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CLINICAL APPLICATION NOTES

Introduction to Urodynamics II: Clinical Indications and Preparation

Side Effects of Medications

Any substance that affects the sympathetic alpha and beta receptors or parasympathetic cholinergic receptors will have a potential impact on the urinary tract. There is a veritable wealth of prescription and over-the-counter drugs available that by design, or as a side effect, affect the neuroreceptors in the lower urinary tract. These include cold and allergy, cardiac, blood pressure and respiratory medications, appetite suppressants, narcotics, muscle relaxants and sedatives.

Patients should not discontinue medications specifically to undergo urodynamic testing. The purpose of urodynamics is to reproduce and identify the cause of the patient’ symptoms and if the symptoms occur while taking a medicine, it should be continued.

The following table contains some examples of prescription and over-the-counter medications and the affect they have on the lower urinary tract. The lists of medications are not intended to be all-inclusive, but rather to give general examples of medications in the various classifications.

Patients taking…	Such as…	May complain of…
Sympathetic alpha blockers	Antihypertensives such as Cardura, Hytrin, Minipress, Minizide, Esimil…	Incontinence. The inhibited alpha receptors in the bladder neck cannot maintain a strong contraction and keep the bladder neck closed during storage.
Sympathetic beta blockers	Antihypertensives such as Blocadren, Corzide, Inderal, Lopressor, Normodyne, Toprol, Tenormin, Zebeta, Ziac…	Incontinence. The inhibited beta receptors in the detrusor muscle are kept in a state of availability for contraction, restricting the stretch of the bladder dome. May also present as urgency or diminished bladder capacity with overflow incontinence. Some beta blockers are a diuretic combo (Lopressor), which compounds the urge symptoms.
Parasympathetic blockers (anticholinergics)	Antihistamines, antipsychotics, antidepressants, anti-Parkinson’s, bronchodilators, calcium channel blockers, muscle relaxants and narcotics…	Retention. These substances sedate the CNS, decreasing the ability of the detrusor to contract. Patients on some drug combinations or that have an ineffective outlet may eventually demonstrate overflow incontinence; however, the underlying problem is retention. Previously asymptomatic patients discontinuing long term use of anticholinergics may experience sudden onset urgency because the anticholinergic effect had been previously masking the symptom.
Sympathetic beta agonists (stimulants)	Isuprel and the bronchodilators Ventolin, Proventil, Serevent, Tornalate, Maxair…	Retention. Pharmacologic stimulation of the beta receptors in the bladder dome put it in a state to resist a voiding contraction. Remember, when sympathetic receptors are stimulated, the beta controlled detrusor muscle RELAXES and the STRETCH capacity of the bladder dome is increased.
Sympathetic alpha agonists (stimulants)	Aldomet, Catapres, Aldoril, decongestants, amphetamines, epinephrine, ephedrine, methamphetamine, phenylephrine, pseudoephedrine	Retention. Drugs given for the central adrenergic blockage effect cause alpha stimulation of the bladder neck and can lead to retention. Some patients may present with a complaint of incontinence that turns out to be overflow incontinence due to long term retention.

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Intro to Urodynamics TOC

Lower Urinary Tract Anatomy and Physiology

Clinical Indications and Preparation

Urodynamic Procedures