Why is methadone prescribed to patients with morphine or heroin dependence?

Correct answer: A. It prevents withdrawal symptoms and suppresses craving without producing significant euphoria

• A. CORRECT. Methadone is a long-acting full mu-opioid AGONIST. Its long half-life (roughly 24–36 hours) gives stable plasma levels that PREVENT WITHDRAWAL and suppress craving, while its slow onset means it produces little of the euphoric rush that drives compulsive use. It also blocks the effect of additional illicit opioids through cross-tolerance. This stabilisation is what allows the patient to disengage from drug-seeking behaviour.
• B. Methadone carries substantial risks, including QT prolongation and torsades, respiratory depression, and dangerous accumulation because its analgesic duration is much shorter than its elimination half-life. 'Fewer side effects' is not why it is used.
• C. Methadone is a Schedule II controlled substance dispensed through federally regulated opioid treatment programmes.
• D. Methadone absolutely DOES cause physical dependence — it is a full opioid agonist, and abrupt cessation produces a withdrawal syndrome that is more prolonged than heroin withdrawal. Substitution therapy replaces one dependence with a medically managed one; it does not eliminate dependence.

Note: ⚠️ The source keyed 'it has less side effects,' which is not the pharmacological rationale. The correct answer is prevention of withdrawal and craving. Please correct in the group file. Dental relevance: methadone patients have real pain and full cross-tolerance — they need adequate analgesia, not less.