Peppermint Oil Pharmacokinetics/Dynamics

In children 7-12 years of age with functional abdominal pain (n=42) determine: Aim 1 - To examine and characterize the threshold of the exposure (PK) vs. response (PD) relationship of PMO (menthol) Aim 2 - PD of PMO as assessed by: 1. Microbiome composition (16S RNA sequencing) 2. Transit rate/contractile activity (using the SmartPill®) Aim 3 - Evaluate the potential association between PD response and clinical symptoms (abdominal pain and stooling pattern via validated diary), psychosocial distress (anxiety, depression, somatization), and characterize potential side effects (questionnaire)