Careful evaluation key in patients with refractory OAB

April 1, 2005

Philadelphia--Urologists who manage patients with overactive bladder are challenged not only with choosing from a growing list of pharmacologic treatment options, but also with the prospect that some patients may not respond to oral anticholinergic treatment at all. In these patients with "refractory detrusor overactivity," it is important to realize that a number of factors mitigate against successful therapy, said Roger R. Dmochowski, MD, professor of urology at Vanderbilt University Medical Center, Nashville, TN.

Some, but not all of these factors are related specifically to characteristics of the drugs themselves. Other issues, including the fact that OAB is increasingly being understood to be a heterogenous condition, also must be considered.

The need to identify these factors and rule out other conditions is critical before proceeding to a more invasive treatment modality, Dr. Dmochowski told attendees at PROAB (Program on Overactive Bladder), a CME event sponsored by the University of Pennsylvania and Advanstar Communications, the publisher of Contemporary Urology and Urology Times.

Dose-related problems-both underdosing and insufficient temporal exposure-may be contributing to failure.

"There is a concern about safety," especially among primary care physicians, Dr. Dmochowski said. "And there is a hesitancy to push the envelope, even with those medications that do allow dose escalation.

"The other thing that I commonly find is insufficient temporal exposure-patients aren't on the drug long enough. We're going to see increasing amounts of data implying that drugs work early, and indeed they do. However, we do realize that there's a certain amount of exposure time that patients should have before drug exposure is considered to be insufficient."

Lack of drug tolerability and compliance also may play a part in refractory OAB. Patients may stop taking anticholinergics because of their more common side effects, such as dry mouth and constipation. In addition, it is also important to consider the possibility that certain agents may cause specific adverse events in some individuals that may not be found with other agents, Dr. Dmochowski said.

And some patients may simply be unwilling to take a drug on a daily basis, incorrectly assuming that utilizing an agent on as-needed basis will alleviate their symptoms.

A number of factors not specifically related to pharmacotherapy must also be remembered in patients who do not respond to initial drug therapy:

"Receptor interactions, both on an individual and population basis, certainly mitigate with this population heterogeneity against overall pharmacologic success for these individuals," he said.