From: Clinical evaluation of the efficacy of methylnaltrexone in resolving constipation induced by different opioid subtypes combined with laboratory analysis of immunomodulatory and antiangiogenic effects of methylnaltrexone
Opioid
Probability that constipation is opioid induced
Occupation of the peripheral μ receptor by opioid subtype
Expected response rate to methylnaltrexone
Morphine Sulphate
70%
High
60%
Oxycodone
75%
Intermediate-high
Fentanyl
40%
Low
25%