title: Influence of Ginkgo biloba extract on the pharmacodynamic effects and pharmacokinetic properties of ticlopidine: an open-label, randomized, two-period, two-treatment, two-sequence, single-dose crossover study in healthy Korean male volunteers.
abstract: BACKGROUND
  Ginkgo biloba extract is an herbal medicine used in the treatment of vascular disorders that may be coadministered with antiplatelet agents such as ticlopidine. Regulatory authorities requested evaluation of the pharmacodynamic and pharmacokinetic interactions between these entities, according to the drug-development guidance for fixed-dose combination formulations in Korea.
  
  
  OBJECTIVE
  This study was performed to evaluate the potential pharmacodynamic and pharmacokinetic interactions between ticlopidine and Ginkgo biloba extract.
  
  
  METHODS
  An open-label, randomized, 2-period, 2-treatment, 2-sequence, single-dose crossover study was conducted in healthy Korean male volunteers. All volunteers were randomly assigned to a sequence group for the 2 treatments, which consisted of ticlopidine 250 mg alone and ticlopidine 250 mg with Ginkgo biloba extract 80 mg, separated by a 1-week washout period between the treatments. Bleeding time was determined just before dosing and at 5, 12, and 48 hours after dosing. Platelet aggregation was evaluated before dosing and at 4, 8, 26, and 48 hours after dosing. Blood samples (8 mL) from each of the volunteers were collected from an indwelling intravenous cannula inserted into a forearm vein before dosing and at 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 12, 24, and 48 hours after dosing. Ticlopidine concentrations were determined by a validated method using HPLC and ultraviolet detection. Adverse events were identified using general health-related questions, vital signs, physical examinations, ECGs, and laboratory tests.
  
  
  RESULTS
  A total of 24 healthy men participated in the study (mean [SD] age, 24.1 [4.3] years; weight, 66.6 [7.4] kg; height, 174.7 [5.0] cm). The baseline corrected bleeding times were not significantly different between the ticlopidine-alone and ticlopidine/ Ginkgo biloba groups, and changes in platelet aggregation were not significantly different between the groups. Likewise, the pharmacokinetic parameters of ticlopidine were not significantly different between the groups; the geometric mean ratios of the ticlopidine/ Ginkgo biloba group to the ticlopidine-alone group were 1.03 (90% CI, 0.92-1.16) for C(max), 1.08 (90% CI, 0.98-1.19) for AUC(0-last), and 1.10 (90% CI, 1.00-1.20) for AUC(0-infinity). A total of 28 adverse events were reported: 11 in the ticlopidine-alone group and 17 in the ticlopidine/Ginkgo biloba group. The adverse events judged to be possibly related to ticlopidine in the ticlopidine-alone group were epigastric discomfort (2 cases), diarrhea (1), skin eruption (1), and a feeling of being cold (1) or hot (1). The adverse events judged to be related to ticlopidine or Ginkgo biloba in the ticlopidine/Ginkgo biloba group were epigastric discomfort (2), diarrhea (2), nausea (2), and headache (1).
  
  
  CONCLUSIONS
  In this small group of healthy Korean men, the addition of a single dose of Ginkgo biloba extract did not prolong the bleeding time and was not associated with additional antiplatelet effects compared with the administration of ticlopidine alone. The coadministration of Ginkgo biloba extract with ticlopidine was not associated with any significant changes in the pharmacokinetic profile of ticlopidine compared with ticlopidine administered alone.
authors.affiliation: Department of Pharmacology and Clinical Pharmacology, Seoul National University College of Medicine and Hospital, Seoul, Korea.
authors.forename: Bo-Hyung
authors.initials: BH
authors.lastname: Kim
authors.forename: Kyu-Pyo
authors.initials: KP
authors.lastname: Kim
authors.forename: Kyoung Soo
authors.initials: KS
authors.lastname: Lim
authors.forename: Jung-Ryul
authors.initials: JR
authors.lastname: Kim
authors.forename: Seo Hyun
authors.initials: SH
authors.lastname: Yoon
authors.forename: Joo-Youn
authors.initials: JY
authors.lastname: Cho
authors.forename: Yong-Oh
authors.initials: YO
authors.lastname: Lee
authors.forename: Kyung-Hee
authors.initials: KH
authors.lastname: Lee
authors.forename: In-Jin
authors.initials: IJ
authors.lastname: Jang
authors.forename: Sang-Goo
authors.initials: SG
authors.lastname: Shin
authors.forename: Kyung-Sang
authors.initials: KS
authors.lastname: Yu
mesh_terms: D000328:Adult; D044466:Asian People; D001760:Bleeding Time; D001792:Blood Platelets / Q000187:drug effects*; D002851:Chromatography, High Pressure Liquid; D018592:Cross-Over Studies; D020441:Ginkgo biloba; D006470:Hemorrhage / Q000139:chemically induced; D041743:Herb-Drug Interactions; D006801:Humans; D008297:Male; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology*; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D056910:Republic of Korea; D013988:Ticlopidine / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D055815:Young Adult
chemical_list: D010936:Plant Extracts; D010975:Platelet Aggregation Inhibitors; D013988:Ticlopidine