British journal of clinical pharmacology
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Br J Clin Pharmacol · Jan 1996
Randomized Controlled Trial Clinical TrialContribution of monoaminergic modulation to the analgesic effect of tramadol.
1. In humans, the central analgesic effect of tramadol 100 mg orally is only partially reversed by the opioid antagonist naloxone (0.8 mg intravenously). As suggested by in vitro and animal data tramadol analgesia may thus result from an action on opioid as well as monoaminergic pathways. ⋯ Peak analgesic effect was observed at 3.7 h (RIII + 39.6 +/- 3.9% and PINS 50.1 +/- s.e.mean 5%) and the analgesia lasted about 6 h. 4. Yohimbine significantly reversed the analgesic effects of tramadol for 2.8 h with a maximum decrease of 97 +/- 4% (RIII) and 67 +/- 12% (PINS), whereas the addition of naloxone abolished tramadol effects throughout the study period with a decrease of 90 +/- 6% (RIII) and 79 +/- 9% (PINS), P < 0.05). 5. Yohimbine alone did not significantly reduce pain thresholds. 6. alpha 2-Adrenoceptor antagonism reverses tramadol effects, thus pointing to the significant role of monoaminergic modulation and the synergy with opioid agonism in tramadol antinociception after a single oral dose.
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Br J Clin Pharmacol · Jan 1996
Randomized Controlled Trial Comparative Study Clinical Trial Controlled Clinical TrialThe effect of acute vs chronic treatment with beta-adrenoceptor blockade on exercise performance, haemodynamic and metabolic parameters in healthy men and women.
1. Variable results have been reported on the effect of beta-adrenoceptor blockers on maximal oxygen uptake (VO2 max) and exercise endurance. This may in part be due to different subject populations, but it could also be due to an adaption of metabolic and haemodynamic responses to exercise during chronic treatment with beta-adrenoceptor blockers. ⋯ Diastolic blood pressure and subjective perception of fatigue were similar across the treatment regimens. 5. The study has demonstrated that acute and chronic administration of propranolol result in different haemodynamic and metabolic response to exercise, although endurance and peak oxygen consumption were reduced to the same extent. The response to propranolol was not significantly different between men and women.