Nalamachu, S.R., Pergolizzi, J., Taylor, R., Slatkin, N.E., Barrett, A.C., Yu, J., . . . Forbes, W.P. (2015). Efficacy and tolerability of subcutaneous methylnaltrexone in patients with advanced illness and opioid-induced constipation: A responder analysis of 2 randomized, placebo-controlled trials. Pain Practice, 15, 564–571.
To examine the influence of demographic and baseline characteristics on the efficacy and tolerability of methylnaltrexone (MNTX) in patients with advanced illness and opioid-induced constipation
Data were pooled from two multicenter, randomized, double-blinded, placebo-controlled, phase 3 clinical studies of subcutaneous MNTX (0.15 and 0.03 mg/kg). The primary outcome analyzed was the percentage of patients with rescue medication-free bowel movement (RFBM) within four hours of the first dose.
More than 50% of 165 patients treated with MNTX dose experienced a rescue-free bowel movement (RFBM) within four hours versus 14.6% of the placebo-treated patients. The largest difference was observed in patients taking the MNTX 0.3 mg/kg without cancer versus the placebo group.
Subcutaneous MNTX provides a rapid and robust and consistent RFBM response in patients with advance illness and OIC. MNTX 0.3 mg/kg may have a more favorable response in selected patient populations.
MNTX continues to show efficacy for opioid-induced constipation for various types of patients. Additional work is warranted to determine most effective doses.