[Pharmacodynamics of carteolol].

The compound known as 5-(3-tert-butylamino-2-hydroxy-propoxy)-3,4-dihydro-2 (1H)-quinolinone hydrochloride (carteolol hydrochloride, Endak, Endak mite) has been tested in extensive experimental pharmacological investigations both in vivo in various animal species and in appropriate in vitro systems. From the results it is clear that carteolol is a beta-adrenolytic agent with the following characteristics: 1. Carteolol exerts potent and long lasting blockade of adrenergic receptors, by oral or intravenous administration alike. 2. The effect comprises beta 1- and beta 2-receptors to an equal extent, and for this reason the drug produces haemodynamic changes and metabolic shifts in addition to cardiac effects. Carteolol can therefore be classified as a nonspecific beta-adrenergic blocker. 3. The drug displays a striking feeble local anaesthetic or nonspecific membrane-stabilizing action, probably owing to its pronounced hydrophilia. 4. There is evidence that carteolol has a relatively strong intrinsic sympathomimetic activity (ISA). This has been shown by appropriately planned investigations, and is also apparent after exceeding the doses or concentrations required for adrenolysis. 5. Carteolol causes dose-dependent changes in the electrophysiological parameters of cardiac function. In low doses or concentrations it slows heart rate and in higher doses it sometimes accelerates it. 6. Carteolol is converted - with species-specific differences - almost exclusively and to a relatively small extent into 8-hydroxycarteolol. This metabolite closely resembles the original substance and exceeds it only in ISA.