title: Cerebrospinal fluid and plasma concentrations of clonidine in pigs after epidural, intravenous and intramuscular administration.
abstract: Epidural clonidine is an alternate way to treat severe pain in man. The cerebrospinal fluid (CSF) and plasma concentrations resulting after epidural, intravenous (i.v.) or intramuscular (i.m.) clonidine, 3 ug/kg b.w. have been determined by a sensitive gas chromatographic method. A porcine model was used, where the epidural and intrathecal spaces were cannulated via the atlanto-occipital membrane. After epidural administration of clonidine the CSF concentrations were maximal 20 minutes after the injection, 129 +/- 24 ng/ml (mean +/- S.D.). Clonidine was eliminated from CSF with an apparent half-life of 26 +/- 8.2 minutes (mean +/- S.D.). The plasma concentrations stayed below 1 ng/ml. Low plasma and undetectable CSF concentrations resulted after i.v. clonidine. Thus, epidural clonidine readily penetrates the dura mater into the CSF, and there is a marked gradient between CSF and plasma.
mesh_terms: D000818:Animals; D002849:Chromatography, Gas; D003000:Clonidine / Q000008:administration & dosage* / Q000097:blood / Q000134:cerebrospinal fluid; D007268:Injections, Epidural; D007273:Injections, Intramuscular; D007275:Injections, Intravenous; D010146:Pain / Q000188:drug therapy*; D013552:Swine
chemical_list: D003000:Clonidine