Why is methadone considered unique among opioids in practice?

• A. Long, highly variable half-life with potential accumulation; potent NMDA receptor antagonism; numerous drug interactions; notable QT interval prolongation risk.
• B. It has the shortest half-life and no drug interactions.
• C. It does not cause QT prolongation.
• D. It antagonizes NMDA receptors but has no other unique properties.

Answer: (A)