Background: Sodium fusidate (fusidic acid) is an antimicrobial agent that is used in the
treatment of staphylococcal and streptococcal infections. Several case reports have noted a drug interaction
between sodium fusidate and CYP3A4 metabolised statins, leading to statin toxicity. It is unclear
whether sodium fusidate has the potential to cause interactions with other cytochrome P450 enzymes.
Objective: To investigate the effects of sodium fusidate on recombinant cytochrome P450 enzymes
(1A2, 2C9, 2C19, 2D6 and 3A4) in-vitro.
Methods: A range of sodium fusidate concentrations (0.1µM, 1µM, 10µM, 100µM, 300µM, 1000µM and 10000µM) were tested to examine its activity on rCYP1A2, rCYP2C9, rCYP2C19, rCYP2D6 and
rCYP3A4 using a luminescent assay with a luciferin substrate.
Results: Sodium fusidate inhibited all enzymes at tested concentrations which are relevant to those
likely to be achieved in clinical practice. Further, sodium fusidate was found to be a time-dependent inhibitor
of all the tested isoenzymes, with the exception of rCYP2C9.
Conclusion: These findings suggest that there is a potential for sodium fusidate to cause drug
interactions when used with other agents that are substrates for rCYP1A2, rCYP2C9, rCYP2C19,
rCYP2D6 or rCYP3A4. Understanding the basis of this potential drug interaction will assist in safer
use of sodium fusidate in clinical practice.