Pharmacodynamic effects of prenalterol in healthy subjects.
1. Prenalterol induces a dose-dependent effect on different variables reflecting myocardial contractility and heart rate. A clearcut effect can be demonstrated after an oral dose of 2.5 mg. The duration of the effect increases considerably when prenalterol is administered as a controlled release preparation partly due to an increased bioavailability. 2. Prenalterol induces a lipolytic effect manifested as a rise in free fatty acids and glycerol. Also a slight increase of plasma insulin is recorded while plasma potassium decreases somewhat. 3. When prenalterol is administered together with therapeutic doses of a selective or non-selective beta-adrenoceptor blocker it induces the same haemodynamic effects as before the beta-blocker but the dose has to be increased ten-fold. These results suggest that prenalterol might be a useful drug to counteract unwanted haemodynamic effects of a beta-blocker. 4. In animal studies it has been shown that prenalterol has affinity for both beta 1- and beta 2-adrenoceptors. However, it has a stimulating effect mainly on beta 1-adrenoceptors. Therefore, theoretically it might act as a beta 2-adrenoceptor antagonist. Preliminary results from studies in patients with chronic asthma indicate that prenalterol only has an insignificant beta 2-blocking effect when the drug is administered in doses which induce a significant beta 1-adrenoceptor stimulating effect.
D000284:Administration, Oral; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000037:antagonists & inhibitors; D001682:Biological Availability; D001794:Blood Pressure / Q000187:drug effects; D003692:Delayed-Action Preparations; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008066:Lipolysis / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects; D011217:Practolol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D011294:Prenalterol; D011943:Receptors, Adrenergic, beta / Q000187:drug effects
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D003692:Delayed-Action Preparations; D011943:Receptors, Adrenergic, beta; D011294:Prenalterol; D011217:Practolol