A patient with dendritic cell carcinoma who had been taking amiodarone for 18 months, and who had received 6 cycles of chemotherapy including cyclophosphamide over previous 12 months, was admitted to hospital with progressive shortness of breath 18 days after being given a single 4000-mg/m(See reference number 2) dose of cyclophosphamide. He was found to have interstitial pneumonitis and a lung biopsy indicated drug-induced pulmonary toxicity. The patient’s condition improved rapidly over following 10 days with discontinuation of amiodarone and treatment with prednisolone 60mg daily. Over previous year he had also received vincristine, etoposide and prednisone, cisplatin, cytarabine and dexamethasone as part of his chemotherapy.(See reference number 1) A patient with non-Hodgkin’s lymphoma who had been taking amiodarone 300mg twice daily for 4 years,developed acute respiratory distress 2 days after being given a single dose of cyclophosphamide. This was eventually fatal. Autopsy revealed lung damage consistent with effects of amiodarone and cyclophosphamide, with cyclophosphamide major cause. Other drugs used as part of chemotherapy regimen were rituximab, doxorubicin, vincristine and prednisone (See reference number 2).
The early onset of symptoms in patients described above suggests accelerated mechanisms of pulmonary toxicity. Both cyclophosphamide and amiodarone pulmonary toxicity appear to be enhanced by oxygen and combination of cyclophosphamide with amiodarone may enhance oxidative stress and therefore pulmonary toxicity
Although information seems to be limited to two case reports cited, potential for both cyclophosphamide and amiodarone to cause pulmonary toxicity is established. Be alert to possibility of enhanced pulmonary toxicity if these drugs are given together.
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