Improving Treatment of Nontuberculous Mycobacterial Infection in Cystic Fibrosis

The purpose of this study is to determine antimycobacterial drug pharmacokinetics (PK) and pharmacodynamics (PD) in patients with cystic fibrosis (CF) to improve treatment of nontuberculous mycobacterial (NTM) lung disease. Aim 1: Determine the PK profile of oral antimycobacterial drugs (azithromycin, rifampin and ethambutol) under both fasting conditions and when taken with food plus supplemental pancreatic enzymes in subjects with pancreatic insufficient, compared to healthy controls. Aim 2: Begin to investigate the influence of inflammation, host characteristics, and drug metabolism on the PK of the antimycobacterial drugs. Aim 3: Estimate an optimized dosing regimen for the antimycobacterial drugs against Mycobacterium avium complex (MAC) using historic minimum inhibitory concentration (MIC) data and models of Mycobacterium tuberculosis or MAC infection. The central goal of this study is to improve treatment of NTM infection in CF. Upon completion of this study the investigators will determine if and why PK of the antimycobacterial drugs are altered in CF. More importantly, the investigators will develop CF-specific guidelines to achieve therapeutic goals with recommendations for drug dosing (including dose, dose frequency and timing in relation to meals and supplemental pancreatic enzymes) and timing of therapeutic monitoring to be used for future treatment of NTM lung disease in CF.