Indications
Tezacaftor is used to treat cystic fibrosis (CF), an inherited disease that causes thick, sticky mucus in the lungs, gut and other organs. It is always taken in combination with Ivacaftor, either alone or together with Elexacaftor, in people who have certain changes (mutations) in the CFTR gene, most commonly at least one F508del mutation. A genetic test confirms whether it is suitable.
How It Works
In CF, a faulty CFTR protein cannot move salt and water properly in and out of cells, so mucus becomes thick. Tezacaftor is a CFTR corrector: it helps the faulty protein fold into a better shape and reach the cell surface. Ivacaftor (a potentiator) then helps the channel open. Together they improve salt and water flow, thin the mucus and improve lung function.
Dosage and Administration
Take exactly as prescribed by your CF specialist. It is taken by mouth as a combination tablet in the morning and an Ivacaftor tablet in the evening, about 12 hours apart. Each dose should be taken with food that contains fat, such as eggs, butter, cheese, whole milk or nuts, to help absorption. The dose may be lowered for children, liver disease or interacting medicines.
Interactions
- Strong CYP3A inducers such as Rifampicin, Rifabutin, Carbamazepine, Phenytoin, Phenobarbital and St John’s wort greatly reduce its effect and are not recommended.
- Strong or moderate CYP3A inhibitors such as Ketoconazole, Itraconazole, Clarithromycin or Fluconazole raise its levels; the dose must be reduced.
- Avoid grapefruit and Seville oranges.
- It may affect Digoxin, Ciclosporin and some other medicines; tell your doctor about everything you take.
Contraindications
Do not take if you are allergic to Tezacaftor, Ivacaftor or any ingredient of the tablets.
Side Effects
Common side effects include headache, sore throat, nasal congestion, cold-like symptoms, nausea, dizziness, stomach pain and diarrhoea. Raised liver enzymes can occur. Non-harmful cataracts (clouding of the eye lens) have been seen in some children.
Get urgent medical help if you notice yellowing of the skin or eyes, dark urine, pain in the upper right of the abdomen, loss of appetite with nausea and vomiting, or signs of a severe allergic reaction such as swelling of the face or difficulty breathing.
Pregnancy and Lactation
Information on use in pregnancy is limited. Your specialist will weigh the benefits for your lung health against any possible risk; tell them if you are pregnant or planning pregnancy. It is not known if it passes into breast milk in meaningful amounts; discuss with your doctor before breastfeeding.
Precautions and Warnings
- Liver tests are checked before starting, every 3 months in the first year and yearly after that.
- Children should have eye checks before and during treatment.
- Dose changes are needed for moderate liver disease; it is not recommended in severe liver disease.
- Continue your other CF treatments, such as physiotherapy, unless told otherwise.
Overdose
There is no specific antidote. Overdose may increase side effects such as dizziness or diarrhoea. Contact your doctor or the nearest hospital; supportive treatment and monitoring are given.
Therapeutic Class
CFTR corrector; cystic fibrosis transmembrane conductance regulator modulator.
Storage
Store below 30°C in a dry place, away from light, and out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.