of them is a derivatized hydroxyl group, comprising an ester or an orthoester or an acetal residue. A C.sub.3 -alkylene group has a methylene central part, carrying 1 hydroxyl or derivatized hydroxyl group. Polyesters having such C.sub.3 -alkylene or (C.sub.4-10) alkylene units between the carbonic acid ester groups are novel.
They are in principle biodegradable, many quickly, others slowly, depending on their structural type. Preferred are those which biodegrade within 1-90 days.
Preferably all the carbon atoms belonging to the (C.sub.2-8) alkylene central part of the (C.sub.4-10) alkylene groups are oxysubstituted.
The polyesters of the invention can be prepared by methods known per se, e.g. by reacting: 1959. 631, 11, (1973) (1975)
The invention thus also provides a process for the production of a polyester of the invention by reacting a bifunctional r

REFERENCES:
patent: 2789968 (1957-04-01), Reynolds
patent: 4101533 (1978-07-01), Hafferty et al.
patent: 4356166 (1982-10-01), Peterson et al.
patent: 4968611 (1990-11-01), Traussnig et al.
patent: 5188837 (1993-02-01), Domb
M. Takanashi, et al. Die Makromolekulare Chemie, vol. 183, No. 9, Sep. 1982 .

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