Effect of antihistaminics on bradykinin action]

On isolated ileum of the guinea pig the antihistamine drugs dimedrol, diprazin (pipolphen), tavegil and suprastin diminished spasmogenic effects of bradykinin and an enhancement of microvascular permeability induced by this polypeptid. The antihistamine drugs display a nonspecific antibradykinin activity. No relationship between the chemical structure and pronounced antibradykinin action of the antihistamines studied was revealed.     

Determination of compound aminopyrine phenacetin tablets by using artificial neural networks combined with principal components analysis

A method for simultaneous, nondestructive analysis of aminopyrine and phenacetin in compound aminopyrine phenacetin tablets with different concentrations has been developed by principal component artificial neural networks (PC-ANNs) on near-infrared (NIR) spectroscopy. In PC-ANN models, the spectral data were initially analyzed by principal component analysis. Then the scores of the principal components were chosen as input nodes for the input layer instead of the spectral data. The artificial neural network models using the spectral data as input nodes were also established and compared with the PC-ANN models. Four different preprocessing methods (first-derivative, second-derivative, standard normal variate (SNV), and multiplicative scatter correction) were applied to three sets of NIR spectra of compound aminopyrine phenacetin tablets. The PC-ANNs approach with SNV preprocessing spectra was found to provide the best results. The degree of approximation was performed as the selective criterion of the optimum network parameters.     

Effect of succinate on aminopyrine N-demethylase activity

Succinate stimulated the aminopyrine N-demethylase activity in the presence of rate-limiting concentrations of NADPH in the crude mitochondrial preparation, as well as in a reconstituted system containing microsomes and microsome-free mitochondria. The increase in enzyme activity was accompanied by a decrease of the apparent K_m of NADPH.The stimulating effect of succinate was counteracted by malonate, rotenone and pentachlorophenol. No significant formaldehyde oxidation was exhibited by the crude mitochondrial preparation under the conditions of N-demethylase assay.Enhancement of the N-demethylase activity by succinate is supposed to be due to a mitochondrial-microsomal interaction which may play a role in the regulation of drug metabolism.