Response Rates to Methylnaltrexone in Hospitalized Cancer Patients.

Context: Methylnaltrexone is a peripherally-acting mu-opioid receptor antagonist studied in both cancer and non-cancer patients with opioid-induced constipation (OIC), but mostly in the outpatient setting. For adult hospitalized cancer patients with OIC, its effectiveness is unknown.

Objectives

Describe the efficacy of methylnaltrexone for OIC in the inpatient setting, defined as bowel movement (BM) within 24 hours of methylnaltrexone administration.

Methods

We performed a single-center, retrospective chart review of all hospitalized, adult patients with a cancer diagnosis who received methylnaltrexone from the palliative care team between January 1st, 2012 and July 1st, 2019.

Results

We identified 194 patients. The mean age was 59, 50.5% were male and 88% were white. 192 patients (98%) received the 8 mg dose subcutaneously. The median oral morphine equivalent (OME) was 135 mg (IQR 70-354 mg). 45% (95% confidence interval, 38-53%) had a BM within 24 hours. Higher OME was correlated with successful BM, with a response in 93% (86/92) of patients receiving ≥150 OME and 2% (2/102) of patients receiving <150 OME (P < .0001). Prior laxative use did not predict response at 24 hours whether these were osmotic laxatives (40.7% vs 47.1%, P = .52), stimulant laxatives (45.7% vs 45.2%, P > .99), or stool softeners (44.7% vs 46.1%, P = .89).

Conclusion

Methylnaltrexone has a high response rate when used as treatment for OIC in hospitalized adult cancer patients, especially for patients taking ≥150 OME.