Urinary incontinence is the involuntary leakage of urine. Structural abnormalities and muscle and nerve disorders commonly cause bladder control problems. There are four types of urinary incontinence: stress, urge, overflow and functional incontinence. Some people have a combination of these types. Urge incontinence and overflow incontinence are the two types of this disorder that are most likely to improve with medications.
Anticholinergic Drugs
Overactive bladder is a disruptive condition caused by frequent, ill-timed contractions of the detrusor muscle of the urinary bladder. It is normally in a relaxed state allowing the bladder to fill. Contraction of the detrusor muscle occurs when the bladder is full and ready to be emptied. Detrusor contractions coincide with the urge to urinate.
With overactive bladder, the detrusor muscle contracts forcefully and frequently. This causes symptoms including increased urinary frequency, needing to get up to urinate at night, and sudden irrepressible urges to urinate. This last symptom may cause urge incontinence--inability to resist the urge to urinate long enough to get to the bathroom resulting in accidental loss of urine. The Agency for Healthcare Research and Quality noted in a 2009 evidence report that 10 percent to 15 percent of American women have overactive bladder. Five percent to 10 percent experience urinary urge incontinence at least once monthly as a result of overactive bladder.
Anticholinergic medications, also called urinary antispasmotics, decrease detrusor muscle contractions providing relief from symptoms of overactive bladder including urge incontinence events. Drugs in this group of medications include darifenacin, fesoterodine, oxybutynin, solifenacin, tolterodine and trospium. Anticholinergics may be useful for treating other forms of urinary incontinence including neurogenic bladder and reflex neurogenic bladder.
Alpha Blockers
According to the National Institute of Diabetes and Digestive and Kidney Diseases, approximately 17 percent of men age 60 and older are affected by urinary incontinence. Many cases involve overflow incontinence caused by benign prostatic hyperplasia (BPH). BPH obstructs urine outflow from the bladder causing incomplete bladder emptying. The bladder is nearly always full as little urine passes with each attempt to urinate. Urine dribbles involuntarily between urination attempts. This is known as overflow incontinence.
Alpha-adrenergic blockers including tamsulosin, alfuzosin, terazosin and doxazosin inhibit smooth muscle contraction in blood vessels and the prostate. Tamsulosin is more specific to prostatic smooth muscle than are the other medications. By causing smooth muscle relaxation, these drugs facilitate increased urinary outflow from the bladder, thereby decreasing overflow incontinence.
Antiandrogen Drugs
Finasteride and dutasteride are used in men with BPH to inhibit the production of the male hormone dihydrotestosterone (DHT). DHT is the primary hormone responsible for prostate enlargement. By reducing the circulating level of DHT, these drugs may cause shrinkage of the prostate. As the prostate shrinks, urine outflow improves and overflow incontinence is reduced. Finasteride and dutasteride are sometimes used in combination with one of the alpha-adrenergic blockers.
