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Influence of different Hypericum perforatumL. preparations on pharmacokinetic and pharmacodynamic properties of pentobarbital, diazepam and paracetamol

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Herb–drug interactions are an important safety concern and the study was conducted regarding the interaction between the natural top-selling antidepressant remedy Hypericum perforatum and conventional drugs.


This study examined the influence of acute pretreatment with different H. perforatum extracts on pentobarbital-induced sleeping time impairment of motor coordination caused by diazepam and paracetamol pharmacokinetics in mice. The preparations profile of St. John’s wort was determined using RP-HPLC analysis. Ethanolic extract, aqueous extract, infusion, tablet and capsule of H. perforatum were used in the experiment.


By quantitative HPLC analysis of active principles, it has been proved that H. perforatum ethanolic extract has the largest content of naphtodianthrones: hypericin (57.8 µg/ml) and pseudohypericin (155.4 µg/ml). Pretreatment with ethanolic extract of H. perforatum potentiated the hypnotic effect of pentobarbital and the impairment of motor coordination caused by diazepam to the greatest extent and also increased the paracetamol plasma concentration in comparison to the control group. These results were in correlation to naphtodianthrones concentrations.


The obtained results show a considerable influence of H. perforatum on pentobarbital and diazepam pharmacodynamics and paracetamol pharmacokinetics.


This work was supported by the Provincial Secretariat for Science and Technological Development, Autonomous Province of Vojvodina, project no. 114-451-2458/2011.

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Correspondence to Aleksandar Rašković.

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  • Diazepam
  • Paracetamol
  • Pentobarbital
  • Ethanolic Extract
  • Motor Coordination