Drug absorption and elimination

Extensive plasma protein binding will increase the amount of drug that has to be absorbed before effective therapeutic levels of unbound drug are reached. For example, acidic dugs (such as acetyl salicylic acid – aspirin) are often substantially bound to albumin.

Elimination of a highly bound drug may be delayed. Since the concentration of free drug is low, drug elimination by metabolism and excretion may be delayed. This effect is responsible for prolonging the effect of the drug digoxin.