WASHINGTON -- An FDA advisory panel on Friday voted against recommending making oxybutynin transdermal patch (Oxytrol) available over-the-counter (OTC) for overactive bladder (OAB) in women, citing a bevy of concerns about using the product without a doctor's oversight.
In their 5-6 vote, panelists on the FDA's Nonprescription Drugs Advisory Committee were concerned women would use Oxytrol thinking they had OAB when they really had some other ailment that needed a physician's treatment. They also were concerned about men using the product off-label.
Some also were worried about the high amount of misuse of a potential OTC product, whether it was by patients who did not have indications for use, or those it was meant for that didn't use the product correctly.
"I don't think that we have shown that patients can appropriately self-select," Philip Hanno, MD, urology surgeon at the University of Pennsylvania in Philadelphia, said.
The oxybutynin transdermal patch first gained FDA approval in February 2003. The drugmaker Merck, who bought its rights from Watson Laboratories, is seeking to transform it to an OTC drug.
In such a switch, the FDA is looking to see whether patients can use the product safely without the oversight of a physician or pharmacist. This includes ensuring that the right patients use the drug in the appropriate way. The regulator is not evaluating the risk-benefit of the product, since that was done earlier when it was approved as a prescription drug.
Advocates of an OTC switch said women usually suffer from OAB for months or years without seeking help from a physician. An OTC product could offer sufferers an alternative.
But detractors of the switch say other conditions can cause symptoms similar to those of OAB, including urinary tract infection, bladder malignancy, pregnancy, prostate disease, and uncontrolled diabetes mellitus. Panelists who voted no Friday said those conditions need a physician's care, and an OTC oxybutynin could delay treatment of those.
OTC use would be limited to women to eliminate the delayed diagnosis of prostate cancer. The labeling also would restrict the drug's use to 2 weeks if it doesn't work, advising them to see a doctor if that does occur. The FDA said Friday OTC users typically stop using a product if it doesn't work.
Self-selection studies presented by Merck found fewer men and pregnant women correctly deemed the product was right for them than what the FDA determined was safe.
Stuart Howards, MD, urology professor at the University of Virginia School of Medicine in Charlottesville, said he would vote for the OTC switch if the drug's warning label stated not to use the drug above a certain age and to see a doctor if patients have symptoms of OAB.
Panelists also seemed in favor of including educational material in the drug's package to highlight the other conditions that could be mistaken for OAB.
Not all agreed that the concerns expressed warranted oxybutynin not be sold OTC. Committee chair Marcus Reidenberg, MD, pharmacology professor at the Weill Cornell Medical College in New York, said the concerns of misuse raised Friday didn't translate to clinically meaningful events.
In a study of the drug in real patients, of the 1,069 who decided to purchase the drug, 839 (78.5%) had conditions making them ineligible for use according to the label. "The ineligibilities spanned the gamut, from not having two or more OAB symptoms for at least 3 months, to not having spoken with a doctor about symptoms or diagnoses such as weight loss, excessive thirst, liver, or kidney disease," FDA reviewers said in briefing documents released in advance of Friday's meeting.
Proportion of misuse of even a single patch -- regardless of whether the buyers were considered eligible to use it or not -- was between 3.4% and 5%, within an acceptable range for the FDA. And a statistically relevant portion of misusers reported symptoms that should have led them to stop use.
The FDA is scheduled to make a decision on the drug by the end of January. The agency is not required to follow the advice of its advisory panels but usually does.