Peppermint Oil Pharmacokinetics/Dynamics

An initial single-dose PK study will be carried out. Forty-two children (n=21 per dose) will be randomized to receive approximately 10.9 mg·kg-1·d-1 of PMO or to receive approximately 18.2 mg·kg-1·d-1 (1.67-fold the median dose). Following the single-dose PK study, a PD study will be carried out wherein the subjects will receive their assigned dose of PMO for 7 days. At baseline (before the PK study) and after the PK study (i.e., during the PD study), subjects will keep a pain and stooling diary, collect stool for microbiome analysis, and swallow a SmartPill to measure gut motility and transit time. At baseline only, anxiety, depression, somatization will be measured. During the PD study, any side effects will be recorded.