RESUMEN
We have reported previously that phenyl-2-aminoethyl sulfide and its derivatives are excellent substrates for dopamine-beta-monooxygenase and produce an antihypertensive effect in spontaneously hypertensive rats after i.p. administration. In the studies reported herein, we demonstrate that alpha-methyl-phenyl-2-aminoethyl sulfide and 4-hydroxy-alpha-methyl-phenyl-2-aminoethyl sulfide, the methylated and hydroxymethylated derivatives of phenyl-2-aminoethyl sulfide, respectively, decrease mean arterial pressure in conscious, unrestrained spontaneously hypertensive rats after p.o. administration. This antihypertensive effect after p.o. administration occurs without the undesirable transient rise in blood pressure observed previously after i.p. administration. Results using the methodology of food-reinforced operant conditioned behavior are consistent with the interpretation that the ring hydroxylated derivatives, 4-hydroxy-phenyl-2-aminoethyl sulfide and 4-hydroxy-alpha-methyl-phenyl-2-aminoethyl sulfide, do not penetrate into the central nervous system. This finding supports our contention that the primary site of action for the antihypertensive activity of the sulfides may be the peripheral adrenergic nerve ending. In view of the current high degree of interest in chiral development, the enantiomeric specificity of the antihypertensive activity of alpha-methyl-phenyl-2-aminoethyl sulfide was also evaluated. Results from these studies demonstrate that the (S)-enantiomer of alpha-methyl-phenyl-2-aminoethyl sulfide is more effective in lowering blood pressure after p.o. administration than the (R)-enantiomer. The implications of our findings in terms of the mechanism of action of these compounds are discussed.
Asunto(s)
Antihipertensivos/farmacología , Fenoles/farmacología , Propilaminas/farmacología , Sulfuros/farmacología , Administración Oral , Animales , Antihipertensivos/administración & dosificación , Condicionamiento Operante , Alimentos , Masculino , Metilación , Fenoles/administración & dosificación , Propilaminas/administración & dosificación , Ratas , Ratas Endogámicas SHR , Ratas Endogámicas WKY , Ratas Sprague-Dawley , Estereoisomerismo , Sulfuros/administración & dosificaciónRESUMEN
Diabetic patients often have a kidney or pancreas allograft requiring cyclosporine A (CsA) to prevent transplant rejection. These patients usually take p.o. hypoglycemic agents to control their diabetes. Because of the reported adverse effects of CsA on glucose metabolism as well as its potential use in Type II diabetics, we were interested in evaluating the in vivo effect of CsA on the activity of p.o. hypoglycemic agents. We also wanted to determine if tolbutamide produced any adverse effects on the pharmacokinetics of CsA. Male, Holtzman rats were administered CsA (p.o.) followed 1 hr later with the hypoglycemic agent. Two hours later, blood samples were obtained to determine blood glucose levels. Animals treated with CsA alone produced a significant hyperglycemia. The hypoglycemic effects produced by tolbutamide and glyburide were inhibited in animals treated concomitantly with CsA. This inhibitory effect was not observed during the first 3 hr of CsA-treatment, could not be overcome by increasing the dose of the hypoglycemic agent and occurred using small doses. CsA did not, however, interfere with the activity of exogenous NPH insulin. Tolbutamide was found to have no effect on the acute pharmacokinetics of CsA. The distribution of CsA was similar to controls in all tissues studied except the liver in which CsA levels were less in tolbutamide-treated animals. These studies demonstrate that CsA interferes with the effects of p.o. hypoglycemic agents and, therefore, blood glucose levels should be monitored closely in Type II diabetic patients taking combinations of these drugs.