What effect does tight binding of a drug have on its delivery?

Tight binding of a drug to proteins or tissues in the body can significantly hinder its effective delivery. When a drug tightly binds to proteins, it can remain in a bound state for an extended period, which may limit the amount of free, active drug available to exert therapeutic effects at the target site. This can lead to a situation where, despite sufficient overall drug concentrations, the effectiveness is compromised because only the unbound fraction can diffuse to the site of action and exert its pharmacological effect.

In this context, the concept outlines that while some degree of binding can be beneficial for prolonging the drug's action or reducing side effects, excessive tight binding does not facilitate effective delivery to the target tissues. Additionally, this binding can slow down the release of the drug, impacting its absorption and ultimately achieving the desired therapeutic outcome.