T09: Clearance from plasma half-life and volume of distribution.

50. Pharmacokinetics 50.1) PK Basic parameters 50.1.2) Clearance

50.1.2.1) Clearance basic concepts Normal 1


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The plasma half life `t_{1/2}` of a drug is 2.3 h. If its volume of distribution in a patient is 88.88 L, then determine the clearance of the drug.


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lb equals 26.753 L/h kg

    We know that, clearance (Cl) is the product of elimination rate constant (K) and volume of distribution (V).

    ` Cl = K × V `.

    Also, the relationship between K and plasma half life, `t_{½}` is:
    `t_{½}=0.693/K ⇒ K=0.693/(2.3 \quad h)=0.301 \quad h^{-1}`

    Plugging the values given in this question we get:
    ` Cl = 0.301 \quad h^{-1} × 88.88 \quad L = 26.75 \quad L/h ` Ans.

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