Interferons (IFN) are signaling molecules that trigger the body’s immune response. Interferons treat viral diseases, multiple sclerosis, and some malignant neoplasms.
American and Swedish scientists talk about the clinical experience of treating melanoma and chronic myeloid leukemia with interferon-alpha in pregnant and lactating women.
Does Interferon Pass into Breast Milk?
A young breastfeeding mother was diagnosed with malignant melanoma. For treatment, she was prescribed interferon-alpha-2b at a dosage of 30 million IU intravenously over 30 minutes. The patient did not take any other medications.
Before the start of interferon treatment, the patient gave two control samples of breast milk. On the first day of treatment, breast milk samples were collected every 4 hours after interferon administration for 21 hours.
Interferon levels in breast milk before treatment ranged from 894 to 1249 IU/mL plasma. 4 and 8 hours after intravenous administration of 30 million IU of IFN-alpha-2b, interferon levels in milk only slightly increased to 1551 and 1507 IU, respectively. The difference with the control levels before treatment is about 460 IU.
This result shows that even after administering massive doses, interferon-alpha-2b does not pass into breast milk in clinically significant amounts. Therefore, the likelihood that breastfed infants will experience side effects from interferon treatment is low.
The study was published in 2000 in the Journal of Human Lactation.
How Interferon Treatment During Pregnancy Affects IFN Levels in Breast Milk
Swedish scientists describe two more clinical cases of the use of interferon in lactating women. In both cases, young women at 13 weeks pregnant had a significantly elevated white blood cell count, and further tests showed chronic myeloid leukemia.
As the initial treatment, the first patient was given leukapheresis, a procedure to lower a very high white blood cell count. Interferon-alpha at a dosage of 8 million IU 3 times a week was a further treatment. The patient had no side effects and was treated throughout her pregnancy. The number of leukocytes decreased to normal after 6 months. A healthy baby was born at term by cesarean section. Serum IFN-alpha was 20.8 IU/mL in the mother and less than 0.6 IU/mL in the newborn. The concentration of interferon in breast milk was 1.4 IU/ml.
The second patient was treated with interferon-alpha at a dosage of 5 million IU 3 times a week, and the dose was gradually increased to 8 million IU/day. After 6 months of treatment, the number of leukocytes returned to normal, and the initially high level of platelets also returned to normal. There were no side effects, and a healthy baby was born at term. Immediately postpartum, serum IFN-alpha levels were 58 IU/mL in the mother and less than 1 IU/mL in the infant. Interferon levels in breast milk were 6 IU/mL.
The study was published in 1996 in the European Journal of Haematology.
Conclusion
The molecular weight of human interferon-alpha is from 17.5 to 23 kDa. After intravenous administration, the concentration of interferon in serum decreases rapidly – by 2 times in 4-16 hours, and interferon is redistributed to other tissues.
Whether drugs pass into breast milk depends on molecular size, molecular weight, fat-dissolving capacity, and plasma levels of the active ingredient after drug administration.
The milk-secreting cells of the mammary glands do not allow substances with a molecular weight of more than 1 kDa to pass through, especially two weeks after birth. Even with the introduction of huge doses of interferon, its too large molecular weight and rapid redistribution to other tissues exclude the ingress of IFN into breast milk in clinically significant amounts.
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References
- Transfer of interferon alfa into human breast milk
- Two cases of CML treated with third-interferon during second and trimester of pregnancy with analysis of the drug in the newborn immediately postpartum
