Pharmacology & toxicology
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Pharmacology & toxicology · May 1991
Randomized Controlled Trial Clinical Trial Controlled Clinical TrialAssessment of the sedative effects of dexmedetomidine, an alpha 2-adrenoceptor agonist, with analysis of saccadic eye movements.
Single intravenous doses (0.5 microgram/kg and 1.0 microgram kg) of dexmedetomidine (4(5)-(1-(2,3-dimethylphenyl)ethyl)imidazole), a selective alpha 2-adrenoceptor agonist, and saline placebo were administered to six healthy volunteers (4 males and 2 females) in a double-blind, placebo-controlled cross-over study. The effects on vigilance were assessed using both subjective estimation (visual analogue scale, VAS) and objective tests (critical flicker fusion frequency, CFF; the Maddox wing; saccadic eye movement analysis). ⋯ The changes in vigilance were concurrent with moderate reductions in blood pressure and heart rate. CFF, the Maddox wing and peak saccadic velocity all proved sensitive in the assessment of sedation induced by dexmedetomidine.
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Pharmacology & toxicology · Oct 1990
Comparative Study Clinical Trial Controlled Clinical TrialMorphine and oxycodone in the management of cancer pain: plasma levels determined by chemical and radioreceptor assays.
Morphine and oxycodone were administered to ten patients suffering from severe cancer pain in a double-blind cross-over study. The patients titrated themselves pain-free, first intravenously, using a patient-controlled analgesia device, and then orally. Each titration phase lasted for 48 hours. ⋯ The mean morphine-6-glucuronide to morphine concentration ratio was 2.3 after intravenous and 4.6 after oral administration. Results from RRA indicate that oxycodone in vivo is a potent mu-agonist and that at least part of its analgesic action is mediated by active metabolites. In vitro morphine glucuronides enhanced morphine in displacing radioligands from the opioid receptors, thus suggesting their complex interactions in vivo.
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Pharmacology & toxicology · Aug 1990
Comparative StudyBoth alpha 1- and beta-adrenoceptor stimulation determine the time course of the inotropic effect of noradrenaline in rabbit heart.
It has been a matter of controversy whether alpha 1-adrenoceptor stimulation contributes to the final inotropic and lusitropic responses in mammalian myocardium to noradrenaline during concomitant and unopposed beta-adrenoceptor stimulation. In the present paper we report studies that compare time courses of the inotropic and lusitropic responses to separate and combined alpha 1- and beta-adrenoceptor stimulation, respectively, in electrically driven rabbit papillary muscles by a submaximal concentration of noradrenaline. Separate alpha 1- or beta-adrenoceptor stimulation (presence of appropriate receptor blocker) showed the characteristic slow and fast development, respectively, of the inotropic responses. ⋯ However, the maximal lusitropic effect and the shortening of TPT were both slightly less during combined adrenoceptor stimulation compared to separate beta-stimulation thus indicating an influence of the alpha 1-adrenoceptor mediated negative lusitropic effect. Quantitatively, the separate alpha 1- and the separate beta-adrenoceptor mediated inotropic effects were not additive. In accordance with other recent studies, this indicated an inhibitory interaction between the two adrenergic receptor populations in myocardium.