What happens once local anesthetics are absorbed into the bloodstream?

When local anesthetics are absorbed into the bloodstream, they indeed have the potential to accumulate in various tissues, particularly those that have a high blood flow such as the heart and lungs. This accumulation can lead to systemic effects, which may include central nervous system and cardiovascular complications.

Local anesthetics are lipophilic compounds, which allow them to distribute into fatty tissues. Upon entering the circulation, they can bind to various plasma proteins and may exert effects on other organs before being metabolized and excreted. The accumulation in the heart can lead to alterations in cardiac conduction and function, which demonstrates the importance of monitoring for systemic toxicity during and after the administration of local anesthetics.

The other options don’t accurately reflect the behavior of local anesthetics upon absorption. While it’s true that some anesthetics may have difficulty crossing the blood-brain barrier, many can indeed penetrate and affect the central nervous system. The statement regarding rapid excretion by the kidneys might be misleading as the elimination half-life varies among different anesthetics and is not always immediate. Additionally, local anesthetics do not lose their effectiveness instantly upon absorption; rather, they can cause effects systemically while still being effective locally depending on the concentration and site of action.