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Oxybutynin Chloride 10% Gel (Gelnique™)
By William T. Elliott, MD, FACP, and James Chan, PharmD, PhD. Dr. Elliott is Chair, Formulary Committee, Northern California Kaiser Permanente; and Assistant Clinical Professor of Medicine, University of California, San Francisco. Dr. Chan is Pharmacy Quality and Outcomes Manager, Kaiser Permanente, Oakland, CA. Drs. Elliott and Chan report no financial relationship to this field of study.
A new transdermal formulation of oxybutynin has been approved for the treatment of overactive bladder. Oxybutynin gel is marketed by Watson Pharmaceuticals as Gelniqueä.
Oxybutynin gel is indicated for the treatment of overactive bladder with symptoms of urinary incontinence, urgency, and frequency.1
One 1 g sachet (1.14 mL) is applied once daily to dry, intact skin on the abdomen, upper arms/shoulder, or thighs. Sites should be rotated and the same site should not used for consecutive days.1
Transdermal delivery of oxybutynin provides consistent delivery of the drug. Compared to the patch, the gel has lower frequency of dry mouth and possibly improved skin tolerability.2 It is associated with lower frequencies of application site pruritus and erythema compared to the patch (4-6% vs 14-17%) and (1.7- 2.3% vs 8.3-9.6%), respectively.1,3 The overall frequency of application site reactions was 5.4% vs 1.0% for placebo.1 The colorless, alcohol-based gel dries rapidly, does not leave a residue, and showering 1 hour after application does not affect the absorption of oxybutynin.
The most common significant adverse event is dry mouth (6.9% vs 2.8% for placebo). The gel requires daily application compared to weekly application for the patch. Oxybutynin can be transferred to another person with vigorous skin-to-skin contact. The gel is alcohol-based and is flammable. Open fires or smoking should be avoided until the gel dries.
The primary adverse event of antimuscarinics in general and oxybutynin in particular is dry mouth. Orally administered oxybutynin is metabolized by the liver and intestines to N-desmethyloxybutynin (N-DEO), which is active and contributes to the dry mouth. Transdermal delivery bypasses this presystemic metabolism and reduces the plasma level of N-DEO.
The approval of oxybutynin gel was based on a single randomized, double-blind, placebo-controlled, 12-week study in subjects (mainly Caucasian women) with overactive bladder and symptoms of urge incontinence, urgency, and frequency (n = 789).1,2 Oxybutynin gel reduced the daily number of incontinence episodes from a median of 4.7 to 1 compared to 4.7 to 1.7 for placebo (P < 0.001). Daily urinary frequency was reduced from a median of 11.7 to 9.3 vs 11.3 to 9.7 (P = 0.0017). Voided urinary volume was increased by 11.5 mL vs no change for placebo (P = 0.0018). Dry mouth was the most common adverse event (6.9% vs 2.8% for placebo). Discontinuation rates from the clinical trial due to adverse events were the same for each group at 1.8%.
Oxybutynin gel is the latest addition to the long list of drugs for overactive bladder. While there are no comparative trials with other formulations of oxybutynin or other antimuscarinics, its efficacy appears to be similar to that of other formulations and drugs.4
1. Gelnique Product Information. Corona, CA: Watson Pharmaceuticals, Inc.; January 2009.
2. Staskin DR, et al. Efficacy and safety of oxybutynin chloride topical gel for overactive bladder: A randomized, double-blind, placebo controlled, multicenter study. J Urol 2009;181:1764-72.
3. Oxytrol Transdermal System Product Information. Corona, CA: Watson Pharmaceuticals, Inc.; May 2006.
4. Chapple CR, et al. The effects of antimuscarinic treatments in overactive bladder: An update of a systematic review and meta-analysis. Eur Urol 2008;54:543-562.