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- Title
Alprazolam as a probe for CYP3A using a single blood sample: pharmacokinetics of parent drug, and of a- and 4-hydroxy metabolites in healthy subjects.
- Authors
Wennerholm, Agneta; Allqvist, Annika; Svensson, Jan-Olof; Gustafsson, Lars; Mirghani, Rajaa; Bertilsson, Leif
- Abstract
Objectives: (1) To determine the pharmacokinetic parameters of alprazolam and its two metabolites in plasma from healthy volunteers; (2) to identify a suitable single time point to take a plasma sample for CYP3A phenotyping. Methods: Twelve healthy Swedish volunteers received a single oral dose of 1 mg alprazolam. Blood samples were collected before drug intake and frequently up to 72 h thereafter. A liquid-chromatography/mass-spectrometry (LC/MS) method was used for the quantification of alprazolam, and 4- and α-hydroxyalprazolam. Results: The interindividual variation in the area under the concentration-time curve (AUC) was two, three and fourfold for alprazolam, 4-hydroxyalprazolam and ahydroxyalprazolam, respectively. Plasma concentration ratios collected between 1 h and 48 h for both alprazolam/4-hydroxyalprazolam and alprazolam/α-hydroxyalprazolam correlated significantly to the corresponding AUC(0-∞) ratios. Conclusions: The metabolic ratios of alprazolam to respective metabolite in a single plasma sample at 3-24 h are suggested to reflect the alprazolam 4- and α-hydroxylation activities. In future, it will be important to study these activities in populations where CYP3A5, in addition to CYP3A4, is expressed at a high frequency and to clarify the relative importance of the two enzymatic pathways for in vivo clearance of alprazolam.
- Subjects
ALPRAZOLAM; TRANQUILIZING drugs; PHARMACOKINETICS; CHEMICAL kinetics; METABOLITES; CHEMICAL reactions
- Publication
European Journal of Clinical Pharmacology, 2005, Vol 61, Issue 2, p113
- ISSN
0031-6970
- Publication type
Article
- DOI
10.1007/s00228-004-0861-x