Cognitive effects of oxybutynin chloride topical gel in older healthy subjects: a 1-week, randomized, double-blind, placebo- and active-controlled study.

Oxybutynin is a common antimuscarinic therapy for overactive bladder. Transdermally administered oxybutynin chloride topical gel 10% (OTG) has a low propensity for anticholinergic adverse effects and possibly also a low risk of cognitive impairment. A randomized, double-blind, placebo- and active-controlled study evaluated the effects of OTG on cognitive and psychomotor functions in older healthy adults. Healthy adults aged 60-79 years were assigned randomly (1:1:1) to 1-week's treatment with OTG (1 g [100 mg oxybutynin] applied once daily on rotating sites of upper arms/shoulders, abdomen or thighs) plus oral placebo, immediate-release oxybutynin (OXB-IR; 5 mg capsule three times/day) plus placebo gel, or double placebo. Delayed recall Name-Face Association Test (NFAT) score was the primary end point. Treatments were compared by analysis of covariance. Of 152 participants (mean age, 68 years), 49 received OTG, 52 OXB-IR and 51 placebo. NFAT Delayed Recall tests revealed no significant treatment differences (overall, p = 0.2733; OTG vs placebo, p = 0.1551; OXB-IR vs placebo, p = 0.1767). However, a significant effect (p = 0.0294) was noted for the Misplaced Objects Test, with scores declining only for OXB-IR. Approximately twice as many participants receiving OXB-IR (n = 10) as those receiving OTG (n = 5) or placebo (n = 6) showed a significant decline (≥6 points) in Total Recall score for the Hopkins Verbal Learning Test-Revised. No significant effects on psychomotor reaction time were observed. The most common adverse event, dry mouth, occurred in 6.1%, 73.1% and 7.8% of participants receiving OTG, OXB-IR and placebo, respectively. OTG applied for 1 week had no clinically meaningful effect on recent memory or other cognitive functions in healthy, older adults. Registered as NCT00752141 at www.clinicaltrials.gov.