title: Determination of ephedra alkaloid and caffeine concentrations in dietary supplements and biological fluids.
abstract: Dietary supplements containing botanical forms of caffeine and ephedra alkaloids have been widely promoted and used in the U.S. for weight loss and athletic enhancement despite a lack of adequate research on the pharmacology of these botanical stimulants. In order to analyze dietary supplements and perform human pharmacokinetic studies, an analytical approach with good precision and accuracy was needed with sufficient sensitivity to detect very low levels of ephedra alkaloids. A liquid chromatography-atmospheric pressure chemical ionization (APCI) tandem mass spectrometry (LC-MS-MS) method was developed for quantitating the various ephedrine-group alkaloids found in dietary supplements that contain Ephedra species, and in plasma and urine of persons consuming these supplements. Using this method, low nanogram-per-milliliter concentrations of ephedrine, pseudoephedrine, norephedrine, norpseudoephedrine, methylephedrine, methylpseudoephedrine, and caffeine can be quantitated in a 12-min LC-MS-MS run.
authors.affiliation: University of California, San Francisco, Department of Medicine, Division of Clinical Pharmacology, San Francisco General Hospital, 1001 Potrero Avenue, Building 30, 3rd floor, San Francisco, California 94110, USA. peyton@itsa.ucsf.edu
authors.forename: Peyton
authors.initials: P
authors.lastname: Jacob
authors.forename: Christine A
authors.initials: CA
authors.lastname: Haller
authors.forename: Minjiang
authors.initials: M
authors.lastname: Duan
authors.forename: Lisa
authors.initials: L
authors.lastname: Yu
authors.forename: Margaret
authors.initials: M
authors.lastname: Peng
authors.forename: Neal L
authors.initials: NL
authors.lastname: Benowitz
mesh_terms: D000470:Alkaloids / Q000032:analysis*; D002110:Caffeine / Q000032:analysis*; D002853:Chromatography, Liquid / Q000379:methods; D019587:Dietary Supplements / Q000032:analysis* / Q000145:classification; D004365:Drugs, Chinese Herbal / Q000032:analysis*; D029790:Ephedra sinica / Q000737:chemistry; D004809:Ephedrine / Q000032:analysis* / Q000097:blood / Q000652:urine; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D028321:Plant Preparations / Q000737:chemistry; D015203:Reproducibility of Results; D014481:United States; D029789:Ephedra
chemical_list: D000470:Alkaloids; D004365:Drugs, Chinese Herbal; D028321:Plant Preparations; D002110:Caffeine; C099950:Ephedrae herba; D004809:Ephedrine