Excretion of tiapamil in breast milk

The excretion of tiapamil in breast milk was studied in six lactating mothers (3-7 days post partum) following a single oral 600 mg dose of the drug. The milk/plasma ratio of tiapamil derived from the areas under the plasma and milk concentration-time curves was 0.44 +/- 0.10 mean +/- s.d.). Assuming an intake of 350 ml of milk during a dosing interval of 12 h, the newborn would be exposed at the maximum to 0.053 mg tiapamil. This small amount does not represent a risk for the baby.