A stability-indicating high performance liquid chromatographic (HPLC) assay for the simultaneous determination of atorvastatin and amlodipine in commercial tablets.

Simultaneous determination of metoprolol succinate and amlodipine besylate in pharmaceutical dosage form by HPLC

The study describes development and subsequent validation of a stability indicating reverse-phase HPLC method for the simultaneous estimation of atorvastatin (ATV), and amlodipine (AML) from their combination drug product. The proposed RP-HPLC method utilizes a Lichrospher 100 C18, 5 microm, 250 mm x 4.0 mm i.d. column, at ambient temperature, optimum mobile phase consisted of acetonitrile and 50 mM potassium dihydrogen phosphate buffer (60 : 40, v/v), apparent pH adjusted to 3+/-0.1 with 10% phosphoric acid solution, effluent flow rate monitored at 1.0 ml/min, and UV detection at 254 nm. ATV, AML, and their combination drug product were exposed to thermal, photolytic, hydrolytic, and oxidative stress conditions, and the stressed samples were analyzed by proposed method. The method was applied for the in vitro dissolution of marketed combination drug products. The described method was linear over the range of 1-90 microg/ml and 1-80 microg/ml for ATV and AML, respectively. The mean recoveries were 99.76 and 98.12% for ATV and AML, respectively. The intermediate precision data obtained under different experimental setup, the calculated value of coefficient of variation (CV, %) was found to be less than critical value. The limit of detection for ATV and AML were found to be 0.4 and 0.6 mug/ml, respectively and the limit of quantification was 1.0 microg/ml for both drugs. The average percentage drug release was found to be more than 70% within 30 min for both drugs. Chromatographic peak purity data of ATV and AML indicated no co-eluting peaks with the main peaks of drugs which demonstrated the specificity of assay method for their estimation in presence of degradation products. The proposed method can be useful in the quality control and in vitro dissolution of combination drug products.

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Stability Indicating RP-HPLC Method for Simultaneous Determination of Atorvastatin and Amlodipine from Their Combination Drug Products

The European pharmacopoeia.

The antihypertensive drug amlodipine has been characterized voltammetrically in a carbon paste electrode by means of anodic stripping voltammetry. An adsorptive stripping method in a carbon paste electrode for trace determination of amlodipine has been described. Cyclic voltammetric studies indicated the oxidation of amlodipine besylate at the electrode surface through a single two-electron irreversible step fundamentally controlled by adsorption. A study of the variation in the peak current with solution variables such as pH, ionic strength, concentration of amlodipine, possible interference, and instrumental variables, such as preconcentration time and accumulation potential, has resulted in the optimization of the oxidation signal for analytical purposes. By anodic adsorptive anodic stripping voltammetry, the calibration plot was linear in the range 9.9 × 10−9 − 1.4 × 10−7 M with a detection limit of 2 × 10−10 M in a carbon paste electrode at pH 11.0. The procedure was successfully applied to the assay of amlodipine besylate in some commercial products in the market (Amlopres®, Amlodipine, and Norvasc®). The percentage recoveries were in agreement with those obtained by the reference method.

Use of adsorptive square-wave anodic stripping voltammetry at carbon paste electrode for the determination of amlodipine besylate in pharmaceutical preparations

Stability indicating RP-HPLC method for simultaneous determination of amlodipine and benazepril hydrochloride from their combination drug product.

A thin layer chromatographic method with densitometric detection has been developed for determination of nicorandil, in the presence of its degradation products and impurities, in tablet formulations. Nicorandil tablet solution was subjected to stress tests under thermal, photolytic, hydrolytic, and oxidative conditions, to induce degradation of the drug. Nicorandil was separated from the degradation products on RP18 TLC plates by isocratic elution and was determined densitometrically. To assess the specificity of the method two dimensional chromatography was performed with a second mobile phase of different selectivity. Because no interference from degradation products was observed in the assay of nicorandil by the described method, it can be regarded as a stability-indicating method and can be used for analysis of stability study samples and routine quality-control samples. The method requires no sample pretreatment and is accurate (recovery = 100.20%), reproducible, rugged (intermediate precision, %RSD = 1.73; n = 18), and selective. The calibration plot for nicorandil was linear in the range 35 to 65 μg (70 to 130% of assay concentration).

K. Raghu Naidu

Papers

Stability indicating RP-HPLC method for simultaneous determination of amlodipine and benazepril hydrochloride from their combination drug product.

A stability-indicating thin-layer chromatographic and densitometric method for determination of nicorandil in tablet formulations