Development and validation of a HPTLC method for Estimation of Duloxetine Hydrochloride in Bulk Drug and in Tablet Dosage Form.

Duloxetine hydrochloride is a potent dual reuptake inhibitor of serotonin and norepinephrine used to treat major depressive disorders. The present work describes a simple, precise and accurate HPTLC method for its estimation as bulk and in tablet dosage form. The chromatographic separation was carried out on precoated silica gel 60 F254 aluminium plates using mixture of chloroform:methanol (8:1 v/v) as mobile phase and densitometric evaluation of spots was carried out at 235 nm using Camag TLC Scanner-3 with win CAT 1.3.4 version software. The experimental parameters like band size of the spot applied, chamber saturation time, solvent front migration, slit width etc. were critically studied and optimum conditions were evolved. The drug was satisfactorily resolved with Rf value 0.11+/-0.01. The accuracy and reliability of the proposed method was ascertained by evaluating various validation parameters like linearity (40-200 ng/spot), precision (intra-day RSD 0.46-0.75%, inter-day RSD 0.46-1.59%), accuracy (98.72+/-0.20) and specificity according to ICH guidelines. The proposed method can analyse ten or more formulation units simultaneously on a single plate and provides a faster and cost-effective quality control tool for routine analysis of duloxetine hydrochloride as bulk drug and in tablet formulation.

UV and Three Derivative Spectrophotometric Methods for Determination of Ezetimibe in Tablet Formulation.

UV, first, second and third derivative spectrophotometric methods have been developed for the determination of ezetimibe in pharmaceutical formulation. The solutions of standard and sample were prepared in methanol. For the first method, UV spectrophotometry, the quantitative determination of the drug was carried at 233 nm and the linearity range was found to be 6-16 mug/ml. For the first, second and third derivative spectrophotometric methods the drug was determined at 259.5 nm, 269 nm and 248 nm with the linearity ranges 4-14 mug/ml, 4-14 mug/ml and 4-16 mug/ml. The calibration graphs constructed at their wavelength of determination were found to be linear for UV and derivative spectrophotometric methods. All the proposed methods have been extensively validated. The described methods can be readily utilized for the analysis of pharmaceutical formulation. There was no significant difference between the performance of the proposed methods regarding the mean values and standard deviations.

Application of stability-indicating HPTLC method for quantitative determination of metadoxine in pharmaceutical dosage form.

A sensitive, selective, precise and stability-indicating high-performance thin-layer chromatographic method for analysis of metadoxine both as a bulk drug and in formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of acetone-chloroform-methanol-ammonia (7.0:4.0:3.0:1.2, v/v/v/v). Densitometric analysis of metadoxine was carried out in the absorbance mode at 315 nm. This system was found to give compact spots for metadoxine (Rf value of 0.45+/-0.02, for six replicates). Metadoxine was subjected to acid, alkali and neutral hydrolysis, oxidation, dry and wet heat treatment and photo and UV degradation. The drug undergoes degradation under all stress conditions. Also, the degraded products were well resolved from the pure drug with significantly different Rf values. The method was validated for linearity, precision, robustness, LOD, LOQ, specificity and accuracy. Linearity was found to be in the range of 100-1500 ng/spot with significantly high value of correlation coefficient r2=0.9997+/-1.02. The linear regression analysis data for the calibration plots showed good linear relationship with r2=0.9999+/-0.58 in the working concentration range of 200-700 ng/spot. The mean value of slope and intercept were 0.11+/-0.04 and 18.73+/-1.89, respectively. The limits of detection and quantitation were 50 and 100 ng/spot, respectively. Statistical analysis proves that the method is repeatable and specific for the estimation of the said drug. As the method could effectively separate the drug from its degradation products, it can be employed as a stability-indicating one. Moreover, the proposed HPTLC method was utilized to investigate the kinetics of acid and base degradation process. Arrhenius plot was constructed and activation energy was calculated respectively for acid and base degradation process.

Application of HPLC and HPTLC for the simultaneous determination of tizanidine and rofecoxib in pharmaceutical dosage form.

Two methods are described for the simultaneous determination of tizanidine and rofecoxib in binary mixture. The first method was based on HPTLC separation of the two drugs followed by densitometric measurements of their spots at 311 nm. The separation was carried out on Merck HPTLC aluminium sheets of silica gel 60 F254 using toluene:methanol:acetone (7.5:2.5:1.0, v/v/v) as mobile phase. The linear regression analysis data was used for the regression line in the range of 10-100 and 100-1500 ng/spot for tizanidine and rofecoxib, respectively. The second method was based on HPLC separation of the two drugs on the reversed phase kromasil column [C18 (5 microm, 25 cm x 4.6 mm, i.d.)] at ambient temperature using a mobile phase consisting of phosphate buffer pH 5.5 and methanol (45:55, v/v). Flow rate was 1.0 ml/min with an average operating pressure of 180 kg/cm2. Quantitation was achieved with UV detection at 235 nm based on peak area with linear calibration curves at concentration ranges 10-200 and 100-2000 microg/ml for tizanidine and rofecoxib, respectively. Both methods have been successively applied to pharmaceutical formulation. No chromatographic interference from the tablet excipients was found. Both methods were validated in terms of precision, robustness, recovery and limits of detection and quantitation. The analysis of variance (ANOVA) and Student's t-test were applied to correlate the results of tizanidine and rofecoxib determination in dosage form by means of HPTLC and HPLC method.