Pharmacometric dose optimization of buprenorphine in neonatal opioid withdrawal syndrome

Abstract

Results from BBORN, a previous phase III trial in infants with neonatal opioid withdrawal syndrome (NOWS), demonstrated that sublingual buprenorphine resulted in a shorter duration of treatment and shorter length of hospital stay than the comparator, oral morphine. Objectives of BPHORE, a new trial with buprenorphine in a similar population were to 1) optimize initial dose, up-titration to achieve symptom control and weaning steps of pharmacologic treatment and 2) investigate safety of the revised regimen. A pharmacodynamic model linked buprenorphine exposure to NOWS symptom scores. Adaptive dose regimens were simulated using BBORN results to compare dosing regimens for times to stabilization, weaning and cessation. A clinical trial using model informed doses (BPHORE), was conducted. Simulations indicated benefits in time to stabilization and weaning when uptitration rates increased to 30%. Stabilization time was not greatly impacted by the starting dose.Time to wean and time to cessation were dose-dependent. A weaning rate of 25% shortened time to cessation. Ten infants were enrolled in BPHORE using buprenorphine starting dose of 24 ug/kg/day, 33% titration and 15% wean rate. Five subjects required adjuvant therapy. EC50 values indicated maximum buprenorphine doses did not generate maximal effect size, suggesting potential efficacy of a further increased dose if a goal was to reduce the use of adjunct agents. Simulations indicated that further benefits can be gained by increasing starting doses of buprenorphine and increasing wean rates. Use of a model-based analysis to provide focused guidelines for care can be used with goals of reducing treatment time and hospital stays in infants with NOWS.