Articles: narcotic-antagonists.
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Randomized Controlled Trial
Effect of low-dose naloxone infusion on fentanyl requirements in critically ill children.
Sedating critically ill patients often involves prolonged opioid infusions causing opioid tolerance. Naloxone has been hypothesized to limit opioid tolerance by decreasing adenylate cyclase/cyclic adenosine monophosphate activation. The study purpose was to investigate the effect of low-dose naloxone on the maximum cumulative daily fentanyl dose in critically ill children. ⋯ We conclude that administration of low-dose naloxone (0.25 microg/kg per hour) does not decrease fentanyl requirements in critically ill, mechanically ventilated children.
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J Pain Symptom Manage · May 2008
Randomized Controlled TrialSubcutaneous methylnaltrexone for the treatment of opioid-induced constipation in patients with advanced illness: a double-blind, randomized, parallel group, dose-ranging study.
Methylnaltrexone, a peripherally-acting quaternary opioid antagonist, is an investigational treatment for opioid-induced constipation in patients with advanced illness. This randomized, parallel-group, repeated dose, dose-ranging trial included a double-blind phase for one week followed by an open-label phase for a maximum of three weeks. Opioid-treated patients with advanced illness who met criteria for opioid-induced constipation despite laxative therapy were potentially eligible. ⋯ There was no apparent dose-response above 5mg. Most adverse events were related to the gastrointestinal system, were mild, and did not lead to discontinuation. In conclusion, methylnaltrexone relieved opioid-induced constipation at doses >or=5mg in patients with advanced illness, and did not reduce analgesia or cause opioid withdrawal symptoms.
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Multicenter Study Comparative Study
Unplanned admissions to two Sydney public hospitals after naltrexone implants.
To describe hospital presentations related to the use of naltrexone implants, an unlicensed product used in Australia for treating heroin dependence. ⋯ These severe adverse events challenge the notion that naltrexone implants are a safe procedure and suggest a need for careful case selection and clinical management, and for closer regulatory monitoring to protect this marginalised and vulnerable population.
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Cochrane Db Syst Rev · Apr 2008
Review Meta AnalysisSustained-release naltrexone for opioid dependence.
Naltrexone is an opioid antagonist which effectively blocks heroin effects. Since opioid dependence treatment with naltrexone tablets suffers from high dropout rates, several depot injections and implants are under investigation. Sustained-release formulations are claimed to be effective, but a systematic review of the literature is lacking. ⋯ There is insufficient evidence to evaluate the effectiveness of sustained-release naltrexone for treatment of opioid dependence. For naltrexone injections, administration site-related adverse effects appear to be frequent, but of moderate intensity and time limited. For a harm-benefit evaluation of naltrexone implants, more data on side effects and adverse events are needed.
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The agonist-antagonist kappa-opioid nalbuphine administered for postoperative pain produces greater analgesia in females than in males. In fact, males administered nalbuphine (5 mg) experience pain greater than those receiving placebo, suggesting the existence of an anti-analgesic effect. These sexually dimorphic effects on postoperative pain can be eliminated by coadministration of a fixed ratio of the prototypical opioid receptor antagonist naloxone with nalbuphine, implying a role for opioid receptors in the anti-analgesic as well as analgesic effects of nalbuphine. In the present study, we further evaluated the role of opioid receptors in the sex-specific effects on pain produced by nalbuphine by coadministering a dose of morphine low enough that it does not produce analgesia. After extraction of bony impacted third molar teeth, nalbuphine (5 mg) was administered alone or in combination with either of 2 low doses of morphine (2 mg or 4 mg). Both doses of morphine reversed nalbuphine-induced anti-analgesia in males, but only the lower dose (2 mg) reached statistical significance. Neither dose affected nalbuphine-induced analgesia in females, and when administered alone in either males or females, morphine (2 mg) had no analgesic effect. Though not observed in females, the effect of morphine in males argues that, like naloxone, low-dose morphine may act as an anti-analgesia opioid receptor antagonist. ⋯ Previously, we reported that the nalbuphine produces both analgesic and anti-analgesic effects and that the opioid antagonist naloxone can enhance nalbuphine analgesia by selectively antagonizing the anti-analgesic effect. Here we show that morphine, given in a subanalgesic dose, reverses nalbuphine-induced anti-analgesia in males, perhaps by a similar mechanism.