Pharmacology Notes

The absorption of itraconazole can be unpredictable. Absorption of the capsule formulation is substantially improved in the presence of food and acidic drinks. The bioavailability of the oral solution is approximately 60% higher than that of the capsules although, in contrast, food reduces its absorption. If itraconazole is being administered for the treatment of invasive fungal infection in immunocompromised patients, levels should be monitored. The long elimination half-life implies that levels are best measured at least 5 days after commencing therapy. Peaks of 1 mg/L or more, taken 2 to 4 hours after dosing, are thought to be associated with better outcomes. Patients whose levels on oral capsules are considered to be inadequate should be tried on oral solution and their levels re-checked after a further 5 days.