Efavirenz + Itraconazole = Precautionary

Effect on Concentration

Efavirenz
No change
Applies within class?
No
Itraconazole
Decrease
Applies within class?
No

Pharmacologic Effects

Efavirenz
Effect
N/A
Applies within class?
No
Itraconazole
Effect
N/A
Applies within class?
No

Interaction History

N/A

Last Updated 30-Jul-2018

Summary

Sources

Efavirenz versus Itraconazole ^

Study Design

Data regarding this information stem from clinical case reports only. Although there is a presumed drug-drug interaction between itraconazole and nonnucleoside reverse-transcriptase inhibitors, the medical literature lacks such documentation. Authors describe a drug-drug interaction between itraconazole and efavirenz in a patient with disseminated histoplasmosis and acquired immunodeficiency syndrome (AIDS).

Study Results

The drug combination resulted in persistently elevated urinary Histoplasma antigen levels and subtherapeutic plasma itraconazole concentrations. Changing treatment from efavirenz to a protease inhibitor was accompanied by improvements in the desired urinary Histoplasma antigen level and plasma itraconazole concentration.

Study Conclusions

Itraconazole metabolism is likely induced by EFV and NVP to significantly low concentrations. The authors concluded that a PI regimen may be optimal over an NNRTI among patients on itraconazole. If not possible, itraconazole blood levels should be closely monitored.

References

Koo HL, Hamill RJ, Andrade RA. Drug-drug interaction between itraconazole and efavirenz in a patient with aids and disseminated histoplasmosis. Clinical Infectious Diseases. 2007; 6: e77-e79.