Opioid physical dependence development: effects of single versus repeated morphine pretreatments and of subjects' opioid exposure history.

摘要: In acute dependence, signs and symptoms of opioid withdrawal are precipitated when an antagonist (naloxone) is administered following (e.g. single dose) pretreatment with amu agonist. This study examined the influence amount previous exposure, both immediate remote, on intensity effects in dependence model. Two groups subjects, abusers (n=20) nonabusers (n=20), received either one 15 mg/70 kg IM morphine or two such pretreatments spaced 24 h apart. Naloxone challenge (30 kg) followed 4.33 after second pretreatment. There were clear condition (single versus repeated mg) responses elicited by naloxone. More intense seen pretreatment, suggesting that physical escalates exposures at appropriate intervals. Subjects abuse history reported greater liking agonist drug than did nonabusers, whereas more sedating effects. However, not signs. The latter finding suggests a exposure does dramatically modulate initial stages development during subsequent episodes.