title: Acute tolerance to methylphenidate in the treatment of attention deficit hyperactivity disorder in children.
abstract: OBJECTIVE
  To evaluate the efficacy of several drug delivery patterns of methylphenidate and to determine whether acute tolerance develops to this widely used stimulant medication in the treatment of children with attention deficit hyperactivity disorder.
  
  
  METHODS
  Double-blind trials were conducted in a laboratory school setting in which multiple measures of efficacy were obtained frequently in the morning and afternoon across the school day. In study I, relative efficacy was determined for three dosing patterns of methylphenidate: a standard twice-daily profile, a flat profile, and an ascending profile. In study II, tolerance was assessed by comparison of three-times-a-day regimens in which the time of the middle dose varied.
  
  
  RESULTS
  In study I, the efficacy of the ascending treatment increased across the day, and in the afternoon it was equal to the efficacy of the twice-daily treatment, indicating that an initial bolus was not required for efficacy. The efficacy of the flat treatment declined across the day, and in the afternoon it was significantly less than in the twice-daily treatment, suggesting that tolerance may be developing. In study II, acute improvements in efficacy were reduced to the second of two closely spaced but not to two widely spaced bolus doses, suggesting that shortly after exposure to high concentrations, efficacy is reduced to given concentrations of methylphenidate. In a concentration-effect model, a tolerance term was needed to account for counterclockwise hysteresis.
  
  
  CONCLUSIONS
  Acute tolerance to methylphenidate appears to exist. This should be considered in the design of an optimal dosing regimen for the treatment of children with attention deficit hyperactivity disorder.
authors.affiliation: University of California Irvine, Child Development Center, 92612, USA.
authors.forename: J
authors.initials: J
authors.lastname: Swanson
authors.forename: S
authors.initials: S
authors.lastname: Gupta
authors.forename: D
authors.initials: D
authors.lastname: Guinta
authors.forename: D
authors.initials: D
authors.lastname: Flynn
authors.forename: D
authors.initials: D
authors.lastname: Agler
authors.forename: M
authors.initials: M
authors.lastname: Lerner
authors.forename: L
authors.initials: L
authors.lastname: Williams
authors.forename: I
authors.initials: I
authors.lastname: Shoulson
authors.forename: S
authors.initials: S
authors.lastname: Wigal
mesh_terms: D000704:Analysis of Variance; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy*; D000697:Central Nervous System Stimulants / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D002648:Child; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D008297:Male; D008774:Methylphenidate / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D000697:Central Nervous System Stimulants; D008774:Methylphenidate