title: Mephedrone pharmacokinetics after intravenous and oral administration in rats: relation to pharmacodynamics.
abstract: BACKGROUND
  Mephedrone (4-methylmethcathinone) is a still poorly known drug of abuse, alternative to ecstasy or cocaine.
  
  
  OBJECTIVE
  The major aims were to investigate the pharmacokinetics and locomotor activity of mephedrone in rats and provide a pharmacokinetic/pharmacodynamic model.
  
  
  METHODS
  Mephedrone was administered to male Sprague-Dawley rats intravenously (10 mg/kg) and orally (30 and 60 mg/kg). Plasma concentrations and metabolites were characterized using LC/MS and LC-MS/MS fragmentation patterns. Locomotor activity was monitored for 180-240 min.
  
  
  RESULTS
  Mephedrone plasma concentrations after i.v. administration fit a two-compartment model (α = 10.23 h(-1), β = 1.86 h(-1)). After oral administration, peak mephedrone concentrations were achieved between 0.5 and 1 h and declined to undetectable levels at 9 h. The absolute bioavailability of mephedrone was about 10% and the percentage of mephedrone protein binding was 21.59 ± 3.67%. We have identified five phase I metabolites in rat blood after oral administration. The relationship between brain levels and free plasma concentration was 1.85 ± 0.08. Mephedrone induced a dose-dependent increase in locomotor activity, which lasted up to 2 h. The pharmacokinetic-pharmacodynamic model successfully describes the relationship between mephedrone plasma concentrations and its psychostimulant effect.
  
  
  CONCLUSIONS
  We suggest a very important first-pass effect for mephedrone after oral administration and an easy access to the central nervous system. The model described might be useful in the estimation and prediction of the onset, magnitude, and time course of mephedrone pharmacodynamics as well as to design new animal models of mephedrone addiction and toxicity.
authors: Department of Pharmacology and Therapeutic Chemistry (Pharmacology Section) and Institute of Biomedicine (IBUB), Faculty of Pharmacy, University of Barcelona, Av. Joan XXIII s/n, 08028, Barcelona, Spain.
authors: J
authors: J
authors: Martínez-Clemente
authors: R
authors: R
authors: López-Arnau
authors: M
authors: M
authors: Carbó
authors: D
authors: D
authors: Pubill
authors: J
authors: J
authors: Camarasa
authors: E
authors: E
authors: Escubedo
mesh_terms: D061605:Administration, Intravenous; D000284:Administration, Oral; D000818:Animals; D019540:Area Under Curve; D001682:Biological Availability; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D000697:Central Nervous System Stimulants / Q000008:administration & dosage* / Q000097:blood / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D008297:Male; D053858:Metabolic Networks and Pathways; D008694:Methamphetamine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism; D009043:Motor Activity / Q000187:drug effects*; D011485:Protein Binding / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D053719:Tandem Mass Spectrometry; D013997:Time Factors
chemical_list: D000697:Central Nervous System Stimulants; D008694:Methamphetamine; C548233:mephedrone
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