Mirabegron is Not Indicated for Primary Nocturnal Enuresis
Mirabegron should not be used for primary nocturnal enuresis in a 27-year-old woman, as it is specifically indicated only for overactive bladder syndrome, not for enuresis. The established treatments for adult primary nocturnal enuresis are desmopressin, enuresis alarms, and imipramine 1.
Why Mirabegron is Inappropriate
Mirabegron is a β3-adrenoceptor agonist approved exclusively for overactive bladder symptoms (urgency, frequency, urge incontinence), not for nocturnal enuresis 2, 3.
The mechanism of action—bladder relaxation during filling and increased bladder capacity—addresses daytime storage symptoms rather than the pathophysiology of primary nocturnal enuresis, which involves nocturnal polyuria, arousal dysfunction, and/or nocturnal detrusor overactivity 2, 4.
No guidelines or research evidence supports mirabegron use for primary nocturnal enuresis 5, 2.
Appropriate Treatment Approach for Adult Primary Nocturnal Enuresis
First-Line Therapy: Desmopressin
Desmopressin 20-40 mcg nightly is the initial pharmacotherapy of choice, achieving continence in 66% of adult patients with primary nocturnal enuresis 1.
However, only 7% maintain continence after discontinuation, indicating most patients require ongoing therapy 1.
Second-Line Therapy: Enuresis Alarm
For patients who fail desmopressin or relapse after discontinuation, an enuresis alarm for 6 months should be initiated 1.
Enuresis alarms achieved continence in 33% of patients who were non-responsive to desmopressin, with better long-term cure rates off medication 1.
Third-Line Therapy: Imipramine
Imipramine 50 mg nightly can be considered for patients unresponsive to both desmopressin and enuresis alarms 1.
In refractory cases, imipramine achieved continence in 29% of patients who failed other modalities 1.
Overall Treatment Success
- Using this sequential approach, 83% of adult patients with primary nocturnal enuresis achieve continence: 38% remain dry off all medications and 45% maintain continence on ongoing pharmacotherapy 1.
Critical Distinction: Enuresis vs. Nocturia
Primary nocturnal enuresis (involuntary urination during sleep without waking) differs fundamentally from nocturia (waking to void intentionally) 5.
The evaluation for persistent nocturia in adults should screen for underlying SCREeN conditions (Sleep disorders, Cardiovascular disease, Renal disease, Endocrine disorders, Neurological conditions) 5.
If this patient actually has nocturia rather than true enuresis, a 72-hour bladder diary, assessment for nocturnal polyuria, and screening for medical comorbidities would be appropriate before considering any pharmacotherapy 5.