San Francisco—With the advent of transdermal
methods of dispensing medication for the treatment of
overactive bladder (OAB), patients have the opportunity
to experience positive outcomes while avoiding some
of the side effects associated with oral formulations.
During the 2009 Society of Urologic Nurses and
Associates Annual Symposium, Diane Newman, RNC,
MSN, CRNP, FAAN, who is the codirector of the Penn
Center for Continence and Pelvic Health at the
University of Pennsylvania Health System in Phil -
adelphia, provided a presentation on the application of
oxybutynin chloride topical gel (OTG).
Ms. Newman began her presentation by discussing
the evolution of OAB treatment with oxybutynin from
the oral formulation to transdermal patch to transdermal
gel. She described transdermal products as “the
new wave” in OAB treatment alternatives.
Although oral formulations have ease of use, they are
associated with dry mouth and other anticholinergic
adverse effects. The introduction of the transdermal
patch helped to combat these ill effects.
However, a concern that was raised with regard to
transdermal patches is that if other medications pursue
this type of formulation, patients may end up with
“many patches on them.” In addition, caregivers and
nursing staff tending to patch-wearers need to be vigilant
in removing them according to recommended dosing.
For these reasons, Ms. Newman is very interested in
the introduction of a gel formulation of oxybutynin
chloride, which was recently approved by the US Food
and Drug Administration for the treatment of patients
with OAB. The gel avoids some of the concerns raised
by patches, specifically first-pass hepatic metabolism of
oxybutynin to N-desethyloxybutynin (N-DEO), which
is associated with anticholinergic events. “I think the
next progression is, of course, the use of gel,” Ms.
Newman commented.
“Of all of the antimuscarinic drugs, oxybutynin is
the only one that can be made into a skin product,”
Ms. Newman explained. It is an ethanol-based gel
because the ethanol gives it the ability to dry, which is
why it is used in drug formulations and not used in regular
skin care products. Furthermore, the OTG is a
once-daily topical application and is clear and fragrance-
free.
There are other positive features of OTG, including the
minimal effect of showering on oxybutynin concentrations,
as long as the patient applies the gel 1 hour before
showering or 1 hour after showering. Also, sunscreen
applied 30 minutes before or after OTG application did
not substantially change the level of systemic exposure to
oxybutynin compared with the gel being applied alone.