Tenofovir disoproxil fumarate

An accurate, precise and reproducible high performance liquid chromatographic method was developed for quantitative estimation of emtricitabine, efavirenz and tenofovir disoproxil fumarate simultaneously in tablet dosage forms. Separation of the drugs was achieved within 15.0 min on a Xterra RP-18 column (150 x 4.6 mm; 5µ) by gradient elution using mixtures of ammonium acetate buffer and acetonitrile as the mobile phase. The analytes in the eluate were monitored at 260 nm. The retention times obtained for emtricitabine, efavirenz and tenofovir disoproxil fumarate were 4.611, 9.098 and 7.512 min respectively. The calibration curves were linear over the range of 20.11-60.33 µg/mL for emtricitabine, 60.28-180.45 µg/mL for efavirenz and 30.13-90.18 µg/mL for tenofovir disoproxil fumarate. The performance of the method was validated according to ICH guidelines. The method was found to be suitable for accurate determination of these drugs in tablet dosage forms without any interference from excipients or endogenous substances.

  The present research work aimed at development and optimization of niosome based gel (NBG) for the vaginal delivery of Tenofovir disoproxil fumarate (TDF). The TDF was   incorporated into niosomes using span 60 and cholesterol. Box-Behnken statistical screening design with 3 factors, 3 levels, and 15 runs was selected to statistically optimize the formulation parameters. The independent variables selected were parts of cholesterol (X1), surfactant loading (X2), amount of stabilizer (X3). Fifteen batches were prepared by thin film hydration method and evaluated for percentage drug entrapment (PDE) and vesicle size. The transformed values of the independent variables and the PDE (dependent variable) were subjected to multiple regressions to establish a full-model second-order polynomial equation. F value was calculated to confirm the omission of insignificant terms from the full-model equation to derive a reduced-model polynomial equation to predict the PDE of niosome. A model was validated for accurate prediction of the PDE by performing checkpoint analysis. The niosomal dispersion was incorporated in to Carbopol 940NF gel. The NGB was evaluated for drug content, pH, spreadability, consistency and texture analysis. The in-vitro drug release study shows sustained release gel effect whereas the in-vivo study shows no signs of irritation on the applied vaginal site in rat. The gel was kept for 6 weeks accelerated stability studies. The niosomes and niosomal gel showed maximum stability at 2 to 8 °C.   Key-words: Niosome, vaginal drug delivery, Tenofovir disoproxil fumarate, span 60, Box Behnken design