Methylphenidate and impulsivity: A comparison of effects of methylphenidate enantiomers on delay discounting in rats

Jonathan M. Slezak, George Ricaurte, Ronald J. Tallarida, Jonathan L. Katz

Research output: Contribution to journalArticle

Abstract

Rationale: Current formulations of methylphenidate (MPH) used in treatment of attention-deficit/hyperactivity disorder (ADHD) result in significantly different bioavailability of MPH enantiomers. Daytrana®, a dl-MPH transdermal patch system, produces higher levels of l-MPH than when dl-MPH is administered orally (e.g., Ritalin®). One potential limitation of increased l-MPH was indicated in a preclinical study showing l-MPH may attenuate effects of d-MPH. Objectives: The objective of the study was to investigate the interactive effects of MPH enantiomers by (1) assessing drug effects via a preclinical model of "impulsivity" and (2) performing a quantitative dose equivalence analysis of MPH enantiomer interactions. Methods: Sprague-Dawley rats were trained to emit either of two responses, one producing an immediate food pellet, the other producing four pellets delivered at increasing delays (0, 8, and 32 s). The percent selection of the larger food amount was graphed as a function of delay with the area under the curve (AUC) assessed. Increases in AUC are consistent with decreases in " impulsivity" (i.e., selection of the smaller, immediate over the larger, delayed reinforcer). Results: Systemic administration of dl-MPH and d-MPH dose-dependently increased AUC, while l-MPH, morphine, and pentobarbital did not alter AUC. An analysis based upon dose equivalence indicated that dl-MPH produced additive effects that were not different from that predicted from effects of the enantiomers administered alone. Conclusions: The present results indicate pharmacologically selective effects in that only drugs prescribed for the treatment of ADHD symptoms decreased a measure of "impulsivity" and that l-MPH likely does not attenuate or enhance the effects of d-MPH in the current delay-discounting task.

Original languageEnglish (US)
Pages (from-to)191-198
Number of pages8
JournalPsychopharmacology
Volume231
Issue number1
DOIs
StatePublished - Jan 2014

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Methylphenidate
Impulsive Behavior
Area Under Curve
Delay Discounting
Attention Deficit Disorder with Hyperactivity
Transdermal Patch
Food Preferences

Keywords

  • ADHD
  • Delay discounting
  • Dose equivalence
  • Enantiomers
  • Impulsivity
  • Methylphenidate
  • Psychostimulants
  • Rat

ASJC Scopus subject areas

  • Pharmacology

Cite this

Methylphenidate and impulsivity : A comparison of effects of methylphenidate enantiomers on delay discounting in rats. / Slezak, Jonathan M.; Ricaurte, George; Tallarida, Ronald J.; Katz, Jonathan L.

In: Psychopharmacology, Vol. 231, No. 1, 01.2014, p. 191-198.

Research output: Contribution to journalArticle

Slezak, Jonathan M. ; Ricaurte, George ; Tallarida, Ronald J. ; Katz, Jonathan L. / Methylphenidate and impulsivity : A comparison of effects of methylphenidate enantiomers on delay discounting in rats. In: Psychopharmacology. 2014 ; Vol. 231, No. 1. pp. 191-198.
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