Relistor (methylnaltrexone) is a peripherally acting mu-opioid receptor antagonist (PAMORA) used to treat opioid-induced constipation (OIC). It works by blocking the effects of opioids on receptors in the gut, which helps restore normal bowel function without affecting the opioid's pain-relieving effects in the brain. The appropriate frequency of Relistor depends on the patient's condition and the form of the medication used.
Understanding the Mechanism Behind Relistor
Opioids can cause constipation by activating mu-opioid receptors in the gastrointestinal tract, slowing down movement, reducing fluid secretion, and increasing fluid absorption. Relistor counteracts these effects by selectively blocking these peripheral receptors.
Dosing Frequency for Specific Conditions
For Chronic Non-Cancer Pain (CNCP)
For adults with chronic non-cancer pain experiencing OIC, Relistor can be administered as oral tablets or subcutaneous injection. The typical frequency for both forms in this population is once daily.
For Advanced Illness or Palliative Care
For adults with advanced illness receiving palliative care who have OIC, the subcutaneous injection is typically administered every other day as needed. The specific amount is often weight-based.
Relistor Dosing Frequency Comparison
| Condition | Formulation | Administration Frequency | Key Notes |
|---|---|---|---|
| Chronic Non-Cancer Pain (CNCP) | Oral Tablet | Once daily, in the morning | Take on an empty stomach. |
| Chronic Non-Cancer Pain (CNCP) | Subcutaneous Injection | Once daily | |
| Advanced Illness / Palliative Care | Subcutaneous Injection | Every other day, as needed | No more than one dose in 24 hours. |
Important Considerations for Administration
- Other Laxatives: For CNCP, maintenance laxatives should generally be stopped before starting Relistor and can be resumed if needed. For advanced illness, other laxatives may be continued as directed. Relistor should be discontinued if the patient stops taking opioid medication.
- Injection Site: Rotate subcutaneous injection sites.
- Kidney and Liver Function: Patients with moderate to severe kidney or liver impairment may need adjustments to the amount and frequency of administration.
- Proximity to Toilet: Be near toilet facilities after taking Relistor.
Potential Side Effects and Precautions
Common side effects include abdominal pain, nausea, and diarrhea. A serious but rare risk is gastrointestinal perforation. Severe abdominal pain requires immediate medical attention. Opioid withdrawal symptoms have also been reported. Always use Relistor as prescribed under medical supervision.
For comprehensive safety information, refer to the U.S. Food and Drug Administration's official labeling for Relistor {Link: accessdata.fda.gov https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/021964s018,208271s002lbl.pdf}.
Conclusion
The frequency of Relistor administration depends on the patient's condition. For chronic non-cancer pain, it is given once daily. For advanced illness, the injection is typically given every other day as needed. The appropriate amount and frequency, including adjustments for renal or hepatic impairment, should always be determined by a healthcare provider. Consult your doctor for personalized guidance.
