Pharmacokinetics of clonidine and its relation to the hypotensive effect in patients.

Abstract

1 The kinetics of clonidine and its relation to the blood pressure response after single intravenous doses of 75 micrograms–275 micrograms in hypertensive patients were determined. 2 Clonidine disposition could be described by a two compartment open model and pharmacokinetic parameters show a rapid distribution phase of 20–30 min and a mean plasma clearance of 4.6 ml min‐1 kg‐1 (75–200 microgram). The half‐life of the beta‐phase was found to be in the range of 7.4–11.4 h. Indications of dose dependent kinetics were obtained. 3 A dose‐dependent decrease in blood pressure was obtained. 4 The maximal reduction in MAP (mean arterial blood pressure) was significantly (P less than 0.01) related to plasma concentrations of clonidine. 5 The reduction in MAP was always related to plasma concentrations of clonidine (r = 0.88, P less than 0.01) when pseudoequilibrium of distribution of the drug was achieved. 1978 The British Pharmacological Society