Articles: narcotic-antagonists.
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Expert Opin Investig Drugs · May 2006
ReviewMethylnaltrexone, a novel peripheral opioid receptor antagonist for the treatment of opioid side effects.
Methylnaltrexone is an investigational peripheral opioid receptor antagonist, a quaternary derivative of naltrexone. Methylnaltrexone has greater polarity and lower lipid solubility, thus it does not cross the blood-brain barrier in humans. Methylnaltrexone offers the therapeutic potential to block or reverse the undesired side effects of opioids that are mediated by receptors located in the periphery (e.g., in the gastrointestinal tract), without affecting analgesia or precipitating the opioid withdrawal symptoms that are predominantly mediated by receptors in the CNS. This article reviews preclinical studies and clinical opioid bowel dysfunction trial data, and briefly discusses other potential roles of this compound in clinical practice.
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Addictive behaviors · May 2006
Provision of naloxone to injection drug users as an overdose prevention strategy: early evidence from a pilot study in New York City.
Naloxone, an opiate antagonist that can avert opiate overdose morality, has long been prescribed to drug users in Europe and in a few US cities. However, there has been little documented evidence of naloxone distribution programs and their feasibility in the peer reviewed literature in the US. ⋯ Naloxone administration by injection drug users is feasible as part of a comprehensive overdose prevention strategy and may be a practicable way to reduce overdose deaths on a larger scale.
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Exp Clin Psychopharmacol · May 2006
Assessment of agonist and antagonist effects of tramadol in opioid-dependent humans.
The subjective, behavioral, and physiologic effects of racemic tramadol, an analgesic with low abuse liability and dual mu-opioid agonist and monoamine reuptake actions, were evaluated in 2 clinical pharmacology studies in dependent opioid abusers. In the withdrawal precipitation study, participants (N = 8) were maintained on methadone 60 mg/day orally and challenged with intramuscular tramadol, hydromorphone, naloxone, and placebo 20 hr after methadone administration. In the withdrawal suppression study, participants (N = 6) were maintained on hydromorphone given orally 10 mg 4 times daily, and spontaneous opioid withdrawal was produced by withholding doses for 23 hr. ⋯ In both studies a comprehensive panel of participant-rated, observer-rated, and physiologic measures were collected. In both studies, naloxone and naltrexone significantly increased measures of opioid withdrawal, whereas tramadol showed no discernible antagonist effects. In contrast, tramadol's pattern of effects was more similar to that of hydromorphone and suggestive of mild opioid-agonist effects (withdrawal suppression), though not to a statistically significant degree.