Effect of sodium oxybate on body mass index in pediatric patients with narcolepsy

Study Objectives: We examined body mass index (BMI) changes associated with sodium oxybate treatment (SXB) in pediatric patients with narcolepsy with cataplexy who participated in a double-blind, placebo -controlled, randomized withdrawal study and an open -label continuation period. Methods: Participants were aged 7-16 years at screening. SXB-naive participants titrated to twice -nightly dosing of SXB then entered a 2 -week stable -dose period; participants taking SXB at study entry entered a 3 -week stable -dose period. After a 2 -week randomized withdrawal period, all participants entered an openlabel safety period (OLP; main study duration: <= 52 weeks). Participants who completed the OLP were allowed to enter the open -label continuation period (an additional 1-2 years). BMI percentile categories were defined as underweight (< 5th), normal (5th to < 85th), overweight (>= 85th to < 95th), and obese (>= 95th). Results: Median BMI percentile decreased from baseline to OLP week 52 in SXB-naive participants who were normal weight at baseline (decreased from 77.0 to 35.0) or overweight/obese at baseline (98.0 to 86.7). Median BMI percentile decreased to a lesser extent in participants taking twice -nightly SXB at study entry who were normal weight at baseline (54.6 to 53.0) or overweight/obese at baseline (96.5 to 88.9). Shifts in BMI category from baseline to week 52 were sometimes noted. In SXB-naive participants, 9/10 (90.0%) who were overweight became normal weight, 7/25 (28.0%) who were obese became normal weight, 3/25 (12.0%) who were obese became overweight, and 1/16 (6.3%) who was normal weight became obese. In participants taking SXB at baseline, 5/8 (62.5%) who were overweight became normal weight, 3/6 (50.0%) who were obese became overweight, 1/14 (7.1%) who was normal weight became overweight, and 2/14 (14.3%) who were normal weight became underweight. Median BMI percentiles at months 6 and 12 of the open -label continuation period were similar to those at OLP end (OLP week 52). In SXB-naive participants, the evident BMI z -score decrease over time was relative to the screening values. Conclusions: Decreases in BMI percentile and z -score, and downward shifts in BMI category, were observed within 1 year of SXB treatment in pediatric participants with narcolepsy with cataplexy. BMI decreases plateaued after approximately 1 year.