How can medication bound to protein affect drug availability?

Medication bound to protein reduces the availability of the drug to produce desired medicinal effects because only unbound drugs can effectively bind to active receptor sites. When a drug is bound to protein, it cannot bind with receptor sites, limiting its therapeutic impact. Choice A is incorrect because drug availability is reduced when it is bound to protein. Choice B is incorrect as rapid distribution to receptor sites is not possible if the drug is bound to protein and cannot bind with receptors. Choice D is incorrect as metabolism does not increase when the drug is bound to protein; the liver first needs to separate the drug from the protein before metabolism can occur.