Anteneh Belete

Formulation of Sustained Release Floating Microspheres of Furosemidefrom Ethylcellulose and Hydroxypropyl Methylcellulose Polymer Blends

Furosemide is a potent and commonly used loop diuretic. It is absorbed largely in the stomach and upper small intestine. This narrow absorption window is responsible for its low bioavailability of about 50%, and variable and erratic absorption. The objective of the present investigation was to formulate and evaluate floating microspheres of furosemide for prolonged buoyancy with sustained delivery of the drug into the gastric content. Furosemide loaded microspheres were prepared by the solvent evaporation method. The drug entrapment efficiency was high for all of the formulations ranging from 86.2 to 98.4%. The yield of microspheres production was good partticularly at increased EC/HPMC ratio and lower temperatures. Drug amount and EC/HPMC ratio showed highly significant effects (p<0.0001) on cumulative drug release and buoyancy of microspheres. Floating microspheres that effectively sustain the drug release more than 12 h and exhibit buoyancy of greater than 77% in 12 h were developed. Finally the study confirmed that various furosemide loaded EC/HPMC microspheres formulations could be developed that effectively sustain the drug release for a desired period by varing the ratio of EC and HPMC, and drug amount.

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