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Biomedical subjects

M Mitchard

Publications and source records attributed to M Mitchard.

At least 37 records · Page 2Linked to original sources
PubMed1976

A comparison of slow release with conventional oxprenolol: plasma concentrations and clinical effects.

1 Plasma concentrations of oxprenolol have been compared in six healthy volunteers after 80 and 160 mg doses of a new slow release (SR) oxprenolol preparation, after an 80 ng dose of conventional oxprenolol (CO), and after the second of two 80 mg doses of conventional oxprenolol given 12 h apart. Basal pulse rates and blood pressures, and pulse rates before and after a standard exercise test have been compared after the four active treatments and after a placebo. 2 Peak plasma concentrations of oxprenolol attained after 160 mg of the slow release preparation were similar to the peak concentrations after the single 80 mg dose of conventional oxprenolol. Higher concentrations, however, persisted for much longer after the slow release preparations than after the conventional preparations. 3 Neither oxprenolol formulation had any effect on resting pulse rate or blood pressure in normotensive volunteers. 4 Comparison with placebo showed that the single dose of the conventional oxprenolol produced a significant reduction in exercise induced tachycardia for 8 h whereas the high dose of the slow release preparation produced a similar reduction which lasted for at least 14 hours.

Administration, Oral↗
PubMed1975

General pharmacokinetic equations for linear mammillary models with drug absorption into peripheral compartments.

General equations are derived for the disposition functions of any compartment in a linear mammillary model, when the system input occurs into a peripheral compartment. Laplace transforms and matrix algebra are used to derive these equations. Equations describing the time-course of a drug in any compartment are readily obtainable using disposition and input functions.

Intestinal Absorption↗
PubMed1975

A single dose study of trazodone with an assessment of its effect on mood and arousal.

1 A pharmacokinetic study of a single oral dose of a new antidepressant (trazodone) is described, linked to an attempt to measure changes in mood and arousal induced by the drug in normal subjects. 2 The drug had a measurable effect on arousal, but not on mood. It caused bradycardia (compared with placebo) and this persisted through the following night's sleep. This effect has not been completely explained. 3 The technique of mood and arousal measurement employed in this study seems potentially useful.

Adult↗
PubMed1975

The effect of ageing on plasma pethidine concentration.

1. Plasma pethidine levels have been monitored after the administration of 1.5 mg/kg intramuscularly to a group of young (under 30) and old (over 70) subjects. 2. Plasma levels were consistently higher in the old group, this was most marked for the first three hours but for most of the study there was a more than two-fold difference. 3. Differences in uptake from muscle and in metabolism were small and appeared unimportant. 4. Less pethidine was excreted in the elderly and this contributed to the overall differences in serum levels but was not important in explaining the marked disparity noted over the first three hours. 5. Red cell binding of pethidine by the young was much greater than by the old and if the differences in drug binding also applies to other tissues this would explain the high serum levels in the old and the increased incidence of side effects.

Adult↗
PubMed1975

Factors influencing the excretion and relative physiological availability of pethidine in man.

Factors influencing the urinary excretion of pethidine, norpethidine and pethidine N-oxide have been examined. The proportion of a dose of pethidine excreted unchanged or as norpethidine depends on the urinary pH and the route of administration. Older people appear to metabolize more of the drug and therefore excrete less unchanged pethidine. The rate of excretion of pethidine in acid urine is directly proportional to the plasma pethidine concentration and under these conditions the relative physiological availability of pethidine has been determined. It has not been possible to explain variations in the amount of pethidine excreted as the N-oxide.

Administration, Oral↗