The influence of exocrine pancreatic function on the exposure and pharmacokinetics of ivacaftor in people with cystic fibrosis

Background: Cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapies target the underlying cause of cystic fibrosis (CF), and show robust treatment effects at group level. The individual effect however, is variable which might be (partially) related to differences in drug exposure. The profound influence of fat containing food compared to fasting on drug exposure gives need to investigate if the exocrine pancreatic function changes the degree and rate of absorption of ivacaftor and thereby may contribute to differences in drug exposure. Methods: Pharmacokinetic parameters of ivacaftor were measured in 10 pancreatic sufficient (PS) and 10 pancreatic insufficient (PI) patients with CF on current treatment with tezacaftor/ivacaftor and compared between both groups. In PI patients pharmacokinetic parameters were investigated with and without the use pancreatic enzymes and compared in each individual. Results: We demonstrated that the pharmacokinetic parameters of ivacaftor did not differ significantly between PS and PI people with CF (pwCF). Pancreatic enzymes did not significantly change the absorption or exposure to ivacaftor in PI pwCF using tezacaftor/ivacaftor. Conclusion: The exocrine pancreatic function of pwCF does not significantly influence the absorption and exposure of ivacaftor. The use of pancreatic enzymes in PI pwCF does not change the absorption and exposure of ivacaftor. Therefore, the dosing advice as mentioned in the SmPC for ivacaftor can be maintained independent of the exocrine pancreatic function.