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A simple, sensitive and precise RP-HPLC method was developed for the determination of dutasteride in tablet dosage form. The RP-HPLC separation was achieved on phenomenex C18 column (250 mm, id 4.6 mm, 5 µm) using mobile phase methanol:water (90:10 v/v) at a flow rate of 1 ml/min at an ambient temperature. Quantification was achieved with photodiode array detection at 235 nm over the concentration range 1-12 µg/ml. The method was validated statistically and was applied successfully for the determination of dutasteride in tablets. [ABSTRACT FROM AUTHOR]

A rapid, selective and stability-indicating high performance thin layer chromatographic method was developed and validated for the simultaneous estimation of olanzapine and fluoxetine in combined tablet dosage form. Olanzapine and fluoxetine were chromatographed on silica gel 60 F254 TLC plate using methanol:toluene (4:2 v/v) as the mobile phase and spectrodensitometric scanning-integration was performed at a wavelength of 233 nm using a Camag TLC Scanner III. This system was found to give compact spots for both olanzapine (Rfvalue of 0.63±0.01) and fluoxetine (Rf value of 0.31±0.01). The polynomial regression data for the calibration plots showed good linear relationship with r²=0.9995 in the concentration range of 100-800 ng/spot for olanzapine and 1000-8000 ng/ spot for fluoxetine with r²=0.9991. The method was validated in terms of linearity, accuracy, precision, recovery and specificity. The limit of detection and the limit of quantification for the olanzapine were found to be 30 and 100 ng/spot, respectively and for fluoxetine 300 and 1000 ng/spot, respectively. Olanzapine and fluoxetine were degraded under acidic, basic and oxidation degradation conditions which showed all the peaks of degraded product were well resolved from the active pharmaceutical ingredient. Both drugs were not further degraded after thermal and photochemical degradation. The method was found to be reproducible and selective for the simultaneous estimation of olanzapine and fluoxetine. As the method could effectively separate the drugs from their degradation products, it can be employed as a stability-indicating method. [ABSTRACT FROM AUTHOR]

Floating tablets of carbamazepine were developed using melt granulation technique. Bees wax was used as a hydrophobic meltable material. Hydroxypropylmethylcellulose, sodium bicarbonate and ethyl cellulose were used as matrixing agent, gas-generating agent and floating enhancer, respectively. The tablets were evaluated for in vitro buoyancy and dissolution studies. A simplex lattice design was applied to investigate the combined effect of 3 formulation variables i.e. amount of hydroxypropyl methylcellulose (X1), ethyl cellulose (X2) and sodium bicarbonate (X3). The floating lag time (Flag), time required for 50% (t50) and 80% drug dissolution (t80) were taken as responses. Results of multiple regression analysis indicated that, low level of X1 and X2, and high level of X3 should be used to manufacture the tablet formulation with desired in vitro floating time and dissolution. Formulations developed using simplex lattice design were fitted to various kinetic models for drug release. Formulation S3 was selected as a promising formulation and was found stable at 40° and 75% relative humidity for 3 months. Present study demonstrates the use of simplex lattice design in the development of floating tablets with minimum experimentation. [ABSTRACT FROM AUTHOR]

A simple and sensitive high performance thin layer chromatography (HPTLC) method has been developed for the quantitative estimation of linezolid in its single component tablet formulations (600 mg). Linezolid was chromatographed on Silica Gel 60 F254 TLC plate using methanol: benzene (2:8 v/v) as mobile phase. Linezolid showed Rf value 0.45 ± 0.03 and scanned at 258 nm using a Camag TLC scanner 3. The method was validated in terms of linearity (200-1400 ng/spot), precision (intra-day variation, 0.75 to 1.26% and inter-day variation, 1.2 to 2.8%), accuracy (97.8 to 100.4%) and specificity. The limit of detection and limit of quantification for linezolid were found to be 16.7 ng/spot and 50.7 ng/spot, respectively. The developed method was successfully used for the assay of linezolid tablet formulations. The method was found to be simple, sensitive, specific, accurate and precise and can be used for the routine quality control testing of linezolid marketed formulations. [ABSTRACT FROM AUTHOR]

Present investigation describes statistically the influence of viscosity of hydroxypropyl methylcellulose and types of filler on dipyridamole release from floating matrix tablets using 32 full factorial design. Tablets were prepared using direct compression technique. Tablets were evaluated for in vitro floating ability and drug release study using USP 24 types II paddle apparatus using 0.1 N HCl (pH 1.2) at rotation of 100 rpm and temperature of 37±0.5°. Multiple regression analysis was performed for dependent variables studied and to evaluate contribution of factors with their levels two way ANOVA was performed followed by Tukey test. Polynomial equations and response surface plots were generated for all dependent variables. It was observed that both the factors had significant influence on all dependent variable studied (p<0.05). It was observed that as viscosity of polymer increases the release rate constant was decreased. Release rate obtained was highest when microcrystalline cellulose was employed as filler followed by dicalcium phosphate and lactose. Mechanism of drug release was anomalous types and depends upon viscosity of polymer and types of filler used. Microcrystalline cellulose gave release mechanism nearer to diffusion mechanism while dicalcium phosphate and lactose gave anomalous release. It was observed that both the factors had significant contribution on all dependent variables studied. A major controlling factor for kinetics of drug release was viscosity of polymer and it can be modified by incorporation of different types of filler. In initial phase of drug release viscosity of polymer and types of filler both governs the drug release while in later phase only the viscosity of polymer predominates. [ABSTRACT FROM AUTHOR]

A binary mixture of trifluoperazine HCl and chlordiazepoxide was determined using reversed-phase liquid chromatography method using methanol:water (97:03, v/v) pumped at a flow rate of 1.0 ml/min. Quantification was achieved with ultraviolet detection at 262 nm over concentration ranges of 0.1-1 and 0.5-5 µg/ml; mean accuracies were 101.05±0.47 and 98.97±0.33 %, respectively. The method was successively applied to tablet dosage forms as no chromatographic interferences from the tablet excipients were observed. The method retained its accuracy and precision when the standard addition technique was applied. [ABSTRACT FROM AUTHOR]

A simple, precise, accurate and rapid high performance thin layer chromatographic method has been developed and validated for the simultaneous estimation of valsartan and hydrochlorothiazide in combined dosage forms. The stationary phase used was precoated silica gel 60F254. The mobile phase used was a mixture of chloroform: methanol: toluene: glacial acetic acid (6:2:1:0.1 v/v/v/v). The detection of spots were carried out at 260 nm. The method was validated in terms of linearity, accuracy, precision and specificity. The calibration curve was found to be linear between 300 to 800 ng/spot for valsartan and 100 to 600 ng/spot for hydrochlorothiazide. The limit of detection and the limit of quantification for the valsartan were found to be 100 and 300 ng/spot respectively and for hydrochlorothiazide 30 and 100 ng/spot respectively. The proposed method can be successfully used to determine the drug content of marketed formulation. [ABSTRACT FROM AUTHOR]

A simple, precise, accurate and rapid high performance thin layer chromatographic method has been developed and validated for the estimation of olmesartan medoxomil and hydrochlorothiazide simultaneously in combined dosage forms. The stationary phase used was precoated silica gel 60F254. The mobile phase used was a mixture of acetonitrile:chloroform:glacial acetic acid (7:2:0.5, v/v/v). The detection of spots was carried out at 254 nm. The method was validated in terms of linearity, accuracy, precision and specificity. The calibration curve was found to be linear between 500 to 750 ng/spot for olmesartan medoxomil and 100 to 600 ng/spot for hydrochlorothiazide. The limit of detection and the limit of quantification for the olmesartan medoxomil were found to be 170 and 500 ng/spot, respectively and for hydrochlorothiazide 30 and 100 ng/spot, respectively. The proposed method can be successfully used to determine the drug content of marketed tablet formulation. [ABSTRACT FROM AUTHOR]