D Sreenivas Rao

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.

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 LC method for the quantitative determination of celecoxib in pharmaceutical dosage forms and purity evaluation in bulk drugs

A new reversed-phase, isocratic LC method was developed for the quantitative determination of COX-2 inhibitor celecoxib in bulk drugs and in pharmaceutical dosages. The proposed method is also applicable for the purity evaluation of celecoxib in bulk drugs. 5-Methyl 2-Nitro phenol has been used as internal standard for the quantitative determination of celecoxib. The method has been completely validated and proven to be rugged. The limit of detection (LOD) and limit of quantitation (LOQ) for celecoxib impurities namely, 4-hydrazino benzene sulfonamide (Intermediate I) and 1-(4-methyl phenyl)-4,4.4-trifluro butan-1,3-dione (Intermediate II) were found to be 32.0 and 97 ng. respectively. The active pharmaceutical ingredient was extracted from its finished dosage form (capsule) using methanol. The percentage recoveries ranged from 90.7 to 93.8. The stability studies were performed for celecoxib solution placed on laboratory bench and in refrigerator for hundred days. The samples were found to be stable for the study period.

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.

A validated LC method for imatinib mesylate

An isocratic reversed-phase liquid chromatography method with UV detection has been developed for the purity evaluation of imatinib mesylate in bulk drug. The method is selective and is capable of detecting all process intermediates and other related compounds, which may be present at trace levels in the drug substance. The method was validated on a Symmetry Shield RP18 analytical column (150 x 4.6 mm, 5 microm), mobile phase consisting of 30 mM sodium octane sulphonic acid in 10 mM aqueous KH2PO4 (pH 2.5 with H3PO4): MeOH in the ratio of 42:58 v/v. The flow rate was set at 1.0 ml/min and the column was maintained at room temperature. The injection volume was set to 10 microl and the detector was set at a wavelength of 237 nm. The method was validated in terms of system precision, method precision, linearity, accuracy, limit of detection and limit of quantification.

Determination of celecoxib, a COX-2 inhibitor, in pharmaceutical dosage forms by MEKC.

A micellar electrokinetic chromatographic (MEKC) method was developed for the quantification of celecoxib, a COX-2 inhibitor in pharmaceutical dosage forms within the total analysis time of 7 min. The method has been validated and proven to be rugged. The quantification was carried out at 35 degrees C and 25 kV, using a 25 mM borate buffer (pH 9.3), 25 mM sodium dodecyl sulphate with an extended light path capillary (48.5 cm x 50 micro I.D., 40 cm to detector). Calibration curves were constructed for celecoxib (0.2-0.6 mg/ml) by the internal standard method with 2-nitro aniline as an internal standard (coefficient of correlation greater than 0.999). The intermediate precision (between day precision) of migration times and peak area ratios of celecoxib to internal standard were 1.44 and 1.58% R.S.D., demonstrates good reproducibility of the method. The method was applied to a commercial celecoxib formulation (Revibra, 100 mg) and the percentage recoveries were ranged from 93.0 to 98.4%.

LC separation of ortho and meta isomers of celecoxib in bulk and formulations using a chiral column

A normal phase, isocratic LC method was developed for the separation of positional isomers of celecoxib (I) using a chiral column, Chiralpak-AD. The method is useful for the quantification of ortho (II) and meta (III) forms in bulk drugs and formulation samples of celecoxib. The method has been completely validated and proven to be rugged. The limit of detection (LOD) and limit of quantitation (LOQ) of ortho and meta forms were found to be 38 ng and 116 ng respectively. The active pharmaceutical ingredient was extracted from its finished dosage form (capsule) using ethanol. The percentage recoveries of ortho isomer was found to be 99.8--102.7 and 97.8--103.2 and the percentage recoveries of meta isomer was found to be 99.3--102.6 and 99.7--104 in spiked bulk and formulation samples of celecoxib respectively.

LC method for the quantitative determination of oxaprozin and its impurities in the bulk drug

A reversed phase linear gradient liquid chromatographic method was developed for the separation and quantitative determination of the seven known process related impurities and one degraded product of oxaprozin in the bulk drug material. An Inertsil-ODS 3V (150 x 4.6 mm), 5 microm column was operated with a phosphate buffer acetonitrile gradient. Detection was carried out on a UV detector at 254 nm. This method has been proved to be accurate and sensitive. The limits of detection (LOD) and limits of quantification (LOQ) of impurities were in the order of 5-60 ng and 16-200 ng, respectively. In addition to its ruggedness and robustness, this method offers identification of all eight impurities in a single run.