WARNING

Foscarnet injection is an antiviral medication primarily used to treat cytomegalovirus (CMV) retinitis in patients with HIV/AIDS. Like any medication, it carries certain risks and side effects. Here’s a brief overview:

• Kidney Function Impairment: Foscarnet can cause kidney problems, including decreased kidney function or kidney failure. Patients with pre-existing kidney issues are particularly at risk.
• Electrolyte Imbalance: Foscarnet can disrupt electrolyte balance in the body, leading to conditions such as low calcium, magnesium, or potassium levels.
• Bone Marrow Suppression: Foscarnet can suppress bone marrow function, which may result in decreased production of blood cells (anemia, leukopenia, thrombocytopenia).
• Central Nervous System Effects: Some patients may experience neurological side effects, such as seizures, confusion, or hallucinations.
• Injection Site Reactions: Pain, inflammation, or irritation at the injection site are common side effects.
• Other Adverse Reactions: These may include gastrointestinal disturbances (nausea, vomiting, diarrhea), skin reactions (rash, itching), and fever.
• Drug Interactions: Foscarnet may interact with other medications, potentially affecting their efficacy or increasing the risk of side effects.

It’s crucial for patients receiving foscarnet injection to be closely monitored by healthcare professionals to mitigate these risks and manage any adverse reactions effectively.

Why is this medication prescribed?

Foscarnet injection is prescribed primarily for the treatment of certain viral infections, particularly cytomegalovirus (CMV) retinitis in patients with HIV/AIDS. It is also used for treating other viral infections caused by herpesviruses, including acyclovir-resistant herpes simplex virus (HSV) and varicella-zoster virus (VZV).

How should this medicine be used?

Here’s how Foscarnet injection is commonly used:

• Administration: Foscarnet is typically administered intravenously (IV) by a healthcare professional in a hospital or clinic setting.
• Dosage: The dosage of foscarnet varies depending on the patient’s condition, weight, kidney function, and other factors. It is crucial to follow the dosage instructions provided by the healthcare provider.
• Frequency: Foscarnet is usually given every 8 to 12 hours, but the frequency may be adjusted based on the patient’s response to treatment and any side effects experienced.
• Duration: Treatment duration with foscarnet varies depending on the type and severity of the viral infection being treated. It is typically continued until the infection is under control or as directed by the healthcare provider.
• Monitoring: Patients receiving foscarnet require regular monitoring of kidney function, electrolyte levels, and blood counts to detect any potential side effects or complications.
• Precautions: Foscarnet should be used with caution in patients with pre-existing kidney problems, electrolyte imbalances, or underlying medical conditions. It may also interact with other medications, so it’s essential to inform the healthcare provider about all medications, supplements, and herbal products being taken.
• Storage: Foscarnet injection should be stored according to the manufacturer’s instructions, typically at room temperature away from light and moisture.

It’s important for patients to adhere to the prescribed dosage and schedule and to report any unusual symptoms or side effects to their healthcare provider promptly.

Other uses for this medicine

Aside from its primary use in treating CMV retinitis and certain herpesvirus infections, foscarnet injection may also be utilized for the management of conditions such as acyclovir-resistant herpes simplex virus (HSV) infections and varicella-zoster virus (VZV) infections. Additionally, it may be considered in specific cases where other antiviral medications have proven ineffective or cannot be used due to resistance or intolerable side effects.

What special precautions should I follow?

Special Precautions for Foscarnet Injection:

• Kidney Function Monitoring: Regular monitoring of kidney function, including serum creatinine levels and urine output, is essential during treatment with foscarnet. Dose adjustments may be necessary in patients with impaired renal function.
• Electrolyte Monitoring: Foscarnet can cause electrolyte imbalances, particularly decreases in calcium, magnesium, and potassium levels. Monitoring of electrolyte levels and appropriate supplementation may be required.
• Fluid Intake: Adequate hydration is crucial during foscarnet therapy to help prevent kidney damage and minimize the risk of kidney-related side effects. Patients should be encouraged to drink plenty of fluids unless contraindicated due to other medical conditions.
• Injection Site Care: Foscarnet is administered intravenously, and proper injection site care should be observed to reduce the risk of irritation, inflammation, or infection at the infusion site.
• Neurological Monitoring: Patients receiving foscarnet should be monitored for neurological symptoms, such as seizures, confusion, or hallucinations. Dose adjustments or discontinuation of treatment may be necessary if such symptoms occur.
• Drug Interactions: Foscarnet can interact with other medications, including nephrotoxic drugs and drugs that affect electrolyte balance. Healthcare providers should review the patient’s medication list carefully and adjust dosages or monitor for potential interactions accordingly.
• Pregnancy and Breastfeeding: The safety of foscarnet during pregnancy and breastfeeding has not been established, and its use in these populations should be carefully weighed against potential risks to the mother and fetus or infant.
• Allergic Reactions: Patients should be monitored for signs of allergic reactions, including rash, itching, swelling, or difficulty breathing. Immediate medical attention should be sought if an allergic reaction occurs.
• Follow-up Care: Regular follow-up appointments with healthcare providers are essential during foscarnet therapy to assess treatment response, monitor for side effects, and adjust treatment as necessary.

Patients should always follow their healthcare provider’s instructions and notify them of any concerning symptoms or side effects experienced during foscarnet therapy.

What special dietary instructions should I follow?

There are no specific dietary restrictions associated with foscarnet injection. However, maintaining a balanced diet and staying well-hydrated can support your overall health and may help mitigate some potential side effects of the medication.

What should I do if I forget a dose?

If you miss a dose of foscarnet injection, contact your healthcare provider or infusion center as soon as possible to discuss the best course of action. Do not attempt to double up on doses to make up for a missed one, as this can increase the risk of side effects. Your healthcare provider may adjust your dosing schedule or provide further instructions based on your individual circumstances.

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 Foscarnet Injection:

• Storage: Foscarnet injection should be stored according to the manufacturer’s instructions, typically at room temperature (between 20-25°C or 68-77°F). It should be protected from light and moisture. Do not freeze.
• Disposal: Unused foscarnet solution or empty vials should be disposed of properly according to local regulations or guidelines. Your healthcare provider or pharmacist can provide guidance on safe disposal methods.

In case of emergency/overdose

In case of an emergency or overdose, seek immediate medical attention or contact a poison control center. Symptoms of overdose may include severe kidney problems, electrolyte imbalances, neurological symptoms such as seizures or confusion, and severe gastrointestinal symptoms.

What other information should I know?

• Follow Instructions: Always follow your healthcare provider’s instructions regarding the dosage, administration, and duration of foscarnet therapy.
• Regular Monitoring: You will likely require regular monitoring of kidney function, electrolyte levels, and blood counts during foscarnet therapy. Attend all scheduled follow-up appointments with your healthcare provider.
• Drug Interactions: Inform your healthcare provider about all medications, supplements, and herbal products you are taking before starting foscarnet therapy to avoid potential drug interactions.
• Pregnancy and Breastfeeding: Discuss the risks and benefits of foscarnet therapy if you are pregnant, planning to become pregnant, or breastfeeding, as the safety of the medication in these situations is not well established.
• Inform Healthcare Providers: Make sure to inform any healthcare providers involved in your care, including dentists and emergency medical personnel, that you are receiving foscarnet therapy.
• Adhere to Hygiene Practices: Practice good hygiene, especially around the injection site, to reduce the risk of infection or irritation.
• Report Side Effects: Report any new or concerning symptoms to your healthcare provider promptly, as they may indicate potential side effects or complications requiring medical attention.

Always consult with your healthcare provider or pharmacist if you have any questions or concerns about foscarnet therapy or its administration.