Formulation and Evoluation of Certain Topically Appied Drugs

Formulation and Characterization of Gliclazide Solid Dispersions.The purpose of this study was to improve the dissolution of Gliclazide (Glz) for enhancing its bioavailability and therapeutic efficacy.Physical mixtures (PMs) and solid dispersions (SDs) of Glz with each of polyethylene glycol 4000 (PEG 4000) and polyethylene glycol 6000 (PEG 6000) in ratios 10: 90, 8: 92, 5: 95 and 1: 99 (drug-to-carrier w/w) were prepared. Glucose (glu) and urea (UR) in ratios 1:1, 1:2, 1: 3, 1: 5 and 1: 10 (drug-to-carrier w/w) were also prepared. All SDs were prepared by solvent evaporation method. The equilibrium solubility of Glz in presence of different concentrations of the above mentioned carriers was determined at 25°C and the influence of different pH on the solubility of Glz was also examined. The dissolution of all prepared samples (PMs and SDs) was carried out in media of pure distilled water pH 6.5. All SDs and PMs as well as individual components were subjected to inspection by FTIR spectroscopy, DSC and X-ray powder diffraction.The results revealed that, the aqueous solubility of Glz was favoured by the presence of PEG 4000 and PEG 6000 while the aqueous solubility was slightly improved when glu or UR was used as a carrier. The solubility of Glz increased with increasing pH (higher in alkaline medium rather than acidic one). The type of carrier and drug to carrier ratio had great influence on the rate and extent of dissolution of Glz from its SDs. All the investigated carriers improved the dissolution rate of Glz. The highest rates were obtained from PEG 6000 followed by PEG 4000, glu and finally UR SDs at mixing ratios of (1:99), (1:99), (1:10) and (1:10) respectively. Physical characterization of all systems prepared revealed structural changes in the prepared SDs from the plain drug, which may account for increased dissolution rates.