title: Sedative, analgesic and cognitive effects of clonidine infusions in humans.
abstract: This placebo-controlled, randomized study evaluated, on separate days, the dose-response relationship for 1 h infusions of clonidine 1, 2 and 4 microg kg(-1) h(-1), in eight healthy volunteers aged 22-30 yr. Response end-points included sedation (bispectral index, visual analogue scale and observer assessment of sedation), analgesia to a cold pressor test, memory (recall of word lists), cognitive function (digit symbol substitution test (DSST)), respiratory function (respiratory rate, end-tidal carbon dioxide, oxygen saturation) and haemodynamic stability (heart rate and mean arterial pressure). Clonidine infusions resulted in significant and progressive sedation, but all subjects were easily awoken to perform tests and evaluations. Statistically significant analgesia, memory impairment and reduced performance on the DSST occurred during 4 microg kg(-1) h(-1) infusions (resulting in a plasma concentration of 2 ng ml(-1). There were no statistically significant changes in cardiorespiratory variables throughout the study.
authors.affiliation: Department of Anaesthesia and Intensive Care Medicine, University of Wales College of Medicine, Cardiff, UK.
authors.forename: J E
authors.initials: JE
authors.lastname: Hall
authors.forename: T D
authors.initials: TD
authors.lastname: Uhrich
authors.forename: T J
authors.initials: TJ
authors.lastname: Ebert
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000328:Adult; D000700:Analgesics / Q000494:pharmacology*; D003000:Clonidine / Q000494:pharmacology*; D003071:Cognition / Q000187:drug effects*; D016292:Procedural Sedation / Q000379:methods; D004305:Dose-Response Relationship, Drug; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D006993:Hypnotics and Sedatives / Q000494:pharmacology*; D008297:Male; D011939:Mental Recall / Q000187:drug effects; D010147:Pain Measurement; D012119:Respiration / Q000187:drug effects
chemical_list: D000316:Adrenergic alpha-Agonists; D000700:Analgesics; D006993:Hypnotics and Sedatives; D003000:Clonidine