Medication Reference Card — Opioid Use Disorder
Oral liquid · S100 (MATOD) · Standard OTP form · Physeptone® tablets (S8) in specific circumstances only
Methadone is a long-acting opioid medication used to reduce cravings and withdrawal from opioid dependence. In Australia, it is most commonly given as a liquid taken daily under supervision at a pharmacy, as part of a structured prescribing program. In some situations — for example, if you are travelling overseas — methadone may be prescribed as a tablet instead of a liquid. Your doctor will explain which form applies to your situation and how your prescription will be managed.
Methadone is a full mu-opioid agonist with high oral bioavailability (80–95%), very long and variable half-life (24–36 hrs, up to 120 hrs in some patients), and NMDA receptor antagonism. It accumulates significantly — dose titration must be slow to avoid inadvertent overdose. Unlike buprenorphine, there is no ceiling effect for respiratory depression.
Before initiation: Confirm MATOD enrolment in Victoria. SafeScript check is mandatory before prescribing. Establish dispensing pharmacy and supervised consumption arrangements before the first dose is given.
Induction — Day 1: Assess opioid tolerance carefully. Start 10–30 mg orally (use 10–20 mg if tolerance is uncertain, mixed opioid use pattern, or any concern about over-sedation risk). Do not re-dose on Day 1 — methadone accumulates and delayed toxicity typically occurs 24–72 hrs after initiation. Clinical review within 24–48 hrs is mandatory. Unlike buprenorphine, no COWS threshold is required before initiation — methadone is a full agonist and does not precipitate withdrawal.
Titration: Increase by 5–10 mg no more frequently than every 3–5 days. This interval is not negotiable. The long, variable half-life means each dose increase has a delayed peak effect — increases made more frequently cause inadvertent accumulation and fatal toxicity. Reassess at each titration step.
Maintenance: Typically 60–120 mg/day. Adequate dosing (>60 mg/day) is strongly associated with improved retention in treatment and suppression of illicit opioid use. Under-dosing is a common and avoidable cause of treatment failure — dose should reflect clinical response, not an arbitrary ceiling.
Supervised dispensing: Initially daily supervised consumption at the dispensing pharmacy. Takeaway doses are introduced progressively as clinical stability is demonstrated — frequency and number of takeaways require prescriber endorsement and are subject to MATOD program criteria. SafeScript monitoring applies throughout treatment.
Physeptone® 5 mg tablets: scored, divisible. Prescribed under S8 Authority — not S100. Use is restricted to circumstances permitted under the Victorian MATOD policy (see below). Conversion from liquid: 1:1 mg-for-mg — bioequivalent pharmacokinetics; no dose adjustment required when switching a stable patient.
Outside the MATOD supervised pharmacotherapy programme (e.g. prescription opioid analgesic dependence not enrolled in MATOD), use of methadone tablets is a matter of clinical and professional judgement — document reasoning clearly.
The evidence base for methadone treatment is derived from oral liquid formulation studies. Dole & Nyswander (1965) — foundational evidence for methadone OTP. Mattick RP et al. Cochrane Database Syst Rev 2014: methadone significantly superior to placebo for retention and heroin abstinence. No RCTs compare tablet to liquid formulation in OUD — tablets are bioequivalent (equivalent Cmax, AUC, half-life). Tablet-specific risks documented in literature include higher diversion rates and injection misuse risk relative to supervised liquid dispensing.