BACKGROUND: Poorly controlled asthma especially in children remains a major public health problem. Many children with poor asthma control experience gastroesophageal reflux (GERD). The effect of mild GERD on asthma remains controversial despite studies involving proton-pump inhibitors (PPIs) assessing their effect on asthma. Past inconsistent findings regarding the effect of PPIs on asthma control may have resulted from ineffective dosing strategies of proton-pump inhibitors employed in these studies. Drug levels and efficacy vary widely in the population and depend on genetics. Dosing in children which adjusts for the gene CYP2C19 may improve efficacy and reduce side-effects leading to improved asthma control.~HYPOTHESIS: #1: The investigators hypothesize that genotype-tailored lansoprazole dosing will reduce asthma symptoms in children with mild symptoms of GERD compared to placebo. #2: CYP2C19 and ABCB1 genetic variants influence the pharmacokinetics (drug levels) of lansoprazole as determined by population pharmacokinetic modeling.~METHODS: The investigators will conduct a 6-month randomized controlled trial comparing genotype-tailored lansoprazole dosing versus matched placebo in the control of asthma symptoms in 6-17 year olds with asthma and mild reflux. All participants will have baseline pharmacokinetics analysis following a single genotype-tailored dose to assess the effects of CYP2C19 and ABCB1.~IMPACT: These results would be a major advance in the science of safe dosing of proton-pump inhibitors in children and for the management of the millions of children struggling with reflux and asthma.
This study will evaluate the effect of CYP2C19 and ABCB1 genes on pharmacokinetics of lansoprazole in children with mild gastroesophageal reflux (GER) and uncontrolled asthma. It will determine if genotype-guided lansoprazole dosing of lansoprazole improves GER and asthma control.