Methadone

Full Opioid Agonist·Addiction Medicine

TGA/PBS — Opioid agonist treatment for opioid dependence under supervised program arrangements; methadone products also have analgesia indications depending on formulation/product

S8PBSOUD / S8Biodone Forte, Physeptone10 mg tablet+1

Max Dose

Titrated

Half-life

15-60 h

QTc Risk

DOSE-DEP

Overdose Risk

CRITICAL INIT.

Rapid Summary

Overview

Long-acting full mu-opioid receptor agonist used in opioid agonist treatment and selected pain settings. Its long, variable half-life makes supervised initiation and slow titration essential.

Maximum Dose

No simple fixed maximum for OAT; titrate under specialist/program protocol. MATOD guidance describes maintenance generally 60-100 mg, with induction increases kept slow.

Clinical Focus

Methadone accumulates because respiratory-depressant effects last longer than analgesic effects and the half-life is highly variable. Early dose increases must be conservative, with sedation/respiratory checks before escalation.

Bottom Line

Methadone is effective but high-risk: initiation/titration, QTc risk, CNS depressant interactions, renal/hepatic impairment, pregnancy/neonatal issues, and program access rules need active management.

Formulation & Access

Brand Names

Biodone Forte, Physeptone

Oral Routes

Oral liquid syrup (5 mg/mL). Tablets (10 mg).

Prescribing & PBS

Methadone access depends on indication, formulation, and local OAT program rules. PBS item 13334T covers methadone hydrochloride oral liquid; confirm jurisdictional authority, supervised dosing, and dispensing requirements.

Indications & Use

Primary

PBSTGA

TGA/PBS — Opioid agonist treatment for opioid dependence under supervised program arrangements; methadone products also have analgesia indications depending on formulation/product.

Clinical Place

Highly effective for retaining severe addicts in treatment due to the lack of withdrawal/craving, but carries far higher toxicity risks than Buprenorphine.

Quick reference

Class & Role

Full Opioid Agonist — Synthetic, ultra-long-acting, full mu-opioid receptor agonist.

Route / Formulation

Oral liquid syrup (5 mg/mL). Tablets (10 mg). (Biodone Forte, Physeptone)

Usual Dose & Max

OAT induction: usually 20-30 mg daily; up to 40 mg only with higher tolerance and supervised monitoring. Avoid extra dosing for at least 3 hours; increase by 5-10 mg every few days if no sedation/intoxication. Maintenance is generally 60-100 mg.

Key Indication Doses

OUD: supervised induction and maintenance under OAT rules. Analgesia use follows product-specific pain dosing and requires separate careful conversion because respiratory depression lasts longer than analgesia.

Best Uses

Methadone is a long-acting opioid for substitution therapy and chronic pain, but has unpredictable pharmacokinetics, accumulates causing delayed respiratory depression, and prolongs QTc.

Avoid / Cautions

Contraindicated with severe respiratory depression, MAOI use/current or within 2 weeks, severe hepatic impairment, renal/biliary tract spasm, and existing QT prolongation/congenital long QT. Use caution in renal impairment and QT-risk states.

Key Risks

Delayed respiratory depression from accumulation, sedation/overdose during initiation, QT prolongation/torsade, constipation, sweating, and major interaction risk with CNS depressants, QT-prolongers, CYP inducers, and electrolyte-lowering medicines.

Key Interactions

CNS depressants increase sedation/respiratory depression. MAOIs are contraindicated. QT-prolongers and electrolyte-lowering medicines increase torsade risk. CYP inducers such as rifampicin, phenytoin, carbamazepine, St John's Wort, and some antiretrovirals can precipitate withdrawal.

Monitoring

Monitor sedation and respiratory status during initiation/titration, QTc and electrolytes where risk factors exist, constipation, adherence/diversion, hepatic impairment, renal impairment, and interacting medicines.

Clinical Pearl

The patient will complain on Day 2 that the 30mg dose 'isn't holding them' and demand more. You MUST say no. Because of the 40-hour half-life, that 30mg dose will organically stack in their blood, reaching the equivalent of 60mg by Day 5. If you increase the dose on Day 2, they will stop breathing on Day 5.

Access

Biodone Forte, Physeptone10 mg tablet

Brand: Biodone Forte, Physeptone
Formulation: Oral liquid syrup (5 mg/mL)