Busulfan Kabi Special Precautions

The following warnings pertain to different physiologic effects of busulfan in the setting of allogeneic transplantation.
Myelosuppression: The most frequent serious consequence of treatment with busulfan at the recommended dose and schedule is prolonged myelosuppression, occurring in all patients (100%). Severe granulocytopenia, thrombocytopenia, anemia, or any combination thereof may develop. Hematopoietic progenitor cell transplantation is required to prevent potentially fatal complications of the prolonged myelosuppression. Monitor complete blood counts, including white blood cell differentials, and quantitative platelet counts daily during treatment and until engraftment is demonstrated. Absolute neutrophil counts dropped below 0.5x10⁹/L at a median of 4 days post-transplant in 100% of patients treated in the busulfan clinical trial. The absolute neutrophil count recovered at a median of 13 days following allogeneic transplantation when prophylactic G-CSF was used in the majority of patients. Thrombocytopenia (less than 25,000/mm³ or requiring platelet transfusion) occurred at a median of 5-6 days in 98% of patients. Anemia (hemoglobin less than 8.0 g/dL) occurred in 69% of patients. Use antibiotic therapy and platelet and red blood cell support when medically indicated.
Seizures: Seizures have been reported in patients receiving high-dose oral busulfan at doses producing plasma drug levels similar to those achieved following the recommended dosage of busulfan. Despite prophylactic therapy with phenytoin, one seizure (1/42 patients) was reported during an autologous transplantation clinical trial of busulfan. This episode occurred during the cyclophosphamide portion of the conditioning regimen, 36 hours after the last busulfan dose. Anti-convulsant prophylactic therapy should be initiated prior to busulfan treatment. Caution should be exercised when administering the recommended dose of busulfan to patients with a history of a seizure disorder or head trauma or who are receiving other potentially epileptogenic drugs.
Hepatic Veno-Occlusive Disease (HVOD): Current literature suggests that high busulfan area under the plasma concentration verses time curve (AUC) values (>1,500 µM·min) may be associated with an increased risk of developing hepatic veno-occlusive disease (HVOD). Patients who have received prior radiation therapy, greater than or equal to three cycles of chemotherapy, or a prior progenitor cell transplant may be at an increased risk of developing HVOD with the recommended busulfan dose and regimen. Based on clinical examination and laboratory findings, hepatic veno-occlusive disease was diagnosed in 8% (5/61) of patients treated with busulfan in the setting of allogeneic transplantation, was fatal in 2/5 cases (40%), and yielded an overall mortality from HVOD in the entire study population of 2/61 (3%). Three of the five patients diagnosed with HVOD were retrospectively found to meet the Jones' criteria. The incidence of HVOD reported in the literature from the randomized, controlled trials was 7.7%-12%. Monitor serum transaminases, alkaline phosphatase, and bilirubin daily through BMT Day +28 to detect hepatotoxicity, which may herald the onset of HVOD.
Cardiac Tamponade: Cardiac tamponade has been reported in pediatric patients with thalassemia (8/400 or 2% in one series) who received high doses of oral busulfan and cyclophosphamide as the preparatory regimen for hematopoietic progenitor cell transplantation. Six of the eight children died and two were saved by rapid pericardiocentesis. Abdominal pain and vomiting preceded the tamponade in most patients. Monitor for signs and symptoms, promptly evaluate and treat if cardiac tamponade is suspected.
Bronchopulmonary Dysplasia: Bronchopulmonary dysplasia with pulmonary fibrosis is a rare but serious complication following chronic busulfan therapy. The average onset of symptoms is 4 years after therapy (range 4 months to 10 years).
Cellular Dysplasia: Busulfan may cause cellular dysplasia in many organs. Cytologic abnormalities characterized by giant, hyperchromatic nuclei have been reported in lymph nodes, pancreas, thyroid, adrenal glands, liver, lungs and bone marrow. This cytologic dysplasia may be severe enough to cause difficulty in the interpretation of exfoliative cytologic examinations of the lungs, bladder, breast and the uterine cervix.
Carcinogenesis, Mutagenesis and Impairment of Fertility: Busulfan is a mutagen and a clastogen. In in vitro tests it caused mutations in Salmonella typhimurium and Drosophila melanogaster. Chromosomal aberrations induced by busulfan have been reported in vivo (rats, mice, hamsters, and humans) and in vitro (rodent and human cells). The intravenous administration of busulfan (48 mg/kg given as biweekly doses of 12 mg/kg, or 30% of the total busulfan dose on a mg/m² basis) has been shown to increase the incidence of thymic and ovarian tumors in mice.
Busulfan depleted oocytes of female rats and induced sterility in male rats and hamsters. The solvent DMA ((Dimethylacetamide) may also impair fertility. A DMA daily dose of 0.45 g/kg/d given to rats for nine days (equivalent to 44% of the daily dose of DMA contained in the recommended dose of Busulfan on a mg/m² basis) significantly decreased spermatogenesis in rats. A single sc dose of 2.2 g/kg (27% of the total DMA dose contained in busulfan on a mg/m² basis) four days after insemination terminated pregnancy in 100% of tested hamsters.
Renal Impairment: Busulfan has not been studied in patients with renal impairment.
Hepatic Impairment: Busulfan has not been administered to patients with hepatic insufficiency.
Use in Pregnancy: Embryo-fetal Toxicity: Busulfan can cause fetal harm when administered to a pregnant woman based on animal data. Busulfan was teratogenic in mice, rats, and rabbits. The solvent, DMA, may also cause fetal harm when administered to a pregnant woman based on findings in animals. Advise pregnant women of the potential risk to a fetus. Advise females and males of reproductive potential to use effective contraception during and after treatment with busulfan.
Use in the Elderly: Five of sixty-one patients treated in the busulfan clinical trial were over the age of 55 (range 57-64). All achieved myeloablation and engraftment.