Attention-deficit/hyperactivity disorder: focus on pharmacologic management

Acute dose-related differential effects of methylphenidate on murine cystometric parameters

Purpose

Methylphenidate is the most widely used central nervous system stimulant in patients with attention deficit hyperactivity disorder. However, few studies have assessed its effects on voiding. Various doses of methylphenidate were investigated for their effects on cystometric parameters in conscious mice.

Methods

Ten male C57BL/6 mice, weighing between 20 and 23 g, were used in this study. To compare the acute drug responses before and after the oral medication was administered in the awake condition, we injected the solution through a catheter inserted into the stomach. Methylphenidate (1.25, 2.5, and 5 mg/kg) in an injection volume of 0.05 mL was administered.

Results

Four mice that received high doses of methylphenidate (2.5 and 5 mg/kg) showed no voiding contraction, with urine leakage. Six mice that received a low dose of methylphenidate (1.25 mg/kg) showed typical micturition cycles before and after administration. The micturition pressure decreased and bladder capacity increased without an increased residual volume after administration.

Conclusions

Methylphenidate has differential, dose-dependent effects on the function of the lower urinary tract, due to the dependent relationship between the brain and lower urinary tract. Especially at higher doses, this drug may interfere with normal micturition. Therefore, more detailed clinical or experimental studies are warranted in the future.

Attention deficit hyperactivity disorder: an update

Attention deficit hyperactivity disorder (ADHD) is the most common neurobehavioral disorder, affecting 3% to 5% of school-aged children. Of the 3 subtypes--predominantly inattentive, predominantly hyperactive/impulsive, and a combined subtype--the latter is the most commonly represented group, accounting for 50% to 70% of all ADHD individuals. Stimulant medication is the cornerstone of management; however, stimulants with a short duration of action have been problematic for some patients. Recent technologic advances in delivery systems offer many patients the option of a once-daily dosage.