Abstract: 
Sustained-release microcapsules of mebendazole were prepared using Prosopis africana peel powder (PAPP), a novel biopolymer, in the ratios of 1:1, 1:2 and 1:3 by the emulsification method. The microcapsules were evaluated for particle size, morphology, encapsulation efficiency, thermal property, in vitro drug release and larvicidal activity on 20 active mosquito larvae. The results show that particle size and encapsulation efficiency (EE%) of the mostly irregularly shaped microcapsules were independent of polymer concentrations, yet the 1:3 (inner coat) and 1:2 (outer coat) microcapsules gave the highest EE% of 72 and 81 % respectively. Thermograms of the microcapsules generally revealed lower melting temperatures suggesting total disappearance of mebendazole peak, indicating that mebendazole was molecularly dispersed in the polymeric microcapsules. The in vitro release study indicates that drug release in simulated intestinal fluid (SIF, pH 7.2) followed a pattern: 1:1>1:2>1:3 (for the inner coat microcapsule) and 1:1>1:3>1:2 (for the outer coat) better than in simulated gastric fluid (SGF, pH 1.2). Microcapsules (1:3 outer coat) recorded 65% death of mosquito larvae in 24 h while mebendazole recorded 100 % death in 24 h; microcapsules made with the inner coat recorded death of 50 % of the mosquito larva in 24 h. The larvicidal activity of mebendazole was sustained for up to 3 days in all the formulations unlike the reference standard. This study suggests that PAPP could be employed in sustained delivery of mebendazole for improved patient compliance thus reducing the frequency of drug administration with associated side effects of mebendazole.

Keywords: Mebendazole, Microcapsule, Prosopis africana Peel Powder (PAPP), Sustained Drug Release, Larvicidal Activity.