Antibacterial effect of four phenothiazines

Various types of phenothiazines were examined for antibacterial effect on 61 Gram-positive and Gram-negative bacterial strains in vitro. The investigated phenothiazines were two neuroleptic drugs, fluphenazine and chlorpromazine, and two antihistaminic drugs, alimemazine and promethazine. All four drugs have antibacterial effects in vitro, the phenothiazines being more potent against the Gram-positive microorganisms. The antibacterial potency of the drugs was measured as IC50: Fluphenazine 29 microM (15 micrograms/ml), alimemzaine 49 microM (37 micrograms/ml), promethazine 88 microM (28 micrograms/ml) and chlorpromazine 92 microM (29 micrograms/ml). The antibacterial potency of the drugs was linked neither to the neuroleptic nor the antihistaminic potency of the drugs, which is in agreement with results of earlier stereoisomeric investigations. Thus, the known phenothiazines may represent a pool of potentially new antimicrobial drugs. A therapeutic application of these results, however, requires additional in vitro an in vivo testing in an animal model. The bacterial model might be of value as a model system in the study of the interaction of neuropharmacological agents and other membrane active compounds on biological membranes.     

Lack of stereoselectivity in the inotropic and phosphodiesterase inhibitory effects of saterinone enantiomers

The enantiomers of the positive inotropic and a1-adrenoceptor blocking agent saterinone (+/-)-1,2-dihydro-5-[4-[2-hydroxy-3- [4-(2-methoxyphenyl)-1-piperazinyl]propoxy] phenyl]-6-methyl-2-oxo-3-pyridine-carbonitrile, BDF 8634) have been investigated with in vitro and in vivo models in laboratory animals. In the guinea pig papillary muscle, saterinone enantiomers had equipotent inotropic activity and were also as potent as racemic saterinone; the (R)-enantiomer, however, exhibited a greater efficacy than the related compounds. Saterinone and its enantiomers were equipotent in the inhibition of phosphodiesterase PDE III activity in the guinea pig myocardium. The equipotent inotropic effects were also observed after parenteral and enteral administration in cats. In receptor binding studies, (S)-saterinone was 10-fold more potent than (R)-saterinone by inhibiting [3H]-prazosin binding to specific alpha 1-adrenoceptor sites in rat brain cortex membranes. However, in the isolated thoracic aorta of the rabbit, (S)-saterinone was only 3-fold more potent than (R)-saterinone at preventing the pressor effects of phenylephrine. When the enantiomers were tested in vivo against the pressor effects of phenylephrine in the pithed rat, (S)-saterinone was only 2-fold more potent than (R)-saterinone in its alpha 1-adrenoceptor blocking potency. Thus the enantiomers of saterinone do not display enantio-selectivity in their inotropic and PDE III inhibitory effects in vitro, nor in their cardiotonic effects in vivo. There is a slight enantio-selectivity at alpha 1-adrenoceptors in receptor binding studies, but this is reduced to biologically irrelevant magnitude in functional studies in vitro and in vivo.     

The prevention of cisplatin-induced renal dysfunction by hydroxyl-containing dithiocarbamates.

Two hydroxyl containing dithiocarbamates, sodium N-methyl-D-glucamine dithiocarbamate (NaG) and sodium dihydroxyethyl dithiocarbamate (NaY) have been examined as agents for the control of the renal dysfunction in rats given cisplatin. Of these, NaG was found to be the more effective in controlling such renal dysfunction when administered at 1 and 3 h after 5 mg cisplatin kg-1, i.p. Renal function was examined 5 days after the administration of cisplatin by measurement of serum and urinary levels of creatinine and urea, creatinine clearance, serum and urinary levels of Na+, K+, Mg2+, Ca2+, as well as the concentrations of these ions in the renal medulla and cortex. Treatment of rats given cisplatin with NaG at 1 and 3 h post cisplatin resulted in indices of renal function which were not significantly different from those of animals which had received no cisplatin. The sole difference was found to be a slight increase in renal cortical Na+ concentration.