In vitro evidence of baicalein’s inhibition of the metabolism of zidovudine (AZT)

Background: Herb-drug interaction (HDI) has been regarded as a key factor limiting the clinical application of herbs and drugs.
Aims: Potential baicalein-zidovudine (AZT) interaction was predicted in the present study.
Methods: In vitro evaluation of baicalein’s inhibition towards human liver microsomes (HLMs)-catalyzed metabolism of zidovudine (AZT) was performed. Dixon and Lineweaver-Burk plots were used to determine the inhibition kinetic type, and second plot with the slopes from Lineweaver-Burk plot versus the concentrations of baicalein was employed to calculate the inhibition parameter (Ki). In combination with the in vivo concentration of baicalein, in vitro-in vivo extrapolation (IVIVE) was carried out to predict in vivo baicalein-AZT interaction.
Results: Competitive inhibition of baicalein towards AZT metabolism was demonstrated, and the K_i value was calculated to be 101.2 μM. The value of AUC_i/AUC was calculated to be 2.
Conclusion: Potential baicalein-AZT interaction was indicated in the present study, indicating the need for monitoring when AZT is co-administrated with baicalein or baicalein-containing herbs.