Overactive bladder topical gel unaffected by showering, sunscreen

Absorption of oxybutynin chloride topical gel, an investigational therapy for overactive bladder, is not affected by showering or sunscreen use, according to data presented at the Society of Urologic Nurses and Associates annual conference in Philadelphia.

Three open-label, randomized studies in healthy men and women showed that showering 1 hour or later, or the application of sunscreen 30 minutes before or after application of the topical gel did not significantly alter its absorption or systemic blood level. The data also found limited transference of the drug when treated people came into contact with their untreated partner.

In the showering study, participants received oxybutynin topical gel for 35 days. Every 7 days, starting at day 14, subjects either did not shower or showered at 1, 2, or 6 hours after dosing. At the time points tested, showering did not have a meaningful impact on delivery of the drug into the bloodstream.

In the sunscreen study, participants received oxybutynin topical gel alone or 30 minutes before or after applying sunscreen. All three regimens resulted in similar oxybutynin absorption and time to maximum blood plasma concentration.

Editor’s note: A recent Urology Times article discussing oxybutynin topical gel reported an incorrect dose of the drug used in a study (“OAB gel may overcome side effects of patch,” Oct. 15, 2008, page 1). The article should have stated: "Subjects received 18 days of gel therapy (1 gram once daily) or one patch every 3.5 days for 2 weeks, followed by a 4-day application (3.9 mg/day)." Urology Times apologizes for this error and any confusion it may have caused.