Why is methylnaltrexone only used for very sick palliative care patients? there are some very constipated post op patients

FDA Approved: This could be used for other causes of refractory constipation, but it is fda approved for opioid induced constipation in the palliative setting. Other uses would be considered off label. Insurance companies usually do not cover off label meds, especially new, costly ones.

Limited studies: The best studies for effectiveness for methylnatrexone is for patients with opioid-induced constipation (it works on the same receptors as opioids like morphine). As many sick palliative care patients require opioids this is typically the group that would benefit if standard laxatives (many which are over the counter) do not work. Postop patients constipation or ileus may not be due to opioids.