BETHESDA, MD 28 June 2012—FDA today announced the approval of mirabegron extended-release tablets for the treatment of overactive bladder in adults.

Mirabegron will be marketed as Myrbetriq by Astellas Pharma of Northbrook, Illinois. The company said it expects the new product to be available in pharmacies in the fourth quarter of 2012.

FDA-approved labeling (PDF) for mirabegron describes the drug as a beta-3 adrenergic agonist that relaxes a muscle involved with the storage of urine in the bladder.

The recommended starting dosage of mirabegron is 25 mg taken once daily with or without food. The dosage may be increased to 50 mg per day on the basis of the patient's response and ability to tolerate the drug.

In patients with severe kidney impairment or moderate liver impairment, the dosage should not exceed 25 mg, the labeling states. Patients with end-stage renal disease, severe liver disease, or uncontrolled hypertension should not use mirabegron.

Mirabegron should be used with caution in patients who take antimuscarinic drugs for overactive bladder symptoms and in patients with bladder outlet obstruction.

Patients who are starting treatment with mirabegron in combination with digoxin should receive the lowest dosage of digoxin and have blood levels of the cardiac drug monitored to determine the appropriate regimen, according to the labeling for miragegron.

Dosage adjustments for drugs that are metabolized by the cytochrome P-450 2D6 pathway may be necessary for patients who take these medications concurrently with mirabegron.

In clinical trials, the most frequent adverse events associated with the use of mirabegron included nasopharyngitis, urinary tract infection, constipation, fatigue, hypertension, tachycardia, and abdominal pain.

Mirabegron will be supplied as 25- and 50-mg tablets in bottles of 30 or 90 each and in unit dose packs of 100 each. The tablets should be stored at controlled room temperature.