06/28/2012 01:52 pm ET Updated Aug 28, 2012

Myrbetriq: FDA Approves Drug For Overactive Bladder

WASHINGTON, June 28 (Reuters) - U.S. drug regulators approved Astellas Pharma Inc's pill for overactive bladder on Thursday, boosting the Japanese drugmaker's foothold in the market for the condition.

The Food and Drug Administration approved the once-daily pill, to be sold as Myrbetriq, for adults who cannot control their bladder muscles, following a positive recommendation from FDA advisers.

The FDA said about 33 million Americans have an overactive bladder, whose symptoms include frequent urination and urgency to urinate. The condition is especially common among those 75 years of age and older.

Myrbetriq, the first drug in its class, works by activating a protein receptor in bladder muscles that relaxes them and helps the bladder fill and store urine. The pill is already approved in Japan.

"Overactive bladder ... is uncomfortable, disrupting and potentially serious," said Dr. Victoria Kusiak, deputy director in an FDA office for drug evaluation.

In April, a panel of outside advisers to the FDA voted 7-4 that the benefits of the pill, known chemically as mirabegron, outweighed its possible risks to the heart and liver.

In clinical trials, a 50-milligram dose of the drug meant four fewer trips to the bathroom over seven days compared with placebo, and three fewer episodes of urine leakage, or incontinence.

Some FDA advisers had said that may not greatly help people who often go to the bathroom at least eight times a day. However, the FDA had said clinical trials only had to prove the drug was better than a placebo, prompting a majority of panelists to vote in favor of the drug.

Common side effects were elevated blood pressure, urinary tract infection, elevated heart rate and abdominal pain. The FDA said people with very high uncontrolled blood pressure or serious kidney or liver disease should not take the pill.

Astellas, Japan's second-largest drugmaker, already makes the overactive bladder drug Vesicare. It is one of the company's biggest products, and had global sales of 86.7 billion yen ($1.1 billion) in 2010.

Shares of Astellas closed up 1.5 percent in Tokyo at 3,405 yen.