فهرست مطالب hassan jalalizadeh

Licorice is obtained from Glycyrrhiza glabra (G. glabra) in Iran. Glycyrrhizin is the main constituent of G. glabra and has several pharmacological effects. It is hydrolyzed to glycyrrhetic acid (GA) in the intestine after oral administration. In this study, a novel HPLC method was used to determine the concentration of GA in rat plasma after oral administration of licorice aqueous extract. The method was linear (r2 >0.999) in the range of 0.1-5.0 μg/ml for GA. Maximum plasma concentration of GA was achieved 8 h after oral administration of licorice aqueous extract. The developed method was suitable for determination of GA in rat plasma.

Losartan, a highly effective blood pressure lowering agent, has been widely used for the treatment of hypertension. A fast and reliable method for the determination of losartan was highly desirable to support formulation screening and quality control. A first derivative UV spectroscopic method was developed for determination of losartan in the tablet dosage form. The first derivative spectrum recorded between 220 and 320 nm, and a zero-crossing technique for first derivative measurement at 232.5 nm was selected. It is found that the selectivity and sensitivity of method to be in desirable range. In comparison with the direct UV method, the first derivative UV spectroscopy has a definite through without any interference from UV absorbing excipients. This method is also fast and economical in comparison to the more time-consuming HPLC method regularly used for formulation screening and quality control and can be used routinely by any laboratory possessing a spectrophotometer with a derivative accessory. The linear concentration ranges were 2-50 ?g/mL, (Dl = -0.0159C - 0.0056, r =0.9994, n=6). Between days CV% 2.9, within day CV% 2.1, analytical recovery close to 98.1 % shows the suitability of the method for determination in quality control.

A rapid and sensitive HPLC method was developed for determination of losartan in plasma. Losartan was extracted from plasma by a two-step extraction procedure using chloroform as extracting solvent in acidic medium. HPLC analysis was performed on a cyano reversed-phase column using phosphate buffer (pH 4.3), acetonitrile (750:250, v/v) as mobile phase with a flow rate of 0.9 mL/min. Sodium diclofenac was selected as internal standard. Excellent linearity between the peak area ratios and losartan concentrations over the range of 2-200 ng/mL of plasma was observed. The limit of determination with UV detection at 225 nm, with a CV < 5% was 2 ng/mL in 500 L of plasma sample. The assay was rapid, safe and reliable for use in pharmacokinetic studies of losartan in human being.

Abstract: Derivative spectrophotometry offers a useful approach for the analysis of drugs in multi-component mixtures. In this study a third-derivative spectrophotometry method was used for simultaneous determination of anthocyanoside and beta-carotene using the zero-crossing technique. The measurements were carried out at wavelengths of 625 and 540 nm for anthocyanoside and beta-carotene respectively. The method was found to be linear (r2>0.999) in the range of 125-750 µg/mL for anthocyanoside in the presence of 25 µg/mL beta-carotene at 625 nm. The same linear correlation was also obtained (r2>0.997) in the range of 6.25-37.50 µg/mL for beta-carotene in the presence of 500 µg/mL of anthocyanoside at 540 nm. The limit of determination was 125 and 6.25 µg/mL for anthocyanoside and beta-carotene respectively. The method was successfully applied for simultaneous determination of anthocyanoside and beta-carotene in pharmaceutical preparations without any interferences from excipients.