WARNING

Foscavir (foscarnet) is a medication primarily used to treat certain viral infections, particularly cytomegalovirus (CMV) retinitis in patients with weakened immune systems, such as those with HIV/AIDS. While effective, it also carries certain risks and side effects:

• Kidney Toxicity: Foscavir can cause kidney problems, including decreased kidney function and kidney failure. This risk is higher in patients with pre-existing kidney issues or those taking other medications that affect kidney function.
• Electrolyte Imbalance: Foscavir may lead to imbalances in electrolytes such as calcium, magnesium, and potassium, which can cause symptoms like muscle cramps, weakness, and cardiac arrhythmias.
• Neurological Effects: Some patients may experience neurological side effects such as seizures, confusion, or hallucinations.
• Bone Marrow Suppression: Foscavir can suppress the bone marrow’s ability to produce blood cells, leading to anemia, leukopenia (low white blood cell count), and thrombocytopenia (low platelet count).
• Injection Site Reactions: Injection site reactions, such as pain, redness, or swelling, may occur with intravenous administration of Foscavir.
• Drug Interactions: Foscavir can interact with other medications, potentially increasing the risk of side effects or reducing their effectiveness. It’s crucial to inform your healthcare provider about all medications, supplements, and herbal products you’re taking.
• Other Risks: Rare but serious adverse reactions may include allergic reactions, pancreatitis, and abnormal liver function tests.

Due to these risks, Foscavir is typically prescribed under close medical supervision, with regular monitoring of kidney function, electrolytes, blood counts, and other relevant parameters. Patients should be educated about the signs of adverse reactions and instructed to seek medical attention if they occur.

Why is this medication prescribed?

Foscavir (foscarnet) is prescribed primarily for the treatment of certain viral infections, particularly cytomegalovirus (CMV) retinitis in patients with weakened immune systems, such as those with HIV/AIDS. Foscavir is also used for the treatment of herpes simplex virus (HSV) infections that are resistant to other medications.

How should this medicine be used?

Foscavir is typically administered intravenously (IV) by a healthcare professional in a hospital or clinic setting. The dosage and duration of treatment depend on various factors, including the type and severity of the infection being treated, the patient’s kidney function, and other individual considerations.

The general guidelines for the use of Foscavir are as follows:

• Dosage: The recommended dosage varies depending on the specific indication. It is typically administered as a slow IV infusion over 1-2 hours.
• Frequency: Foscavir is usually given every 8 hours, but the frequency may be adjusted based on the patient’s response to treatment and any adverse reactions.
• Hydration: Adequate hydration is important during treatment with Foscavir to help prevent kidney toxicity. Patients are often advised to drink plenty of fluids.
• Monitoring: Patients receiving Foscavir require regular monitoring of kidney function, electrolyte levels, and blood counts to detect any potential adverse effects early.
• Duration: The duration of treatment with Foscavir varies depending on the infection being treated and the patient’s response to therapy. Treatment may continue until the infection is resolved or controlled.

It’s essential for patients to follow their healthcare provider’s instructions carefully and attend all scheduled appointments for monitoring and evaluation during treatment with Foscavir. Additionally, patients should inform their healthcare provider about any other medications, supplements, or health conditions they have to avoid potential drug interactions or complications.

Other uses for this medicine

Foscavir (foscarnet) may be prescribed for other off-label uses, including:

• Treatment of other viral infections, such as acyclovir-resistant herpes simplex virus (HSV) infections and varicella-zoster virus (VZV) infections.
• Management of human herpesvirus 6 (HHV-6) infections.
• Investigational use in treating other viral infections, including adenovirus and Epstein-Barr virus (EBV) infections, particularly in immunocompromised patients.

What special precautions should I follow?

Special precautions should be observed when using Foscavir:

• Kidney Function Monitoring: Regular monitoring of kidney function, including serum creatinine levels and urine output, is essential during treatment with Foscavir. Dose adjustments may be necessary in patients with impaired renal function to minimize the risk of kidney toxicity.
• Electrolyte Monitoring: Monitoring of electrolyte levels, including calcium, magnesium, and potassium, is important due to the potential for electrolyte imbalances during Foscavir therapy.
• Adequate Hydration: Patients receiving Foscavir should maintain adequate hydration throughout treatment to help prevent kidney toxicity. Healthcare providers may recommend increased fluid intake or intravenous hydration.
• Injection Site Care: Foscavir is administered intravenously, so proper care of the injection site is important to minimize the risk of infection or irritation.
• Avoiding Drug Interactions: Patients should inform their healthcare provider about all medications, supplements, and herbal products they are taking, as Foscavir may interact with certain medications, potentially increasing the risk of side effects or reducing their effectiveness.
• Pregnancy and Breastfeeding: The safety of Foscavir during pregnancy and breastfeeding has not been established, so its use in pregnant or breastfeeding women should be carefully considered based on the potential benefits and risks.
• Neurological Effects: Foscavir may cause neurological side effects such as seizures, confusion, or hallucinations. Patients should be monitored for these effects, particularly those with a history of neurological disorders.

Patients should discuss any concerns or questions about Foscavir with their healthcare provider before starting treatment.

What special dietary instructions should I follow?

Special dietary instructions for Foscavir typically revolve around maintaining adequate hydration and ensuring proper electrolyte balance. Your healthcare provider may recommend increasing fluid intake and consuming foods rich in electrolytes like calcium, magnesium, and potassium. However, specific dietary instructions may vary depending on your individual health status and needs, so it’s best to follow your healthcare provider’s guidance.

What should I do if I forget a dose?

If you forget a dose of Foscavir, contact your healthcare provider or pharmacist for instructions. Do not double the dose to make up for a missed one unless directed to do so by your healthcare provider. It’s important to maintain the prescribed dosing schedule as closely as possible to ensure the effectiveness of the medication.

What side effects can this medication cause?

Foscarnet injection, like any medication, can cause side effects. Common side effects may include:

• Kidney Problems: Foscarnet can cause kidney damage or kidney failure, leading to changes in urine output and kidney function.
• Electrolyte Imbalance: Foscarnet can disrupt the balance of electrolytes in the body, leading to low levels of calcium, magnesium, and potassium, which may manifest as muscle cramps, weakness, or irregular heartbeats.
• Bone Marrow Suppression: Foscarnet may suppress the bone marrow’s ability to produce blood cells, leading to anemia (low red blood cell count), leukopenia (low white blood cell count), or thrombocytopenia (low platelet count), which can increase the risk of bleeding or infection.
• Neurological Symptoms: Some patients may experience neurological side effects such as seizures, confusion, hallucinations, or tremors.
• Gastrointestinal Issues: Nausea, vomiting, diarrhea, and abdominal pain are common gastrointestinal side effects of foscarnet.
• Injection Site Reactions: Pain, redness, swelling, or irritation at the injection site can occur with intravenous administration of foscarnet.
• Skin Reactions: Rash, itching, or other skin reactions may occur in some patients.
• Fever or Chills: Flu-like symptoms such as fever, chills, or fatigue may occur during foscarnet therapy.
• Electrocardiogram (ECG) Changes: Foscarnet may cause changes in the electrical activity of the heart, which can be detected on an ECG.
• Other Side Effects: Less common side effects may include liver function abnormalities, allergic reactions (e.g., rash, swelling, difficulty breathing), and metabolic disturbances.

It’s important to note that not all patients will experience these side effects, and some side effects may be more severe or persistent than others. Patients should report any new or concerning symptoms to their healthcare provider promptly. Additionally, healthcare providers will monitor patients closely for potential side effects during foscarnet therapy.

What should I know about storage and disposal of this medication?

Storage and Disposal of Foscavir (foscarnet):

Storage:

• Store Foscavir vials (powder for injection) at room temperature (between 20-25°C or 68-77°F).
• Keep the vials in their original packaging to protect them from light.
• Do not freeze Foscavir.
• Once reconstituted, the solution should be used immediately. If not used immediately, it can be stored at room temperature for up to 24 hours or refrigerated at 2-8°C (36-46°F) for up to 48 hours. Discard any unused portion after this time.

Disposal:

• Dispose of unused or expired Foscavir vials and solutions properly according to local regulations for hazardous waste disposal.
• Do not flush medications down the toilet or pour them into drains unless instructed to do so. Consult your pharmacist or local waste disposal company for guidance on proper disposal methods.

In case of emergency/overdose

• If you suspect an overdose or experience severe symptoms such as seizures, difficulty breathing, or loss of consciousness, seek emergency medical attention immediately.
• Contact a poison control center or emergency room for guidance on managing an overdose of Foscavir.

What other information should I know?

• Keep all appointments with your healthcare provider for monitoring and follow-up during Foscavir treatment.
• Inform your healthcare provider about all medications, supplements, and herbal products you’re taking to avoid potential drug interactions.
• Avoid driving or operating heavy machinery if you experience dizziness or other neurological side effects while taking Foscavir.
• Do not share Foscavir with others, as it is prescribed specifically for your condition and may not be suitable for others.
• Store Foscavir out of reach of children and pets.
• Always follow your healthcare provider’s instructions and ask any questions you may have about your treatment with Foscavir.