Relistor produces rescue-free laxation in patients with opioid-induced constipation
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A single dose of Relistor injection produced rescue-free laxation in severely ill patients with opioid-induced constipation who had an insufficient response to laxative therapy, according to a study published in the Journal of Emergency Medicine.
“Methylnaltrexone (Relistor) works in the majority of opioid-induced constipation patients within four hours, and its use doesn’t change the analgesic effects of the opioid,” W. Frank Peacock, MD, FACEP, FACC, lead author and director of research at Baylor College of Medicine in Houston, told Healio.
In an analysis of three randomized, double-blind, placebo-controlled trials of opioid-treated patients with advanced illness and opioid-induced constipation (OIC), a single dose of Relistor (methylnaltrexone, Salix Pharmaceuticals) effectively produced rescue-free laxation responses compared with placebo.
Of 518 patients, 54% received methylnaltrexone (mean age, 66.2; 51% men), while the remaining 45% received a placebo (mean age, 65.8; 49% men). Researchers evaluated participants at baseline using scales from the WHO performance status and Eastern Cooperative Oncology Group (ECOG) status.
Compared with placebo, patients who received methylnaltrexone experienced a rescue-free laxation within 4 hours (61.4%; 95% CI, 55.7-67.1 vs. 16%; 95% CI, 11.4-20.7) and 24 hours (72.1%; 95% CI, 66.9-77.4 vs. 40.1%; 95% CI, 33.8-46.3).
The percentage of patients with a WHO/ECOG score less than or equal to 2 who experienced a rescue-free laxation response within 4 hours of receiving methylnaltrexone or placebo was 65.5% (95% CI, 56.6-74.3) vs. 20.2% (95% CI, 12.3-28.1). The response among patients with a WHO/ECOG score greater than 2 was 58.8% (95% CI, 51.4-66.2) vs. 13.0% (95% CI, 7.4-18.7).
Further, rescue-free laxation response among patients with a WHO/ECOG score less than or equal to 2 who experienced a response within 24 hours of receiving methylnaltrexone or placebo was 75.5% (95% CI, 67.4-83.5) vs. 45.5% (95% CI, 35.6-55.3). The response among patients with a WHO/ECOG score greater than 2 was 70% (95% CI, 63.1-76.9) vs. 36.2% (95% CI, 28.2-44.3).
More than 98% of the patients were laxative refractory at baseline, which suggests that methylnaltrexone may be suitable for a wide range of ED patients with opioid-induced constipation presenting with various baseline etiologies, according to researchers.
“These results demonstrate that methylnaltrexone provides effective, safe and rapid relief of OIC symptoms without compromising opioid analgesia in OIC patients with diverse forms of severe illnesses having varying degrees of disability,” Peacock and colleagues wrote.
In an interview, Peacock noted that “there are many next steps in terms of research, including economic evaluation of ER use – namely, does this save money? – whether outpatient use could help patients avoid coming to the ER in the first place as well as prospective evaluation in fragile patients, such as those older than age 85 years.”
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