T01) Find Ct from C0, k and t

50. Pharmacokinetics 50.2) Plasma concentrations over time 50.2.1) Plasma concentrations over time

T01: Later plasma concentration Normal 1


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A 68 Kg patient was intravenously administered a drug. The plasma concentration was found to be 0.58 mg/L, when the blood was first collected. If the drug follows a first order elimination and the elimination rate constant (k) is `0.123 \quad h^{-1}`, then determine the plasma concentration after 3.3 hours.


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lb equals 0.386 mg/L kg

    For a first order process,
    `C_{t}=C_{0}×e^(-kt)`
    Plugging the values in this equation, we get:
    `C_{t}=0.58 × e^(- 0.123 × 3.3)`
    `∴ C_{t}=0.386`
    Thus, the later concentration is: 0.386 mg/L. (Ans).