Which agent is used to slow the intake and increase the duration of a local anesthetic?

The agent used to slow the intake and increase the duration of a local anesthetic is epinephrine. Epinephrine is a vasoconstrictor, meaning it narrows the blood vessels in the area where the anesthetic is applied. By doing this, it reduces blood flow to the area, which helps to prolong the effect of the local anesthetic. This effective mechanism allows the anesthetic to remain localized, minimizing systemic absorption and enhancing its duration of action.

In contrast, procaine, lidocaine, and bupivacaine are all types of local anesthetics themselves. While they provide pain relief by blocking nerve signals, they do not have the properties to prolong the duration of their effects on their own. Using epinephrine in conjunction with these anesthetics can enhance their effectiveness, but they do not serve the primary function of slowing intake and increasing duration as epinephrine does.