Development of a calcium phosphate-gelatin composite as a bone substitute and its use in drug release

This study was carried out to develop a calcium phosphate-gelatin composite implant that would mimic the structure and function of bone for use in fil ling voids or gaps and to release bioactive compounds like drugs, growth ho rmones into the implant site to assist healing. XDS analysis of the synthes ized calcium phosphate revealed a calcium to phosphorus molar ratio of ca. 2.30, implying a less erodible material than hydroxyapatite (1.67). Release of the antibiotic gentamicin from the implant was with a burst, whether in situ or in vivo, followed by an almost constant release for about three mo nths. It was found that the release rate could be decreased by increasing t he density of the gelatin membrane. Upon implantation into rabbit tibia the release duration was substantially shortened (to about 4 weeks) with respe ct to the in situ tests basically due to the degradation of gelatin. In viv o studies with rabbits confirmed this degradation. The composite was perfec tly biocompatible as shown by the histological studies. It, thus! has a gre at potential as a bone substitute material. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.