IsavuconazoleIsavuconazonium Sulfate

About Isavuconazole

Isavuconazole blocks an enzyme fungi need to build their cell membrane. The label approves Cresemba capsules for invasive aspergillosis and invasive mucormycosis in adults and in pediatric patients 6 years and older who weigh 16 kg or more. Treatment starts with a loading phase: for adults, 372 mg (two 186 mg capsules or five 74.5 mg capsules) every 8 hours for six doses over 48 hours, then 372 mg once a day starting 12 to 24 hours after the last loading dose. Children take the 74.5 mg capsules, dosed by weight. Some patients start on the IV form, which is given by infusion and not covered here; the label allows a switch to capsules without a new loading dose.

Cresemba has no boxed warning. It must not be taken by anyone allergic to isavuconazole, with strong CYP3A4 inhibitors such as ketoconazole or high-dose ritonavir, with strong CYP3A4 inducers such as rifampin, carbamazepine, St. John’s wort or long-acting barbiturates, or by people with familial short QT syndrome, because it shortens the QTc interval. Serious liver reactions can occur, so liver tests are checked during treatment. Severe allergic reactions have been reported. Common side effects include nausea, vomiting, diarrhea, headache, abnormal liver tests and low potassium.

What is distinctive is the packaging: each capsule sits in its own blister pocket beside a desiccant pocket and stays there until use, so it cannot go into a pill organizer. They are swallowed whole and not given through a feeding tube. The label says it may cause fetal harm: women who could become pregnant should use effective birth control during treatment and for 28 days after the last dose, and breastfeeding should stop during treatment. Cresemba is not a controlled substance.

Taking Isavuconazole

How to take it

If loading doses were not already given, take the capsules every 8 hours for the first six doses, then once a day at about the same time, with or without food. Swallow each capsule whole; do not open, chew, crush or dissolve it.

If you miss a dose

Take the missed dose as soon as you remember, unless it is almost time for the next one; then skip it and continue your usual schedule. Do not take a double dose.

Storage

Keep the capsules in the original blister packaging at room temperature, 20 to 25 degrees C (68 to 77 degrees F), protected from moisture, and open a pocket only when you take that dose. Do not swallow the desiccant. Use a take-back program for leftovers.

Interactions to know about

Ketoconazole, high-dose ritonavir, rifampin, carbamazepine, long-acting barbiturates and St. John’s wort must not be used with it. It can raise levels of tacrolimus, sirolimus, cyclosporine, digoxin and midazolam, so levels or doses may need checking. Ask about grapefruit, too.

This summarizes the official prescribing information. Your prescriber’s and pharmacist’s instructions, and the leaflet that comes with your medicine, take priority.

Why the cash price for Isavuconazole differs from pharmacy to pharmacy

Cresemba is a single source brand with no equivalent to substitute, so quotes differ only in how each pharmacy buys and prices it. Many community pharmacies do not keep it on the shelf and have to order it in.

The capsules come in sealed cartons of blister sheets that are meant to stay intact, so quotes are usually for whole cartons. On a fill this costly, the dispensing fee is a small part of the quote.

Ways to pay less for Isavuconazole without insurance

• Compare quotes from more than one pharmacy and ask how quickly each can get the capsules, so no dose is missed.
• Ask the prescriber whether the strength written fits the daily dose with the fewest capsules; for an adult dose, two 186 mg capsules replace five 74.5 mg capsules.
• Ask whether loading doses were already given in the hospital, so the home fill covers only the daily doses still needed.
• Ask Astellas whether its patient assistance program applies to someone paying cash.
• Upload the prescription to Script Unlock so licensed pharmacies can quote their cash price. You pay the pharmacy directly.

Questions to ask your pharmacist about Isavuconazole

1. 1.Do any of my other medicines interact with my Cresemba?
2. 2.When should my liver tests be checked while I take my capsules?
3. 3.How should I store my blister packs at home, and what do I do if a pocket is torn open early?
4. 4.If my doctor stops my treatment, how should I dispose of my leftover capsules?

Related medications