Propantheline, 7.5 to 15 mg, may also work well at bedtime or on a tid schedule. Anticholinergic agents, used in the treatment of detrusor hyperactivity, reduce detrusor contractions, an effect that may worsen voiding problems in patients with detrusor hypoactivity or outlet obstruction. Detrusor hyporeflexia, producing incomplete bladder emptying and urinary frequency, may respond to a reduction in the dosage of an anticholinergic antiparkinsonian medication when that is the cause. It is therefore essential that PD patients with urinary dysfunction have urologic evaluations that include recording of bladder and sphincter pressure, sphincter electromyography, and fluoroscopy and that these tests be performed only by a urologist familiar with their interpretation. When cystometric studies reveal a hypoactive detrusor, benefit may be obtained from alpha adrenergic-blocking agents such as phenoxybenzamine or prazosin, which decrease tone in the bladder neck.
Intermittent catheterization is necessary with myogenic overdystension.
In men, the most common problem is achieving or sustaining an erection. Propranolol or other beta-adrenergic blockers, sometimes used to control postural or action tremor in patients with PD, are common offenders. Guanethidine, although less frequently used, is a potential offender, as are thiazide diuretics, anxiolytics, digoxin, and cimetidine. Tricyclics also have been implicated as a less frequent cause of impotence. Depressed patients should be treated with either tricyclic antidepressants or serotonin uptake inhibitors, despite the problems described above.