The oral cystic fibrosis drug ivacaftor (Kalydeco) was well tolerated in preschool-age children with cystic fibrosis who had CFTR gating mutations, with a safety profile similar to that seen in older children and adults, a manufacturer-funded study found.

In a study of 34 patients, the most frequent adverse events were cough (n=19, 56%) and vomiting (n=10, 29%). Five of the study’s patients (15%) also had liver function test (LFT) results (ie transaminase levels) that were more than 8 times higher than the upper limit of normal, with one of these children discontinuing treatment and four having treatment interrupted.