Which is a potential risk when two drugs compete for the same protein binding site?

When two drugs compete for the same protein binding site, one of the significant risks involved is an increased risk of drug toxicity. This occurs because when a drug that is normally highly protein-bound is displaced from its binding sites by another compound, the level of free (unbound) drug in the bloodstream rises.

The free drug is typically the active form that exerts pharmacological effects; thus, an increase in the unbound concentration can lead to an exaggerated response or toxicity, especially if the drug has a narrow therapeutic index. In situations where the concentrations of the free drug surpass therapeutic levels, this can result in adverse effects, organ damage, or harmful interactions.

Understanding this risk is crucial for healthcare providers in managing medication regimens, particularly in polypharmacy scenarios or when dealing with patients who have altered protein levels, such as those with liver disease or malnutrition where albumin levels might be low.