1). A combination of both drugs is recently launched in market. Literature survey

revealed spectrophotometric6 and chromatographic7, 8, 9 and 10 methods for estimation of TDF in pharmaceutical formulation and biological Modulators fluids. Few chromatographic11, 12 and 13 methods has been reported for estimations of ETB from biological fluids. TDF and ETB are not official in IP, BP and USP. However, to our knowledge, no information related to the stability-indicating SRT1720 cost high-performance thin-layer chromatography (HPTLC) determination of TDF and ETB in pharmaceutical dosage forms has ever been mentioned in literature. The parent drug stability test guidelines (Q1A) issued by International Conference on Harmonisation (ICH) requires that analytical test procedures for stability samples should be fully validated and the assays should be stability-indicating.13, 14, 15 and 16 Adriamycin solubility dmso The present paper describes a reliable, rapid and accurate stability – indicating HPTLC method for determination of TDF and ETB using HPTLC densitometry. TDF

and ETB were kindly supplied as a gift sample by Emcure Pharmaceuticals Ltd., Pune India. All the reagents used were of analytical reagent grade (S.D. Fine Chemicals, Mumbai, India) and used without further purification. The samples were spotted in the form of bands of width 6 mm with 100 μL sample syringe on precoated silica gel aluminium plate 60 F254 (20 cm × 10 cm) with 250 μm thickness; (E MERCK, Darmstadt, Germany) using a Camag Linomat V (Switzerland). The plates were prewashed with methanol and activated at 110 °C for 5 min, prior to chromatography. A constant application rate of 150 nl/sec was employed and space between two bands was 15.4 mm. The slit dimension was kept at 6 mm × 0.45 mm. The mobile phase consists of toluene: ethyl acetate: methanol: acetic acid (6: 4: 3:0.4, v/v/v). Linear ascending development was carried out in 20 cm × 10 cm twin trough glass chamber (Camag, Muttenz, Switzerland). The optimised

chamber saturation time for mobile phase was 20 min, at temperature (25 °C ± 2); through the relative humidity (60% ± 5%); the length of chromatogram run was 8 cm and TLC plates were air dried. Densitometric scanning was performed on Camag TLC Scanner 3 equipped with winCATS software version 1.3.0 at 276 nm. The source of radiation utilised was deuterium lamp. Evaluation was performed using peak area with linear regression. Combined standard stock solution containing 1500 μg/ml of TDF and 1000 μg/ml of ETB was prepared in methanol. Calibration was done by Hamilton syringe with the help of automatic sample applicator Linomat V on TLC plate that gave concentration 150–1500 ng/spot of TDF and 100–1000 ng/spot of ETB, respectively. Each concentration was spotted six times on the TLC plates. The plates were developed using previously described mobile phase. The calibration graph was plotted as peak areas versus corresponding concentrations.