title: Effects of trimethaphan on arterial blood histamine and systemic hemodynamics in humans.
abstract: Because of lack of direct evidence of histamine release by trimethaphan, the authors determined serum histamine levels and hemodynamic responses to trimethaphan administration in 19 consecutive patients. Group 1 patients (n = 7) received a single intravenous injection of trimethaphan, 0.5 mg X kg-1, while awake and again during stable halothane-nitrous oxide anesthesia. Group 2 patients (n = 6) were pretreated with intravenous H1 (chlorpheniramine, 0.1 mg X kg-1) and H2 (cimetidine, 4 mg X kg-1) receptor antagonists administered 15 min before trimethaphan, 0.5 mg X kg-1, in the awake and anesthetized states. In Group 3 (n = 6), the effects of infusion of trimethaphan, 3 mg X min-1 for 15 min, were studied during halothane-nitrous oxide anesthesia. In Group 1, bolus doses of trimethaphan were associated with maximal increases in serum histamine from 0.56 +/- 0.14 to 2.56 +/- 0.35 ng X ml-1 (P less than 0.01) and from 0.60 +/- 0.11 to 2.58 +/- 0.33 ng X ml-1 (P less than 0.01) 2 min after drug administration in the awake and anesthetized states, respectively; there were also clinical manifestations of histamine release. Mean arterial pressure decreased maximally after 5 min in the awake (from 92.0 +/- 3.4 to 69.9 +/- 2.2 mmHg; P less than 0.01) and anesthetized (from 82.6 +/- 3.7 to 57.3 +/- 2.5 mmHg; P less than 0.01) states, and was associated with increases in cardiac output and heart rate; stroke volume increased in the awake state only.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.forename: N R
authors.initials: NR
authors.lastname: Fahmy
authors.forename: N A
authors.initials: NA
authors.lastname: Soter
mesh_terms: D000328:Adult; D001158:Arteries; D002302:Cardiac Output / Q000187:drug effects; D002744:Chlorpheniramine / Q000494:pharmacology; D002927:Cimetidine / Q000494:pharmacology; D004347:Drug Interactions; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006632:Histamine / Q000097:blood*; D006636:Histamine Release / Q000187:drug effects; D006801:Humans; D007023:Hypotension, Controlled; D008875:Middle Aged; D014294:Trimethaphan / Q000494:pharmacology*
chemical_list: D002744:Chlorpheniramine; D014294:Trimethaphan; D002927:Cimetidine; D006632:Histamine