Which of the following is an example of a highly protein-bound drug?

Coumadin, also known as warfarin, is an example of a highly protein-bound drug, primarily binding to albumin in the bloodstream. Approximately 99% of warfarin is bound to plasma proteins, which significantly impacts its pharmacokinetics. The high protein binding influences its distribution in the body, as only the unbound or free fraction of the drug is pharmacologically active and available to exert an effect or be metabolized.

In contrast, the other drugs listed have lower protein binding percentages, which allows for a higher proportion of the drug to be freely available in the circulation for therapeutic action. For instance, ibuprofen and acetaminophen are known for their analgesic properties but do not exhibit the same degree of protein binding as warfarin. Aspirin also has a relatively lower protein binding compared to Coumadin. Understanding the degree of protein binding is crucial for comprehending how these medications interact with each other and how they behave in different physiological conditions.