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Difficulty: MediumPelvic Floor Disorders and Urogynecology

An 82-year-old woman is brought to the clinic by her daughter due to a 3-month history of urinary incontinence. The patient experiences a sudden, overwhelming urge to urinate and frequently leaks urine before reaching the bathroom. She has a history of hypertension, Alzheimer dementia, and narrow-angle glaucoma. Her current medications include lisinopril, donepezil, and timolol ophthalmic drops. Vital signs are within normal limits. Abdominal examination reveals no suprapubic tenderness. Pelvic examination shows normal postmenopausal vaginal mucosa and no evidence of pelvic organ prolapse. A post-void residual volume is 40 mL. Urinalysis is negative for leukocyte esterase and nitrites. The patient has attempted timed voiding and pelvic floor muscle exercises for the past 6 weeks without significant improvement. Which of the following is the most appropriate pharmacotherapy for this patient's urinary symptoms?

  1. MirabegronAnswer
  2. B
    Oxybutynin
  3. C
    Bethanechol
  4. D
    Ciprofloxacin
  5. E
    Amitriptyline

Answer

Mirabegron
Mirabegron is a beta-3 adrenergic agonist that causes detrusor muscle relaxation, increasing bladder capacity and effectively treating urgency urinary incontinence. It is the most appropriate choice for this patient because she has Alzheimer dementia and narrow-angle glaucoma, both of which are major contraindications to antimuscarinic medications (the other first-line therapy for overactive bladder). Furthermore, antimuscarinics would directly antagonize the mechanism of donepezil, an acetylcholinesterase inhibitor used to manage her dementia.

Step-by-Step Solution

1
Identify the type of urinary incontinence based on the clinical presentation.
The patient has sudden, overwhelming urges to urinate with subsequent leakage, indicating urgency urinary incontinence (overactive bladder).
Determining the specific mechanism of incontinence (stress, urgency, or overflow) is required to guide targeted therapy.
2
Evaluate the patient's medical history for medication contraindications.
The patient has Alzheimer dementia (treated with donepezil, an acetylcholinesterase inhibitor) and narrow-angle glaucoma.
First-line pharmacotherapies for urgency incontinence often have systemic side effects that can dangerously exacerbate pre-existing conditions.
3
Select the appropriate medication class that avoids these contraindications.
A beta-3 adrenergic agonist (mirabegron) is selected over antimuscarinic medications.
Antimuscarinics would directly antagonize her dementia medication, worsen cognitive impairment, and are strictly contraindicated in narrow-angle glaucoma. Mirabegron relaxes the detrusor muscle without these anticholinergic adverse effects.

Key Concept

Management of urgency urinary incontinence in patients with contraindications to antimuscarinic therapy
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Topics

Pelvic Floor Disorders and Urogynecology

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