A validated simple and selective spectrophotometric method was developed for the selective determination of amlodipine and nicardipine in bulk powders and pharmaceutical formulation. The proposed method was based on the formulation of a binary complex between either of the studied drugs and eosin Y in aqueous buffered medium. The surfactant, methylcellulose, was added to enhance the solubility of the formed complex. The binary complexes showed absorption maxima at 549 nm. The different experimental parameters affecting the development of stability of the colors were studied and optimized. Under the optimum reaction conditions, linear relationship with good correlation coefficients (0.9981 and 0.9995) were found between the absorbances and the concentrations of amlodipine and nicardipine respectively in the range of 5-60 µg/ml for both drugs. The limits of detection were 1.8 and 1.2 µg/ml while the limits of quantitation were 6.0 and 3.6 µg/ml for both drugs respectively. The analytical parameters were fully validated and results were satisfactory. No interference was observed from the excipients that are commonly present in pharmaceutical formulations. The proposed method was successfully applied to the analysis of the cited drugs in some pharmaceutical formulations. The mean percentage recoveries were 100.04 ± 0.83 and 99.98 ± 0.80. The results obtained are reproducible with a coefficient of variation less than 2% and were in good agreement with those obtained using the reference methods.

The present study aims to investigate the possibility of interaction of donepezil (DP) and galantamine (GAL) as acetylcholinestrase inhibitors, on memantine (MT) hydrochloride in rat plasma by HPLC-fluorescence detection. The separation of MT was achieved within 12 min without interference of DP and GAL on the chromatogram. MT levels in rat plasma with a single administration of MT (2.5 mg/kg, i.p.) and those with a co-administration of DP (5.0 mg/kg, i.p.) and GAL (3 mg/kg, i.p.) were monitored. MT concentrations determined in rat plasma ranged from 10.0 to 245.6 ng/mL. Significant difference was observed in the behavior of MT with a co-administration of DP, while no significant difference was observed with a co-administration of GAL.

A simple, sensitive, and specific method was developed for simultaneous determination of Amlodipine besylate (AML), Valsartan (Vals) and Hydrochlorothiazide (HCT) by high performance liquid chromatography without previous separation. Satisfactory resolution was achieved using a RP-C18 chromatographic column, Phenomenex Kinetex (150 mm × 4.6 mm i.d) and a mobile phase consisting of acetonitrile-phosphate buffer (0.05 M) with pH 2.8 in the proportion of (40/60, v/v) at a flow rate 0.8 mL/min and the wavelength detection was 227 nm. The retention time for HCT, AML and VAls was 2.26, 3.16 and 11.19 min; respectively. The described method was linear over a range of 4-28 μg /ml, 5-40 μg /ml and 1-12 μg /ml for AML, Vals and HCT; respectively. The mean percent recoveries were 99.94%, 99.96% and 99.78% for AML, Vals and HCT; respectively. F-test and t-test at 95%confidence level were used to check the intermediate precision data obtained under different experimental setups. The method could be used for analysis of combined dose tablet formulation containing AML, Vals, HCT as well as spiked human plasma.

The present study aims to investigate the possibility of interaction of donepezil (DP) and galantamine (GAL) as acetylcholinestrase inhibitors, on memantine (MT) hydrochloride in rat plasma by HPLC-fluorescence detection. The separation of MT was achieved within 12 min without interference of DP and GAL on the chromatogram. MT levels in rat plasma with a single administration of MT (2.5 mg/kg, i.p.) and those with a co-administration of DP (5.0 mg/kg, i.p.) and GAL (3 mg/kg, i.p.) were monitored. MT concentrations determined in rat plasma ranged from 10.0 to 245.6 ng/mL. Significant difference was observed in the behavior of MT with a co-administration of DP, while no significant difference was observed with a co-administration of GAL.

The smart novel ratio difference spectrophotometric method was developed and validated for the determination of a binary mixture of Sodium cromoglicate (SCG) and Fluorometholone (FLU) in presence of benzalkonium chloride without prior separation. The results were compared to that of the conventional methods (dual wavelength and first derivative of ratio spectra). The suggested methods were validated in compliance with the ICH guidelines and were successfully applied for determination of SCG and FLU in their laboratory prepared mixtures and commercial ophthalmic solution. The novel method showed significant advantages over the conventional methods regarding simplicity, minimal data manipulation and maximum reproducibility and robustness; which enabled the analysis of binary mixtures with overlapped spectra for routine quality control testing with quite satisfactory.

A simple and sensitive spectrophotometric method has been developed for the determination of cetirizine (I), ebastine (II),fexofenadine (III), ketotifen (IV), and loratadine (V) based on ion-pair complex formation with erythrosine B. The pink color of the produced complex was measured at 550 nm without solvent extraction. Appropriate conditions were established by studying the color reaction between erythrosine B and the studied drugs to obtain the maximum sensitivity. Beer-Lambert’s law is obeyed in the concentration ranges 1–7, 1–8, and 1–6

A simple and sensitive spectrophotometric method has been developed for the determination of cetirizine (I), ebastine (II),fexofenadine (III), ketotifen (IV), and loratadine (V) based on ion-pair complex formation with erythrosine B. The pink color of the produced complex was measured at 550 nm without solvent extraction. Appropriate conditions were established by studying the color reaction between erythrosine B and the studied drugs to obtain the maximum sensitivity. Beer-Lambert’s law is obeyed in the concentration ranges 1–7, 1–8, and 1–6

A simple and sensitive spectrophotometric method has been developed for the determination of cetirizine (I), ebastine (II),fexofenadine (III), ketotifen (IV), and loratadine (V) based on ion-pair complex formation with erythrosine B. The pink color of the produced complex was measured at 550 nm without solvent extraction. Appropriate conditions were established by studying the color reaction between erythrosine B and the studied drugs to obtain the maximum sensitivity. Beer-Lambert’s law is obeyed in the concentration ranges 1–7, 1–8, and 1–6

A simple and sensitive spectrophotometric method has been developed for the determination of cetirizine (I), ebastine (II),fexofenadine (III), ketotifen (IV), and loratadine (V) based on ion-pair complex formation with erythrosine B. The pink color of the produced complex was measured at 550 nm without solvent extraction. Appropriate conditions were established by studying the color reaction between erythrosine B and the studied drugs to obtain the maximum sensitivity. Beer-Lambert’s law is obeyed in the concentration ranges 1–7, 1–8, and 1–6

A novel, highly sensitive and selective fluorimetric liquid chromatographic method for simultaneous determination of medium chain aliphatic aldehydes was developed. The method was based on the derivatization of aliphatic aldehydes with 1,2-di(2-furyl)-1,2-ethanedione (2,2'-furil), a novel fluorogenic reagent, to form highly fluorescent difurylimidazole derivatives. The fluorescence derivatives were separated in less than 20 min on a reversed-phase ODS column using an isocratic elution with a mixture of methanol-water (80:20, v/v%). The detection limits were from 0.19 to 0.50 nM (1-10 fmol/injection) at a signal-to-noise ratio (S/N) of 3. This method was successfully applied for monitoring of aliphatic aldehydes in healthy human sera by a simple pretreatment procedure without interferences from serum constituents.