From the Guidelines
Cyclophosphamide precautions in patients with active viral infections require careful consideration of antiviral prophylaxis and monitoring. When using Cyclophosphamide in patients with active viral infections, it is essential to take precautions to prevent viral reactivations and exacerbations.
- Herpes simplex virus (HSV) prophylaxis: Acyclovir or valacyclovir can be used as prophylaxis against HSV and varicella-zoster virus (VZV) in patients undergoing chemotherapy, including those receiving Cyclophosphamide 1.
- Hepatitis B prophylaxis: Patients with chronic hepatitis B or positive HBsAg should receive lamivudine 100 mg qd to prevent HBV reactivation, which can occur in up to 20-50% of HBsAg positive patients undergoing immunosuppressive or antineoplastic treatment 1.
- Influenza prophylaxis: Yearly influenza vaccination with inactivated vaccine is recommended for all patients being treated for cancer, including those receiving Cyclophosphamide 1.
- Monitoring for viral infections: Regular monitoring for viral infections, including HSV, VZV, and CMV, is crucial in patients receiving Cyclophosphamide, especially those with neutropenia or immunosuppression 1.
- Treatment of viral infections: Antiviral treatment should be initiated promptly if there is clinical or laboratory evidence of active viral disease, and the choice of antiviral agent should be based on the specific viral infection and susceptibility patterns 1.
From the FDA Drug Label
Cyclophosphamide can cause myelosuppression (leukopenia, neutropenia, thrombocytopenia and anemia), bone marrow failure, and severe immunosuppression which may lead to serious and sometimes fatal infections, including sepsis and septic shock. Latent infections can be reactivated [see Adverse Reactions (6. 2)]. Cyclophosphamide treatment may not be indicated, or should be interrupted, or the dose reduced, in patients who have or who develop a serious infection.
When using Cyclophosphamide in patients with active viral infections, the following precautions are necessary:
- Monitoring: Close monitoring of complete blood counts is essential during cyclophosphamide treatment.
- Dose adjustment: The dose of cyclophosphamide may need to be adjusted or interrupted in patients who develop a serious infection.
- Antimicrobial prophylaxis: Antimicrobial prophylaxis may be indicated in certain cases of neutropenia at the discretion of the managing physician.
- Antiviral therapy: Antivirals may be indicated in patients with active viral infections.
- Caution: Cyclophosphamide should be used with caution in patients with active infections, and the risk of severe immunosuppression and fatal infections should be carefully considered 2, 2, 2.
From the Research
Precautions for Using Cyclophosphamide in Patients with Active Viral Infections
- Patients with active viral infections should be closely monitored when using cyclophosphamide, as it can increase the risk of opportunistic infections such as pneumonia secondary to pneumocystic carinii 3.
- Prophylactic co-trimoxazole is frequently prescribed to patients on cyclophosphamide to prevent opportunistic infections 3.
- Cyclophosphamide can increase the risk of infection due to its immunosuppressive properties, and the risk is dose-dependent 4.
- Patients on cyclophosphamide should be screened for tuberculosis, hepatitis B, Strongyloides stercoralis, and Pneumocystis jirovecii pneumonia (PJP) 4.
- PJP prophylaxis should be considered when using combination therapy of cyclophosphamide and corticosteroids until a prednisone-equivalent dose of ≤ 5 mg/d is reached 4.
- Cyclophosphamide can convert a relatively harmless infection with an avirulent strain of influenza virus into a fatal pneumonic illness in mice 5.
- The use of cyclophosphamide in patients with active viral infections requires careful consideration of the potential risks and benefits, and patients should be closely monitored for signs of infection 3, 4, 5.
Administration and Monitoring
- Regular blood tests are important to detect bone marrow suppression and lymphopaenia in patients on cyclophosphamide 3.
- Cyclophosphamide dose adjustment may be necessary in patients with kidney disease 6.
- Patients on cyclophosphamide should be monitored for adverse reactions, including changes in white blood cells, platelets, neutrophils, and sodium 6.
- Guidelines for post-chemotherapy patients should include monitoring for rare but serious side effects, such as hepatotoxicity, severe hyponatremia, and heart failure 6.