A simple, rapid, economic, accurate, and precise method for the estimation of rifampicin in a mixture of isoniazid and pyrazinamide by UV spectrophotometeric technique (guided by the theoretical investigation of physicochemical properties) was developed and validated. Theoretical investigations revealed that isoniazid and pyrazinamide both were freely soluble in water and slightly soluble in ethyl acetate whereas rifampicin was practically insoluble in water but freely soluble in ethyl acetate. This indicates that ethyl acetate is an effective solvent for the extraction of rifampicin from a water mixture of isoniazid and pyrazinamide. Computational study indicated that pH range of 6.0–8.0 would favor the extraction of rifampicin. Rifampicin is separated from isoniazid and pyrazinamide at pH 7.4 ± 0.1 by extracting with ethyl acetate. The ethyl acetate was then analyzed at λmax of 344.0 nm. The developed method was validated for linearity, accuracy and precision according to ICH guidelines. The proposed method exhibited good linearity over the concentration range of 2.5–35.0 μg/mL. The intraday and inter-day precision in terms of % RSD ranged from 1.09 to 1.70% and 1.63 to 2.99%, respectively. The accuracy (in terms of recovery) of the method varied from of 96.7 ± 0.9 to 101.1 ± 0.4%. The LOD and LOQ were found to be 0.83 and 2.52 μg/mL, respectively. In addition, the developed method was successfully applied to determine rifampicin combination (isoniazid and pyrazinamide) brands available in Bangladesh.

Tamarind or Tamarindus indica L. is a multipurpose plant distributed throughout the tropics including Bangladesh. The present study was conducted to establish the preliminary antioxidant, antimicrobial, anti-inflammatory and thrombolytic activities of methanol extract of T. indica seeds along with its Kupchan fractions. To evaluate the antioxidant properties, the total phenolic content of T. indica was determined and expressed in gallic acid equivalent (GAE). Alongside, DPPH free radical scavenging assay was performed to ensure the antioxidant properties of the seeds where the methanolic crude extract revealed the maximum activity having IC50 value of 9.43 μg/ml. In the antimicrobial assay by disk diffusion method, only non-polar fractions of the extract showed mild antimicrobial activity against the test organisms tested while the polar crude methanol extract exhibited the maximum inhibition (58.16%, p < 0.001) of hypotonic solution-induced erythrocyte rupture in anti-inflammatory investigation among all the partitionates. During evaluation of thrombolytic activity in terms of percent of clot lysis, the methanol soluble fraction exhibited the highest percent of thrombolysis (23.5%) as compared to the reference standard, streptokinase (64.25%). The findings of the current study rationalize some of the traditional uses of T. indica and preliminarily ascertain its bioactive potential, which may act as a base for phytochemical and mechanism-based pharmacological studies of the plant in future. Bangladesh Pharmaceutical Journal 25(1): 9-15, 2022 (January)

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A simple, economic, selective, accurate, precise reverse phase high performance liquid chromatographic method for the simultaneous estimation of naproxen and rabeprazole sodium in pure and pharmaceutical dosage forms was developed and validated. Naproxen and rabeprazole sodium were well separated using a phenomenex ODS C18 column of dimension 4.6 mm × 250 mm, 10 µm and mobile phase comprised of sodium dihydrogen phosphate buffer (pH 7.5±0.1) and acetonitrile in the ratio of 70:30 (v/v) at the flow rate 1 mL/min and the detection was performed at 275nm. The retention time for naproxen and rabeprazole sodium were found to be 3.33 ± 0.027 and 7.61 ± 0.043 min, respectively. The developed method was validated for specificity, linearity, precision and accuracy according to ICH guidelines. The proposed method is highly specific and linear over the concentration range of 2.0-60.0 µg/mL and 1.0-30.2 µg/mL for naproxen and rabeprazole sodium, respectively. The intraday precision (% RSD) of naproxen and rabeprazole sodium was in the range of 0.39 -1.88% and 0.20 -1.51% while the interday precision ranged from 0.08 -1.34% and 0.73 -0.87%, respectively. The accuracy (in terms of recover) of the method varied from 99.4-104.2% and 98.1-100.6% for naproxen and rabeprazole sodium, respectively. The LOD and LOQ of naproxen and rabeprazole sodium were found to be 0.6 and 0.1 µg/mL and 1.7 and 0.4 µg/mL, respectively. The sample solutions were stable for at least three hours. However, the developed method was successfully applied to assay naproxen and rabeprazole sodium brands available in Bangladesh.