Detection of the principal synthetic route indicative impurity in lamotrigine

An analytical method has been developed for the detection of trace amounts of the principal synthetic route indicative impurity in lamotrigine (3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine). A sample extract was preconcentrated by normal-phase high-performance liquid chromatography (HPLC) and analysed by subsequent on-line reversed-phase HPLC-thermospray mass spectrometry (TSP-MS). During the sample extraction and concentration step, carried out by semipreparative normal-phase chromatography, the preliminary separation of the impurity from the lamotrigine takes place. The organic solvent (dichloroethane-methanol, 90:10, v/v) is evaporated from the collected fraction and the material is redissolved in a smaller volume of the reversed-phase mobile phase. The collected fraction is then subjected to reversed-phase HPLC-TSP-MS. The influence of an ultrasonic extraction step has been examined. When the method was applied to lamotrigine tablets, a shake flask partitioning step using 1 mg/ml EDTA in water-dichloroethane was used instead of the ultrasonic extraction. Detection limit and recovery measurements showed that the route indicative impurity formed during the synthesis could be detected in the 50-100 ppb (w/w) range.

Clinical trial of pentazocine as analgesic in paediatric cases

This study was undertaken with the objective of relieving pain which has been poorly understood and managed in peri-operative period specially in children. Here the analgesic efficacy of pentazocine was studied in 50 cases, aged between 5 and 9 years subjected to both major and minor surgeries. No premedication was given to assess the sole analgesic effect of the drug. Pentazocine was given during induction, dose being 0.5 mg/kg body weight intravenously. Subsequently small incremental doses were repeated after every 30-45 minutes during surgery. Satisfactory analgesia was obtained during intra- and postoperative period. No respiratory depression, no change in pulse, BP and no other complications were observed after administration of intravenous pentazocine.

Effect of emetine treatment on subcellular nucleic acid and protein metabolism

The subcellular RNA and protein metabolism have been studied in emetine-treated rats. Emetine treatment for a period of 10 days reduced the incorporation in vivo of [14C]-leucine into proteins of nuclear fraction of liver. This was accompanied by a reduction in the nuclear protein content. The mitochondrial fraction of heart exhibited an increase in the protein content after emetine treatment. This was, however, not accompanied by an increased rate of incorporation into its protein. On the other hand, the nuclear fraction of heart of emetine-treated rats showed a diminution in the rate of incorporation into its protein without having been reduced in protein content. The mitochondrial and microsomal RNA of liver and the microsomal RNA of heart responded to emetine treatment by showing increased levels. The liver RNase activity was reduced after emetine treatment, while the heart RNase remained independent of the treatment. It has been suggested that both synthesis and breakdown of liver proteins are reduced by emetine treatment. The synthesis of liver nuclear proteins was supposedly affected more than was its breakdown by emetine. The synthesis of rapidly turningover proteins of heart nuclear fraction and the catabolism of slowly turningover proteins of its mitochondrial fraction are thought to be reduced by the emetine treatment.