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Pharmacokinetics and concentration‐effect relationships of intravenous and oral clonidine
Author(s) -
Davies D. S.,
Wing L. M. H.,
Reid J. L.,
Neill E.,
Tippett P.,
Dollery C. T.
Publication year - 1977
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 - 10.1002/cpt1977215593
Subject(s) - clonidine , pharmacokinetics , pharmacology , medicine , anesthesia
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 (tllza = 10.8 ± 4.7 min) but slowly eliminated (t ½ β = 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 mm 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 nglml but at higher concentrations the hypotensive effect was attenuated.