By: Bethsy Jacob, PharmD Candidate 2014
On January 18, 2013, the U.S. Food and Drug Administration (FDA) announced a new approval for Botox, generically known as OnabotulinumtoxinA. Patients diagnosed with urinary incontinence due to an overactive bladder can be prescribed Botox, if they are unable to take or are unresponsive to anticholinergic medications. This new indication is supported by two clinical trials of 1,105 patients with symptoms of overactive bladder, where patients randomly received injections of 100 units of Botox or placebo. After 12 weeks, those treated with Botox experienced urinary incontinence an average of 1.6 to 1.9 times less per day and also needed to urinate on average 1.0 to 1.7 times less per day than the placebo group.1
Currently, anticholinergics are the standard drug class used to treat overactive bladder and urge urinary incontinence. Urinary incontinence (UI) can be classified based on etiology into urge urinary incontinence (UUI), stress urinary incontinence (SUI), mixed UI, overflow UI, and functional UI.2 UUI is due to over stimulation of the bladder, resulting in increased urinary frequency and urgency. Possible symptoms of urinary incontinence related to bladder overactivity are increased urinary frequency (>8 micturitions per day), urgency with or without urge incontinence, nocturia (>1 micurition per night) and enureseis.3 Inhibition of M3 receptors in the bladder is the primary target of the antimuscarinic agents oxybutynin, tolterodine, solifenacin, darifenacin, and trospium.2 However, with these drugs is the typical adverse effect profile of antimusicarinics, such as dry mouth, constipation, confusion, and visual impairment. Oxybutynin remains the drug of choice and the gold standard against which other drugs are compared.3
A clinical trial published in October 2012 in the New England Journal of Medicine compared anticholinergic therapy to OnabotulinumtoxinA to treat urgency urinary incontinence. The study included only women and looked for reductions in episodes of UUI over 6 months, improved quality of life, and side effects.4 Participants were randomized into two groups. One group was given oral solifenacin at a starting dose of 5 mg daily with an initial option of dose escalation followed by an option to switch to trospium XR, in addition to a placebo single injection. In the second group, participants were given a single injection of 100 U of OnabotulinumtoxinA along with an oral placebo regimen. The authors found no significant difference between anticholinergic drugs and OnabotulinumtoxinA in reducing the frequency of episodes of urgency incontinence or improving quality of life. What distinguished each therapy was the regimen, the route of administration, and the adverse effect profile. Anticholinergic medications resulted in more occurrences of dry mouth whereas OnabotulinumtoxinA resulted in higher risks of intermittent catheterization and urinary tract infections.4
For overactive bladder, the recommended dose is 100 Units of Botox, which is also the maximum recommended dose. Prophylactic treatment for urinary tract infection is also important. Antibiotics, other than aminoglycosides, should be administered 1 – 3 days pre-treatment, on the day of treatment, and 1 – 3 days post-treatment to reduce this risk.5
In conclusion, prescribers and pharmacists now have an alternative they can offer or recommend to patients who are unresponsive to anticholinergic therapy, intolerant of anticholinergic side effects, or have difficulty adhering to a daily regimen. Adherence may become a problem for those taking daily anticholinergics. Of course, prescribers should also consider the cost of both treatment options when choosing what is optimal for the patient.
- Yao S. FDA approves Botox to treat overactive bladder. U.S. Food and Drug Administration. January 18, 2013. Available at http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm336101.htm
- Canales AE, Nixon-Lewis BD. Chapter 32. Urinary Incontinence. In: Wofford MR, Posey LM, Linn WD, O’Keefe ME, eds. Pharmacotherapy in Primary Care. New York: McGraw-Hill; 2009. http://www.accesspharmacy.com/content.aspx?aID=3603757. Accessed January 22, 2013.
- Rovner E, Wyman J, Lackner T, Guay D.Urinary Incontinence, In: In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 7th ed. New York, NY: McGraw-Hill; 2008:1399, 1413
- Visco AG, Brubaker L, Richter HE, et al; Anticholinergic therapy vs. onabotulinumtoxina for urgency urinary incontinence. N Engl J Med. 2012 Nov 8;367(19):1803-13. doi: 10.1056/NEJMoa1208872. Epub 2012 Oct 4. PubMed PMID: 23036134; PubMed Central PMCID: PMC3543828.
- Botox [package insert]. Allergan Pharmaceuticals, Inc., Irvine, CA; January 2013. http://www.allergan.com/assets/pdf/botox_pi.pdf. Accessed January 29, 2013.