Ivacaftor
KalydecoPubChem CID 16220172 · 3D model
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Props open a faulty channel on the surface of lung and other cells (called CFTR) that's supposed to move salt and water in and out, so mucus stays thinner instead of getting thick and sticky, but only in people whose specific CFTR gene mutation is one this drug can act on.
How it works
Cystic fibrosis is caused by a faulty version of a protein called CFTR that normally acts like a channel, letting salt and water move in and out of cells lining the lungs and other organs; when that flow is disrupted, mucus becomes thick and sticky. Ivacaftor works like a wedge that props this faulty channel open more often, so a working, if imperfect, channel can move salt and water more normally. It only helps if a person's specific CFTR mutation is one where the channel reaches the cell surface but doesn't open properly — a doctor confirms this with genetic testing before prescribing it.
What it’s used for
Ivacaftor is prescribed for people with cystic fibrosis age 1 month and older, but only if genetic testing shows they carry at least one specific CFTR gene mutation that this drug is known to work on — it doesn't help with all forms of CF. Because it can occasionally raise liver enzyme levels, doctors check liver function with a blood test before starting treatment and periodically afterward.
- Mechanism
- CFTR potentiator, increases chloride channel open probability
- Drug class
- Small molecule
- Therapeutic area
- Respiratory
The first cystic fibrosis drug to fix the broken protein, not just the symptoms
Cystic fibrosis is caused by a broken chloride channel in cells, which leads to thick mucus, lung infections, and other symptoms doctors used to treat one by one. Ivacaftor was the first CF drug to instead go after the actual broken part: for patients with a specific version of the defect (the G551D mutation), it helps the faulty channel open more normally, treating the root cause rather than just the downstream problems it causes. It only works for the roughly 4-5% of CF patients with this particular mutation, but it proved that fixing the gene's protein directly was possible — a breakthrough that later led to combination drugs covering most people with CF.
Pivotal trial
A randomized, placebo-controlled phase 3 trial in CF patients 12 and older with at least one G551D allele, showing sustained improvement in lung function (FEV1) and reduced pulmonary exacerbations over 48 weeks.