Version July 2025
Tablets: Busulfan is a potent drug. Busulfan should not be used unless a diagnosis of chronic myelogenous leukemia (CML) has been adequately established and the responsible health care provider is knowledgeable in assessing response to chemotherapy.
Tablets: Busulfan can induce severe bone marrow hypoplasia. Reduce or discontinue the dosage of busulfan immediately at the first sign of any unusual depression of bone marrow function as reflected by an abnormal decrease in any of the formed elements of the blood. A bone marrow examination should be performed if the bone marrow status is uncertain.
Injection: Busulfan causes severe and prolonged myelosuppression at the recommended dosage. Hematopoietic progenitor cell transplantation is required to prevent potentially fatal complications of the prolonged myelosuppression.
Dosage guidance:
Safety: Premedicate with prophylactic antiseizure therapy (eg, phenytoin, levetiracetam, benzodiazepines, or valproic acid) beginning 12 hours prior to high-dose busulfan treatment and continuing for 24 hours after the last busulfan dose (when using as a conditioning regimen for transplant or hematopoietic cell–based gene therapy).
Clinical considerations: Antiemetics may be recommended to prevent nausea and vomiting; depending on dose and/or administration route, busulfan is associated with a moderate or high emetic potential in adults. Antiemetics are recommended when used for transplantation. Refer to the protocol or institutional guidance for additional details of off-label dosing.
Hematopoietic cell transplant conditioning regimen in chronic myeloid leukemia: Note: Consider therapeutic drug monitoring and personalized busulfan dosing to minimize sinusoidal obstruction syndrome, lower graft rejection, and lower relapse rates when clinically indicated (Ref). Consider using harmonized busulfan plasma exposure units when conducting busulfan therapeutic drug monitoring (Ref).
IV: 0.8 mg/kg/dose (ideal or actual body weight, whichever is lower) every 6 hours for 4 days (a total of 16 doses) beginning 7 days prior to transplant (followed by cyclophosphamide). For patients with obesity (including severe obesity), the use of an adjusted body weight is recommended.
Hematopoietic cell transplant conditioning regimen in other malignancies (off-label use):
Conditioning regimens; regimen specific dosing (off-label): Note: Myeloablative conditioning regimens generally include total busulfan doses >8 mg/kg (per course) and reduced intensity conditioning regimens typically include total busulfan doses ≤8 mg/kg (per course). Consider therapeutic drug monitoring and personalized busulfan dosing to minimize sinusoidal obstruction syndrome, lower graft rejection, and lower relapse rates when clinically indicated (Ref). Consider using harmonized busulfan plasma exposure units when conducting busulfan therapeutic drug monitoring (Ref).
Busulfan IV regimens:
Bu4/Cy regimen: IV: 0.8 mg/kg every 6 hours for 16 doses (total busulfan dose of 12.8 mg/kg over 4 days; followed by 2 days of cyclophosphamide, then allogeneic HSCT after 1 day of rest) (Ref) or 3.2 mg/kg once daily for 4 doses (total busulfan dose of 12.8 mg/kg over 4 days; followed by 2 days of cyclophosphamide) starting 7 days prior to transplant (Ref) or 1.6 mg/kg every 12 hours for 4 days (total busulfan dose of 12.8 mg/kg over 4 days; followed by 2 days of cyclophosphamide) starting 7 days prior to transplant (Ref) or 3.2 mg/kg once daily for 4 doses (followed by 2 days of cyclophosphamide) beginning 5 days prior to transplant (Ref).
Flu/Bu4 regimen: IV: 0.8 mg/kg every 6 hours for 16 doses beginning 6 days before allogeneic transplant (total busulfan dose 12.8 mg/kg over 4 days; in combination with 4 days of fludarabine) (Ref) or once-daily regimens: 130 mg/m2 over 3 hours once daily for 4 days (in combination with 4 days of fludarabine ± thymoglobulin [administer busulfan after fludarabine each day], followed by allogeneic transplant) (Ref) or 3.2 mg/kg once daily for 4 doses (in combination with 4 days of fludarabine) beginning 5 days prior to transplant (Ref).
Flu/Bu regimen (reduced intensity conditioning regimen): IV: 0.8 mg/kg once daily for 4 days beginning 5 days before allogeneic transplant (total busulfan dose 3.2 mg/kg over 4 days; in combination with 4 days of fludarabine) (Ref).
Flu/Bu2 regimen (reduced intensity conditioning regimen): IV: 3.2 mg/kg once daily for 2 days (in combination with fludarabine and antithymocyte globulin) (Ref) or 0.8 mg/kg every 6 hours for 8 doses (in combination with 5 to 6 days of fludarabine) (Ref).
TBC regimen (for primary CNS lymphoma): IV: 0.67 to 0.8 mg/kg over 2 hours every 6 hours for 12 doses beginning 6 days prior to transplant (total busulfan dose of 8.04 to 9.6 mg/kg over 3 days) in combination with thiotepa and cyclophosphamide, followed by autologous cell transplant (Ref).
Busulfan oral regimens: Note: Oral busulfan preparative regimens may continue to be utilized in some regions, however, due to better pharmacokinetic and toxicity profiles, IV busulfan may be preferred (Ref).
Bu/Cy regimens: Oral: 1 mg/kg every 6 hours for 16 doses (total busulfan dose of 16 mg/kg over 4 days; followed by 2 days of cyclophosphamide, then allogeneic HSCT 2 days later on day 8) (Ref) or 1 mg/kg every 6 hours for 16 doses beginning 9 days prior to transplant (total busulfan dose of 16 mg/kg over 4 days; followed by 4 days of cyclophosphamide, followed by allogeneic or autologous marrow transplant) (Ref).
Bu/Mel regimen: Oral: 1 mg/kg every 6 hours for 16 doses beginning 6 days prior to transplant (total busulfan dose of 16 mg/kg over 4 days; followed by IV melphalan, followed by autologous transplant) (Ref).
Bu/Mel/TT regimen: Oral: 1 mg/kg every 6 hours for 12 doses beginning 8 days prior to transplant (total busulfan dose of 12 mg/kg over 3 days; followed by 2 days of IV melphalan and then 2 days of thiotepa (Ref).
Flu/Bu2 regimen: Oral: 1 mg/kg every 6 hours for 8 doses beginning 6 days prior to transplant (total busulfan dose of 8 mg/kg over 2 days; in combination with 6 days of fludarabine and 4 days of ATG) (Ref).
Flu/Bu4 regimen: Oral: 1 mg/kg every 6 hours for 16 doses (total busulfan dose of 16 mg/kg over 4 days; in combination with 4 days of fludarabine) (Ref).
Myelo ablative conditioning prior to betibeglogene autotemcel in beta thalassemia (off-label use): IV: 3.2 mg/kg/day over 3 hours for 4 consecutive days on day −6 to day −3 for a total of 4 doses or 0.8 mg/kg over 2 hours every 6 hours for 4 consecutive days (on day −6 to day −3) for a total of 16 doses; adjust busulfan dose based on busulfan pharmacokinetics (Ref). Allow at least 48 hours to elapse after the last busulfan dose prior to administering betibeglogene autotemcel.
Myeloa blative conditioning prior to lovotibeglogene autotemcel in sickle cell anemia (off-label use): Note: Calculate initial busulfan dose based on ideal or actual body weight, whichever is lower (Ref).
IV: 3.2 mg/kg/day over 3 hours for 4 consecutive days on day −7 to day −4 for a total of 4 doses or 0.8 mg/kg over 2 hours every 6 hours for 4 consecutive days (on day −7 to day −4) for a total of 16 doses; adjust busulfan dose based on busulfan pharmacokinetics. Allow at least 48 hours to elapse after the last busulfan dose prior to administering lovotibeglogene autotemcel (Ref).
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
IV: There are no dosage adjustments provided in the manufacturer's labeling (has not been studied). If clinically appropriate, may adjust dose based on pharmacokinetic assessment (Ref).
Oral: There are no dosage adjustments provided in the manufacturer's labeling (elimination appears to be independent of kidney function); however, it has been suggested that adjustment is not necessary (Ref).
IV: There are no dosage adjustments provided in the manufacturer's labeling (has not been studied); however, no need for dosage adjustment is expected in mild or moderate impairment; use is not recommended in severe impairment (Ref).
Oral: There are no dosage adjustments provided in the manufacturer's labeling.
Busulfan (IV): For patients with obesity (including severe obesity), use of an adjusted body weight [IBW + 0.25 × (actual – IBW)] is recommended (Busulfex manufacturer's labeling).
American Society for Blood and Marrow Transplantation (ASBMT) practice guideline committee position statement on conditioning chemotherapy dosing in obesity (Ref):
Busulfan (oral): Note: For total doses over 12 mg/kg (per cycle), utilize pharmacokinetically targeted dosage (as appropriate for disease state). When busulfan and cyclophosphamide are used in combination for hematopoietic cell transplantation conditioning, the maximum tolerated busulfan dose is 4 mg/kg/day for 4 days. The maximum tolerated busulfan dose has not been determined when used in combination with other agents.
Body surface area (BSA) dosing: Adults: Utilize actual body weight (ABW) to calculate BSA
Weight based dosing (mg/kg): Adults: Utilize ABW25 for patients with or without obesity
ABW25: Adjusted wt (kg) = Ideal body weight (kg) + 0.25 [actual wt (kg) - ideal body weight (kg)]
Cardiac tamponade: Promptly evaluate and treat if cardiac tamponade is suspected.
Hematologic toxicity: May require platelet or RBC transfusion support and/or antibiotics.
Pulmonary toxicity: Discontinue busulfan.
Oral: Refer to adult dosing. Start with lowest recommended doses for adults.
(For additional information see "Busulfan: Pediatric drug information")
Note: Dose, frequency, number of doses, and/or start date may vary by protocol and treatment phase. Refer to individual protocols and/or therapeutic drug monitoring. Premedicate with prophylactic antiseizure therapy (eg, phenytoin, levetiracetam, benzodiazepines, valproic acid) beginning 12 hours prior to high-dose busulfan treatment and continuing for 24 hours after last busulfan dose. The units of measure for the busulfan AUC (ie, busulfan plasma exposure units) have been modified; previously micromolar/minute was used; however, newer consensus recommends mg × hour/L or mg(hour)/L; use caution when interpreting AUC (Ref).
Busulfan is associated with a high emetic potential; antiemetics are recommended to prevent nausea and vomiting (Ref). Antiemetics are recommended when used for transplantation.
Hematopoietic stem cell transplant (HSCT) conditioning regimen:
IV: Infants, Children, and Adolescents:
Every-6-hour dosing: Note: Although busulfan dosed every 6 hours has been frequently reported in various HSCT conditioning regimens, more recent protocols and expert consensus have suggested that every-24-hours dosing be used; see "Every-24-Hours Dosing" for suggested dosing conversion; refer to specific protocol for appropriate dose interval (Ref). Therapeutic drug monitoring should be considered early in regimen (eg, after first dose) and doses adjusted accordingly. Dosing is based on actual body weight or adjusted body weight in overweight individuals (Ref); refer to individual protocols.
Initial:
≤12 kg: IV: 1.1 mg/kg/dose every 6 hours for 16 doses (over 4 days followed by cyclophosphamide).
>12 kg: IV: 0.8 mg/kg/dose every 6 hours for 16 doses (over 4 days followed by cyclophosphamide).
Dosing adjustment: Doses are adjusted based upon AUC. The desired AUCs are variable and may be dependent upon multiple factors, including indication for transplant, type of transplant, and donor source; specific protocols should be consulted. A desired AUC of ~3.6 to 6.2 mg × hour/L (Ref) or 900 to 1,350 micromolar/minute (Ref) has been suggested. Adjusted dose may be determined from the following formula:
Adjusted dose (mg) = Actual dose (mg) × [target AUC (mg × hour/L) / actual AUC (mg × hour/L)]
Every-24-hours dosing: Limited data available:
Initial: To increase likelihood of target busulfan exposure being achieved early in therapy, utilization of a larger dose every 24 hours has been suggested to replace every-6-hours dosing in some protocols; refer to specific protocols for busulfan dose and frequency. The initial dose is based off of European Medicines Agency (EMA) every-6-hour dosing and a once-daily dose is then calculated. Dose calculations should be based on actual body weight and therapeutic drug monitoring should be considered early in regimen (eg, after first dose) and doses adjusted accordingly (Ref):
|
Busulfan Every-24-Hours Dosing | ||
|---|---|---|
|
Weight (kg) |
EMA Every-6-Hours Busulfan Dose (mg/kg)a |
Every-24-Hours Busulfan Dose (mg/kg) |
|
a Dosing for every 6 hours was used to calculate every-24-hours dosing. | ||
|
<9 kg |
1 mg/kg |
4 mg/kg |
|
9 to <16 kg |
1.2 mg/kg |
4.8 mg/kg |
|
16 to <23 kg |
1.1 mg/kg |
4.4 mg/kg |
|
23 to 34 kg |
0.95 mg/kg |
3.8 mg/kg |
|
>34 kg |
0.8 mg/kg |
3.2 mg/kg |
Dosing adjustment: Doses are adjusted based upon AUC. The desired AUCs are 15.6 to 24.6 mg × hour/L or 3,800 to 6,000 micromolar/minute (Ref). Adjusted dose may be determined from the following formula:
Adjusted dose (mg) = Actual dose (mg) × [target AUC (mg × hour/L) / actual AUC (mg × hour/L)]
Reduced intensity conditioning regimens: Limited data available:
12-dose regimen: Children ≥2 years and Adolescents: IV: 0.8 mg/kg/dose every 6 hours for 12 doses starting on day −6; used in combination with fludarabine and melphalan for patients receiving haploidentical, peripheral blood HSCT for acute leukemia (Ref).
8-dose regimen: Infants, Children, and Adolescents: 0.8 mg/kg/dose for one dose on either day −7 (related donor) or day −10 (unrelated donor or cord recipient) prior to transplant, followed by 7 additional doses of ~0.8 mg/kg/dose every 6 hours (actual dose based on pharmacokinetic analysis after initial dose) beginning days −3 and −2 (related donor) or days −6 and −5 (unrelated donor or cord recipient) prior to transplant; used in combination with fludarabine and antithymocyte globulin (rabbit). In clinical trials, there was no minimum age for inclusion; the youngest patient treated was 2 years (Ref).
Oral:
Note: Not routinely used for HSCT conditioning regimens; IV formulation is the preferred dosage form. Dosing is variable and dependent upon indication for HSCT. For busulfan IV dosing, use of an adjusted body weight is suggested (Ref); however, for oral dosing, pediatric-specific data are lacking and based on adult data; dosing based on actual body weight is suggested in overweight individuals (Ref).
Acute myeloid leukemia: Limited data available: Adolescents ≥16 years: Oral: 1 mg/kg/dose every 6 hours for 16 doses on days −9 to −6 in combination with cyclophosphamide (Ref).
Thalassemia major: Limited data available:
Class 1 or Class 2 (ie, low-risk for GVHD or transplant mortality):
Infants and Children <3 years: Oral: 1.25 mg/kg every 6 hours for 16 doses on day −9 to day −6 prior to transplant in combination with cyclophosphamide and antithymocyte globulin (horse) (Ref).
Children ≥3 years and Adolescents: Oral: 1 mg/kg/dose every 6 hours for 16 doses on day −9 to day −6 prior to transplant in combination with cyclophosphamide and antithymocyte globulin (horse) (Ref).
Class 3 (ie, high-risk disease): Children ≥10 years and Adolescents: Oral: 2 mg/kg/dose every 12 hours for 4 doses on days −8 and −7 in combination with fludarabine and antithymocyte globulin (horse) (Ref).
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
IV: There are no dosage adjustments provided in the manufacturer's labeling (has not been studied).
Oral: There are no dosage adjustments provided in the manufacturer's labeling; elimination appears to be independent of renal function; some clinicians suggest adjustment is not necessary (Ref).
IV: There are no dosage adjustments provided in the manufacturer's labeling (has not been studied).
Oral: There are no dosage adjustments provided in the manufacturer's labeling.
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified. Reported incidences include IV combination therapy with cyclophosphamide unless otherwise indicated.
>10%:
Cardiovascular: Chest pain (26%), edema (28% to 36%), hypertension (36%), tachycardia (44%), thrombosis (33%), vasodilation (25%)
Dermatologic: Pruritus (28%), skin rash (57%)
Endocrine & metabolic: Hyperglycemia (66%), hypocalcemia (49%), hypokalemia (64%), hypomagnesemia (77%)
Gastrointestinal: Abdominal pain (72%), anorexia (85%), constipation (38%), diarrhea (84%), dyspepsia (44%), enlargement of abdomen (23%), nausea (98%), rectal disease (25%), stomatitis (97%), vomiting (95% to 100%), xerostomia (26%)
Hematologic & oncologic: Anemia (69%), bone marrow depression (100%), neutropenia (100%), thrombocytopenia (98%)
Hepatic: Hepatic sinusoidal obstruction syndrome (8% to 12%), hyperbilirubinemia (49%), increased serum alanine aminotransferase (31%)
Hypersensitivity: Hypersensitivity reaction (26%)
Local: Inflammation at injection site (25%)
Nervous system: Anxiety (72%), asthenia (51%), chills (46%), depression (23%), dizziness (30%), headache (69%), insomnia (84%), pain (44%)
Neuromuscular & skeletal: Back pain (23%)
Renal: Increased serum creatinine (21%)
Respiratory: Cough (28%), dyspnea (25%), epistaxis (25%), pulmonary disease (34%), rhinitis (44%)
Miscellaneous: Fever (80%)
1% to 10%: Dermatologic: Skin hyperpigmentation (oral: 5% to 10%)
<1%: Cardiovascular: Cardiomyopathy (endocardial fibrosis; oral)
Frequency not defined (any route):
Cardiovascular: Atrial fibrillation, cardiac arrhythmia, cardiomegaly, complete atrioventricular block, ECG abnormality, flushing, hypotension, left ventricular failure, pericardial effusion, premature ventricular contractions
Dermatologic: Acne vulgaris, exfoliative dermatitis, maculopapular rash, skin discoloration, vesicular eruption, vesiculobullous dermatitis
Endocrine & metabolic: Adrenocortical insufficiency, amenorrhea, hot flash, hypervolemia, hyponatremia, hypophosphatemia, weight gain
Gastrointestinal: Esophagitis, hematemesis, hiccups, intestinal obstruction, pancreatitis, rectal pain
Genitourinary: Dysuria, hematuria, hemorrhagic cystitis, oliguria, ovarian failure
Hematologic & oncologic: Leukopenia, pancytopenia, prolonged prothrombin time
Hepatic: Hepatomegaly, increased serum alkaline phosphatase, jaundice
Immunologic: Graft-versus-host disease
Local: Pain at injection site
Nervous system: Agitation, cerebral hemorrhage, coma, confusion, delirium, drowsiness, encephalopathy, hallucination, lethargy
Neuromuscular & skeletal: Arthralgia, myalgia
Otic: Ear disease
Renal: Increased blood urea nitrogen
Respiratory: Asthma, atelectasis, hemoptysis, hyperventilation, hypoxia, pharyngitis, pleural effusion, pulmonary alveolar hemorrhage, sinusitis
Postmarketing (any route):
Dermatologic: Alopecia, anhidrosis, cheilosis, erythema multiforme, erythema nodosum, fragile skin, urticaria, xeroderma
Endocrine & metabolic: Gynecomastia, porphyria cutanea tarda
Gastrointestinal: Dry mucous membranes, enamel hypoplasia
Genitourinary: Azoospermia, sterility, testicular atrophy
Hematologic & oncologic: Aplastic anemia, dysplasia (cellular [in lymph nodes, pancreas, thyroid, adrenal glands, liver, lungs, bone marrow]), febrile neutropenia, malignant neoplasm, thrombotic microangiopathy, tumor lysis syndrome
Hepatic: Cholestatic jaundice, hepatic disease (hepatocellular atrophy), hepatic fibrosis (centrilobular sinus), hepatic necrosis
Infection: Infection (including bacterial infection, fungal infection, severe infection, viral infection), sepsis
Nervous system: Myasthenia gravis, seizure
Ophthalmic: Cataract (Soysal 1993), corneal thinning, lens disease
Respiratory: Pneumonia, pulmonary fibrosis (with bronchopulmonary dysplasia), pulmonary hypertension (Hagenburg 2021), pulmonary interstitial fibrosis (Littler 1969)
Hypersensitivity to busulfan or any component of the formulation; oral busulfan is contraindicated in patients without a definitive diagnosis of chronic myeloid leukemia.
Canadian labeling: Additional contraindications (not in the US labeling): Oral busulfan: Neutropenia or thrombocytopenia; disease that has demonstrated resistance to busulfan.
Concerns related to adverse effects:
• Bone marrow suppression: Severe and prolonged bone marrow suppression commonly occurs; reduce dose or discontinue oral busulfan for unusual suppression; may require bone marrow biopsy. Hematopoietic cell transplantation is required to prevent potentially fatal complications from prolonged myelosuppression due to IV busulfan. May result in severe neutropenia, thrombocytopenia, anemia, bone marrow failure, and/or severe pancytopenia; pancytopenia may be prolonged (1 month up to 2 years) and may be reversible. The onset of neutropenia is a median of 4 days post-transplant; recovery is within a median of 13 days following allogeneic transplant (with prophylactic filgrastim use in most patients). Thrombocytopenia occurred at a median of 5 to 6 days. Use with caution in patients with compromised bone marrow reserve (due to prior treatment or radiation therapy).
• Cardiovascular: Cardiac tamponade has been reported in children with thalassemia treated with high dose oral busulfan in combination with cyclophosphamide. Abdominal pain and vomiting preceded tamponade in most children.
• Hepatic sinusoidal obstruction syndrome: High busulfan area under the concentration versus time curve (AUC) values (>6.2 mg × hour/L [1,500 micromolar•minute]) with every-6-hours dosing are associated with increased risk of hepatic sinusoidal obstruction syndrome (SOS; formerly called veno-occlusive disease [VOD]) due to conditioning for allogeneic hematopoietic cell transplant. Patients with a history of radiation therapy, prior chemotherapy (≥3 cycles), or prior hematopoietic cell transplantation are also at increased risk of hepatic SOS at recommended dosing regimens. Oral busulfan doses above 16 mg/kg (based on IBW) and concurrent use with alkylating agents may also increase the risk for hepatic SOS.
• Pulmonary toxicity: Bronchopulmonary dysplasia with pulmonary fibrosis (“busulfan lung”) is associated with chronic busulfan use; onset is delayed with symptoms occurring at an average of 4 years (range: 4 months to 10 years) after treatment; may be fatal. Symptoms generally include a slow onset of cough, dyspnea and fever (low-grade), although acute symptomatic onset may also occur. Diminished diffusion capacity and decreased pulmonary compliance have been noted with pulmonary function testing. Differential diagnosis should rule out opportunistic pulmonary infection or leukemic pulmonary infiltrates; may require lung biopsy. Pulmonary toxicity may be additive if administered with other cytotoxic agents also associated with pulmonary toxicity.
• Secondary malignancies: Tumors and acute leukemias have been reported following use. Chromosomal alterations may also occur.
• Seizures: Seizures have been reported with IV busulfan and with high-dose oral busulfan. When using as a conditioning regimen for transplant, initiate prophylactic antiseizure therapy (eg, phenytoin, levetiracetam, benzodiazepines, or valproic acid) prior to treatment. Use with caution in patients predisposed to seizures, with a history of seizures, head trauma, or with other medications associated with inducing seizures.
• Tissue dysplasia: Cellular dysplasia in many organs has been observed (in addition to lung dysplasia); giant hyperchromatic nuclei have been noted in adrenal glands, liver, lymph nodes, pancreas, thyroid, and bone marrow. May obscure routine diagnostic cytologic exams (eg, cervical smear).
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Solution, Intravenous:
Generic: 6 mg/mL (10 mL)
Solution, Intravenous [preservative free]:
Busulfex: 6 mg/mL (10 mL) [contains polyethylene glycol (macrogol)]
Generic: 6 mg/mL (10 mL)
Tablet, Oral:
Myleran: 2 mg
May be product dependent
Solution (Busulfan Intravenous)
6 mg/mL (per mL): $13.80 - $248.40
Solution (Busulfex Intravenous)
6 mg/mL (per mL): $60.00
Tablets (Myleran Oral)
2 mg (per each): $360.43
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Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Solution, Intravenous:
Generic: 6 mg/mL (10 mL)
Tablet, Oral:
Myleran: 2 mg
Antiemetics may be recommended to prevent nausea and vomiting; depending on dose and/or administration route, busulfan is associated with a moderate or high emetic potential in adults. Antiemetics are recommended when used for transplantation.
IV: Intravenous busulfan should be infused over 2 hours via central line. Once daily IV busulfan (off-label dose) has been infused over 3 hours (Ref). Use an administration set with a minimal residual priming volume (2 to 5 mL). Flush line before and after each infusion with 5 mL D5W or NS. Busulfan IV is incompatible with polycarbonate; do not use syringes, filters, or IV tubing containing polycarbonate for preparation or administration.
Busulfan injection contains N,N-dimethylacetamide, which may be incompatible with some closed-system transfer devices (CSTDs); the plastic components of some CSTDs may dissolve and result in subsequent leakage and potential infusion of dissolved plastic into the patient (Ref). Refer to the specific CSTD device manufacturer for compatibility data.
Oral (hematopoietic cell transplant only): To facilitate ingestion of high oral doses, may place multiple tablets into an empty gelatin capsule.
Busulfan is associated with a high emetic potential; antiemetics are recommended to prevent nausea and vomiting (Ref). Antiemetics are recommended when used for transplantation.
Oral: May be administered without regard to meals. To facilitate ingestion of high doses (for hematopoietic stem cell transplant [HSCT]), may insert multiple tablets into clear gelatin capsules for administration.
Parenteral: Infusion time is dependent on dosing interval; for every-6-hours dosing, infuse over 2 hours; in trials for every-24-hours administration, doses were infused over 3 hours (Ref) or as defined in specific protocols or institutional policy. Administer through a central venous catheter; use an administration set with a minimal residual priming volume (1 to 3 mL for pediatric patients); flush line before and after each infusion with 5 mL of D5W or NS. Do not use polycarbonate syringes, filter needles, or IV tubing for preparation or administration.
Hazardous agent (NIOSH 2024 [table 1]).
Use appropriate precautions for receiving, handling, storage, preparation, dispensing, transporting, administration, and disposal. Follow NIOSH and USP 800 recommendations and institution-specific policies/procedures for appropriate containment strategy (NIOSH 2023; NIOSH 2024; USP-NF 2020).
Hematopoietic cell transplant conditioning regimen in chronic myeloid leukemia: Injection: Conditioning regimen (in combination with cyclophosphamide) prior to allogeneic hematopoietic cell transplantation for chronic myeloid leukemia (CML).
Essential thrombocythemia, high risk, refractory or resistant; Hematopoietic cell transplant, conditioning regimen in other (non–chronic myeloid leukemia) malignancies (IV busulfan); Hematopoietic cell transplant conditioning regimen (oral busulfan); Myeloablative conditioning prior to betibeglogene autotemcel in beta thalassemia; Myeloablative conditioning prior to lovotibeglogene autotemcel in sickle cell anemia; Polycythemia vera, high risk, refractory or resistant
Myleran may be confused with Alkeran, Leukeran, melphalan, Mylicon
The Institute for Safe Medication Practices (ISMP) includes this medication among its list of drug classes (chemotherapeutic agent, parenteral and oral) which have a heightened risk of causing significant patient harm when used in error (High-Alert Medications in Acute Care, Community/Ambulatory Care, and Long-Term Care Settings).
A solvent in IV busulfan, N,N-dimethylacetamide, may be incompatible with some closed system transfer devices (CSTDs) used for preparing injectable antineoplastics. The plastic components of some CSTDs may dissolve and result in subsequent leakage and potential infusion of dissolved plastic into the patient (ISMP [Smetzer 2015]). Refer to the specific CSTD device manufacturer for compatibility data.
Busulfan IV is incompatible with polycarbonate; do not use syringes, filters, or IV tubing containing polycarbonate.
None known.
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.
5-Aminosalicylic Acid Derivatives: May increase myelosuppressive effects of Myelosuppressive Agents. Risk C: Monitor
Abrocitinib: May increase immunosuppressive effects of Immunosuppressants (Cytotoxic Chemotherapy). Risk X: Avoid
Acetaminophen: May increase serum concentration of Busulfan. Risk C: Monitor
Androgens: Hypertension-Associated Agents may increase hypertensive effects of Androgens. Risk C: Monitor
Antithymocyte Globulin (Equine): Immunosuppressants (Cytotoxic Chemotherapy) may increase adverse/toxic effects of Antithymocyte Globulin (Equine). Specifically, these effects may be unmasked if the dose of cytotoxic chemotherapy is reduced. Immunosuppressants (Cytotoxic Chemotherapy) may increase immunosuppressive effects of Antithymocyte Globulin (Equine). Specifically, infections may occur with greater severity and/or atypical presentations. Risk C: Monitor
Antithyroid Agents: Myelosuppressive Agents may increase neutropenic effects of Antithyroid Agents. Risk C: Monitor
Baricitinib: Immunosuppressants (Cytotoxic Chemotherapy) may increase immunosuppressive effects of Baricitinib. Risk X: Avoid
BCG Products: Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of BCG Products. Immunosuppressants (Cytotoxic Chemotherapy) may increase adverse/toxic effects of BCG Products. Specifically, the risk of vaccine-associated infection may be increased. Risk X: Avoid
Blinatumomab: May increase serum concentration of Busulfan. Risk C: Monitor
Brincidofovir: Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of Brincidofovir. Risk C: Monitor
Brivudine: May increase adverse/toxic effects of Immunosuppressants (Cytotoxic Chemotherapy). Risk X: Avoid
Chikungunya Vaccine (Live): Immunosuppressants (Cytotoxic Chemotherapy) may increase adverse/toxic effects of Chikungunya Vaccine (Live). Specifically, the risk of vaccine-associated infection may be increased. Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of Chikungunya Vaccine (Live). Risk X: Avoid
Chloramphenicol (Ophthalmic): May increase adverse/toxic effects of Myelosuppressive Agents. Risk C: Monitor
Chloramphenicol (Systemic): Myelosuppressive Agents may increase myelosuppressive effects of Chloramphenicol (Systemic). Risk X: Avoid
Cladribine: Immunosuppressants (Cytotoxic Chemotherapy) may increase immunosuppressive effects of Cladribine. Risk X: Avoid
CloZAPine: Myelosuppressive Agents may increase adverse/toxic effects of CloZAPine. Specifically, the risk for neutropenia may be increased. Risk C: Monitor
Coccidioides immitis Skin Test: Coadministration of Immunosuppressants (Cytotoxic Chemotherapy) and Coccidioides immitis Skin Test may alter diagnostic results. Management: Consider discontinuing cytotoxic chemotherapy several weeks prior to coccidioides immitis skin antigen testing to increase the likelihood of accurate diagnostic results. Risk D: Consider Therapy Modification
COVID-19 Vaccine (Inactivated Virus): Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of COVID-19 Vaccine (Inactivated Virus). Risk C: Monitor
COVID-19 Vaccine (mRNA): Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of COVID-19 Vaccine (mRNA). Management: Give a 3-dose primary series for all patients aged 6 months and older taking immunosuppressive medications or therapies. Booster doses are recommended for certain age groups. See CDC guidance for details. Risk D: Consider Therapy Modification
COVID-19 Vaccine (Subunit): Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of COVID-19 Vaccine (Subunit). Risk C: Monitor
Deferasirox: May increase serum concentration of Busulfan. Management: Discontinue deferasirox 2 to 3 days (approximately 5 half-lives) before initiation of busulfan. If combined, monitor for increased busulfan concentrations and effects. Decreased busulfan doses may be required during concomitant use. Risk D: Consider Therapy Modification
Deferiprone: Myelosuppressive Agents may increase neutropenic effects of Deferiprone. Management: Avoid the concomitant use of deferiprone and myelosuppressive agents whenever possible. If this combination cannot be avoided, monitor the absolute neutrophil count more closely. Risk D: Consider Therapy Modification
Dengue Tetravalent Vaccine (Live): Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of Dengue Tetravalent Vaccine (Live). Immunosuppressants (Cytotoxic Chemotherapy) may increase adverse/toxic effects of Dengue Tetravalent Vaccine (Live). Specifically, the risk of vaccine-associated infection may be increased. Risk X: Avoid
Denosumab: May increase immunosuppressive effects of Immunosuppressants (Cytotoxic Chemotherapy). Management: Consider the risk of serious infections versus the potential benefits of coadministration of denosumab and cytotoxic chemotherapy. If combined, monitor patients for signs/symptoms of serious infections. Risk D: Consider Therapy Modification
Deucravacitinib: May increase immunosuppressive effects of Immunosuppressants (Cytotoxic Chemotherapy). Risk X: Avoid
Etrasimod: May increase immunosuppressive effects of Immunosuppressants (Cytotoxic Chemotherapy). Risk X: Avoid
Fexinidazole: Myelosuppressive Agents may increase myelosuppressive effects of Fexinidazole. Risk X: Avoid
Filgotinib: May increase immunosuppressive effects of Immunosuppressants (Cytotoxic Chemotherapy). Risk X: Avoid
Fosphenytoin-Phenytoin: May decrease serum concentration of Busulfan. Risk C: Monitor
Ifosfamide: Busulfan may increase adverse/toxic effects of Ifosfamide. Specifically, the risk of hemorrhagic cystitis may be increased. Risk C: Monitor
Inebilizumab: Immunosuppressants (Cytotoxic Chemotherapy) may increase immunosuppressive effects of Inebilizumab. Risk C: Monitor
Influenza Virus Vaccines: Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of Influenza Virus Vaccines. Management: Administer influenza vaccines at least 2 weeks prior to initiating chemotherapy if possible. If vaccination occurs less than 2 weeks prior to or during chemotherapy, revaccinate at least 3 months after therapy discontinued if immune competence restored. Risk D: Consider Therapy Modification
Itraconazole: May increase serum concentration of Busulfan. Risk C: Monitor
Leflunomide: Immunosuppressants (Cytotoxic Chemotherapy) may increase immunosuppressive effects of Leflunomide. Management: Increase the frequency of chronic monitoring of platelet, white blood cell count, and hemoglobin or hematocrit to monthly, instead of every 6 to 8 weeks, if leflunomide is coadministered with immunosuppressive agents, such as cytotoxic chemotherapy. Risk D: Consider Therapy Modification
Lenograstim: Antineoplastic Agents may decrease therapeutic effects of Lenograstim. Management: Avoid the use of lenograstim 24 hours before until 24 hours after the completion of myelosuppressive cytotoxic chemotherapy. Risk D: Consider Therapy Modification
Linezolid: May increase myelosuppressive effects of Myelosuppressive Agents. Risk C: Monitor
Lipegfilgrastim: Antineoplastic Agents may decrease therapeutic effects of Lipegfilgrastim. Management: Avoid concomitant use of lipegfilgrastim and myelosuppressive cytotoxic chemotherapy. Lipegfilgrastim should be administered at least 24 hours after the completion of myelosuppressive cytotoxic chemotherapy. Risk D: Consider Therapy Modification
MetroNIDAZOLE (Systemic): May increase serum concentration of Busulfan. Management: Avoid coadministration metronidazole and busulfan due to increased risks of busulfan toxicity. If coadministration is required, monitor busulfan concentrations closely and adjust the busulfan dose as needed. Risk D: Consider Therapy Modification
Mumps- Rubella- or Varicella-Containing Live Vaccines: Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of Mumps- Rubella- or Varicella-Containing Live Vaccines. Immunosuppressants (Cytotoxic Chemotherapy) may increase adverse/toxic effects of Mumps- Rubella- or Varicella-Containing Live Vaccines. Specifically, the risk of vaccine-associated infection may be increased. Risk X: Avoid
Nadofaragene Firadenovec: Immunosuppressants (Cytotoxic Chemotherapy) may increase adverse/toxic effects of Nadofaragene Firadenovec. Specifically, the risk of disseminated adenovirus infection may be increased. Risk X: Avoid
Natalizumab: Immunosuppressants (Cytotoxic Chemotherapy) may increase immunosuppressive effects of Natalizumab. Risk X: Avoid
Ocrelizumab: Immunosuppressants (Cytotoxic Chemotherapy) may increase immunosuppressive effects of Ocrelizumab. Risk C: Monitor
Ofatumumab: Immunosuppressants (Cytotoxic Chemotherapy) may increase immunosuppressive effects of Ofatumumab. Risk C: Monitor
Olaparib: Myelosuppressive Agents may increase myelosuppressive effects of Olaparib. Risk C: Monitor
Palifermin: May increase adverse/toxic effects of Antineoplastic Agents. Specifically, the duration and severity of oral mucositis may be increased. Management: Do not administer palifermin within 24 hours before, during infusion of, or within 24 hours after administration of myelotoxic chemotherapy. Risk D: Consider Therapy Modification
Pidotimod: Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of Pidotimod. Risk C: Monitor
Pimecrolimus: May increase immunosuppressive effects of Immunosuppressants (Cytotoxic Chemotherapy). Risk X: Avoid
Piperacillin: May increase hypokalemic effects of Antineoplastic Agents. Risk C: Monitor
Pneumococcal Vaccines: Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of Pneumococcal Vaccines. Risk C: Monitor
Poliovirus Vaccine (Live/Trivalent/Oral): Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of Poliovirus Vaccine (Live/Trivalent/Oral). Immunosuppressants (Cytotoxic Chemotherapy) may increase adverse/toxic effects of Poliovirus Vaccine (Live/Trivalent/Oral). Specifically, the risk of vaccine-associated infection may be increased. Risk X: Avoid
Polymethylmethacrylate: Immunosuppressants (Cytotoxic Chemotherapy) may increase hypersensitivity effects of Polymethylmethacrylate. Management: Use caution when considering use of bovine collagen-containing implants such as the polymethylmethacrylate-based Bellafill brand implant in patients who are receiving immunosuppressants. Consider use of additional skin tests prior to administration. Risk D: Consider Therapy Modification
Promazine: May increase myelosuppressive effects of Myelosuppressive Agents. Risk C: Monitor
Propacetamol: May increase serum concentration of Busulfan. Risk C: Monitor
Rabies Vaccine: Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of Rabies Vaccine. Management: Complete rabies vaccination at least 2 weeks before initiation of immunosuppressant therapy if possible. If combined, check for rabies antibody titers, and if vaccination is for post exposure prophylaxis, administer a 5th dose of the vaccine. Risk D: Consider Therapy Modification
Ritlecitinib: Immunosuppressants (Cytotoxic Chemotherapy) may increase immunosuppressive effects of Ritlecitinib. Risk X: Avoid
Ropeginterferon Alfa-2b: Myelosuppressive Agents may increase myelosuppressive effects of Ropeginterferon Alfa-2b. Management: Avoid coadministration of ropeginterferon alfa-2b and other myelosuppressive agents. If this combination cannot be avoided, monitor patients for excessive myelosuppressive effects. Risk D: Consider Therapy Modification
Ruxolitinib (Topical): Immunosuppressants (Cytotoxic Chemotherapy) may increase immunosuppressive effects of Ruxolitinib (Topical). Risk X: Avoid
Sipuleucel-T: Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of Sipuleucel-T. Management: Consider reducing the dose or discontinuing the use of immunosuppressants, such as cytotoxic chemotherapy, prior to initiating sipuleucel-T therapy. Risk D: Consider Therapy Modification
Solriamfetol: May increase hypertensive effects of Hypertension-Associated Agents. Risk C: Monitor
Sphingosine 1-Phosphate (S1P) Receptor Modulators: May increase immunosuppressive effects of Immunosuppressants (Cytotoxic Chemotherapy). Risk C: Monitor
Tacrolimus (Topical): Immunosuppressants (Cytotoxic Chemotherapy) may increase immunosuppressive effects of Tacrolimus (Topical). Risk X: Avoid
Talimogene Laherparepvec: Immunosuppressants (Cytotoxic Chemotherapy) may increase adverse/toxic effects of Talimogene Laherparepvec. Specifically, the risk of infection from the live, attenuated herpes simplex virus contained in talimogene laherparepvec may be increased. Risk X: Avoid
Tertomotide: Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of Tertomotide. Risk X: Avoid
Tofacitinib: Immunosuppressants (Cytotoxic Chemotherapy) may increase immunosuppressive effects of Tofacitinib. Risk X: Avoid
Typhoid Vaccine: Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of Typhoid Vaccine. Immunosuppressants (Cytotoxic Chemotherapy) may increase adverse/toxic effects of Typhoid Vaccine. Specifically, the risk of vaccine-associated infection may be increased. Risk X: Avoid
Ublituximab: Immunosuppressants (Cytotoxic Chemotherapy) may increase immunosuppressive effects of Ublituximab. Risk C: Monitor
Upadacitinib: Immunosuppressants (Cytotoxic Chemotherapy) may increase immunosuppressive effects of Upadacitinib. Risk X: Avoid
Vaccines (Live): Immunosuppressants (Cytotoxic Chemotherapy) may increase adverse/toxic effects of Vaccines (Live). Specifically, the risk of vaccine-associated infection may be increased. Vaccines (Live) may decrease therapeutic effects of Immunosuppressants (Cytotoxic Chemotherapy). Risk X: Avoid
Vaccines (Non-Live/Inactivated/Non-Replicating): Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of Vaccines (Non-Live/Inactivated/Non-Replicating). Management: Give non-live/inactivated/non-replicating vaccines at least 2 weeks prior to starting chemotherapy when possible. Patients vaccinated less than 14 days before or during chemotherapy should be revaccinated at least 3 months after therapy is complete. Risk D: Consider Therapy Modification
Yellow Fever Vaccine: Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of Yellow Fever Vaccine. Immunosuppressants (Cytotoxic Chemotherapy) may increase adverse/toxic effects of Yellow Fever Vaccine. Specifically, the risk of vaccine-associated infection may be increased. Risk X: Avoid
Zoster Vaccine (Live/Attenuated): Immunosuppressants (Cytotoxic Chemotherapy) may increase adverse/toxic effects of Zoster Vaccine (Live/Attenuated). Specifically, the risk of vaccine-associated infection may be increased. Immunosuppressants (Cytotoxic Chemotherapy) may decrease therapeutic effects of Zoster Vaccine (Live/Attenuated). Risk X: Avoid
Patients who could become pregnant should use effective contraception to avoid pregnancy during treatment and for 6 months after the last dose of busulfan. Patients with partners who could become pregnant should use effective contraception during treatment and for 3 months after the last busulfan dose.
Busulfan is associated with a high risk of infertility (ESMO [Lambertini 2020]). Busulfan has been associated with ovarian suppression, amenorrhea, azoospermia, and testicular atrophy. High-dose busulfan may cause temporary or permanent infertility when administered prior to puberty.
Recommendations are available for fertility preservation of patients to be treated with anticancer agents (ASCO [Oktay 2018]; Klipstein 2020).
Busulfan has a high teratogenic and abortive risk (Lishner 2016). Based on the mechanism of action, and data from animal reproduction studies, in utero exposure to busulfan may cause fetal harm. The solvent in IV busulfan, DMA, is also associated with teratogenic effects in animal studies.
Outcome data following maternal use of busulfan during pregnancy are limited (NTP 2013). Outcome data for pregnancies occurring following use of busulfan as a conditioning agent in patients with a hematopoietic cell transplant prior to puberty are available (Balashov 2011; Chabut 2023; Diesch-Furlanetto 2021; İskender 2022; Shah 2011).
The European Society for Medical Oncology (ESMO) has published guidelines for diagnosis, treatment, and follow-up of cancer during pregnancy. The guidelines recommend referral to a facility with expertise in cancer during pregnancy and encourage a multidisciplinary team (obstetrician, neonatologist, oncology team) approach. In general, if chemotherapy is indicated, it should be avoided in the first trimester and there should be a 3-week time period between the last chemotherapy dose and anticipated delivery, and chemotherapy should not be administered beyond week 33 of gestation (ESMO [Peccatori 2013]). Guidance is available for patients with hematologic malignancies during pregnancy (Lishner 2015). A long-term observational research study is collecting information about the diagnosis and treatment of cancer during pregnancy. For additional information about the pregnancy and cancer registry or to become a participant, contact Cooper Health (877-635-4499).
It is not known if busulfan is present in breast milk.
Due to the potential for serious adverse reactions in the breastfed infant, breastfeeding is not recommended by the manufacturer.
CBC with differential and platelet count (weekly for palliative treatment; daily during treatment and until engraftment for hematopoietic cell transplant [HCT]); liver function tests (evaluate transaminases, alkaline phosphatase, and bilirubin daily for at least 28 days post transplant). Monitor for signs/symptoms of cardiac tamponade, sinusoidal obstruction syndrome, infection, and bleeding. Monitor adherence (for oral busulfan).
The American Society of Clinical Oncology hepatitis B virus (HBV) screening and management provisional clinical opinion (ASCO [Hwang 2020]) recommends HBV screening with hepatitis B surface antigen, hepatitis B core antibody, total Ig or IgG, and antibody to hepatitis B surface antigen prior to beginning (or at the beginning of) systemic anticancer therapy; do not delay treatment for screening/results. Detection of chronic or past HBV infection requires a risk assessment to determine antiviral prophylaxis requirements, monitoring, and follow-up.
If conducting therapeutic drug monitoring for AUC calculations in HCT, monitor blood samples at appropriate collections times (record collection times). Do not collect blood sample during busulfan infusion; collect blood sample from a different port than that used for infusion. Blood samples should be placed on wet ice immediately after collection and should be centrifuged (at 4°C [39.2°F]) within 1 hour. The plasma, harvested into appropriate cryovial storage tubes, should be frozen immediately at −20°C (−4°F). All plasma samples should be sent frozen (on dry ice) to the assay laboratory for the determination of plasma busulfan concentrations.
Busulfan is an alkylating agent which reacts with the N-7 position of guanosine and interferes with DNA replication and transcription of RNA. Busulfan has a more marked effect on myeloid cells than on lymphoid cells and is also very toxic to hematopoietic cells. Busulfan exhibits little immunosuppressive activity. It interferes with the normal function of DNA by alkylation and cross-linking the strands of DNA.
Absorption: Rapid and complete
Distribution: Vd: Pediatric (IV): ~0.64 L/kg; crosses blood brain barrier and distributes into CSF with levels equal to plasma
Protein binding: ~32% to plasma proteins and 47% to red blood cells
Metabolism: Extensively hepatic (may increase with multiple doses); glutathione conjugation followed by oxidation
Bioavailability: Oral: Children ≥13 years and adults: 80% (range: 47% to 103%); Children 1.5 to 6 years: 68% (range: 22% to 120%)
Half-life elimination: 2 to 3 hours
Time to peak, serum: Oral: ~1 hour; IV: Within 5 minutes
Excretion: Urine (25% to 60% predominantly as metabolites; <2% as unchanged drug)
Clearance: Children: 3.37 mL/minute/kg; Adults: 2.52 mL/minute/kg (range: 1.49 to 4.31 mL/minute/kg)
Altered kidney function: In a patient with chronic kidney failure undergoing autologous hematopoietic cell transplantation, the apparent oral clearance of busulfan during a 4-hour hemodialysis session was increased 65%, but the 24-hour oral clearance of busulfan was increased only 11%.
