title: Effect of danshen extract on pharmacokinetics of theophylline in healthy volunteers.
abstract: BACKGROUND
  Danshen extract is widely used for the treatment and prevention of coronary heart disease and other diseases of senility in Asia. Danshen extract and theophylline may be prescribed together to treat patients with asthma. In human, theophylline with low therapeutic index is mainly metabolized by CYP1A2. In vitro findings have shown that human CYP1A2 is inhibited by the ethyl acetate extract of danshen and danshen pharmaceutical product. There may be drug interactions between danshen extract and theophylline (CYP1A2 substrate).
  
  
  CONCLUSIONS
  This study concerned drug interactions between danshen extract and theophylline in Chinese volunteers. Long-term oral intake of danshen extract does not change the basic pharmacokinetic parameters of theophylline. Dose adjustment of theophylline thus may not be necessary in patients receiving concomitant therapy with danshen extract.
  
  
  OBJECTIVE
  To examine the potential effect of danshen extract on the pharmacokinetics of theophylline.
  
  
  METHODS
  In a sequential cross-over study with two phases, 12 volunteers took 100 mg theophylline on day 1 and day 15. From day 2 to day 15, volunteers received danshen extract tablets three times daily, four tablets each time for 14 days. On day 15, they received four danshen extract tablets with 100 mg theophylline. Plasma concentrations of theophylline were measured on days 1 and 15 periodically for 24 h.
  
  
  RESULTS
  The 90% confidence interval of C(max), t(1/2) and CL/F of theophylline with 14-day danshen extract tablets vs. without comedication were (101.42, 121.36) (84.57, 106.72) and (88.82, 105.72), respectively. The time to peak plasma theophylline concentration was unchanged by danshen (P > 0.05). The pharmacokinetics parameter of theophylline was unaffected by danshen extract.
  
  
  CONCLUSIONS
  Danshen extract does not influence the metabolism of theophylline in healthy volunteers. Dose adjustment of theophylline thus may not be necessary in patients receiving concurrent therapy with danshen extract tablets.
authors.affiliation: Key Laboratory of Pharmacokinetics, China Pharmaceutics University, Nanjing Hospital, Wannan Medical College, Wuhu, China.
authors.forename: Furong
authors.initials: F
authors.lastname: Qiu
authors.forename: Guangji
authors.initials: G
authors.lastname: Wang
authors.forename: Yanan
authors.initials: Y
authors.lastname: Zhao
authors.forename: Hua
authors.initials: H
authors.lastname: Sun
authors.forename: Guoguang
authors.initials: G
authors.lastname: Mao
authors.forename: Jiyi
authors.initials: J
authors.lastname: A
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
mesh_terms: D018592:Cross-Over Studies; D004347:Drug Interactions / Q000502:physiology; D004365:Drugs, Chinese Herbal / Q000493:pharmacokinetics*; D006801:Humans; D010618:Phenanthrolines / Q000097:blood / Q000493:pharmacokinetics; D027561:Salvia miltiorrhiza; D013806:Theophylline / Q000097:blood / Q000493:pharmacokinetics*; D013997:Time Factors
chemical_list: D004365:Drugs, Chinese Herbal; D010618:Phenanthrolines; C028972:dan-shen root extract; D013806:Theophylline