Posted 25 January 2013
By Alexander Gaffney, RF News Editor
The US Food and Drug Administration (FDA) has just approved the use of an over-the-counter (OTC) product intended to treat patients with overactive bladders, highly unusual in one regard: While the product is available OTC for women, it is still prescription-only for men-a rare development known as a partial OTC switch.
The product, Oxytrol, is an FDA-approved patch that administers oxybutynin to patient over the course of four days at a controlled rate of 3.9 mg per day, and helps to treat uncontrollable bladders. The condition is thought to affect approximately 33 million Americans, the majority of whom are older women, FDA notes.
Oxybutynin is an anticholinergic, a substance that blocks certain neurotransmitters, lessening the effects of involuntary muscle spasms, which also cause overactive bladder (OAB) syndrome.
Partial OTC Switch
While regulators said the drug would be made available OTC to women, men with the same condition would still require a prescription to obtain the product.
That arrangement is highly unusual, particularly because it leaves open the prospect that men might obtain the product OTC as well unless it is sold in a semi-restrictive way, such as "behind the counter" of a pharmacist. Even those arrangements leave open the possibility that men would be able to access the products, as similar OTC products such as Plan B (levonorgestrel) are available for purchase by men despite being indicated for women only.
In a November 2012 Advisory Committee meeting, participants referred to the arrangement as a "partial OTC switch." FDA regulations state that a partial switch requires the submission of a new drug application (NDA), as opposed to a full switch application which only requires a supplemental NDA.
That same advisory committee actually voted 5-6-that is, against the idea-that consumers would be able to appropriately self-select to use Oxytrol, finding that the anticholinergic effects of the drug were concerning enough to warrant the consultation of a pharmacist or physician before taking the product, especially in older populations.
Regulators said this was the first time a drug of that type had ever been approved for OTC use, though other drugs with anticholinergic effects are already available as OTC products, the Advisory Committee said.
The drug's exclusion from OTC use by male populations is a result of the male anatomy, not the drug itself. The drug's approved prescription labeling indicated that "there were no significant differences in the pharmacokinetics of oxybutynin in healthy male and female volunteers following application of Oxytrol."
The difference, it turns out, is not on what the drug does, but what it hides: other problems.
Statements made at the November 2012 advisory committee indicated that male patients would be more susceptible to misdiagnosing their overactive bladders, which can also be indicative of prostate cancer or bladder cancer (the latter of which, while not exclusive to males, is more prevalent in males).
"The exclusion of males from the use of the proposed product, and the rarity of typical OAB symptoms at first presentation in a consumer with bladder cancer may limit the risk of delayed diagnosis," FDA wrote in its briefing document for the Nonprescription Drugs Advisory Committee.
Concerns that patients might delay treatment, leading to worse outcomes, was chief among regulators' concerns.
Similar concerns have weighed heavily on FDA regulators in the past. For instance, in the case of prescription asthma inhalers, regulators questioned if making the products OTC would prevent consumers from better managing their asthma with the help of a physician. The products are still prescription only, and FDA forced one of the only OTC alternatives-primatine mist-off the market in 2012 after it failed to meet environmental standards for the release of chlorofluorocarbons (CFCs), which it uses as a propellant.
But another question remains outstanding: can the product be controlled? Despite Merck's attempts to recruit only women for its trials, approximately four dozen male patients attempted to enroll, leaving open the possibility that men might seek to obtain the product despite its female-only indications.
Neither Merck's or FDA's statements indicated any physical controls on the product. In a statement to Regulatory Focus, FDA spokeswoman Lisa Kubaska said that the controls on Oxytrol would be labeling-based--not physical.
"As with other approved OTC
medications, the labeling informs consumers about whether or not this drug
would be appropriate for them to use, and the self-selection studies found that
consumers are able to decide on the appropriateness of this medicine for their
own use," wrote Kubaska. "There are no current regulations supporting 'behind-the-counter' marketing status for drugs in the United States."
While she said that FDA has considered the use of physical controls, FDA did not believe men who improperly obtain the product OTC "will be at significant risk for having done so."
"The requirement that consumers have their symptoms for at least three months before using this product, and the other labeled contraindictations, will help to maximize the safe use of this product," Kubaska added.
Oxytrol has one other notable aspect, noted another industry publication. The Tan Sheet, a publication of Elsevier, said the product is the "first first-in-class Rx-to-OTC switch since GlaxoSmithKline's Alli (orlistat) was approved in 2007"-a long time between switches, even by regulatory standards.