What is the conversion of bleomycin units to milligrams (mg)?

Bleomycin Unit to Milligram Conversion

One unit of bleomycin is equal to 1 mg of bleomycin activity. 1

Explanation of Bleomycin Units

Bleomycin is a mixture of cytotoxic glycopeptide antibiotics isolated from Streptomyces verticillus. The FDA drug label clearly states that "a unit of bleomycin is equal to the formerly used milligram activity." 1 This means that when dosing bleomycin:

• 1 unit = 1 mg of activity
• The term "milligram activity" was changed to "units" for precision
• This is not the same as the actual physical weight of the compound

Clinical Dosing of Bleomycin

Bleomycin dosing appears in several standard chemotherapy regimens:

BEP Regimen (Testicular Cancer)

• 30 mg (units) IV bolus on days 1,8, and 15 2
• Usual adult dose for testicular cancer is a fixed dose in BEP regimen 2

ABVD Regimen (Hodgkin Lymphoma)

• 10 mg/m² IV on days 1 and 15 2

Pleural Effusion Management

• 60 units mixed in normal saline as a sclerosant 2

Important Clinical Considerations

1. Risk of Hypersensitivity Reactions:

   • Incidence of 1% of infusion reactions
   • Usually occurs after first or second dose
   • Symptoms include hypotension, mental confusion, fever, chills, wheezing
   • Lymphoma patients should be treated with 2 units or less for first 2 doses 2

2. Pulmonary Toxicity:

   • Major adverse effect of bleomycin
   • Consider avoiding in patients with pre-existing pulmonary disease
   • PEI/VIP regimens may be used if contraindication against bleomycin exists 2

3. Fixed Dosing Considerations:

   • Bleomycin is one of the few cytotoxic agents where fixed dosing (independent of BSA) may be appropriate 2

4. Mechanism of Action:

   • Binds to DNA and produces free radicals that cause DNA strand breaks
   • Cytotoxicity is cell-cycle specific for G2 phase 3

Common Pitfalls

• Do not confuse units with the actual physical weight of the drug
• Be aware that bleomycin has unique toxicity profiles, particularly pulmonary toxicity
• When calculating doses, remember that the unit conversion (1 unit = 1 mg activity) is already factored into standard protocols
• Avoid exceeding recommended cumulative doses due to risk of pulmonary fibrosis

In summary, when you see bleomycin prescribed in units, this is equivalent to the same number in milligrams of activity, as confirmed by the FDA drug label.