Population Exposure-Response Modeling of Naloxegol in Patients With Noncancer-Related Pain and Opioid-Induced Constipation.

Naloxegol is a polyethylene glycol derivative of naloxone approved in the US as a once-daily oral treatment for opioid-induced constipation (OIC) in adults with chronic noncancer pain. Population exposure-response models were constructed based on data from two phase III studies comprising 1,331 adults with noncancer pain and OIC. In order to characterize the protocol-defined naloxegol responder rate, the number of daily spontaneous bowel movements (SBMs) was characterized by a longitudinal ordinal nonlinear mixed-effects logistic regression dose-response model, and the incidence of diary entry discontinuation was described by a time-to-event model. The mean number of SBMs per week increased with increasing naloxegol dose. The predicted placebo-adjusted responder rates (90% confidence interval) were 10.4% (4.6-13.4%) and 11.1% (4.8-14.4%) for naloxegol 12.5 and 25 mg/day, respectively. Model-predicted response to naloxegol was influenced by the baseline SBM frequency and characteristics of the opioid treatment.