Use of tolterodine in children with neurogenic detrusor overactivity: Relationship between dose and urodynamic response

Purpose: Three exploratory studies were conducted to investigate the pharmacokinetics (PK) and safety of tolterodine in children 1 month to 15 years old with neurogenic detrusor overactivity. We urodynamically evaluated the dose and concentration effects of tolterodine to establish safe and effective dosing regimens. Materials and Methods: Three open-label, dose escalating studies were conducted in children with stable neurological disease and detrusor overactivity. In studies 1 (patient aged 1 month to 4 years) and 2 (5 to 10 years) patients received 0.03, 0.06 and 0.12 mg/kg tolterodine solution day twice daily for 4 weeks each. In study 3 (patient age 11 to 15 years) patients received 2, 4 and 6 mg tolterodine extended-release capsules once daily for 4 weeks each. PK was assessed after 8 weeks, urodynamic assessments were conducted after each 4-week dosing period and 3-day micturition diaries were completed. Results: Patients in studies 1 (19) and 2 (15) showed some dose related increases in volume to first detrusor contraction and cystometric bladder capacity. In study 3 (11 patients) there were no obvious dose-response relationships. PK results from studies 1 and 2 suggest that there was no apparent effect of age (<= 10 y) on these parameters. In study 3 time of maximum observed serum concentration and apparent terminal half-life were delayed, which is consistent with the extended-release formulation. Tolterodine was well tolerated, and there was no apparent relationship between tolterodine dose and adverse events in any study. Conclusions: These results support the safety of age and body weight adjusted dosing regimens for further clinical evaluation of tolterodine in children with neurogenic detrusor overactivity.