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Biomedical subjects

L Endrenyi

Publications and source records attributed to L Endrenyi.

88 records · Page 5Linked to original sources
PubMed1973

Relative bioavailability of commercial ampicillin formulations in man.

The relative bioavailability of three commercial ampicillin products was examined in 12 human subjects using a crossover experimental design. Based upon the areas under the ampicillin plasma concentration-time curves after the oral administration of 250 mg. ampicillin and using an analysis of variance technique no statistically significant differences were found between the products examined. These findings are in contrast to those of a recent report and appear to be explained by formulation differences. These relatively minor differences in formulation reflect the importance of formulation variables in providing efficient drug therapy. The intrasubject variation associated with several of these products is quite marked and is consistent with the incomplete and erratic absorption of this antibiotic in man.

Administration, Oral↗
PubMedDate not supplied

The fate of [7-3H]isoproterenol in cats after intravenous administration.

The fate of intravenously administered [7-3H]isoproterenol was investigated in cats. Ten minutes after injection the concentration of 3H was highest in the heart, lungs, adrenals, and kidneys, but after 5 hr most of the radioactivity was found in the liver. The concentration of the unchanged drug in the serum declined in a biphasic manner with half-lives of 2.1--2.5 min for the first phase, and 58--77 min for the second phase. The drug was rapidly metabolized to 3-O-methylisoproterenol (MISP) and then conjugated. In 5 hr 44--55% of the administered 3H was excreted in the urine, 2--2.5% as unchanged drug, 21--41% as MISP, and 12--22% as conjugated MISP. Conjugated MISP was also found in the bile. The results indicate that the rate of formation of MISP in cats is much faster than its rate of conjugation and excretion.

Animals↗
PubMedDate not supplied

Effects of verapamil on [3H]norepinephrine release.

If calcium entry blocking drugs affect norepinephrine release, this may alter their cardiovascular action by modifying the activity of baroreceptor reflexes. We investigated the effect of verapamil on 3H-release in [3H]norepinephrine-incubated rat arteries and guinea pig vas deferens. Superfusion of tail artery with verapamil (10(-6) - 10(-4) M) increased the 3H-overflow induced by transmural stimulation (1 Hz, 2 ms, 10 V) both in Wistar Kyoto and in spontaneously hypertensive rats. The effect was present also in vessels pretreated with cocaine to inhibit neuronal uptake or with yohimbine to block alpha 2-adrenoceptors. The greatest increase in 3H-overflow--around 400% in the various groups--was observed after perfusion with 10(-4) M verapamil. In other experiments, we found that verapamil also enhanced 3H-overflow from vessels not stimulated transmurally; this effect again was dose-related (p less than 0.001). In the vas deferens of the guinea pig, 10(-5) M verapamil increased spontaneous and electrical stimulation-induced 3H-release (p less than 0.001), whereas superfusion of the tissue with 10(-9) and 10(-7) M verapamil was ineffective. The results indicate that verapamil can act on sympathetic nerves to release norepinephrine.

Animals↗