One of the bothersome complications of opiate therapy is constipation. Methylnaltrexone (Relistor, Wyeth) is a medication that can significantly reduce this problem.
Methylnaltrexone is a selective antagonist to mu-opioid receptors in the gastrointestinal tract that does not interfere with the central analgesic effects or precipitate withdrawal.
Route of injection: subcutaneous injection into upper arm, abdomen or thigh
Usual dosing is done once a day, every other day. The maximum dose involves giving a dose daily.
Body Weight in kilograms
Usual Dose
< 38 kg
0.15 mg per kg
38 to 61.99 kg
8 mg
62 to 114 kg
12 mg
> 114 kg
0.15 mg per kg
If the creatinine clearance is < 30 mL per minute, then the dose is 50% of the usual dose.
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