Correlation Between Methylphenidate and Ritalinic Acid Concentrations in Oral Fluid and Plasma
- 1 April 2010
- journal article
- Published by Oxford University Press (OUP) in Clinical Chemistry
- Vol. 56 (4), 585-592
- https://doi.org/10.1373/clinchem.2009.138396
Abstract
Background: We studied the excretion profile of methylphenidate (MPH) and its metabolite ritalinic acid (RA) in oral fluid and plasma, the oral fluid-to-plasma (OF/P) drug ratio, and the variations of oral fluid pH after drug administration. Methods: We analyzed oral fluid and plasma samples, obtained from 8 healthy volunteers after ingestion of a single dose of 20 mg fast-release or extended-release MPH, for MPH and RA by LC-MS. We estimated the apparent pharmacokinetic parameters of MPH in plasma and oral fluid and calculated the OF/P ratio for each time interval. Results: MPH and RA were detected in oral fluid. Whereas parent drug concentrations in oral fluid were an order of magnitude higher than those in plasma, the opposite was observed for RA. Oral fluid concentrations of MPH ranged between 0.5 and 466.7 μg/L and peaked at 0.5 h after administration of the fast-release formulation; they ranged between 0.7 and 89.5 μg/L and peaked at 2 h after administration of the extended-release formulation. Both formulations presented bimodal time-course curves for the OF/P ratio, ranging between 1.8 and 242.1 for the fast-release formulation and between 2.6 and 27.0 for extended-release. Oral fluid pH did not appear to be modified by the administration of the drug, and its influence on OF/P ratio did not affect the correlation of MPH between the 2 body fluids. Conclusions: The results obtained support the measurement of MPH in oral fluid as an alternative to plasma if the extended-release formulation is used.Keywords
This publication has 16 references indexed in Scilit:
- Pharmacokinetics and Therapeutic Drug Monitoring of Psychotropic Drugs in PediatricsTherapeutic Drug Monitoring, 2009
- An Update on Central Nervous System Stimulant Formulations in Children and Adolescents with Attention-Deficit/Hyperactivity DisorderAnnals of Pharmacotherapy, 2009
- Safety of therapeutic methylphenidate in adults: a systematic review of the evidenceJournal of Psychopharmacology, 2008
- The role of alternative specimens in toxicological analysisBiomedical Chromatography, 2008
- Characteristics and Motives of College Students Who Engage in Nonmedical Use of MethylphenidateThe American Journal on Addictions, 2008
- Review: Pharmacokinetics of illicit drugs in oral fluidForensic Science International, 2005
- An overview of the use of urine, hair, sweat and saliva to detect drug useDrug and Alcohol Review, 2004
- Clinical Pharmacokinetics of Amfetamine and Related SubstancesClinical Pharmacokinetics, 2004
- Single-Dose Pharmacokinetics of Methylphenidate in CYP2D6 Extensive and Poor MetabolizersJournal of Clinical Psychopharmacology, 2000
- Pharmacokinetics and Clinical Effectiveness of MethylphenidateClinical Pharmacokinetics, 1999