Cf George

The influence of levodopa on gastric emptying in healthy elderly volunteers.

SummaryParacetamol absorption and 99Tc-DTPA measurements have been used to determine the influence of levodopa on gastric emptying in 8 healthy elderly volunteers.In the absence of levodopa 7 subjects showed a rapid gastric emptying pattern by gamma-camera and a single major peak in the plasma concentration-time curve of paracetamol. One subject showed two rapid phases of gastric emptying separated by a period of negligible emptying and had 2 separate peaks in the paracetamol plasma concentration-time curve.In the presence of levodopa, the gamma-camera data for 6 subjects showed a pattern of gastric emptying consisting of 2 rapid phases separated by a plateau. In each case secondary peaks in the plasma concentration-time curve of paracetamol occurred about 30 min after the end of the plateau. The time to 90% emptying on the gamma scan was increased significantly from 40 min to 65 min in the presence of levodopa.Comparison of the present data with those reported previously indicates that levodopa affects gastric emptying in the both elderly and young volunteers to a similar extent.

Hemodynamic responses of trazodone and impramine

The hemodynamic effects of trazodone (150 mg) and Imipramine (75 mg) were examined in eight healthy subjects. Trazodone significantly increased left ventricular ejection time 1 (LVETI), but decreased both preejection period (PEP) and PEP/LVET ratio. It also decreased heart rate and systolic and diastolic blood pressure at 90 min after dosing. Imipramine initially increased total electromechanical systole I (QS2I) and PEP (30 min, P < 0.01), but at 150 and 180 min after dosing QS2I was significantly lower. Imipramine increased diastolic blood pressure at 30 min (P < 0.05) and increased systolic blood pressure between 90 and 180 min (P < 0.05). At 30 and 60 min heart rate was significantly depressed by imipramine. There were no significant changes in the values of stroke volume and cardiac output. These results suggest that trazodone has its major effect on the circulation through its alpha‐receptor blocking activity, whereas the effects of imipramine are probably mediated through its ability to block reuptake of norepinephrine.

BETA-ADRENOCEPTOR ANTAGONISTS PLUS NIFEDIPINE IN THE TREATMENT OF CHRONIC STABLE ANGINA PECTORIS

SummaryThe antianginal effects of beta-adrenoceptor antagonists are achieved by a reduction in myocardial oxygen demand. This is a rational approach to treatment in patients whose angina is caused by a fixed stenosis. However, dynamic coronary vasospasm is an important factor in patients with chronic stable angina. Nifedipine increases myocardial oxygen supply by reducing coronary vascular tone and is a logical approach to treatment in these patients. For monotherapy of angina, nifedipine is less effective than the beta-adrenoceptor antagonists, but the combination has additive effects in reducing the frequency of anginal episodes and improving exercise tolerance.Plasma concentrations of nifedipine are closely related to clinical efficacy, and the variable first-pass metabolism of the drug leads to wide interindividual differences in peak concentrations and duration of action. Increasing the size of individual doses of nifedipine carries a risk of enhanced side effects due to high peak plasma concentrations. Optimal treatment may be more appropriately achieved in some patients by a slow release formulation, but with an increased frequency of administration.