Mechlorethamine

No drug interaction studies have been performed with VALCHLOR. Systemic exposure has not been observed with topical administration of VALCHLOR; therefore, systemic drug interactions are not likely.

8.1 Pregnancy Risk Summary Based on case reports in humans, findings in animal reproduction studies, its mechanism of action, and genotoxicity findings, mechlorethamine may cause fetal harm. Available published case reports in pregnant women receiving intravenous mechlorethamine demonstrate that mechlorethamine can cause major birth defects when a pregnant woman is systemically exposed. In animal reproduction studies, subcutaneous administration of mechlorethamine to pregnant rats and ferrets during organogenesis resulted in embryo‐fetal mortality, alterations to growth, and structural abnormalities.

Based on limited available data with VALCHLOR use in pregnant women, if VALCHLOR is used during pregnancy or if the patient becomes pregnant while taking this drug, patient should be advised of the potential risk to the fetus. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively.

Data Human Data The limited available data with VALCHLOR use in pregnant women does not show evidence of congenital malformation in newborns. Cases of newborns with congenital malformations have been reported in women who received systemic mechlorethamine during pregnancy. Animal Data Mechlorethamine caused fetal malformations in the rat and ferret when given as single subcutaneous injections of 1 mg/kg. Other findings in animals included embryo lethality and growth retardation when administered as a single subcutaneous injection.

8.2 Lactation Risk Summary There are no data on the presence of mechlorethamine or its metabolites in human milk, the effects of the drug on the breastfed child, or the effects of the drug on milk production. Because of the potential for topical or systemic exposure to VALCHLOR through exposure to the mother's skin and the potential for serious adverse reactions in the breastfed child from mechlorethamine, advise patients not to breastfeed during treatment with VALCHLOR.