ISSN:
1432-1041
Keywords:
betablocker
;
haemodynamics
;
cardioselectivity
;
impedance cardiography
;
intrinsic sympathomimetic activity
;
healthy volunteers
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Medicine
Notes:
Summary Changes in cardiac output, heart rate and arterial blood pressure were determined in 31 healthy volunteers after i. v. administration of equipotent doses of five different adrenergic betareceptor blocking drugs. Propranolol was given to seven subjects, atenolol to five, practolol to seven, pindolol to five, and (a new drug) ICI 89,406 to seven. Each drug was given in six logarithmically spaced doses. Propranolol is non-cardioselective and lacks intrinsic sympathomimetic activity. Atenolol, practolol, and ICI 89,406 are cardioselective. Practolol, pindolol, and ICI 89,406 have intrinsic sympathomimetic activity. Cardiac output was determined by impedance cardiography at supine rest. The dose-response curves for cardiac output and heart rate were of three different types: one obtained after administration of drugs without intrinsic activity, represented by propranolol and atenolol, both of which caused a maximal decrease in cardiac output of about 27%, and in heart rate of about 21%. A second type, obtained after drugs with moderate intrinsic sympathomimetic activity, represented by practolol, showed small but significant decreases in cardiac output of 12%, and in heart rate of 11 per cent. A third type, after drugs with marked intrinsic sympathomimetic activity, was represented by pindolol and ICI 89,406, which did not significantly reduce cardiac output or heart rate. The blood pressure was essentially unchanged in all subjects, even after the largest dose of any of the drugs. It was concluded that the degree of intrinsic sympathomimetic activity possessed by an adrenergic betareceptor blocking agent is responsible for acute changes in heart rate and cardiac output, and cardioselectivity is of no importance in this respect.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00618509
