Methylprednisolone Concentrations in Breast Milk and Serum of Patients with Multiple Sclerosis Treated with IV Pulse Methylprednisolone

•During and after pulse therapy, the concentration of methylprednisolone in breast milk is quite low.•Absolute infant dose is below levels likely to cause harm.•Transfer of methylprednisolone from maternal serum to breast milk is low.•Intravenous methylprednisolone treatment has no adverse effects on infants in short term. It is commonly known that women with multiple sclerosis (MS) have an increased risk for relapses during the post-partum period. High-dose IV methylprednisolone is the first-line treatment for acute relapses. Methylprednisolone is administered to lactating women although there is insufficient data as to the levels of concentration in breast milk and serum, and the calculated steroid exposure to infants. The study aimed to measure the transfer of methylprednisolone into breast milk and the correlation of milk and serum methylprednisolone concentrations in breastfeeding MS patients during and after infusion therapy. IV methylprednisolone pulse therapy was given to 12 lactating MS patients. Breast milk and maternal serum samples were obtained; before infusion, 30 minutes into the infusion, at the end of infusion and at the 1st, 2nd, 4th, 8th, 12th and 24th hours subsequently. The highest level of methylprednisolone concentration in breast milk (2.09 μg/ml) and serum (6.09 μg/ml) was detected at the end of the infusion. According to the measurements recorded at the 1st, 2nd, 4th, 8th, 12th, and 24th hours after infusion, the concentrations showed a gradual decrease both breast milk and serum. The milk and serum methylprednisolone concentrations were below detection limits just before infusion and at the 24th hour after infusion. A highly significant correlation was found between breast milk and maternal serum levels. The absolute infant dose was calculated to be 69.50 μg/kg/day and the relative infant dose (RID) was 0.50%. Results have shown that the transfer of methylprednisolone into breast milk seems to be low. Although, concentration levels may not seem to pose a threat to the infant, mothers can choose to wait 2 to 4 hours to further limit the level of exposure.