Delivery of metronidazole from purified Nigerian sheabutter in comparison to standard and modified ointment bases

Abstract

The drug delivery propensities of 1 %w/w metronidazole (MTZ) ointment formulations in purified Nigerian sheabutter base have been compared to those of similar formulations produced with standard or  modified bases, with a view to determining bases capable of ensuring rapid release of MTZ from ointment formulations intended for topical treatment of rosaceae. Ten bases, having four different combined characteristics, were studied. MTZ ointment samples were prepared in each base by levigation technique. Drug release rates were determined by an in vitro dialysis method using the Erweka dissolution apparatus at pH 5, and 37°C in 180-min tests; and the dissolution samples quantified by UV analysis. The release pattern of MTZ from the bases was: hydrophilic hydrous bases > hydrophilic anhydrous bases > hydrophobic (hydrous or anhydrous) bases. The highest drug release rate and extent occurred from cetomacrogol cream (5.39 mg min^-½ ; 61.5%), while the lowest occurred from simple ointment (SO) base (0.30 mg min^-½ ; 4.2%). The drug release capacity of SO was significantly improved by incorporation of a surfactant (cetrimide). MTZ in sheabutter ointment exhibited intermediate drug release values (0.73 mg min^-½ , 9.30%), which were neither enhanced by hydration nor by the surfactant.

Key Words: Metronidazole, Sheabutter, Ointment Bases, In Vitro Drug Release