Simultaneous determination of montelukast and loratadine by HPLC and derivative spectrophotometric methods.

In this study, high performance liquid chromatography (HPLC) and second derivative spectrophotometry have been used and described for the simultaneous determination of montelukast and loratadine in pharmaceutical formulations. HPLC separation was achieved with a Symmetry C18 column and sodium phosphate buffer (pH adjusted to 3.7): acetonitrile (20:80, v/v) as eluent, at a flow rate of 1.0 ml/min. UV detection was performed at 225 nm. The LC method is simple, rapid, selective and stability indicating for the determination of montelukast. 5-Methyl 2-nitrophenol was used as internal standard for the purpose of quantification of both the drugs in HPLC. In the second-order derivative spectrophotometry, for the determination of loratadine the zero-crossing technique was applied at 276.1 nm, but for montelukast peak amplitude at 359.7 nm (tangent method) was used. Both methods were fully validated and a comparison was made for assay determination of selected drugs in formulations. The results confirm that the methods are highly suitable for its intended purpose.

Determination of zafirlukast by stability indicating LC and derivative spectrophotometry.

Two analytical methods have been developed for the determination of zafirlukast, a novel anti-asthmatic drug: high performance liquid chromatography (HPLC) and derivative spectrophotometry (DS). HPLC with ultraviolet detection at 225 nm is carried out with a Symmetry Shield RP18 column and a mobile phase constituted of acetonitrile and 0.01 M potassium dihydrogen phosphate buffer, adjusted the pH to 3.5 with 0.1 M KOH. The LC method is simple, rapid, selective and stability indicating. Indole was used as internal standard for the purpose of quantification of zafirlukast in HPLC. Spectrophotometry uses the third order derivative of the UV spectrum at 251.1 nm (deltalambda value 2.1 nm) for determination. Both methods were fully validated and a comparison was made. The results confirm that the methods are highly suitable for its intended purpose.

Determination of pioglitazone hydrochloride in bulk and pharmaceutical formulations by HPLC and MEKC methods.

High Performance Liquid Chromatographic (HPLC) and Micellar Electrokinetic Chromatographic (MEKC) methods have been developed for the determination of pioglitazone, a new englycemic antidiabetic agent. Pioglitazone and its unsaturated impurity were separated by MEKC in less than 7 min using a 43 cm x 50 microm i.d. uncoated fused-silica capillary with extended light path for better sensitivity (25 kV at 30 degrees C) and a background electrolyte (BGE) consisting of 20% acetonitrile (v/v) in 20 mM sodium borate buffer pH 9.3 containing 50 mM sodium dodecyl sulphate (SDS). The influence of various parameters on the separation such as pH of the buffer, SDS concentration, buffer concentration, organic modifiers, temperature and voltage were investigated. The MEKC method was compared with HPLC method using a 5 microm symmetry C18 column (250 x 4.6 mm i.d.) eluted with a mobile phase consisting of a mixture of 50% (v/v) acetonitrile and 10 mM potassium dihydrogen phosphate buffer, adjusting the pH to 6.0 with 0.1 M KOH. The HPLC method is capable of detecting all process related compounds, which may be present at trace levels in finished products. Both methods were fully validated and a comparison was made. The results confirm that the methods are highly suitable for its intended purpose.

Simultaneous determination of fexofenadine and its related compounds by HPLC.

A simple reversed phase liquid chromatographic (RPLC) method has been developed and subsequently validated for the determination of fexofenadine hydrochloride and its related compounds A and B. The method utilizes a C8 column for the separation and determination of meta-isomer (related compound B). The separation was achieved using an Eclipse XDB C8, 5 microm, 4.6 x 150 mm column and a mobile phase comprising 1% triethylamine phosphate (pH 3.7), acetonitrile and methanol in the ratio 60:20:20 (v/v/v). 5-Methyl 2-nitrophenol has been used as internal standard for the purpose of quantitation of fexofenadine. The described method was linear over a range of 0.7-18.7 microg/ml for related compounds A and B and 60-750 microg/ml for assay of fexofenadine. The relative standard deviation (n=3) was 0.5% for the drug and 3.4% for related compounds. The intermediate precision was 0.79% (n=9) for assay and 5.16% (n=9) for related impurities. The mean recovery of both the related compounds were in the range of 94-103%. Limits of detection (LOD) and quantification (LOQ) for the related compounds A and B were 0.18, 0.12 and 0.56, 0.48 microg/ml, respectively. The precision of the method was checked by F-test using a reported method as reference and the calculated value (1.35) was found to be less than the table value at 95% confidence levels. The obtained results confirm that the method is highly suitable for its intended purpose.

LC determination of rosiglitazone in bulk and pharmaceutical formulation.

An isocratic reversed phase liquid chromatographic (RP-LC) method has been developed and subsequently validated for the determination of rosiglitazone and its related impurities. Separation was achieved with a Symmetry C18 column and sodium phosphate buffer (pH adjusted to 6.2):acetonitrile (50:50, v/v) as eluent, at a flow rate of 1.0 ml/min. UV detection was performed at 245 nm. The method is simple, rapid, selective and stability indicating. Indole was used as internal standard for the purpose of quantification of rosiglitazone. The described method is linear over a range of 0.45-10 microg/ml for related impurities and 180-910 microg/ml for assay of rosiglitazone. The method precision for the determination of assay and related compounds was below 1.0 and 3.6% RSD, respectively. The mean recoveries of impurities were found to be in the range of 95-102%. The percentage recoveries of Active Pharmaceutical Ingredient (API) from dosage forms ranged from 99.02 to 101.30. The method is useful in the quality control of bulk manufacturing and also in pharmaceutical formulations.

LC determination of rofecoxib in bulk and pharmaceutical formulations.

An isocratic reversed phase-liquid chromatographic (RP-LC) method has been developed for the determination and purity evaluation of rofecoxib in bulk and pharmaceutical dosage forms using photodiode array detection set at 225 nm. The method is simple, rapid and selective. The method is capable of detecting all process intermediates and other related compounds, which may be present at trace levels in finished products. Hence the method is very useful for process monitoring during the production of rofecoxib. Chlorophenyl methyl sulphone has been used as internal standard for the quantitative determination of rofecoxib. The method is linear in the range of 125-500 microg. The precision for inter- and intra-day assay variation of rofecoxib is below 1.6% relative standard deviation (R.S.D.). The accuracy determined as relative mean error (R.M.E.) for the intra-day assay is within +/-2.0%. The drug was extracted from tablets (Vioxx) using acetonitrile. The percentage recoveries from dosage forms were ranged from 98.2 to 102.6.

LC method for the determination of assay and purity of sibutramine hydrochloride and its enantiomers by chiral chromatography.

Two isocratic liquid chromatography (LC) methods have been developed for the purity estimation and quantitative determination of sibutramine HCl, using 4-chloro aniline and lovastatin as internal standards, respectively. The precision has been checked in terms of F-test variance ratio using latter method as reference. The ratio of variances of the two methods is close to unity, confirming their good precision. The correlation coefficient for linear regression is more than 0.999. The inter and intra-day precision is found to be < 1.3% RSD. The accuracy determined as relative mean error (RME) for the intra-day assay is +/- 1.7%. The enantiomeric separation of sibutramine by chiral chromatography method has been described also. This method is capable of separating the two enantiomers with a selectivity of 1.4 and a resolution of 4.0. Both methods are found to be stability indicating and useful in the quality control of the bulk material.

A validated method for the determination and purity evaluation of benazepril hydrochloride in bulk and in pharmaceutical dosage forms by liquid chromatography.

A gradient liquid chromatographic (LC) method has been developed for the determination and purity evaluation of benazepril hydrochloride in bulk and pharmaceutical dosage forms. The method is simple, rapid and selective. 5-Methyl-2-nitro phenol has been used as internal standard. The method is linear in the range of 50-800 microg. The precision for inter and intra-day assay variation of benazepril hydrochloride is below 1.6% RSD. The accuracy determined as relative mean error (RME) for the intra-day assay is within +/- 2.0%. The method is stability indicating, and is useful in the quality control of bulk manufacturing and also in pharmaceutical formulations.