Voriconazole

Common Uses

Voriconazole is primarily used to treat serious fungal infections that affect various parts of the body. It is often prescribed for conditions such as:

• Invasive aspergillosis: A serious infection caused by the Aspergillus fungus, which often starts in the lungs.
• Esophageal candidiasis: A yeast infection of the esophagus (the tube connecting the throat to the stomach).
• Candidemia: A yeast infection that has spread into the bloodstream.
• Other Candida infections: Fungal infections affecting the skin, stomach, kidneys, bladder, or wounds.
• Scedosporiosis and Fusariosis: Rare but serious fungal infections in patients who do not respond to or cannot tolerate other treatments.

This medication works by slowing or stopping the growth of the fungi causing the infection. It is available in several forms, including tablets, an oral liquid suspension, and an intravenous injection for more severe cases.

Mechanism of Action

Voriconazole belongs to a class of drugs known as azole antifungals. It works by disrupting the process that fungi use to build and maintain their cell membranes.

Disrupting Fungal Cells

To survive and grow, fungi must produce a substance called ergosterol, which is a vital component of their outer cell membrane. Voriconazole blocks a specific enzyme that the fungus needs to create ergosterol. Without this substance:

• The fungal cell membrane becomes unstable and begins to leak.
• The fungus can no longer grow or multiply effectively.
• The infection is weakened, making it easier for the body's immune system to eliminate it.

Because human cells use a different process to maintain their membranes, the medication specifically targets the fungi causing the infection while leaving human cells largely unaffected.

Common Side Effects

• Vision changes, including blurred vision, sensitivity to light, or seeing colors differently
• Nausea, vomiting, or stomach pain
• Diarrhea
• Headache
• Fever
• Swelling of the hands, ankles, or feet
• Mild skin rash

Serious Side Effects

Contact a healthcare provider immediately if you experience any of the following serious symptoms:

• Signs of liver damage, such as yellowing of the skin or eyes, dark urine, or pale stools
• Severe skin reactions, including peeling, blistering, or painful rashes
• Irregular heartbeat or palpitations
• Confusion, hallucinations, or unusual changes in behavior
• Kidney problems, such as decreased urination or swelling
• Bone pain, which may develop during long-term treatment
• Signs of a severe allergic reaction, such as hives, swelling of the face or throat, and difficulty breathing

Vision changes are common and usually occur shortly after taking a dose. These effects are typically temporary but may affect your ability to drive or operate machinery safely.

Liver Toxicity

Voriconazole can cause serious liver injury, including hepatitis, cholestasis, and liver failure. Healthcare providers typically monitor liver function tests before starting treatment and regularly during therapy. Treatment may need to be stopped if liver enzymes become significantly elevated.

Visual Disturbances

Many patients experience temporary vision changes, such as blurred vision, altered color perception, or sensitivity to light. These effects usually occur within 30 minutes of a dose and often resolve within an hour. Because of these potential effects, caution is advised when driving or operating machinery, especially at night.

Skin Reactions and Photosensitivity

Voriconazole can cause the skin to become highly sensitive to sunlight. Long-term use has been linked to an increased risk of skin cancer, specifically squamous cell carcinoma. Severe, potentially life-threatening skin reactions, such as Stevens-Johnson syndrome and toxic epidermal necrolysis, have also been reported. It is recommended to avoid intense or prolonged exposure to direct sunlight and to use sun protection.

Heart Rhythm Issues

This medication can cause QT prolongation, a condition that affects the heart's electrical rhythm. This may lead to a serious or life-threatening heart rhythm called torsades de pointes. The risk is higher for patients with existing heart conditions, electrolyte imbalances, or those taking other medications that affect the heart rhythm.

Kidney Function

The intravenous (IV) form of voriconazole contains an ingredient called sulfobutylether beta-cyclodextrin sodium (SBECD), which can accumulate in patients with moderate to severe kidney disease. Healthcare providers will monitor kidney function and may switch to the oral form if kidney function declines.

Drug Interactions

Voriconazole has many significant drug interactions because it is processed by specific liver enzymes. It can increase the levels of other medications in the body to dangerous levels, or other drugs may decrease the effectiveness of voriconazole. A thorough review of all medications, including supplements and over-the-counter drugs, is necessary before starting treatment.

Pregnancy and Fetal Risk

Voriconazole may cause fetal harm when administered to pregnant individuals. Effective contraception is recommended for those of childbearing potential during treatment.

Pregnancy

Voriconazole can cause harm to a developing fetus. Research in animals has shown that the medication can lead to birth defects, such as cleft palate and kidney issues, when used during pregnancy. Because of these risks, voriconazole is typically only used in pregnant women if the healthcare provider determines that the benefit to the mother justifies the potential risk to the baby.

Women who are able to become pregnant should use effective contraception while taking voriconazole to prevent pregnancy. If you become pregnant or think you might be pregnant while using this medication, notify your healthcare provider immediately.

Breastfeeding

It is not currently known whether voriconazole passes into human breast milk. Because many drugs are excreted in milk and there is a potential for serious side effects in a nursing infant, a decision must be made whether to stop breastfeeding or stop taking the medication. This decision should be made in consultation with a healthcare provider, considering how important the drug is for the mother's health.

Oral Formulations

Voriconazole is available for oral administration in the following forms:

• Tablets: These are film-coated tablets intended to be swallowed.
• Powder for Oral Suspension: This is a powder that is reconstituted into a liquid suspension by a pharmacist before being taken by mouth.

Injectable Formulations

• Powder for Solution for Injection: This is a sterile, lyophilized powder provided in a single-dose vial. It must be reconstituted and then further diluted by a healthcare professional before it is administered as an intravenous infusion.

FDA Approval Status

Voriconazole was first approved by the U.S. Food and Drug Administration (FDA) in 2002. It is classified as a triazole antifungal agent and is available in oral tablet, oral suspension, and intravenous injection forms.

Approved Indications

The FDA has approved voriconazole for the treatment of the following conditions in both adult and pediatric patients:

• Invasive aspergillosis.
• Candidemia in non-neutropenic patients.
• Disseminated Candida infections in the skin, abdomen, kidney, bladder wall, and wounds.
• Esophageal candidiasis.
• Serious fungal infections caused by Scedosporium apiospermum and Fusarium species in patients who cannot tolerate or do not respond to other treatments.

Safety Communications and Monitoring

Voriconazole does not currently have a boxed warning or a Risk Evaluation and Mitigation Strategy (REMS) program. However, the FDA requires professional labeling to include warnings for several significant safety concerns:

• Liver Health: Due to the risk of hepatotoxicity, healthcare providers are advised to monitor liver function tests at the start of and during treatment.
• Dermatologic Risks: There are warnings regarding the risk of squamous cell carcinoma of the skin and melanoma, especially with long-term use. Patients are advised to avoid intense or prolonged sunlight exposure.
• Visual Effects: Monitoring for visual disturbances, including blurred vision and changes in color perception, is recommended as these effects are common.
• Embryo-Fetal Toxicity: Voriconazole can cause fetal harm when administered to pregnant women, and regulatory labeling includes warnings for use during pregnancy.
• Skeletal Toxicity: Long-term use has been associated with fluorosis and bone inflammation (periostitis), particularly in transplant recipients.

Voriconazole has the potential to cause serious liver problems. Because alcohol also affects liver function, consuming alcohol while taking this medication may increase the risk of liver-related side effects. You should inform your healthcare provider if you drink or have a history of drinking large amounts of alcohol before starting treatment.

Your doctor will likely perform regular blood tests to monitor your liver health while you are using voriconazole. Seek medical attention immediately if you notice signs of liver damage, such as:

• Yellowing of the eyes or skin
• Dark urine
• Loss of appetite
• Pain in the upper right part of the stomach
• Nausea or vomiting
• Unusual tiredness or weakness