Paracetamol, ambroxol hydrochloride, levocetirizine dihydrochloride, and phenylephrine hydrochloride are used in combination for the treatment of chronic sinusitis, rhinitis, fever, nasal discharge, sore throat, and wheezing. The present work deals with method development for simultaneous estimation of paracetamol, ambroxol hydrochloride, levocetirizine dihydrochloride, and phenylephrine hydrochloride in tablet formulation by first-order derivative spectrosphotometry. For determination of sampling wavelength, 10 μg/mL of each of paracetamol, ambroxol hydrochloride, levocetirizine dihydrochloride, and phenylephrine hydrochloride was scanned in 200–400 nm ranges and sampling wavelengths were found to be 305.5 nm for paracetamol, 321 nm for ambroxol hydrochloride, 244 nm for levocetirizine dihydrochloride, and 280 nm for phenylephrine hydrochloride in first-order derivative spectrophotometry. In this method, linearity was observed in the ranges of 20–140 μg/mL for paracetamol and 10–70 μg/mL for ambroxol hydrochloride, levocetirizine dihydrochloride, and phenylephrine hydrochloride. The % recovery was within the range between 98 and 102%, and % relative standard deviation for precision and accuracy of the method was found to be less than 2%. The method is validated as per International Conference on Harmonization Guidelines. The method can be successfully applied for the simultaneous analysis of these drugs in pharmaceutical dosage forms.

A reverse-phase high-performance liquid chromatographic (RP-HPLC) method was developed for the simultaneous estimation of amlodipine besylate (AMB), valsartan (VAL), and hydrochlorothiazide (HCT) in pharmaceutical formulation using RP-C 18 column. The mobile phase (acetonitrile:methanol:50 mM phosphate buffer adjusted to pH 3 with orthophosphoric acid) was pumped at a flow rate of 1.0 mL min −1 in the ratio of 20:50:30% v/v and the eluents were monitored at 239 nm. Linearity was obtained in the concentration range of 0.5-5 μg mL −1 for AMB, 4-40 μg mL −1 for VAL, and 1-10 μg mL −1 for HCT. The method was validated as per International Conference on Harmonization (ICH) guidelines and statistically. The method was validated for accuracy and precision. For precision, the coefficient of variance (COV) was found to be 0.3794, 0.1703 and 0.0578, and for accuracy, it was found to be 0.6351, 0.7688 and 1.1305 for AMB, VAL, and HCT, respectively. The COV values for all the drugs were found to be less than 2%, indicating high degree of precision and accuracy of the proposed highperformance liquid chromatographic (HPLC) method. Owing to its simplicity, rapidness, high precision and accuracy, the proposed HPLC method can be applied for determining AMB, VAL, and HCT in bulk and in pharmaceutical dosage form.

A simple and cost effective spectrophotometric method is described for the determination of fluvastatin sodium in pure form and in pharmaceutical formulations. When the drug reacts with sodium hydroxide shows absorption maximum at 304 nm and obeys beer's law in the concentration range 5-25 µg mL -1 . The absorbance was found to increase linearly with increasing concentration of FVS, which is corroborated by the calculated correlation coefficient value of 0.9999 (n=5). The apparent molar absorptivity and sandell sensitivity were 1.1905 X 10 4 and 0.0368844 µg cm -2 cm respectively. The slope and intercept of the equation of the regression line are 0.027112 and 0.003539 respectively. The limit of detection and limit of quantification was found to be 0.0811 µg mL -1 & 0.2460 µg mL -1 . The validity of the described procedure was assessed. Statistical analysis of the result has been carried out revealing high accuracy and good precision. The proposed method was successfully applied to the determination of FVS in pharmaceutical formulations without any interference from common excipients. The relative standard deviations were ≤ 0.937%, with recoveries of 98.60% -101.70%.

A simple, rapid, and precise reversed phase high performance liquid chromatographic method for the simultaneous determination of lamivudine, tenofovir disoproxil fumarate and efavirenz in bulk and tablet dosage form has been developed and validated. Chromatography was performed on a 150 mm × 4.6 mm i.d., 5 µm particle, Phenomenex Luna C 18 column with 30 : 45 : 25 (v/v/v) acetonitrile : methanol : water as mobile phase at a flow rate of 0.5 mL/min. UV detection was done at 258 nm; lamivudine, tenofovir diso proxil fumarate and efavirenz were eluted with retention times of 3.27, 4.58 and 10.90 min, respectively. The method was validated in accordance with ICH guidelines. Validation revealed the method is specific, rapid, accurate, precise, reliable and reproducible. Calibration plots were linear over the concentration ranges 1-6 µg/mL for lamivudine and tenofovir disoproxil fumarate and 2-12 µg/mL for efavirenz. Limits of detec tion were 0.05, 0.09 and 0.11 µg/mL and limits of quantification were 0.15, 0.28 and 0.34 µg/mL for lamivu dine, tenofovir disoproxil fumarate and efavirenz, respectively. The high recovery and low coefficients of vari ation confirm the suitability of the method for the simultaneous determination of these three drugs in bulk and tablets.

A simple, efficient, precise and accurate absorbance ratio method have been developed for the estimation of eprosartan mesylate and hydrochlorothiazide in pure and in fixed dose combination. In this method, UV spectra of eprosartan mesylate and hydrochlorothiazide were overlayed which involves the formation of Q-absorbance equation at 249.1 nm (isobestic point) and 274.5 nm, the max of hydrochlorothiazide. Both the drugs obeyed Beers law in the concentration range of 6-36 μg/ml and 1-10 μg/ml for eprosartan mesylate and hydrochlorothiazide, respectively. The accuracy of the method was determined by recovery studies and was found to be in the range of 102.29-103.10% and 99.52-101.60% for eprosartan mesylate and hydrochlorothiazide, respectively. The method was validated as per ICH guidelines and statistically. The method showed good reproducibility and recovery with % RSD less than 2. The method was found to be simple, economic, accurate and reproducible and can be used for routine analysis of eprosartan mesylate and hydrochlorothiazide in pure and in fixed dose combinations.