Objective: To develop a simple UPLC-MS/MS method for simultaneous determination of norephedrine

norpseudoephedrine

ephedrine

pseudoephedrine

methylephedrine

amygdalin and prunasin in rat tissues and to analysis tissue distribution of these compounds in rats after oral administration of Ephedrae Herba-Amygdalus Communis Vas extract. Method: The current method was validated according to the FDA guidelines for the validation of biological sample analysis method. Diphenhydramine hydrochloride and puerarin were selected for quantitative analysis of alkaloids in Ephedrae Herba

amygdalin and prunasin

respectively. Result: Nine active compounds

including 3 pairs of epimers

were separated and quantified within 18 min by a sensitive and reliable UPLC-MS/MS method. Alkaloids in Ephedrae Herba were widely distributed in major tissues. Poor tissue distribution of amygdalin was observed

and prunasin (metabolite of amygdalin) can be detected in tissues except the brain. Contrary to D-amygdalin in vivo

D-prunasin had lower concentration (its concentrations in heart

liver

spleen

lung

kidney were 170.5

112.8

98.4

152.3

381.7 ng·g-1) in tissues by comparing with L-prunasin (its concentrations in heart

liver

spleen

lung

kidney were 906.4

652.3

177.4

500.9

2 060.4 ng·g-1). Conclusion: The method is successfully applied to tissue distribution study in rats after intragastric administration of Ephedrae Herba-Amygdalus Communis Vas extract. Reduction of D-prunasin in tissues may be the reason of toxicity antagonism in vivo. High concentration of alkaloids in Ephedrae Herba

amygdalin and prunasin are found in lung

which may be correlated with its synergistic anti-asthmatic effects.