Abstract |
This study examined naloxone-precipitated withdrawal symptoms from 24 to 168 h after pretreatment with a single 30-mg i.m. dose of methadone in 6 male subjects who were experienced users of opioid drugs but were not currently dependent. The study showed that acute physical dependence signs and symptoms could be reliably precipitated with a small dose of naloxone (0.75 mg/70 kg i.m.) for as long as 96 h (4 days) after a single dose of methadone. The intensity of symptoms at 24 h post- methadone was similar to that observed at 96 h; no precipitated withdrawal effects were observed at 168 h (7 days) after methadone administration. The magnitude of precipitated withdrawal effects at 96 h was not attenuated by the administration of a prior naloxone challenge at 24 h post- methadone. Agonist effects (pupillary constriction; subjective effects) were detectable at 24 h but not at 96 h post- methadone. The results suggest that methadone engenders long-lasting physical dependence effects that can be detected beyond the dissipation of acute agonist effects. Methadone pretreatments may provide a convenient mechanism for the production and examination of long-term mu- opiate receptor physical dependence.
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Authors | M L Stitzer, C Wright, G E Bigelow, H L June, L J Felch |
Journal | Drug and alcohol dependence
(Drug Alcohol Depend)
Vol. 29
Issue 1
Pg. 39-46
(Dec 1991)
ISSN: 0376-8716 [Print] Ireland |
PMID | 1665778
(Publication Type: Clinical Trial, Journal Article, Randomized Controlled Trial, Research Support, U.S. Gov't, P.H.S.)
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Chemical References |
- Receptors, Opioid
- Receptors, Opioid, mu
- Naloxone
- Methadone
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Topics |
- Adult
- Arousal
(drug effects, physiology)
- Humans
- Injections, Intramuscular
- Male
- Metabolic Clearance Rate
(physiology)
- Methadone
(administration & dosage, pharmacokinetics)
- Naloxone
(administration & dosage)
- Neurologic Examination
- Opioid-Related Disorders
(physiopathology, rehabilitation)
- Receptors, Opioid
(drug effects, physiology)
- Receptors, Opioid, mu
- Substance Withdrawal Syndrome
(physiopathology)
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