Articles: analgesics.
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Randomized Controlled Trial Clinical Trial
Effects of intravenous ketamine, alfentanil, or placebo on pain, pinprick hyperalgesia, and allodynia produced by intradermal capsaicin in human subjects.
The importance of N-methyl-D-aspartate (NMDA) receptor-mediated sensitization of central nervous system (CNS) neurons is well established in animal models of acute and chronic pain. A human model of central sensitization would be useful in screening new NMDA antagonists and establishing dose regimens for clinical trials in patients with pain related to sensitization of CNS neurons. We used this model to examine the effects of intravenous infusions of two centrally acting analgesics, the NMDA receptor antagonist ketamine and the morphine-like opioid agonist alfentanil. ⋯ Because the drugs were given systemically and produced side effects in all subjects, we cannot specify the site or sites of action nor conclusively rule out a non-specific 'active placebo' response as the cause for reduction of symptoms. Arguing against an 'active placebo' response, however, was the lack of analgesic effect of intravenous midazolam (mean dose; 3.4 mg, titrated to produce side effects of similar magnitude to ketamine and alfentanil) given at 145 min after capsaicin in 9 subjects who had received saline from 25 to 60 min. The results of this study suggest that neural systems sensitive to NMDA receptor antagonists and opioids participate in capsaicin-evoked pain phenomena, and support the feasibility of pharmacological studies using the intradermal capsaicin model.
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Randomized Controlled Trial Comparative Study Clinical Trial
Measured context-sensitive half-times of remifentanil and alfentanil.
The context-sensitive half-time, rather than the terminal elimination half-life, has been proposed as a more clinically relevant measure of decreasing drug concentration after a constant infusion of a given duration. The context-sensitive half-time is derived from computer modelling using known pharmacokinetic parameters. The modelled context-sensitive half-time for a 3-h infusion of alfentanil is 50-55 min and is 3 min for remifentanil. The terminal elimination half-life is 111 min for alfentanil and 12-30 min for remifentanil. It has not been tested whether the modelled context-sensitive half-time reflects the true time for a 50% decrease in drug concentration or drug effect. ⋯ The measured context-sensitive half-times were in close agreement with the context-sensitive half-times previously modelled for these drugs. The results of this study confirm the value of the context-sensitive half-time in describing drug offset compared to the terminal elimination half-life.
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Fertility and sterility · Nov 1995
Randomized Controlled Trial Clinical TrialFollicular fluid levels of midazolam, fentanyl, and alfentanil during transvaginal oocyte retrieval.
To investigate the time course of changes in follicular fluid (FF) concentrations of midazolam (Roche Products Ltd., Welwyn Garden City, United Kingdom), fentanyl (Janssen Pharmaceuticals Ltd., Wantage, United Kingdom), and alfentanil (Janssen Pharmaceuticals Ltd.) during ultrasound-guided transvaginal oocyte collection. ⋯ We conclude that midazolam, fentanyl, and alfentanil are found in FF after a single IV dose, but further investigation needs to be undertaken to investigate any potential influence on fertilization and implantation rates.
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Randomized Controlled Trial Comparative Study Clinical Trial
A comparison between ketorolac and diclofenac in laparoscopic sterilization.
We compared ketorolac and diclofenac for the prevention and treatment of post-operative pain in patients undergoing laparoscopic sterilization. Fifty ASA I or II women were allocated randomly to receive either diclofenac 75 mg or ketorolac 30 mg intramuscularly 30-90 min before general anaesthesia. Pain scores were assessed half-hourly in the recovery room and then at 2 h and 4 h in the ward. ⋯ Pain at the injection site was more common after diclofenac than ketorolac (12 vs. 3, P < 0.05). In conclusion, both intramuscular diclofenac and ketorolac were relatively ineffective in controlling the pain after laparoscopic sterilization. The drugs were equally well tolerated, but more patients complained of pain at the injection site after diclofenac.
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of continuous brachial plexus infusion of butorphanol, mepivacaine and mepivacaine-butorphanol mixtures for postoperative analgesia.
We have reported recently that continuous administration of butorphanol into the brachial plexus sheath provided analgesia of a quality superior to that of continuous i.v. administration. In the present study, we have compared postoperative pain relief produced by continuous infusion of one of three types of solution into the axillary sheath: opioid alone, local anaesthetic alone or a mixture of local anaesthetic and opioid. In patients undergoing upper extremity surgery with continuous axillary brachial plexus block, we injected one of the three solutions into the axillary neurovascular sheath: butorphanol 2 mg (group B), 0.5% mepivacaine alone (group M) and 0.5% mepivacaine-butorphanol (group MB); the volume of each solution was 50 ml, administered at a rate of 50 ml per 24 h. At 3 h after operation, visual analogue scale (VAS) scores were significantly higher in group M than in group MB (P < 0.01), and higher in group B than in group MB (P < 0.05).