DEVELOPMENT AND IN VITRO EVALUATION OF MICROEMULSION FOR TWO DIFFERENT LOG P COMPOUNDS
Vijaya R.* and Rajagopal R.
ABSTRACT
The investigation was aimed to study the effect of physico chemical properties particularly logP of compounds in the development of microemulsion (ME). Here telmisartan and glipizide having different logP were selected as model compounds. The microemulsion was prepared after appropriate screening of oil, surfactant and co surfactant. The formulations were optimized with respect to oil solubility of drug, clarity and the ratio of surfactant and co surfactant (Smix) for which pseudoternary phase diagram was constructed. Formulations of high, medium and low solubilizing oil with high proportion of oil, Smix and water (TF1 to TF9 & GF1 to GF9) were evaluated for size, drug content and in vitro release. Both drugs had exhibited maximum solubility in Capmul oil, medium solubility in capryol 90 and low solubility in Lauroglycol FCC. Surfactants of
cremophore EL, Tween 80 and co surfactants of labrasol, transcutol were used and the ratio of Smix for maximum solubility in oil was found to be 80:20. The drug content had ranged from 96.52% to 108.98% when analysed by HPLC. The size of microemulsion was 220.7nm and 210.5nm for telmisartan and glipizide respectively. Glipizide, formulations of high solubilising oil with low oil content (GF1 & GF2) (25.08mcg/ml & 40.42mcg/ml) showed a higher drug release than their medium and low solubilising oil counterparts. In case of telmisartan, formulations of low solubilising oil (TF7, TF8 & TF9) (15.17mcg/ml, 16.69mcg/ml & 16.49mcg/ml) showed a higher drug release than their medium and high solubilising oil. Overall, glipizide has elicited a higher amount of drug release and permeability coefficient (Kp) value than telmisartan. The investigation revealed that, there is an impact of logP of compound in release behavior from microemulsion.
Keywords: Microemulsion, logP, Telmisartan, Glipizide, Cremophore EL, Tween 80, In vitro release.
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