A randomized clinical study to evaluate the safety and efficacy of using the Beta 3 agonist drug (Mirabegron) combined with standard behavioral therapy in comparison to using the anticholinergic drug (Solifenacin) combined with behavioral therapy, for children with non-neurogenic voiding dysfunction refractory to behavioral therapy alone, using improvement of dysfunctional voiding symptom score as a primary measurement of efficacy.

The study aims to evaluate the beta 3 agonist drug (Mirabegron) as regard its safety and efficacy when used in children with non neurogenic voiding dysfunction, including children suffering from frequency, urgency, urgency incontinence and hesitancy who do not have neurological disease explaining these symptoms and who failed behavioral urotherapy.

The patients will be randomly allocated into two groups, one will receive standard behavioral therapy plus Mirabegron, the other will receive standard behavioral therapy plus the anticholinergic drug Solifenacin for three months. Patients will be assessed initially and after three months using:

• Medical and voiding history (bladder voiding diary, Dysfunctional voiding symptom score (DVSS) , Bristol Stool Scale)
• Dysfunctional voiding symptom score (DVSS) , Bristol Stool Scale
• Urine analysis and mid-stream urine culture.
• Uroflowmetry.
• Pelvic US and post-void residual urine (PVR).

Inclusion Criteria:

• Children with non-neurogenic voiding dysfunction predominantly filling phase dysfunctions or OAB, refractory to behavioral therapy as a primary monotherapy, with dysfunctional voiding symptom score of ≥6 for females and ≥9 for males, between the age of 5 & 18 years old.

Exclusion Criteria:

• Neurogenic or anatomical bladder problems.
• Patients with contraindications to Beta 3 agonists or anticholinergic drugs.