Low versus standard dose mCPP challenge in obsessive-compulsive patients

Neuropsychopharmacology. 2001 Jan;24(1):31-6. doi: 10.1016/S0893-133X(00)00178-0.


In several reports, the acute oral administration of the partial serotonergic agonist meta-chlorophenylpiperazine (mCPP) in dose of 0. 5 mg/kg induced a significant worsening of obsessive-compulsive (OC) symptoms in a number of patients. The aim of our study was to test the 0.25 mg/kg mCPP dose, which was hypothesized to be more specific for OC symptoms and was until now tested only on healthy subjects. In a double-blind, controlled crossover study, 12 OC patients participated on three test days, receiving one of the following on each day: oral 0.5 mg/kg mCPP (standard dose), 0.25 mg/kg mCPP (low dose), or placebo. Behavioral ratings were obtained by means of Visual Analogue Scale (VAS) ratings. The low dose mCPP induced a significant worsening of OC symptoms in 50% (6/12) of the patients, whereas 8.3% (1/12) of the patients showed a worsening after the standard dose. On the other hand, only the standard dose mCPP induced a worsening, although not statistically significant, of anxiety ratings. Our data show that the 0.25 mg/kg dose mCPP induces a specific response in OC symptoms, with little anxiogenic effect. To confirm these preliminary data, future studies will be needed on larger samples and with more sensitive rating scales.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Affect / drug effects
  • Anxiety / drug therapy
  • Behavior / drug effects
  • Behavior / physiology
  • Cross-Over Studies
  • Disease Progression
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Female
  • Humans
  • Male
  • Obsessive-Compulsive Disorder / drug therapy*
  • Piperazines / administration & dosage*
  • Piperazines / adverse effects*
  • Serotonin / metabolism
  • Serotonin Receptor Agonists / administration & dosage*
  • Serotonin Receptor Agonists / adverse effects*
  • Treatment Outcome


  • Piperazines
  • Serotonin Receptor Agonists
  • Serotonin
  • 1-(3-chlorophenyl)piperazine