title: Pharmacokinetic Effects of Cinnamic Acid, Amygdalin, Glycyrrhizic Acid and Liquiritin on Ephedra Alkaloids in Rats.
abstract: OBJECTIVE
  Ephedra alkaloids, including ephedrine (EP), pseudoephedrine (PEP) and methylephedrine (MEP), are sympathomimetic compounds with known toxicities but many Ephedra (Ephedrae herba) preparations, such as Ephedra decoction, have been clinically applied for centuries. In order to explore the possible detoxification mechanism of Ephedra alkaloids, four representative compounds in Ephedra decoction (cinnamic acid, amygdalin, glycyrrhizic acid and liquiritin) were studied for their pharmacokinetic effects on Ephedra alkaloids in Sprague-Dawley rats.
  
  
  METHODS
  Animals were randomly divided into six groups, with six rats in each. Rats were treated orally with EP-PEP-MEP (20 mg/kg EP + 20 mg/kg PEP + 20 mg/kg MEP) and different combinations of cinnamic acid (3.03 mg/kg), amygdalin (56.97 mg/kg), glycyrrhizic acid (12.42 mg/kg), liquiritin (3.79 mg/kg) with EP-PEP-MEP, and 20 mg/kg EP + 20 mg/kg PEP + 20 mg/kg MEP + 3.03 mg/kg cinnamic acid + 56.97 mg/kg amygdalin + 12.42 mg/kg glycyrrhizic acid + 3.79 mg/kg liquiritin. Blood samples (0.5 mL) were taken from the orbital sinus venous plexus into heparinized tubes at 5, 10, 20, 30, 45, 60, 90, 120, 180, 240, 300 and 360 min (6 rats per time point in each group) following single administration. The concentrations of Ephedra alkaloids in rat plasma were determined using a validated high performance liquid chromatography method.
  
  
  RESULTS
  Area under the concentration-time curve from 0 to 360 min (AUC0-t) of EP, PEP and MEP were 666.99, 650.76 and 632.37 µg·min/mL, respectively. Maximum plasma concentration (Cmax) of EP, PEP and MEP were 4.15, 4.08 and 3.59 μg/mL, respectively. Mean residence time (MRT) of EP, PEP and MEP were 197.00, 173.97 and 183.87 min, respectively, when the rats were treated with EP-PEP-MEP. Cinnamic acid increased the AUC0-tof EP while decreased Cmaxof EP, amygdalin and glycyrrhizic acid increased Cmaxand AUC0-tof EP and PEP, while liquiritin decreased AUC0-tof EP and PEP. The four representative compounds reduced MRT of EP, PEP and MEP, four compounds decreased AUC0-tof MEP. The EP-PEP-MEP + cinnamic acid + amygdalin + glycyrrhizic acid + liquiritin group increased AUC0-tof EP while decreased MRT of EP, increased MRT of PEP while decreased AUC0-tof PEP. The EP-PEP-MEP + cinnamic acid + amygdalin + glycyrrhizic acid + liquiritin group decreased MRT, AUC0-tand Cmaxof MEP.
  
  
  CONCLUSIONS
  Significant changes in pharmacokinetic parameters of EP, PEP and MEP were observed after oral administration with different combinations. The pharmacokinetic results reported here might provide reference for clinical usage of Ephedra alkaloids.
authors: College of Pharmaceutical Science, Zhejiang Chinese Medical University, 548 Binwen Road, Hangzhou, 310053, China.
authors: Yinghong
authors: Y
authors: Tang
authors: College of Pharmaceutical Science, Zhejiang Chinese Medical University, 548 Binwen Road, Hangzhou, 310053, China.
authors: Mengkai
authors: M
authors: Zheng
authors: College of Pharmaceutical Science, Zhejiang Chinese Medical University, 548 Binwen Road, Hangzhou, 310053, China.
authors: Yu-Lin
authors: YL
authors: Chen
authors: College of Pharmaceutical Science, Zhejiang Chinese Medical University, 548 Binwen Road, Hangzhou, 310053, China.
authors: Jianzhen
authors: J
authors: Chen
authors: College of Pharmaceutical Science, Zhejiang Chinese Medical University, 548 Binwen Road, Hangzhou, 310053, China. heyu0923@hotmail.com.
authors: Yu
authors: Y
authors: He
mesh_terms: D000470:Alkaloids / Q000493:pharmacokinetics*; D000678:Amygdalin / Q000493:pharmacokinetics*; D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002934:Cinnamates / Q000493:pharmacokinetics*; D004365:Drugs, Chinese Herbal; D029789:Ephedra / Q000737:chemistry*; D044950:Flavanones / Q000493:pharmacokinetics*; D005960:Glucosides / Q000493:pharmacokinetics*; D019695:Glycyrrhizic Acid / Q000493:pharmacokinetics*; D008297:Male; D010936:Plant Extracts / Q000493:pharmacokinetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D000470:Alkaloids; D002934:Cinnamates; D004365:Drugs, Chinese Herbal; D044950:Flavanones; D005960:Glucosides; D010936:Plant Extracts; C029010:cinnamic acid; D000678:Amygdalin; D019695:Glycyrrhizic Acid; C512196:liquiritin