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 7.7 h. If its volume of distribution in a patient is 61.56 L, then determine the clearance of the drug.
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lb equals 5.54 L/h kg
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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/(7.7 \quad h)=0.09 \quad h^{-1}`
Plugging the values given in this question we get:
` Cl = 0.09 \quad h^{-1} × 61.56 \quad L = 5.54 \quad L/h ` Ans