In a one-compartment model, distribution is assumed to be

In a one-compartment model, distribution is assumed to be

• A. Drugs instantaneously distribute throughout the single compartment
• B. Distribution occurs between multiple compartments
• C. There is no distribution phase and clearance is immediate
• D. Only peripheral compartments exist

Answer: (A)

In a one-compartment model, the body is treated as a single, homogeneous space, so the drug distributes instantly within that space after administration. Because distribution is assumed to be instantaneous, there is no separate distribution phase to distinguish from elimination—the concentration we measure reflects only elimination from that single compartment. This leads to a simple monoexponential decline over time, since the drug concentration is uniform throughout the body from the start. In contrast, models with multiple compartments describe a distribution phase where the drug moves between central and peripheral tissues before elimination dominates. The option stating that drugs instantaneously distribute throughout the single compartment best captures this idea.

In a one-compartment model, the body is treated as a single, homogeneous space, so the drug distributes instantly within that space after administration. Because distribution is assumed to be instantaneous, there is no separate distribution phase to distinguish from elimination—the concentration we measure reflects only elimination from that single compartment. This leads to a simple monoexponential decline over time, since the drug concentration is uniform throughout the body from the start. In contrast, models with multiple compartments describe a distribution phase where the drug moves between central and peripheral tissues before elimination dominates. The option stating that drugs instantaneously distribute throughout the single compartment best captures this idea.