### T11: Mixed problems from T7 - T11.

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 3.98 h. If its volume of distribution in a patient is 33.6 L, then determine the clearance of the drug.

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lb equals 5.846 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/(3.98 \quad h)=0.174 \quad h^{-1}

Plugging the values given in this question we get:
 Cl = 0.174 \quad h^{-1} × 33.6 \quad L = 5.85 \quad L/h  Ans