Table 3. Methylnaltrexone efficacy studies.

SC: subcutaneous, IV: intravenous.

Dose	Route	Bowel movements	Author
Methylnaltrexone 0.15 mg/kg or 0.3 mg/kg, vs placebo	SC	The median time to bowel movement response was 0.5 hours in the methylnaltrexone group and 2.0 hours in the placebo group (P = 0.013).	Chamberlain et al. [46]
Methylnatrexone 1 mg, 5 mg, 12.5 mg, 20 mg	SC	The median time to laxation was >48 hours for the 1 mg dose group, compared to 1.26 hours for all patients receiving ≥5 mg	Portenoy et al. [37]
Methylnaltrexone (0.15 mg/kg) vs placebo	SC	After the first dose: the median time to bowel movement response was four hours in 48% in the methylnaltrexone group versus 15% in the placebo.	Thomas et al. [38]
Methylnatrexone 8 mg or 12 mg vs placebo once daily	SC	After ≥2 doses: median time to bowel movement response was four hours in 62.9% in the methylnaltrexone group versus 9.6% in the placebo	Bull et al. [39]
Methylnaltrexone 12 mg once daily or placebo	SC	Did not assess bowel movements	Iyer et al. [40]
Methylnatrexone 12 mg once daily, methylnaltrexone 12 mg alternate days vs placebo	SC	58.7% of patients in the methylnaltrexone once-daily group, 45.3% in the alternate-day dosing group, and 38.3% in the placebo group had at least three rescue-free bowel movements per week.	Michna et al. [41]
Methylnatrexone 12 mg once daily	SC	Methylnaltrexone elicited a bowel movement within four hours in 34.1% of the injections throughout the 48-week treatment period.	Webster et al. [43]
Methylnatrexone 0.15 mg/kg as a first dose, adjusted to 0.3 mg/kg or 0.075 mg/kg as needed	SC	Following administration of the first dose through the 15th dose, rescue-free laxation response usually occurred in a median time of 30 minutes or less.	Lipman et al. [47]
Methylnatrexone 0.15 mg/kg, 0.3 mg/kg vs. placebo	SC	More than 50% of patients treated with either methylnaltrexone dose experienced a rescue-free bowel movement within four hours vs. 14.6% of placebo-treated patients. The largest differences vs. placebo were observed for patients taking methylnaltrexone 0.30 mg/kg with a noncancer primary diagnosis and for patients taking methylnaltrexone 0.30 mg/kg maintained on ≥150 mg/day baseline morphine equivalent doses.	Nalamachu et al. [48]
Methylnatrexone 0.1 mg/kg in six subjects, and 0.3 mg/kg in six subjects	SC	Not assessing bowel movements	Yuan et al. [49]
Methylnaltrexone 150, 300 or 450 mg once daily vs. placebo	Oral	Median time to bowel movement response was shorter for patients treated with both oral methylnaltrexone 300 mg and 450 mg. Only the 300 mg dose produced a statistically significant response compared with the placebo	Webster and Israel [36]
Methylnaltrexone 150, 300 or 450 mg once daily vs. placebo	Oral	Median time to bowel movement response was four hours: in 25.4% of patients receiving methylnaltrexone 300 mg; in 23.5% of patients receiving methylnaltrexone 450 mg; in 8% of patients in the placebo group.	Rauck et al. [42]
Methylnatrexone 0.2 mg/kg	IV	Not assessing bowel movements	Yuan et al. [45]