Intravenous (IV) infusion is often utilized when continuous and controlled drug delivery is necessary, such as during surgery or in the treatment of chronic diseases. This method offers numerous advantages, including immediate drug action, precise control over dosage, and bypassing the first-pass metabolism.

The one-compartment model for IV infusion uses mathematical equations to describe the rate of change in drug quantity in the body. At steady-state or infusion equilibrium, the drug input equals the drug output, leading to a constant concentration in the body. A semi-logarithmic plot of plasma concentration versus time helps determine the elimination rate constant, k.

In cases where rapid therapeutic concentration is needed, an initial loading dose is administered along with the infusion. The impact of both can be calculated using specific equations. Pharmacokinetic parameters such as volume of distribution (V_d) and half-life (t_1/2) can be determined from k, the elimination rate constant, and clearance. These calculations are crucial in dosage regimen design, ensuring effective and safe drug therapy.