Pharmacokinetic basis for Loading dose and Maintenance dose in therapy

In critical care medicine, the goal is to deliver therapeutic drug concentrations rapidly in blood and then maintain therapeutic concentrations for extended durations for optimum therapeutic outcome.  Oral dosing has the disadvantage of not being able to rapidly achieve therapeutic concentrations in blood due to delay in absorption and bioavailability issues. IV infusion to reach steady state concentrations can take time depending on the elimination half-life of drug. A combination of IV loading dose and maintenance dose (IV/oral) can meet this specific objective.