Opioid Use Disorder
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Direct answer
Opioid use disorder is a pattern of opioid use (heroin, pharmaceutical opioids, or in the Indian context commonly injected or misused prescription preparations such as dextropropoxyphene, tramadol and pentazocine-containing products) leading to impairment, tolerance and withdrawal. Intoxication produces euphoria, analgesia, sedation, pinpoint pupils and constipation; overdose causes coma, respiratory depression and death, reversed urgently by the antagonist naloxone. Withdrawal — lacrimation, rhinorrhoea, sweating, piloerection, mydriasis, diarrhoea, muscle aches and intense craving — is severe but rarely life-threatening, and treatment follows substitution with methadone or buprenorphine, gradual detoxification, antagonist maintenance with naltrexone and psychosocial rehabilitation.
What you must remember
- Intoxication triad: pinpoint pupils, respiratory depression and depressed consciousness; the antidote is naloxone, repeated as needed because its half-life is shorter than most opioids.
- Withdrawal timeline: begins 6-24 hours after the last short-acting opioid (peaking 36-72 hours, settling in 5-7 days) with "cold turkey" features — lacrimation, rhinorrhoea, yawning, piloerection, myalgia, cramps, diarrhoea and craving; longer for methadone.
- Withdrawal scoring: the Clinical Opioid Withdrawal Scale guides substitution dosing; clonidine dampens noradrenergic symptoms but substitution is more effective.
- Agonist maintenance: methadone (full mu agonist) or buprenorphine (partial agonist, safer in overdose) — the backbone of deaddiction; buprenorphine is widely used in India, methadone in designated centres.
- Detoxification: gradual tapering over days to weeks with symptomatic cover (clonidine, NSAIDs, loperamide); rapid antagonist-accelerated protocols under anaesthetic cover for selected cases.
- Relapse prevention: oral naltrexone only after full detoxification, take-home naloxone for overdose safety per current guidance, plus psychosocial intervention and self-help groups.
- Complications: injecting use carries HIV, hepatitis, endocarditis and abscesses; neonatal abstinence syndrome in exposed infants.
Common confusion
Opioid withdrawal versus sedative or alcohol withdrawal is a life-or-death distinction: opioid withdrawal is miserable but not lethal, whereas abrupt alcohol or benzodiazepine withdrawal can cause seizures and death — so a shaky, sweating patient with dilated pupils and diarrhoea gets opioid detoxification, while one with tremor, disorientation and a history of drinking gets benzodiazepines. Buprenorphine versus methadone is also tested: buprenorphine is a partial agonist with a ceiling on respiratory depression, and precipitated withdrawal occurs if it is started too early after a full agonist. Pentazocine and tramadol produce both opioid and atypical withdrawal features worth remembering.
Exam-focused takeaway
NEET-PG vignettes show a young injected-drug user with pinpoint pupils and drowsiness (naloxone answer), or 24 hours after last heroin with yawning, gooseflesh and diarrhoea (buprenorphine-methadone detoxification answer). One-liners test miosis in intoxication versus mydriasis in withdrawal, naloxone as the overdose antidote, the partial-agonist status of buprenorphine, and naltrexone for antagonist maintenance after detoxification. Expect an HIV-screening or needle-exchange angle reflecting Indian national programme teaching.
Frequently asked questions
What are the features of acute opioid intoxication?
Sedation, miosis, respiratory depression and constipation; overdose progresses to coma and apnoea.
Which drug reverses opioid overdose?
Naloxone, repeated as needed because many opioids outlast its effect.
What characterises opioid withdrawal?
Lacrimation, rhinorrhoea, yawning, piloerection, mydriasis, cramps, diarrhoea and craving — severe but not life-threatening.
Why is buprenorphine preferred in many deaddiction programmes?
Partial agonism with a ceiling on respiratory depression allows safe sublingual maintenance.
When is naltrexone used in opioid dependence?
Only after complete detoxification, as antagonist maintenance for motivated patients.
What is the role of clonidine in opioid withdrawal?
It suppresses noradrenergic symptoms such as sweating and restlessness but not craving.