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(for veterinary information only)
AVAILABLE IN
100 mg CAPSULES
OR AS
ORAL SOLUTION
The development of oral medications to be used in the treatment of invasive fungal infections has represented an immense medical breakthrough. With oral treatment available, human patients no longer require hospitalization several days per week for intravenous treatment of their disease; a more normal and productive lifestyle is now possible. Further, the toxicity profiles of the newer oral drugs represents vast improvement over those of the injectables.
Ketoconazole was the first such oral antifungal drug but it had room for improvement regarding its side effect potential. There were problems with nausea, liver toxicity, and feminization of male patients. Itraconazole was developed in answer to these concerns. Its potential for side effects is far lower, although its expense, unfortunately, was at first far greater. Generic medications have made this drug much more affordable in recent years.
Itraconazole works by inhibiting the fungal enzymes that produce “ergosterol,” an important component of the fungal cell wall. Without adequate ergosterol, the fungal cell becomes weak, leaky and ultimately dies.
Fungal infections for which itraconazole can be used include:
The chief reason for choosing Itraconazole over other antifungal agents is to avoid side effects. While itraconazole users do not commonly experience side effects, it is important to be aware of what to watch for.
Side effects of concern are appetite loss, vomiting, and/or diarrhea. If they occur, medication should be discontinued and liver enzymes should be checked.
If an adverse side effect occurs, it is expected to resolve with discontinuation of the medication. After recovery, itraconazole can usually be restarted at a lower dose.
IF YOU THINK YOUR PET MAY BE HAVING AN ADVERSE DRUG REACTION,
YOU SHOULD NOTIFY YOUR VETERINARIAN’S OFFICE RIGHT AWAY.
Itraconazole should not be given to patients with known liver disease if possible. In one research publication, an SGPT/ALT enzyme level of 250 IU/L was felt to be the highest tolerable level compatible with itraconazole use. Approximately 5-10% of dogs receiving standard doses of itraconazole will develop liver disease severe enough to warrant discontinuing the medication.
The use of itraconazole in combination with the antacids famotidine (Pepcid®), ranitidine (Rantac®), or cimetidine (Tagamet®), omeprazole (Prilosec®), or with the antibiotic rifampin will lead itraconazole to be less effective. If itraconazole must be used with these medications, it is recommended that at least 2 hours pass between the antacid administration and the administration of itraconazole.
Serious heart abnormalities have resulted when itraconazole was used with the antihistamine Terfenadine (Seldane) or with the intestinal motility modifier cisapride (Propulsid®). These medications should not be used with itraconazole.
The following heart medicines will be stronger in the presence of itraconazole and dosage may need to be reduced: amlodipine, digoxin, warfarin, or quinidine. A similar problem occurs with cyclosporine, an immune suppressant used in immune mediated disease, allergy, or after an organ transplant.
ITRACONAZOLE CAPSULES WORK BEST WHEN GIVEN WITH FOOD.
The 100mg itraconazole capsule is an inconvenient size for most animal patients. For this reason, it is common to have a “compounding pharmacy” make up a prescription as either capsules or flavored liquid in a size that fits the individual patient in question. There is one important caveat regarding going through a compounding pharmacy for itraconazole and this regards the materials the pharmacy uses to make up formulations. Compounded itraconazole can be made up from the prescription product (either brand name or genetic) or it can be made up from itraconazole available in bulk (which is usually much less costly). The bulk substance is not recommended as it is not as stable or available to the patient's body as the prescription capsules. The capsules utilize special itraconazole-coated beads which are responsible for proper absorption of the drug. The compounding pharmacy must keep the beads intact in making their formulations.
More recently a new oral liquid product called "Itrafungol" has been approved for feline use but at this time (Feb 2006) it is only available in Europe.
Itraconazole is able to penetrate most body tissues and thus fight fungal infections in most organs. It cannot penetrate, however, the blood/brain barrier and thus is useless in central nervous system fungal infections. In such a situation, another closely related medication (fluconazole) would be helpful.
FUNGAL INFECTIONS AS A GENERAL RULE ARE VERY RESISTANT
TO TREATMENT AND OFTEN MONTHS OF THERAPY ARE NEEDED.
IT IS IMPORTANT NOT TO DISCONTINUE TREATMENT
PREMATURELY DESPITE EXPENSE.
(An exception might be a malessezia/yeast dermatitis
which frequently clears up in a couple of weeks).
Itraconazole is dangerous if given in pregnancy. If a pet is pregnant, itraconazole should be avoided unless the fungal infection in question is potentially life-threatening.
Itraconazole should also be avoided in lactation as it will be delivered via milk to any nursing young.
Page last updated: 5/9/08
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