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| Interactions: | Astemizole
Adverse Effect: Efavirenz causes inhibition of isoenzyme CYP3A4 Astemizole is mainly metabolized via CYP3A4 so it leads to reducing the clearance of Astemizole resulting in serious adverse events. Clinical Management: Avoid concomitant use of Astemizole and Efavirenz.
Cisapride
Adverse Effect: Efavirenz causes inhibition of isoenzyme CYP3A4 Cisapride is mainly metabolized via CYP3A4 so it leads to reducing the clearance of Cisapride resulting in serious adverse events. Clinical Management: Avoid concomitant use of Cisapride and Efavirenz.
Clarithromycin
Adverse Effect: Rashes, decrease in plasma concentration of Clarithromycin Clinical Management: Use other macrolide antibiotic like Azithromycin if possible.
Ergotamine
Adverse Effect: Efavirenz causes inhibition of isoenzyme CYP3A4 Ergot alkaloids are mainly metabolized via CYP3A4 so it leads to lower clearance of Ergotamine resulting in serious adverse events. Clinical Management: Avoid concomitant use of Ergot alkaloids and Efavirenz.
Ethinyloestradiol
Adverse Effect: Increase in plasma concentration of Ethinyloestradiol Clinical Management: Clinical effects is not known, adjust the dose accordingly.
Indinavir
Adverse Effect: Decrease in plasma concentration of Indinavir Clinical Management: Indinavir dose has to be increased to 1000 mg every 8 hours when given with Efavirenz.
Rifampicin
Adverse Effect: Decrease in plasma concentration of Efavirenz Clinical Management: Clinical effects is not known, increase the dose of Efavirenz if required.
Terfenadine
Adverse Effect: Efavirenz causes inhibition of isoenzyme CYP3A4 Terfenadine is mainly metabolized via CYP3A4 so it leads to lower clearance of Terfenadine resulting in serious adverse events. Clinical Management: Avoid concomitant use of Terfenadine and Efavirenz.
Warfarin
Adverse Effect: Increase in plasma concentration of Warfarin due to inhibition of CYP2C9 and CYP2C19 Clinical Management: Monitor for signs and symptoms of adverse effects & adjust the dose accordingly. |
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