In vitro evaluation of lipid matrices for the development of a sustained-release sulfamethazine bolus for lambs

The aim of this study is the development of a high-density bolus to be given to lambs in order to release sulfamethazine during 4 days after a single oral administration. The suitability of 12 lipid matrix formulations was assessed in order to maintain the integrity of the tablet even after complete dissolution of the active substance. The influence of both nature and concentration of the lipid excipient on the in vitro release of sulfamethazine was investigated. The influences of the granulation method and of the compression force were assessed on a formulation containing Cutina(R) HR as a binding and sustained-release agent. Finally, stability tests showed that the in vitro release characteristics remain unchanged during storage.