Methylphenidate's Effectiveness for Girls: Quicker but Briefer


TORONTO – Girls respond better to methylphenidate in the morning than boys do, but the drug's effectiveness also wanes more quickly in the afternoon for girls, Dr. Edmund Sonuga-Barke reported in a poster at the joint annual meeting of the American Academy of Child and Adolescent Psychiatry and the Canadian Academy of Child and Adolescent Psychiatry.

“Females may require additional assessments later in the treatment day to determine optimal dose for effectiveness,” wrote Dr. Sonuga-Barke of the developmental brain-behavior unit, University of Southampton, England.

Dr. Sonuga-Barke and his colleagues performed a subanalysis of the COMACS study, which compared two extended-release methylphenidate formulations (Concerta and Metadate-CD/Equasym-XL [MCD-EqXL]). The study included 184 children aged 6–12 years, who were randomized to placebo or either of the drugs.

When the gender differences were examined over 12 hours, researchers found that symptoms in both sexes reached a nadir about 1.5 hours after dosing and then slowly increased. Girls had better symptom control in the first 6 hours after dosing than did boys. But girls' symptoms increased more quickly over the 12 hours than boys' symptoms, and by 12 hours after dosing, they had higher symptom scores than did boys. COMACS concluded that MCD-EqXL reduced symptoms better in the morning (up to 6 hours after administration). Concerta produced superior control in the early evening.

Michele G. Sullivan

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