No doubt that nocturnal enuresis is one of the commonest types of urinary incontinence which
affect children and always run in family . Nocturnal enuresis occurs at the age of 5 years
with leakage of urine involuntarily during sleep for two times or more per week in three
consecutive months not due to congenital or acquired cause. Nocturnal enuresis can be
categorized into primary or secondary depending on occurrence of bed dryness for more than
six months or not .
Nocturnal enuresis affects 15% to 20 % of children at five years old mainly due to delay of
bladder development and function more in male children with presence of family history in
half of cases but 15% of children with enuresis recover spontaneously every year .
limitation of fluid intake, urotherapy and bedwetting alarms are non-pharmacological
treatments of nocturnal enuresis while the mostly used drugs for treatment of NE are
tricyclic antidepressants(Imipramine®) an arginine vasopressin analog (Desmopressin®) and
anticholinergic drugs . Enuresis alarms have pitfalls which disgust a lot of patients as skin
irritation, sleep disturbances of other family members and failure to wake the child so that
about 30% of patients stop its usage .
Desmopressin is approved as a first-line drug therapy for nocturnal enuresis , but a lot of
series declared that monotherapy with desmopressin has little efficacy in treating patients
which have bladder storage dysfunction furthermore, high recurrence rate after treatment
cessation .
The International Children's Continence Society (ICCS) recommended combination therapy for
treatment of primary nocturnal enuresis after failure of first line therapy with desmopressin
or enuresis alarms . As regard anticholinergic drugs, oxybutynin was firstly prescribed then
tolterodine with less side effects and lately solifenacin . Cognitive impairment as a
neurological side effect was authenticated for oxybutynin and other side effects (e.g.
headache, dry mouth, behavior change, flushed cheeks, constipation, and blurred vision) were
unbearable to many children and impulsed them to stop treatment early .
Mirabegron, a b3-adrenoceptor (b3-AR) agonist was the answer to the question about a drug
that can relax detrusor muscle and increasing bladder capacity without the limitations of
anti-cholinergic drugs. Mirabegron is the first b3-AR agonist to be prescribed clinically for
OAB symptoms in adults and showed promising outcomes . while it is not licensed to be used in
children with overactive bladder, some early reports declared its efficacy and tolerability
in children .
So investigators will study the efficacy and safety of mirabegron in treatment of primary
nocturnal enuresis