[Use of methadone as analgesic].
Methadone is a synthetic opioid agonist which is mostly used for drug maintenance therapy in opioid addicts. It has also proven to be a powerful analgesic four times more powerful than oral morphine. The main indication is cancer pain as an alternative to oral morphine in case of tolerance or side effects due to accumulation of active metabolites. Methadone however shows wide inter-individual variability in half-life necessitating a carefully scheduled administration scheme. Side effects are similar for morphine and methadone. Methadone might be a safe and effective analgesic in patients with renal disease because its metabolites are almost exclusively excreted in the feces.