Development and in-vitro evaluation of sustained release poloxamer 407 (P407) gel formulations of ceftiofur.

The objective of this study was to develop sustained release Poloxamer 407 (P407) gel formulations of ceftiofur for treating foot infections in cattle. The formulations contained 25-35% (w/v) P407 alone or with polyvinyl pyrrolidone (PVP), carboxy methylcellulose (CMC), or hydroxylpropyl methylcellulose (HPMC) as an additive. The in-vitro release profiles of ceftiofur from the P407 formulations and the gel dissolution profiles were obtained simultaneously. Ceftiofur release followed zero order kinetics and correlated well with the weight percentage of P407 dissolved, indicating that the overall rate of release of ceftiofur is controlled by dissolution of the P407. An increase in P407 content from 25 to 35% resulted in a decrease in the rate of ceftiofur release. However, it appears that other factors may have also affected the drug release rate. Inclusion of PVP, CMC, and HPMC in the gel decreased the rate of release of ceftiofur to some extent. A decrease in the temperatures of the release medium decreased the release rate of ceftiofur, but not the rate of gel dissolution. The pH of the release medium showed a very slight effect on the release of ceftiofur and did not affect gel dissolution due to the non-ionic nature of P407.