Liquid chromatographic determination of ceterizine hydrochloride and paracetamol in human plasma and pharmaceutical formulations.

An accurate, simple, reproducible and sensitive HPLC method for the determination of ceterizine hydrochloride (CTZH) and paracetamol (PARA) has been developed and validated. The separation of CTZH, PARA and Nimesulide (the internal standard) was achieved on a CLC C(18) (5 mu, 25 cm x 4.6 mm i.d) column using UV detection at 230 nm. The mobile phase was consisted of acetonitrile-water (55:45 v/v). The linear ranges of detection for CTZH and PARA were found to be 0.715-55 microg/ml (r(2)=0.9985) and 0.55-39 microg/ml (r(2)=0.9957) respectively. Intra- and inter-day assay relative standard deviations were less than 1%. The method has been applied successfully to the determination of binary combination of CTZH and PARA in human plasma and pharmaceutical preparations. There was no interference from drugs commonly administered with CTZH and PARA. The method has been shown to be linear, reproducible, specific, and rugged.

Spectrophotometric investigations of the assay of physiologically active catecholamines in pharmaceutical formulations.

Two simple, sensitive, and accurate spectrophotometric methods are proposed for the determination of levodopa (LD), methyldopa (MD), dopamine hydrochloride (DP), and pyrocatechol (PC) in pure and pharmaceutical preparations. The methods are based on measurement of the absorbances of tris(o-phenanthroline)iron(II) (method A) and tris(bipyridyl)iron(II) (method B) obtained by the oxidation of the catecholamines by iron(III) in the presence of 1,10-phenanthroline and 2,2'-bipyridyl at 510 and 522 nm, respectively. The absorbances were found to increase linearly with increases in the concentrations of the catecholamines, results which were corroborated by the calculated correlation coefficients (0.9990-0.9996). Beer's law was valid over the concentration ranges of 0.04-0.6, 0.06-0.75, 0.06-0.65, and 0.05-0.70 microg/mL in method A and 0.02-1.0, 0.04-1.3, 0.05-1.0, and 0.06-1.1 microg/mL in method B for PC, MD, LD, and DP, respectively. The common excipients and additives did not interfere in their determinations. The proposed methods were successfully applied to the assay of LD, MD, and DP in various dosage forms. The results were validated by statistical analysis.