Been on methadone, up to 100mgs a day, for the past 12 years for pain control. Developed q-t wave prolongation, meaning the second beat of your heart doesn't beat and you pass out until hopefully, it starts again; if not, you die. Doc said it was from methadone so I began a SLOW taper: Per the pharmacist, reduce by 25%, every 14 days. Methadone has a 36-hr halflife, so this taper to 2-3 years. For various reasons, Ive gone off and on methadone about five times.