title: In vitro activity of commercial valerian root extracts against human cytochrome P450 3A4.
abstract: OBJECTIVE
  Valerian root ( Valeriana officinalis L.) has been used since antiquity as a medicinal herb. Recent studies have found that certain herbal products used concomitantly with conventional therapeutic products can markedly affect drug disposition.
  
  
  METHODS
  The in vitro effect of aliquots from 14 commercially available single-entity and blended products containing valerian root on cytochrome P450 CYP3A4-mediated metabolism and P-glycoprotein transport has been determined with aqueous, ethanol and acetonitrile extracts.
  
  
  RESULTS
  Hydroxyvalerenic acid, acetoxyvalerenic acid and valerenic acid content was analyzed and wide variation was found between samples and compared to the concentrations noted on the product labels. Valerian extracts from the products tested also exhibited a marked capacity to inhibit cytochrome P450 3A4-mediated metabolism and P-glycoprotein transport based upon the ATPase assay.
  
  
  CONCLUSIONS
  There is wide variation between commercially available samples of valerian root. The findings from this study suggest that valerian root may have an initial inhibitory effect when taken with therapeutic products. Further work is warranted to determine whether valerian root can affect other CYP450 isozymes and how the results of this in vitro investigation can be extrapolated to in vivo situations.
authors.affiliation: Office of Science, Therapeutic Products Directorate, Health Canada, Ottawa, Ontario, Canada.
authors.forename: Tania
authors.initials: T
authors.lastname: Lefebvre
authors.forename: Brian C
authors.initials: BC
authors.lastname: Foster
authors.forename: Cathy E
authors.initials: CE
authors.lastname: Drouin
authors.forename: Anthony
authors.initials: A
authors.lastname: Krantis
authors.forename: John F
authors.initials: JF
authors.lastname: Livesey
authors.forename: Scott A
authors.initials: SA
authors.lastname: Jordan
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors; D002264:Carboxylic Acids / Q000032:analysis; D051544:Cytochrome P-450 CYP3A; D065607:Cytochrome P-450 Enzyme Inhibitors; D004304:Dosage Forms; D006801:Humans; D066298:In Vitro Techniques; D007192:Indenes / Q000032:analysis; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D018517:Plant Roots / Q000737:chemistry; D012717:Sesquiterpenes / Q000032:analysis; D014632:Valerian / Q000737:chemistry
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D002264:Carboxylic Acids; D065607:Cytochrome P-450 Enzyme Inhibitors; D004304:Dosage Forms; D007192:Indenes; D010936:Plant Extracts; D012717:Sesquiterpenes; C037133:valerenic acid; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human