Itraconazole is an antifungal drug used primarily in the treatment of immunocompromised patients or fungal infection that Fluconazole cannot deal with, such as the fungus Candida galbrata, which has a resistance to Fluconazole. Itraconazole is taken mainly in a pill form. The oral bioavailability of itraconazole is only 55% and is best when taken with food. Itraconazole is transported from the intestine into the intestinal epithelial cell possibly via solute carrier family 15 member 1, one of 3 drug transporters into epithelial cells. It is then transported into blood vessels via ATP-binding cassette sub-family C member 3. Once there, it travels to the liver and is transported in via P-glycoprotein. On the membrane of the endoplasmic reticulum Itraconazole will slightly inhibit Lanosterol 14-alpha demethylase, the first step in steroid biosynthesis and a very similar enzyme to what it inhibits in fungal yeast cells.It is highly selective for fungal Lanosterol 14-alpha demethylase, but will still inhibit it in humans to a degree. It also inhibits Cytochrome P450 3A5, Cytochrome P450 3A7, Cytochrome P450 3A4, Cytochrome P450 2B6, and Cytochrome P450 2E1, which are similar to Lanosterol 14-alpha demethylase. This all produces adverse but not lethal effects. Itraconazole is then metabolized in the endoplasmic reticulum of the liver into many unknown metabolites, but mainly into hydroxyitraconazole. This metabolite along with the remaining Itraconazole that was not metabolized are transported back into the blood where they travel to the kidney to be excreted renally. 3%-18% is transported into the bile ducts where it goes to the intestines to be excreted through the feces. Only about 0.03% of the dose is excreted as Itraconazole. 40% is excreted as metabolites.

Itraconazole Metabolism References