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Early hemodynamic and humoral effects of lofexidine
Author(s) -
Fouad Fetnat M,
Vidt Donald G,
Williams Hugh,
Tarazi Robert C,
Bravo Emmanuel L
Publication year - 1981
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1038/clpt.1981.69
Subject(s) - hemodynamics , blood pressure , heart rate , supine position , medicine , cardiac output , anesthesia , haemodynamic response , propranolol , cardiology
Hemodynamic and humoral effects of lofexidine were assessed in 11 patients with essential hypertension after a total of 1.5 mg were given orally over 24 hr. Heart rate (bpm) slowed (−12 ± 6 [SEM], p < 0.05) and cardiac output (liters per minute) was reduced (−0.78 ± 0.18, p < 0.01) irrespective of blood pressure response; the latter was related to changes in systemic resistance (TPR) (r = 0.72, p < 0.01). Cardiac performance judged from ejection fraction (0.61 ± 0.03 to 0.59 ± 0.03, NS) and mean transit time (8.73 ± 0.53 sec to 9.20 ± 0.35, NS) were not altered. Plasma volume was expanded more than 10% in two patients but not changed in the others. Supine plasma catecholamines determined in five patients were reduced in all but one with no correlation to changes in either TPR or diastolic blood pressure. On the other hand, there was an increase in plasma catecholamines during head‐up tilt in four of five patients, indicating normal catecholamine release. Orthostatic hypotension occurred de novo in three patients; two of them had simultaneous slowing of heart rate (vasovagal attack). Results suggested that reduction of blood pressure by lofexidine depended on lack of increase in TPR in response to reduction of cardiac output; the hemodynamic pattern of this centrally acting adrenergic blocker closely resembled that reported for beta blockers. Clinical Pharmacology and Therapeutics (1981) 29, 498–504; doi: 10.1038/clpt.1981.69