Botox, an Allergan, Inc.-made injection drug, was approved Wednesday by the U.S. Food and Drug Administration to treat those with urinary incontinence and neurologic conditions such as spinal cord injury and multiple sclerosis who have overactivity of the bladder.

Prior to being approved by federal drug regulators, the effectiveness of Botox, made by Allergan Inc., of Irvine, Calif., to treat this type of incontinence was demonstrated in two clinical studies involving 691 patients.

Botox also is FDA-approved to treat chronic migraine headaches, certain kinds of muscle stiffness and contraction, severe underarm sweating, abnormal twitch of the eyelid and a condition in which the eyes are not properly aligned, said FDA officials in a statement.

The drug also treats people with neurologic conditions, such as spinal cord injury and multiple sclerosis.

Symptoms of urinary incontinence can range from mild leaking to uncontrollable wetting, according to the National Institutes of Health. The syndrome was previously treated with medications to relax the bladder and use of a catheter to regularly empty the bladder.

Each of the patients had urinary incontinence resulting from spinal cord injury or multiple sclerosis.

Urinary incontinence associated with neurologic conditions can be difficult to manage,” said George Benson, deputy director, Division of Reproductive and Urologic Products. “Botox offers another treatment option for these patients.

According to the study, there were significant decreases in the weekly frequency of urinary incontinence episodes in the Botox group compared with placebo.

The drug is injected into the bladder with Botox through a procedure called cystoscopy, which allows a doctor to visualize the interior of the bladder.

The most common symptoms observed following an injection of Botox into the bladder were urinary tract infection and urinary retention.