Relistor for Opioid Induced Constipation in Hospice Patients
Posted by Dr. Jim Joyner
Clinicians now have a unique new medication for management of opioid induced constipation. Relistor (methylnaltrexone) is an opioid antagonist which acts peripherally to block the effects of opioid drugs on the GI tract resulting in a decrease in the constipating effects of opioids. Due to the fact that methylnaltrexone is a quaternary amine, it is not absorbed across the blood-brain barrier and does not have any impact on the opioid mediated analgesic effects.
Results of a double-blind, placebo controlled clinical study of 154 patients showed that 60% of the Relistor treated patients had laxation within 4 hours of a single dose compared with only 14% of patients that received a placebo. In clinical trials, 30% of patients who received Relistor reported laxation in as little at 30 minutes. Possible side effects include: nausea, vomiting, diarrhea, abdominal pain, and dizziness.
The usual dosage is 8 to 12mg by subcutaneous injection every other day as needed. The drug is not available for oral use. Currently it is only available in a 12mg/0.6ml single use vial. If a dose of less than 12 mg is used, the remaining drug left in the vial is supposed to be discarded. The approximate cost to the hospice for a 2 week supply is $320.00 assuming that the drug is administered at a dose of 12mg on every other day.
Relistor is not a first-line drug for treatment of constipation in hospice patients, however, it may be appropriate for the patient with severe opioid induced constipation who has not responded to traditional laxative therapy and who also has constipation that failed to improve with rotation to different opioids.