Final answer:
The absolute highest MRD for a local anesthetic agent is typically used when epinephrine is added to the solution, as it allows for higher doses to be administered safely.
Step-by-step explanation:
The maximum recommended dose (MRD) for a local anesthetic agent is determined by several factors, but the weight of a patient is one of the primary concerns. The use of epinephrine as an adjunct in the local anesthetic solution is known to decrease the rate of absorption of the local anesthetic into the bloodstream, thereby allowing for higher total doses to be used safely. Therefore, the absolute highest MRD of a local anesthetic is typically used when epi is added to the solution. It is important to note that each local anesthetic has its own MRD and the circumstances such as a patient's weight, overall health, and specific medical conditions including geriatric status may alter the safe dosage.