Differential influences of ethanol on early exposure to racemic methylphenidate compared with dexmethylphenidate in humans.
نویسندگان
چکیده
Enantioselective hydrolysis of oral racemic methylphenidate (dl-MPH) by carboxylesterase 1 (CES1) limits the absolute bioavailability of the pharmacologically active d-MPH isomer to approximately 30% and that of the inactive l-MPH to only 1-2%. Coadministration of dl-MPH with ethanol results in elevated d-MPH plasma concentrations accompanied by CES1-mediated enantioselective transesterification of l-MPH to l-ethylphenidate (EPH). The present study tested the hypothesis that administration of the pure isomer dexmethylphenidate (d-MPH) will overcome the influence of ethanol on d-MPH absorption by eliminating competitive CES1-mediated presystemic metabolism of l-MPH to l-EPH. Twenty-four healthy volunteers received dl-MPH (0.3 mg/kg) or d-MPH (0.15 mg/kg), with or without ethanol (0.6 g/kg). During the absorption phase of dl-MPH, concomitant ethanol significantly elevated d-MPH plasma concentrations (44-99%; P < 0.005). Furthermore, immediately following the ethanol drink the subjective effects of "high," "good," "like," "stimulated," and overall "effect" were significantly potentiated (P ≤ 0.01). Plasma l-EPH concentrations exceeded those of l-MPH. Ethanol combined with pure d-MPH did not elevate plasma d-MPH concentrations during the absorption phase, and the ethanol-induced potentiation of subjective effects was delayed relative to dl-MPH-ethanol. These findings are consistent with l-MPH competitively inhibiting presystemic CES1 metabolism of d-MPH. Ethanol increased the d-MPH area under the curve (AUC)(0-inf) by 21% following dl-MPH (P < 0.001) and 14% for d-MPH (P = 0.001). In men receiving d-MPH-ethanol, the d-MPH absorption partial AUC(0.5-2 hours) was 2.1 times greater and the time to maximum concentration (T(max)) occurred 1.1 hours earlier than in women, consistent with an increased rate of d-MPH absorption reducing hepatic extraction. More rapid absorption of d-MPH carries implications for increased abuse liability.
منابع مشابه
Methylphenidate and dexmethylphenidate formulations for children with attention-deficit/hyperactivity disorder.
PURPOSE Current literature on the safety and efficacy of various intermediate- and long-acting preparations of methylphenidate and dexmethylphenidate for pediatric attention-deficit/hyperactivity disorder (ADHD) is reviewed. SUMMARY The efficacy of methylphenidate in controlling ADHD symptoms is firmly established. Given the drug's relatively short half-life in pediatric patients (about 2.5 h...
متن کاملThe Safety and Efficacy of Methylphenidate and Dexmethylphenidate in Adults with Attention Deficit/Hyperactivity Disorder
OBJECTIVE To review the literature on the safety and efficacy of methylphenidate, OROS-methylphenidate, methylphenidate ER, and dexmethylphenidate in adults with Attention-Deficit/Hyperactivity Disorder (ADHD). To analyze the effects of different doses of methylphenidate, it's various formulations, and methylphenidate on efficacy and safety in this population. DATA SOURCES Literature retrieva...
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The postulate that twice the mg/kg dose of dl-methylphenidate (dl-MPH) would result in equal exposure to d-MPH when compared to half that mg/kg dose of the chiral switch product dexmethylphenidate (d-MPH) was tested. Using a randomized, crossover study design, 12 men and 12 women received either immediate-release (IR) dl-MPH (0.3 mg/kg) or IR d-MPH (0.15 mg/kg). Relative bioavailability compari...
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The postulate that twice the milligram/kilogram dose of dl-methylphenidate (dl-MPH) would result in equal exposure to d-MPH compared with half that milligram/kilogram dose of the chiral switch product dexmethylphenidate (d-MPH) was tested. Using a randomized, crossover study design, 12 men and 12 women received either immediate-release (IR) dl-MPH (0.3 mg/kg) or IR d-MPH (0.15 mg/kg). Relative ...
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Attention-deficit/hyperactivity disorder (ADHD) affects a large number of children. For decades, the stimulants have been the mainstay of pharmacological treatment for ADHD. Dexmethylphenidate (d-MPH), the d-isomer of the traditional racemic mixtures of d,l-threo-(R,R)-MPH, was recently introduced as another potential option in the stimulant class of medications. This paper reviews and summariz...
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ورودعنوان ژورنال:
- Drug metabolism and disposition: the biological fate of chemicals
دوره 41 1 شماره
صفحات -
تاریخ انتشار 2013