Combined low-dose antimuscarinics for refractory detrusor overactivity in children

Behavioral therapy and bowel management are the initial and mainstay treatments for overactive bladder (OAB). Antimuscarinic agents are initiated if these measures fail or symptoms are severe. This study reported the results of treatment with a high dosage of a single drug in children with refractory detrusor overactivity (DO). After the children maintained their previous antimuscarinic medication, a second antimuscarinic drug (trospium chloride) was added as a combination therapy.

Seventy-two children with DO were enrolled in this prospective study (Figure). They had persistent urgency and urgency urinary incontinence (UUI), even with behavioral bowel therapy, and used an optimized dosage of oxybutynine. All patients demonstrated DO at urodynamic study and started on oxybutynin and trospium chloride at the lowest weight-adjusted dose (10-20 mg/day for trospium chloride). A bladder diary was recorded for 3 days, and urodynamic studies were repeated at 3 and 6 months.

Sixteen children (22.2%) became dry. Thirty-three children (45.8%) attained a significant decrease in incontinence from an average of 5 to 1.3 episodes per day. A statistically significant increase of mean cystometeric bladder capacity (P = 0.006) was also observed at the 6-month follow-up. The overall success rate was 68%, since 23 children (32%) discontinued combined treatment due to persistent symptoms and/or intolerable side effects. A total of 41 children (57%) reported no side effects, 25 (34.7%) reported mild side effects, six (8.3%) reported moderate side effects, and two withdrew from the study due to their side effects.

The addition of low-dose trospium chloride to oxybutynine seemed to be an effective and safe treatment approach for children with DO who were refractory to high-dosage monotherapy. Different combinations with different antimuscarinics drugs could be evaluated in the future.