IN-VITRO RELEASE OF THEOPHYLLINE FROM CROSS-LINKED GELATIN CAPSULES

Hard gelatin capsules were manufactured in our laboratory and cross-li nked with terephtaloyle chloride before being filled with pure theophy lline powder. Different reaction times were used to carry out the cros s-linking process, either before or after drying of capsules. The in v itro drug release was carried out on comparison with commercial and la boratory-made conventional hard gelatin capsules and with Dilatrane(R) . Release profiles showed that cross-linking before or after drying of capsules allowed sustained release of drug. However, a slower rate of release was shown from capsules cross-linked before drying. The rate of release decreased when the cross-linking reaction time was increase d. When the reaction time was of 30 min, capsules exhibited a nearly z ero-order release (r = 0.999) with a cumulative drug release of 63.24 +/- 10.48% only. Cumulative drug release, DT50% and DE from capsules c ross-linked before drying had nearly the same release characteristics as Dilatrane(R). Cross-linking before and after drying of capsules per mitted showing up the influence of moisture on the cross-linking densi ty and, therefore, on the rate of drug release. Copyright (C) 1996 Els evier Science B.V.