title: Cardiodepressant actions of combined diltiazem and propranolol in dogs.
abstract: The cardiovascular actions of combined intravenous (i.v.) diltiazem and propranolol were studied in barbiturate-anesthetized dogs. When given alone, diltiazem increased cardiac output (CO) and P-R interval duration (P-R) while decreasing mean arterial pressure (MAP), heart rate (HR), and systemic vascular resistance (SVR). Propranolol alone decreased CO and HR while increasing SVR. With the same i.v. doses, combined infusion of diltiazem and propranolol rapidly resulted in depression of CO to levels similar to those achieved with propranolol beta-adrenoceptor blockade alone. The combination decreased MAP to levels achieved with diltiazem-induced calcium channel blockade. P-R increased beyond the durations produced by either drug given alone. Pharmacokinetic interactions were not apparent, although slight increases in propranolol plasma concentrations were observed during combined drug infusions. These studies support clinical observations that the cardiovascular effects resulting from a combination of diltiazem and propranolol may be attributed to the characteristic cardiovascular actions of each individual drug.
authors.affiliation: Department of Anesthesiology, College of Medicine, University of Kentucky, Lexington.
authors.forename: S R
authors.initials: SR
authors.lastname: Hamann
authors.forename: R G
authors.initials: RG
authors.lastname: McAllister
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D004110:Diltiazem / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D004285:Dogs; D004347:Drug Interactions; D004562:Electrocardiography / Q000187:drug effects; D006321:Heart / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D007262:Infusions, Intravenous; D008297:Male; D011433:Propranolol / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*
chemical_list: D011433:Propranolol; D004110:Diltiazem