Oxybutynin

Abstract

Oxybutynin possesses anticholinergic and spasmolytic properties, which together form the basis for its use as a therapeutic option in patients with overactive detrusor function--either idiopathic detrusor instability (DI) or detrusor hyperreflexia. Of the symptoms of detrusor overactivity, urge incontinence is often the most distressing to the patient. Urge incontinence and other subjective parameters (urinary frequency, urgency) improve in tandem with objective (cystometric) measures (maximum detrusor pressure during filling, volume at first desire to void, maximum bladder capacity) in ambulatory, including elderly, patients treated with oxybutynin. However, on the basis of results of limited investigations, the drug appears ineffective in elderly institutionalised individuals. Relative to other anticholinergic drugs, oxybutynin appears at least as effective as propantheline and similar in efficacy to propiverine in small trials, although these results are not definitive. Further investigation of intravesical oxybutynin may lead to this route becoming an option in patients with pre-existing catheters. Adverse effects--dry mouth, constipation, blurred vision--related to the anticholinergic activity of oxybutynin occur frequently and can be sufficiently troublesome to necessitate treatment discontinuation in up to 25% of patients, depending on the dosage. Increases in residual urine volume suggesting urinary retention (undesirable in patients with idiopathic DI), also can develop in some oxybutynin recipients. In summary, oxybutynin is one of the few drugs proven to be beneficial in some patients with overactive detrusor function. Despite the occurrence of unwanted anticholinergic effects in many patients, and apparent lack of efficacy in the elderly institutionalised population, oxybutynin should be considered for the drug of first choice in patients with detrusor overactivity, including the elderly ambulatory population, when pharmacological therapy is indicated.

Muscarinic Receptor Binding Characteristics in Rat Tissues after Oral Administration of Oxybutynin and Propiverine.

“…4,5) Also, a new drug delivery system for oxybutynin has been used clinically and found to be an effective dosage form. 6) Although there are many studies dealing with the pharmacological effects and in vitro receptor binding affinities of anticholinergic agents, 3,[7][8][9] very little in vivo data are available regarding the muscarinic receptor binding characteristics (extent and time-course) in tissues following systemic administration of anticholinergic agents. In general, the results of in vitro receptor binding studies of drugs may not necessarily guarantee in vivo pharmacological specificity, such as organ selectivity, because they do not take into account various pharmacokinetic (absorption, distribution and elimination) and pharmacodynamic factors.…”

“…[13][14][15] Thus, the aim of the present study was to characterize the muscarinic receptor binding in rat tissues, such as the bladder, after oral administration of oxybutynin and propiverine, the most commonly used anticholinergic agents for the treatment of patients with detrusor instability and detrusor hyperreflexia. 3.09 TBq/mmol) was purchased from Dupont-NEN Co., Ltd. (Boston, MA, U.S.A.). Oxybutynin hydrochloride (oxybutynin) and propiverine hydrochloride (propiverine) were generously donated by Meiji Milk Products Co., Ltd. (Odawara, Japan) and Taiho Pharmaceutical Co., Ltd. (Saitama, Japan), respectively.…”

Low–Dose Oxybutynin for the Treatment of Urge Incontinence: Good Efficacy and Few Side Effects

“…It has proven useful for the treatment of idiopathic as well as neurogenic detrusor instability, even in frail, elderly patients [4, 13]. However, the side effects of the regular dose of 5 mg three times daily are considerable.…”

Oxybutynin for the Treatment of Primary Hyperhidrosis: Current State of the Art

“…Wide interindividual variation in pharmacokinetic parameters is evident following the oral administration of oxybutynin [16,17,18]. …”