MONDAY, March 9, 2020 (HealthDay News) -- Isturisa (osilodrostat) oral tablets have been approved to treat adults with Cushing disease, the U.S. Food and Drug Administration announced Friday.

Isturisa is indicated in adults with Cushing disease who are not candidates for pituitary gland surgery or who have had the surgery but still have the disease. The drug works by blocking the enzyme 11-beta-hydroxylase and preventing cortisol synthesis. Isturisa is taken orally twice a day, in the morning and evening. After treatment initiation, health care providers may reevaluate dosage based on the patient's response.

The approval was based on data from a 24-week, single-arm, open-label study of 137 adults with Cushing disease who were aged a mean of 41 years old. About 75 percent of the patients were women, and most had either had pituitary surgery that did not cure their disease or were not surgical candidates. Patients received a starting dose of 2 mg of Isturisa twice a day. Every two weeks, the dose could be increased up to 30 mg twice a day. After 24 weeks, about half of the patients had normal levels of cortisol. Seventy-one patients who did not need additional dose increases and tolerated the drug for 12 weeks were enrolled in an eight-week, double-blind, randomized withdrawal study in which they received Isturisa or placebo. After the withdrawal period, 86 percent of the patients who received Isturisa maintained cortisol levels within the normal limits compared with 30 percent of patients who received placebo.

The most commonly reported side effects in the clinical trial included adrenal insufficiency, headache, vomiting, nausea, fatigue, and edema. Additional potential side effects include hypocortisolism, QTc prolongation, and elevated adrenal hormone precursors and androgens.

Approval was granted to Novartis.

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