title: Plasma concentrations and disposition of clonidine following a constant 14-day epidural infusion in cancer patients.
abstract: Epidural administration of clonidine, a partial alpha 2-adrenergic agonist, provides effective relief for patients with intractable cancer pain. However, clonidine's long plasma elimination half-life suggests a potential for plasma accumulation following repeated doses or constant infusion. Adult male and female cancer patients experiencing severe, intractable pain were administered a continuous epidural infusion (30 micrograms/h) of clonidine hydrochloride for 14 days. Plasma clonidine concentrations were determined for 31 patients using a radioimmunoassay with a limit of quantitation of 0.062 ng/mL. Mean (+/- SD) plasma clonidine concentration and calculated total body clearance after 7 days of infusion (respectively, 2.19 +/- 1.17 ng/mL, n = 24; 279 +/- 184 mL/min, n = 27) were comparable to those following 14 days of infusion (2.50 +/- 1.51 ng/mL, n = 19; 272 +/- 163 mL/min, n = 21). Clonidine does not appear to accumulate in the plasma compartment during prolonged (14-day) continuous epidural infusion in cancer patients.
authors.affiliation: Fujisawa USA, Inc., Deerfield, Illinois, USA.
authors.forename: G
authors.initials: G
authors.lastname: Boswell
authors.forename: I
authors.initials: I
authors.lastname: Bekersky
authors.forename: Q
authors.initials: Q
authors.lastname: Mekki
authors.forename: J
authors.initials: J
authors.lastname: Eisenach
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage* / Q000493:pharmacokinetics; D000328:Adult; D015360:Analgesia, Epidural; D003000:Clonidine / Q000008:administration & dosage* / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D007263:Infusions, Parenteral; D008297:Male; D008657:Metabolic Clearance Rate; D009369:Neoplasms / Q000097:blood / Q000150:complications / Q000188:drug therapy*; D010146:Pain / Q000188:drug therapy* / Q000209:etiology
chemical_list: D000316:Adrenergic alpha-Agonists; D003000:Clonidine