Myrbetriq receives FDA approval for treatment of overactive bladder
On June 28, the US Food and Drug Administration (FDA) approved Myrbetriq (mirabegron) to treat adults with overactive bladder. Myrbetriq is marketed by Astellas Pharma US, Inc. of Northbrook, Ill. “An estimated 33 million Americans suffer from overactive bladder, which is uncomfortable, disrupting, and potentially serious,” noted Victoria Kusiak, M.D., deputy director of the Office of Drug Evaluation III in the FDA’s Center for Drug Evaluation and Research. She added, “Today’s approval provides a new treatment option for patients with this debilitating condition.”
Symptoms of an overactive bladder include the need to urinate too often (urinary frequency), the need to urinate immediately (urinary urgency), and the involuntary leakage of urine as a result of the need to urinate immediately (urge urinary incontinence). Myrbetriq is an extended-release tablet taken once daily, which improves the storage capacity of the bladder by relaxing the bladder muscle during filling. The drug’s safety and effectiveness were demonstrated in three double-blind, placebo-controlled, multicenter clinical trials. A total of 4,116 patients with overactive bladder were randomly assigned to take Myrbetriq at doses of 25 milligrams, 50 mg, 100 mg, or a placebo once daily for 12 weeks.
The studies found that Myrbetriq 25 mg and 50 mg effectively reduced the number of times an individual urinated and the number of times an individual had wetting accidents during a 24-hour period. Patients taking Myrbetriq 50 mg also expelled a greater amount of urine, demonstrating the drug’s effectiveness in improving the storage capacity of the bladder.
The most common side effects observed in the trials were increased blood pressure, common cold-like symptoms (nasopharyngitis), urinary tract infection, constipation, fatigue, elevated heart rate (tachycardia), and abdominal pain. Myrbetriq is not recommended for use in those with severe uncontrolled high blood pressure, end stage kidney disease or severe liver impairment.
A person's ability to hold urine depends on normal function of the lower urinary tract, kidneys, and nervous system. The person must also have the physical and mental ability to recognize and respond to the urge to urinate. The bladder's ability to fill and store urine requires a working sphincter muscle (which controls the flow of urine out of the body) and a stable bladder wall muscle (detrusor). The process of urination involves two phases: filling and storage; and emptying. During the filling and storage phase, the bladder stretches so it can hold the increasing amount of urine. The bladder of an average person can hold 350 ml to 550 ml of urine. Generally, a person feels like they need to urinate when there is approximately 200 ml of urine in the bladder. The nervous system tells you that you need to urinate. It also allows the bladder to continue to fill. The emptying phase requires the detrusor muscle to contract, forcing urine out of the bladder. The sphincter muscle must relax at the same time, so that urine can flow out of the body.
Take home message:
Although this medication has proven effectiveness, it also has side effects that may be significant. In today’s time, many patients present at a physician’s office and ask for a prescription for “that new drug.” Before embarking on a medication program, a thorough evaluation should be conducted to determine the cause of the problem and possible solutions. Other remedies may be simpler and more effective. For example, some women develop urgency following intercourse because of bacteria being forced into the urinary outlet. Getting up to urinate after intercourse may resolve the problem. Men with urinary symptoms may have an enlarged prostate. Some individuals restrict fluid intake while at work to avoid trips to the restroom. This is a bad idea; dehydration can increase the risk of bladder problems. Although family practitioners and internists can handle many bladder problems, specialty care is available. Urologists specialize in diseases of the kidneys and bladder. Urogynecologists are gynecologists who have special training in kidney and bladder problems in women.