Toviaz is one of the newer additions to the crowded market of drugs indicated for the management of urge incontinence. Toviaz, generic name fesoterodine, is available in an extended release form at doses of 4 mg and 8 mg, and is marketed by Prizer as an improvement over the generic options for urge incontinence by having less side effects of dry mouth, drowsiness and constipation. Toivaz was approved by the FDA for use in the U.S on Oct 31, 2008. Toviaz is otherwise closely related to tolterodine (DetrolToviaz is a pro-drug, that is metabolized after in the bloodstream into its active metabolite tolterodine.). In my experience with patients Toviaz does seem to be better tolerated than Detrol or Ditropan, the older generic options for urge incontinence therapy. The in-vogue term for what has been called urge incontinence is overactive bladder. This term is what you will likely hear on TV commercials or magazine ads for these drugs. The likely change in name seems primarily to expand the market to include not just those patients with incontinence, but to include those with urgency to void symptoms who do not leak or wet, and to be something more patients will be willing to discuss with their physician because it does not have the “incontinence” word that implies old-age or infirmity.
The newer branded competition to Toviaz is Vesicare, a viable alternative for many patients, although side effects, metabolism and effectiveness seem to be quite similar for the two drugs in patients that I’ve treated.
Toviaz is extensively metabolized in the liver using the CYP 450 pathway, specifically the CYP 3A4 pathway, and therefore numerous drug interactions are possible. Examples of medications using this pathway for metabolism where drug interactions can be anticipated include Biaxin, antifungal medications like ketoconazole, and cyclosporine. Grapefruit can increase the bioavailablity of Toviaz and should not be taken if you are using Toviaz. Vesicare is also a CYP 3A4 substrate and so has these same drug interaction issues also.
The generic option of a quite similar drug ditropan (generic name oxybutynin) is a fairly effective drug for use in urge incontinence, but its anti-cholinergic side effects are often limiting factors in patients tolerating its use. These side effects are typically dry mouth, drowsiness, dizziness, constipation and blurry vision. Toviaz shares these side effects but if after trying the generic and finding it either not helpful or not tolerated Toviaz is a reasonable option.
The typical cost out-of-pocket for Toviaz is about 170./ month (drugstore.com pricing) as compared to thegeneric oxybutynin listed at Costco for $7.18/ 100 tablets of the 5 mg dosage,so I usually try generic oxybutynin prior to considering Toviaz.
Update: On April 5, 2012 the FDA’s advisory panel recommended a new drug called mirabegron 50 mg for treatment of overactive bladder despite some lingering concerns that it may cause high blood pressure in some patients. Mirabegron is in a brand new class of drugs called beta 3 adrenoceptor agonists, and so should be a truly different addition to the drugs used to treat this difficult and common problem. Stay tuned and if mirabegron gets FDA approval I’ll post an update on this drug. For now Toviaz is the latest and possibly greatest we have for overactive bladder.