Steady state plasma concentration obtained after a dosage regimen depends on
**Core Concept**
The steady state plasma concentration of a drug is a critical concept in pharmacokinetics, referring to the equilibrium concentration of the drug in the plasma after repeated administration. This concentration is essential for determining the efficacy and safety of a medication.
**Why the Correct Answer is Right**
The steady state plasma concentration is achieved when the rate of drug administration equals the rate of drug elimination. This balance is maintained when the area under the concentration-time curve (AUC) of a single dose equals the AUC of multiple doses. The steady state concentration is influenced by factors such as the drug's clearance, volume of distribution, and dosing frequency.
**Why Each Wrong Option is Incorrect**
**Option A:** Clearance is a factor that affects the steady state concentration, but it's not the primary determinant.
**Option B:** The volume of distribution affects the initial concentration of the drug, but it does not directly influence the steady state concentration.
**Option C:** The dosing interval is related to the time it takes to reach steady state, but it's not the primary factor that determines the steady state concentration.
**Clinical Pearl / High-Yield Fact**
Remember the "Rule of 5" for estimating the time to reach steady state: if the elimination half-life of a drug is less than 5 hours, steady state is achieved within 5 dosing intervals.
**Correct Answer:** C. The dosing interval.