Drug-Induced Urinary Incontinence

Abstract and Introduction

Abstract

Urinary incontinence affects both men and women, and especially the elderly. The Agency for Health Care Policy and Research identified four types of urinary incontinence: stress, urge, mixed, and overflow. Pharmacologic agents including oral estrogens, alpha-blockers, sedative-hypnotics, antidepressants, antipsychotics, ACE inhibitors, loop diuretics, nonsteroidal anti-inflammatory drugs, and calcium channel blockers have been implicated to some degree in the onset or exacerbation of urinary incontinence. The pharmacist should consider urinary incontinence–inducing drugs when reviewing patient profiles.

Introduction

In healthy humans, voiding occurs at intervals several times a day, even though the kidneys produce urine continuously. This means that the bladder must store urine for several hours, a feature that requires the musculature of the bladder-outflow tract to contract to generate resistance. Disturbances of this storage function of the bladder lead to urinary incontinence. A number of factors may be responsible, including disease and adverse effects of medical treatment.^[1]

A number of medications have been proposed as possible causes of drug-induced urinary incontinence, including alpha₁-adrenoceptor antagonists, antipsychotics, benzodiazepines, antidepressants, and drugs used for hormone replacement therapy.^[1] Since drugs are frequently metabolized and excreted in the urine, the lower urinary tract is particularly vulnerable to adverse effects. Furthermore, carcinogens or inflammatory agents in the urine are in close proximity to the epithelium for prolonged periods when they are stored in the bladder. The drugs may cause stress incontinence, urge incontinence, or overflow incontinence.^[2]

This article discusses the different types of incontinence, their causes, and the possible mechanisms underlying incontinence resulting from medications.

Table 1. Types of Incontinence and Their Management
Type	Description	Treatment
Stress	Urine leakage associated with increased abdominal pressure from laughing, sneezing, coughing, climbing stairs, or other physical stressors on the abdominal cavity and, thus, the bladder; occurs largely in women	Pelvic-floor physiotherapy, surgery, anti-incontinence devices
Urge	Involuntary leakage accompanied or immediately preceded by urgency; characterized by involuntary detrusor contractions; affects both males and females	Changes in diet, behavioral modification, pelvic-floor exercises, medications, and new forms of surgical intervention
Mixed	Combination of stress and urge incontinence	Pelvic-floor physical therapy, anticholinergic agents, surgery
Overflow	Characterized by inability to expel urine; largely affects males	Catheterization regimen, diversion
Functional	Inability to hold urine for reasons other than neurourologic or lower urinary tract dysfunction	Treatment of underlying cause