Fluconazole is a synthetic triazole antifungal agent used to treat a variety of fungal and yeast infections. The brand name is Diflucan®, and it is available in oral and intravenous (IV) forms. A fluconazole injection is administered intravenously in a hospital or clinic setting, and is typically reserved for severe infections or for patients who are unable to take medication by mouth. While standard fluconazole injection bags are often supplied in 200 mg and 400 mg dosages, a specific fluconazole 250 mg injection would be a compounded dose prepared by a pharmacist based on a healthcare provider's order for a particular patient.
How Fluconazole Works
Fluconazole belongs to the azole class of antifungals and functions by interfering with the synthesis of ergosterol, a vital component of the fungal cell membrane. It works by inhibiting a fungal enzyme called lanosterol 14-α-demethylase. This disruption in ergosterol production leads to the accumulation of 14-α-methyl sterols within the fungal cell, damaging the cell membrane and inhibiting fungal growth. This mechanism of action is highly selective for fungi, minimizing harm to human cells.
Key Indications for Intravenous Use
Because intravenous administration provides rapid and complete absorption, it is particularly useful for serious and widespread fungal infections. Some common indications include:
- Oropharyngeal and Esophageal Candidiasis: Infections of the mouth, throat, and esophagus caused by Candida species, also known as thrush.
- Systemic Candida Infections: Serious, disseminated candidiasis involving the blood (candidemia), lungs (pneumonia), and other organs.
- Cryptococcal Meningitis: Fungal infection of the membranes covering the brain and spinal cord, often requiring high-dose treatment.
- Prophylaxis in Bone Marrow Transplant Patients: Preventing fungal infections in patients with weakened immune systems undergoing cytotoxic chemotherapy and/or radiation therapy.
- Other Infections: Less common uses include fungal infections of the urinary tract and peritonitis.
Dosage and Administration
Fluconazole injection is typically given once daily via intravenous infusion over a period of 1 to 2 hours. The exact dosage is determined by a healthcare provider based on the type and severity of the infection, the patient's weight, and renal function. For serious infections, a loading dose (double the daily dose) may be administered on the first day to achieve steady plasma concentrations more quickly.
Regarding a 250 mg dose, manufacturers do not typically supply pre-mixed 250 mg bags. A pharmacist must prepare this customized dose from a standard stock solution, often by withdrawing the required volume from a larger 200 mg or 400 mg bag. Dosage can range from 50 mg to 400 mg daily for adults, with even higher doses (up to 800 mg) used for severe or life-threatening infections, such as cryptococcal meningitis. For pediatric patients, dosing is based on body weight.
Important Safety Information and Side Effects
Like all medications, fluconazole can cause side effects. Common ones often involve the gastrointestinal system and include nausea, headache, abdominal pain, and diarrhea. More serious side effects can occur, and patients should contact their doctor immediately if they experience any of the following:
- Signs of liver damage (yellowing of the skin or eyes, dark urine, pale stools)
- Serious skin reactions (rash, blistering, swelling)
- Irregular or rapid heart rate
- Adrenal insufficiency (unusual weakness, loss of appetite)
- Seizures
Comparison: Intravenous vs. Oral Fluconazole
The decision to use IV versus oral fluconazole is based on the patient's condition and ability to take and absorb oral medication. The IV and oral routes achieve similar plasma concentrations and efficacy, but the administration method offers distinct advantages and uses.
| Feature | Intravenous (IV) Administration | Oral Administration |
|---|---|---|
| Form | Sterile solution for infusion | Tablets or oral suspension |
| Absorption | Rapid and complete, directly into bloodstream | Rapid and nearly complete, unaffected by food |
| Speed of Effect | Faster onset of action, crucial for severe infections | Onset is slower than IV, suitable for stable patients |
| Typical Uses | Severe or systemic infections; for patients unable to take or absorb oral meds | Mild-to-moderate infections, step-down therapy after IV treatment |
| Setting | Hospital or clinic, administered by healthcare professional | Hospital or at home; patient self-administration |
| Dosage | Daily doses commonly 50 mg to 400 mg; specialized doses may be compounded | Single doses (150 mg) or daily doses (50 mg to 400 mg) |
Important Drug Interactions
Fluconazole can interact with several other medications, which may require dose adjustments or extra monitoring. Some significant interactions include:
- Oral Hypoglycemics: Can cause low blood sugar.
- Coumarin-type Anticoagulants (e.g., Warfarin): Can increase bleeding risk.
- QT-prolonging drugs: Avoid concomitant use with certain drugs like erythromycin and pimozide due to increased risk of cardiac issues.
- Tacrolimus: Fluconazole can significantly increase levels of orally administered tacrolimus, potentially leading to nephrotoxicity.
The Role of Monitoring
Due to the potential for side effects, regular monitoring is crucial during fluconazole therapy. This may include monitoring liver function tests to check for potential hepatotoxicity and kidney function, as dosage adjustments may be necessary for patients with renal impairment. Monitoring electrolytes, especially potassium, is also important due to the risk of QT prolongation.
Conclusion
While a pre-packaged fluconazole 250 mg injection does not exist, a pharmacist can prepare this specific dose for a patient based on medical necessity. Fluconazole injection is a critical medication for treating serious fungal infections, offering a reliable intravenous option for patients who require it. Its use, like all potent medications, requires careful medical supervision and monitoring to ensure efficacy and minimize risks. For comprehensive information on fluconazole, including dosage and safety, healthcare providers often reference the official prescribing information.
