UV derivative spectrophotometric study of the photochemical degradation of nisoldipine

The photodecomposition of nisoldipine ((+/-)3-isobutyl-5-methyl-1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-pyridine-3,5-dicarboxylate), whereby its 4-(2-nitrosophenyl) pyridine analogue is obtained as the photolytic product, was investigated under daylight exposure by means of UV derivative spectrophotometry. The optimal instrumental parameters (120 nm/min scan speed: 2 nm slit width; Delta lambda = 10 nm and 5 s response time) for analogue derivative spectra were established for amplitudes D-1(285) and D-2(291) (measured to the baseline) of the nitroso analogue assay, as well as for D-1(386) of the parent compound-nisoldipine assay. Using the first-order derivative spectrum, the minimum detectable amount of nitroso analogue in the presence of nisoldipine was equivalent to an impurity level of 5% and by the second-order derivative spectrum, the determination limit was equivalent to an impurity level of 2%. The degradation of nisoldipine followed within 30 days and the calculated maximal degradation rate was 1.6% per day for nisoldipine raw material, but significantly lower values of 0.19 and 0.15% per day were obtained for Nisoldin(R) tablets (10 and 5 mg, respectively). (C) 2000 Elsevier Science S.A. All rights reserved

New Tc-99m-diiodine substituted IDA derivative (DIIODIDA) for hepatobiliary imaging

A new diiodine substituted LDA derivative, 2,4-diiodine-6-methyl IDA (DIIODIDA) was synthesized and labeled with Tc-99m. It was established that Tc-99m-DIIODIDA had high radiochemical purity. Biodistribution and influence of bilirubin on Tc-99m-DIIODIDA biokinetics has been studied in rats and compared to the corresponding results for Tc-99m-SOLCOIODIDA. Related to Tc-99m-SOLCOIODIDA, Tc-99m-DIIODIDA has much better biliary exretion (55.18 versus 43.63%). No change of Tc-99m-DIIODIDA biokinetics, under influence of bilirubin was noticed. Biliary excretion of Tc-99m-SOLCOIODIDA has been reduced for about 60%. The protein binding of Tc-99m-DIIODIDA and Tc-99m-SOLCOIODIDA were also determined, using in vitro method of precipitation. These results showed that Tc-99m-DIIODIDA hepatobiliary imaging agent is superior to the presently used Tc-99m-monoiodine IDA derivatives

Determination of 8-hydroxyquinoline sulfate in tuberculin solutions by planar and high performance liquid chromatography

TLC and HPLC methods for the determination of the preservative, 8-hydroxyquinoline sulfate in PPD-T tuberculin solution were developed. The planar chromatography method involved separation of 8-hydroxyquinoline sulfate on a TLC plate using a butyl-acetate: formic acid :2-propanol mobile phase, detection and quantitation by densitometric scanning. The HPLC method was on a LiChrosorb RP-18 column with acetonitrile-water (65:35 v/v) mobile phase, adjusted to pH 3.05 by phosphoric acid. Linearity, reproducibility and accuracy were found to be satisfactory. Under selected conditions, the limit of detection (LOD) of both methods was similar - about 25 ng