Plga Microspheres as a Delivery Vehicle for Sustained Release of Tetracycline: Biodistribution in Mice After Subcutaneous Administration

This study was designed to investigate the preparation, in vitro release, in vivo pharmacokinetics and tissue distribution of tetracycline-loaded microspheres. Tetracycline-loaded microspheres composed of PLGA were prepared by a spray drying method. The prepared microspheres were characterized according to drug loading, size and shape. The in vitro release profiles indicate that the release of tetracycline from the microspheres exhibits sustained release behavior. The results obtained from tissue distribution study by subcutaneous administration were also consistent with the results of in vitro release. After the burst release, the drug release rate was greatly reduced at the administration site, with the whole in vivo release continuing for 21 days. No tetracycline in blood, liver or kidney could be detected after 4 hours. Based on these research data, tetracycline-loaded PLGA microspheres were capable of releasing tetracycline in a controlled way, thereby constantly providing an appropriate drug level at the administration site.