Answer
Sep 09, 2026 - 01:26 PM
For RELISTOR (methylnaltrexone) injection, weight-based dosing applies mainly to adults with opioid-induced constipation (OIC) and advanced illness:
- Less than 38 kg (84 lb): 0.15 mg/kg subcutaneously
- 38 kg to less than 62 kg (84–136 lb): 8 mg subcutaneously
- 62 kg to 114 kg (136–251 lb): 12 mg subcutaneously
- More than 114 kg (251 lb): 0.15 mg/kg subcutaneously
For advanced illness, the dose is generally given every other day as needed, but not more than once in 24 hours.
For adults with chronic non-cancer pain, the standard injection dose is 12 mg once daily rather than routinely weight-based. The oral tablet dose is 450 mg once daily.
Dose reductions are needed in some patients with moderate/severe kidney impairment or significant liver impairment, so the prescribed dose may differ.
