Itraconazole capsules need gastric acid and food to be absorbed, so they work poorly with proton pump inhibitors or on an empty stomach; the oral solution is better absorbed and taken fasting. Levels vary widely, and therapeutic drug monitoring is useful in serious infections.
Itraconazole is a strong CYP3A4 inhibitor and raises levels of many drugs, including some statins, calcium channel blockers, direct oral anticoagulants and immunosuppressants. It also has negative inotropic effects and carries a warning against use in heart failure.
- Give capsules with food and avoid acid suppressants; give the solution on an empty stomach
- Check every co-prescribed drug for CYP3A4 interactions before starting
- Avoid itraconazole in patients with heart failure or ventricular dysfunction
- Consider drug level monitoring in invasive or deep fungal infection
Why it matters
Most itraconazole treatment failures and harms come from absorption and interactions, not resistance.
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