| PATENT EXAMPLES |
Matrices comprising PCPM were formulated either by compression or injection molding, each being deemed equivalent to the other. For evaluation purposes, two kinds of matrices were prepared: a PCPM matrix without any biologically active substance whatsoever, and a PCPM matrix containing cholic acid. To formulate the PCPM matrices without any active substance, purified PCPM polymer in the solid crystalline form was ground into a pulverized powder using a Micro Mill Grinder (Fisher Scientific) and sieved into sized particles ranging from 150300 micrometers (hereinafter "um") in diameter. The polymeric particles were then compressed into circular disc configurations using a Carver Laboratory press in the following manner: the PCPM particles were placed between sheets of aluminum foil and subjected to temperatures ranging from 93.degree. C.-116.degree. C. and pressures ranging from 22kpa-81kpa, using shims to regulate the thickness of the disc being formed. It was found that applying temperatures below 120.degree. C., the pulverized PCPM did not flow well and thus yielded matrices with poor mechanical properties; on the other hand, using temperatures above 145.degree. C., many of the matrices formed were found to be brittle. In addition, there were no discernable differences in the properties of the matrices when pressed within the range 22 - 81 KPSI. Accordingly, the conditions chosen for forming the matrix were 121.degree. C. and 22 KPSI consistently when molding PCPM polymer. These molding conditions gave matrices with useful mechanical properties and minimized the possibilities of morphological changes within the polymer during the molding process. A series of PCPM matrices were then prepared in disc shape configurations whose face surface are ranged from 0.2-0.8 square centimeters and had a thickness ranging from 0.05-0.10 centimeters
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