Opioids

Overdose

Respiratory depression, a stuporous/comatose state, and constricted pupils; pulmonary oedema can also occur. Main treatment: the opioid antagonist naloxone.

Withdrawal

Agitation, sweating, musculoskeletal pain, abdominal cramps, diarrhoea, nausea/vomiting, seizures, and piloerection (“goose flesh”). After heroin cessation, symptoms peak around day 2–3 and largely resolve by day 5–7. Not life-threatening, but treat according to the severity the patient reports.

Buprenorphine (a partial opioid agonist) has largely replaced clonidine and tapered methadone for withdrawal management, and can be used inpatient or outpatient: 4–8 mg sublingually as a single dose on day 1, increasing to a maximum of 12 mg on day 3, then decreasing over the following 2–5 days (smaller inpatient doses may suffice given the added benefit of psychosocial engagement).

Symptomatic support:

• Anxiety/agitation — diazepam 5–20 mg orally, four times daily. Benzodiazepine dependence is common in people who use opioids, and combining benzodiazepines with heroin increases fatal overdose risk — use cautiously in outpatients, and avoid unless supervision is available.
• Diarrhoea — loperamide.
• Nausea/vomiting — metoclopramide.
• Musculoskeletal pain — paracetamol or ibuprofen.

Long-term pharmacotherapy for opioid dependence

Alongside psychosocial interventions (counselling, CBT, social support), methadone and buprenorphine are the mainstays. Methadone (full agonist) has the most robust evidence base. Maintenance treatment — substituting methadone or buprenorphine for heroin/other short-acting opioids — prevents withdrawal, reduces craving, and blunts the euphoric effect of any relapse. An alternative approach after completed withdrawal is naltrexone (opioid antagonist) for relapse prevention.

Methadone — proven effective for reducing opioid use. Requires state/territory Department of Health approval before starting; dose is individualised based on prior opioid use and initial response, with stabilisation typically taking several weeks. Causes QTc prolongation.

Buprenorphine — as a partial agonist, carries a lower overdose/dependence risk than methadone, but its lower agonist activity isn’t suitable for all patients. Also requires Department of Health approval; stabilisation typically takes 2–3 weeks. Its high opioid-receptor affinity means overdose reversal with naloxone may need considerably higher doses (reported cases have needed 10–35 mg) than for heroin/methadone overdose, and it blocks the effect of opioid analgesics given for pain relief. Increasingly used as a combination product with naloxone, which reduces its abuse potential if diverted and injected (naloxone is only clinically active when injected). Depot formulations (e.g. Buvidal, Sublocade) are now an established long-acting alternative to daily supervised dosing.