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FDA approves Symdeko for treatment of cystic fibrosis

Symdeko was approved by the FDA in February 2018 for the treatment of certain types of cystic fibrosis in patients aged 12 years and older. Cystic fibrosis (CF) is estimated to affect 75,000 people across North America, Europe, and Australia, according to Vertex Pharmaceuticals, the company behind the drug. The president of Vertex, Jeffrey Leiden, MD, Ph.D., says Symdeko’s approval by the FDA marks “an exciting day for the CF community.”

What is cystic fibrosis?

Cystic fibrosis is a disease caused by a mutation of genes that control proteins responsible for the secretion of certain liquids in the body, which results in the thickening of sweat, digestive fluids, and mucus. This, in turn, affects the function of the pancreas, liver, intestines, reproductive organs, bladder, and kidneys, but is most impactful on the lungs. The lungs become clogged with thick mucus that causes difficulty breathing and frequent respiratory infections.

What is Symdeko, and how does it work?

Symdeko can be prescribed in patients with a specific mutation (of the CFTR gene). A combination of two drugs—tezacaftor and ivacaftor—Symdeko is prescribed in tablet form. The usual dose is one tablet in the morning (which contains both medications) and one tablet at night (which contains ivacaftor only). The two doses should be taken 12 hours apart. Symdeko should be taken with a fat-containing meal or snack to help the body absorb the medication. The treatment works by allowing malfunctioning proteins in a patient’s respiratory membranes to work more efficiently, which results in a thinner liquid secretion in the lungs. Lung function is improved, as air is able to flow more easily.

The new drug’s approval comes after the FDA examined studies published in the New England Journal of Medicine in November 2017. These studies showed that patients aged 12 or older experienced statistically significant and clinically meaningful improvements in lung function after using Symdeko for 48 weeks.

Side effects of Symdeko

The most common Symdeko side effects include: 

  • sinus congestion
  • headaches
  • nausea
  • dizziness

Patients who experience these symptoms should avoid activities in which dizziness could cause harm to themselves and others. 

More severe side effects can include an increase in liver enzymes in the blood and clouding of the eyes (cataracts). Patients are advised to consult with their healthcare professional about liver function, especially if they see any symptoms of liver problems, including yellowing of the skin or eyes, nausea, or dark-colored urine. Patients taking Symdeko should have their liver function checked periodically.

Symdeko interactions

Symdeko can interact with many drugs, including (but not limited to) azole antifungal drugs, certain seizure medications (phenobarbital, phenytoin, carbamazepine), or antibiotics (rifampin, as well as drugs in the erythromycin family). Patients should consult with a medical professional before taking Symdeko, and let them know of any drugs that they are currently taking. The drug may also react with grapefruit or grapefruit juice, Seville oranges, and St. John’s Wort (an herbal supplement). Patients should avoid these items if taking Symdeko.

Whether Symdeko can interact with the production of breast milk or the growth of a fetus is presently not known. Patients who are pregnant, planning to become pregnant, or breastfeeding should ask a medical professional for advice before taking the drug.

Update: On Jun. 21, 2019, the FDA expanded the indication for Symdeko tablets for treatment of pediatric patients (6 years and older) with cystic fibrosis who have certain genetic mutations (two copies of the F508del mutation, or at least one mutation in the CF gene that is responsive to treatment with Symdeko). Patients can enter their mutations into the Symdeko website to find out if they are eligible for treatment with Symdeko.