Excretion of oxprenolol and timolol in breast milk.

The excretion of oxprenolol and timolol in breast milk was examined by comparing their concentrations in milk with those in plasma. The mean milk to plasma ratio of oxprenolol was 0.29 (SD 0.14; that for timolol was 0.80 (SD 0.21). The total quantity of either drug ingested by a fully breast-fed infant is unlikely to be therapeutically significant.