The binding of bupivacaine to maternal and foetal plasma proteins

The binding of bupivacaine to maternal and foetal plasma proteins has been investigated using a three‐compartment dialysis apparatus, in which maternal and foetal plasma could be examined simultaneously. Maternal protein bound approximately twice as much bupivacaine as foetal protein per gram of protein at drug concentrations in the range 0·05 to 5·0 μg/ml. Over the same range of concentrations, 92–78% of bupivacaine was bound to maternal plasma protein but only 35–31% was bound to human albumin indicating that other proteins are involved in the binding of the drug to plasma proteins.