OAB drugs draw flak for allegedly weak efficacy

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Drugmaker Astellas is declaring a victory of sorts, as an FDA advisory panel endorsed its overactive bladder medication mirabegron April 6. If it gets a full agency endorsement at its June 29 review, it means the company has a medication that could take the place of its billion-dollar earner, Vesicare, which goes generic three years from now. The company said in a statement that mirabegron is unique to the category, because it relaxes bladder muscles by stimulating β3receptors, whereas current medications bind to muscarinic receptors.

Yet not everyone is sold on the new drug's efficacy. Kate Ryan, the program coordinator of the National Women's Health Network is reported to have told the advisory panel that the drug's impact is too insignificant to deserve attention. Authors of a report published in the April 9 Annals of Internal Medicine would appear to agree: they compared the leading treatments for overactive bladder, also known as urinary incontinence, and said the prescription medications help about 200 for every 1000 women treated, or 20%. They also found that side effects deter some women who do derive benefits from the drugs. Dry mouth is the most common side effect. The authors estimate that more than half of the women taking OAB drugs stop within the year.

OAB affects 1 in 6 Americans or 33 million adults, according to various company sites. Sufferers are often women, and the disease is associated with a frequent need to urinate and uncontrolled urination. In extreme cases, sufferers cope with the condition by restricting fluids, avoiding social situations and carrying mental maps of the bathrooms along their daily routes.

“We don't have drugs that make a practical difference in the lives of people who are experiencing . . . extreme conditions,” Amy Allina told MM&M. Allina is the program director for the Washington-based National Women's Health Network. Her criticism included the recent contender from Astellas.

An Astellas spokesperson said: "Antimuscarinics are the standard therapeutic agents for the treatment of overactive bladder. Mirabegron is an important potential new treatment as it offers both an additional pharmacologic treatment option for patients with OAB, and addresses an unmet medical need for patients with OAB who are not candidates for antimuscarinic therapy, who are intolerant to antimuscarinic therapy or those who have an inadequate response to prior antimuscarinic therapy."

Allergan, which already has OAB treatment Sanctura in the mix, is looking to get its blockbuster Botox approved to treat OAB. The company filed an sBLA with the FDA for the additional use and has a similar request in with European authorities. Botox is already approved to treat urinary incontinence that is linked to neurological conditions such as multiple sclerosis, migraines, cervical dystonia and wrinkles, among other conditions.

Allina said it “would be great to have a drug that really worked,” but the what's on the market does little more than cut down on the number of times a patient feels the need to go to the bathroom, and said if a patient goes 10 times a day that “it's not going to make a difference in my life if you lower it to 9 trips to the bathroom.”
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