Pharmacokinetics of Ivacaftor, Tezacaftor, Elexacaftor, and Lumacaftor in Special Cystic Fibrosis Populations: A Systematic Review

Abstract

Background and Objective: Following the development of cystic fibrosis transmembrane conductance regulator (CFTR) modulators (ivacaftor, tezacaftor, elexacaftor, and lumacaftor), the prognosis for people diagnosed with cystic fibrosis (pwCF) has improved. Understanding the pharmacokinetics (PK) of CFTR modulators is crucial to provide optimal care, particularly in special cystic fibrosis (CF) populations such as pwCF with hepatic impairment, pancreatic insufficiency, those who are pregnant or lactating, or who are children. We aim to provide an overview of the PK of CFTR modulators in these populations. Methods: A systematic literature search was carried out in PubMed and Embase on 20 June 2024. Studies were considered relevant when information on PK or exposure of CFTR-modulating drugs was available. Results: PwCF with mild/moderate hepatic impairment do not exhibit substantially higher exposure to CFTR modulators compared with those without liver involvement or healthy individuals. Similarly, exocrine pancreatic insufficiency has no effect on the PK of CFTR modulators in adult pwCF. In contrast, pediatric pwCF are exposed to higher levels of CFTR modulators relative to adults, as children receive higher weight-based doses (mg/kg) to ensure equivalent therapeutic efficacy. Conclusions: The PK of CFTR modulators have been more extensively studied in adults, pwCF with mild/moderate hepatic impairment, and children. However, ensuring adequate dosing remains challenging. Knowledge gaps persist for adults with severe hepatic impairment (Child–Pugh Class C), children with CF-induced hepatic impairment, and pregnant or lactating pwCF. Future research addressing these gaps, through incorporating routine clinical data, is crucial for improving clinical guidelines and optimizing dosing regimens, thereby advancing towards evidence-based utilization of CFTR modulators.