Pharmacokinetics and concentration-effect relationships of intravenous and oral clonidine

D. S. Davies, L. M.H. Wing, J. L. Reid, E. Neill, P. Tippett, C. T. Dollery

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202 Citations (Scopus)

Abstract

The kinetics of the disposition of intravenous and oral clonidine in five normotensive subjects have been determined. It is proposed that a two-compartment model adequately describes the disposition of the drug. The drug is rapidly distributed (t 1 2α = 10.8 ± 4.7 min) but slowly eliminated (t 1 2β = 8.5 ± 0.9 hr). The bioavailability of oral clonidine in the tablets tested averaged 75.2% and 40 to 50% of the bioavailable dose is excreted unchanged in urine. Renal clearance of the drug showed considerable intersubject variation (1.82 ± 0.34 ml/min/kg) and exceed the calculated glomerular filtration rate in some subjects. Oral and intravenous clonidine induced significant falls in blood pressure (>20/15 imn Hg) in our normotensive subjects and consistently caused marked sedation and dryness of the mouth. Sedation and salivary flow correlated with plasma clonidine concentration over the range 0 to 4 ng/ml. Falls in blood pressure were related to plasma concentration to 1.5 to 2 ng/ml but at higher concentrations the hypotensive effect was attenuated.

Original languageEnglish
Pages (from-to)593-601
Number of pages9
JournalClinical Pharmacology and Therapeutics
Volume21
Issue number5
DOIs
Publication statusPublished - May 1977
Externally publishedYes

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