Formulation and optimization of clotrimazole oromucosal emulgels
Clotrimazole is an antifungal agent of choice for the management of oral candidiasis. In order to improve its aqueous release and enhance its residence time at the target site of oral mucosa, emulgel formulations of clotrimazole were investigated. Different oils and Tween 80/ethanol combinations were examined as drug carrier systems and central composite design was used for the optimization of the emulgels. The optimized emulgels were characterized for their globule size, robustness, release kinetics, and the effect of storage conditions on their release profiles. All the prepared formulations showed a shear-thinning rheological behaviour indicating structural breakdown of intermolecular interaction between polymeric chains and were homogeneous with pH very close to that of normal oral cavity. The optimized formulations containing 30% Tween 80/ethanol solution (2:1 ratio), 12.4% olive oil/oleic acid combination (1:1 ratio), and 4% sodium carboxymethyl cellulose released clotrimazole in vitro with approximately zero order release kinetics as a result of polymer relaxation and erosion in the aqueous media. They also showed superior residence time and spreadability in comparison to the marketed oromucosal gels with less than 200 nm globule size and nearly the same release profile over three months of storage at real and accelerated time conditions.
Keywords: clotrimazole, oromucosal emulgel, optimization, central composite design, drug release