Management of overactive bladder with transdermal oxybutynin

Abstract

In clinical trials, transdermal oxybutynin (OXY-TDS) has shown comparable efficacy and improved tolerability when compared with conventional pharmacotherapy. Systemic anticholinergic adverse effects are comparable to those with placebo, most likely owing to avoidance of first-pass hepatic metabolism and conversion of oxybutynin to N-desethyloxybutynin. OXY-TDS has predictable pharmacokinetic absorption and elimination parameters, as shown in both in vitro and in vivo studies. Consistent plasma concentrations of oxybutynin avoid labile peak and trough concentrations seen with immediate-release formulations, paralleling extended-release drug delivery. This novel drug delivery system has unique dermatologic skin application site reactions, including erythema and pruritus. Skin reactions are usually mild and can be minimized by varying the site of patch application. Most eczematous dermatologic reactions can be appropriately treated with a moderately potent topical corticosteroid cream. A small percentage of patients will discontinue therapy as a result of bothersome application site skin reactions.

Figure 1

The transdermal oxybutynin system.

Figure 2

Concentration versus time curve after single-dose (3.9 mg/d), 96-hour transdermal oxybutynin application to the abdomen, buttock, and hip (n = 24). Adapted from Zobrist RH et al, with kind permission of Springer Science and Business Media.

Figure 3

Steady-state oxybutynin and N-desethyloxybutynin plasma concentrations after transdermal and extended-release oral administration. Adapted with permission from Appell RA et al.