Which medications in the drug class Antispasmodic Drugs are used in the treatment of Urinary Incontinence?

Updated: Jan 22, 2021
  • Author: Sandip P Vasavada, MD; Chief Editor: Edward David Kim, MD, FACS  more...
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Antispasmodic Drugs

These agents relax the smooth muscles of the urinary bladder. By exerting a direct spasmolytic action on the smooth muscle of the bladder, these medications have been reported to increase bladder capacity and effectively decrease or eliminate urge incontinence.

The adverse effect profile of antispasmodic drugs is similar to that of anticholinergic agents. These drugs may impair the ability to perform activities requiring mental alertness and physical coordination. Drinking alcohol and using sedatives in combination with these antispasmodic drugs is contraindicated.

In 2001, Appell et al reported the results of the Overactive Bladder: Judging Effective Control and Treatment (OBJECT) trial. This was a large double-blind, multicenter, prospective, randomized controlled study that compared the efficacy and tolerability of oxybutynin (Ditropan XL) (n = 160) with that of tolterodine (Detrol) (n = 170) in men and women with symptoms of overactive bladder. The study concluded that oxybutynin 10 mg was statistically superior to tolterodine 2 mg bid in terms of efficacy. However, both drugs had similar adverse-effect profiles. [68]

Oxybutynin chloride (Ditropan IR, Ditropan XL, Gelnique)

Both the immediate-release and the extended-release forms of oxybutynin have both an anticholinergic and a direct smooth muscle relaxant effect on the urinary bladder. In addition, oxybutynin provides a local anesthetic effect on the irritable bladder.

The human detrusor has M2 and M3 muscarinic receptors. The M3 receptor mediates contractile response of human detrusor. Oxybutynin has greater affinity for the M3 receptor. Urodynamic studies have shown oxybutynin increases bladder size, decreases frequency of symptoms, and delays initial desire to void.

Ditropan XL has an innovative drug delivery system: oral osmotic delivery system (OROS). The Ditropan XL tablet has a bilayer core that contains a drug layer and a "push layer" that contains osmotic components. The outer tablet is composed of a semipermeable membrane with a precision laser-drilled hole that allows the drug to be released at a constant rate.

When the drug is ingested, the aqueous environment in the gastrointestinal tract causes water to enter the tablet via semipermeable membrane at a constant rate. The introduction of water inside the tablet liquefies drug and causes the push layer to swell osmotically. As the push layer swells, it forces the drug suspension out the hole at a constant rate over a 24-h period.

Ditropan XL achieves steady-state levels over a 24-h period. It avoids first pass metabolism in liver and upper gastrointestinal tract to avoid cytochrome P450 enzymes. It has excellent efficacy, with minimal adverse effects.

Flavoxate (Urispas)

Flavoxate is used for symptomatic relief of dysuria, urgency, nocturia, and incontinence, as may occur in cystitis, prostatitis, urethritis, and urethrocystitis/urethrotrigonitis. It exerts a direct relaxant effect on smooth muscles via phosphodiesterase inhibition. It provides relief for a variety of smooth muscle spasms.

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