T20: C0 from AUC and K

50. Pharmacokinetics 50.1) PK Basic parameters 50.1.3) Area Under Curve (AUC)

50.1.3.1) AUC basic concepts Normal 1


Total tried:       Correct:       Wrong:

429.52 mg of a drug (elimination rate constant 0.123 h-1) was administered to a patient as an IV push. The plasma concentration over the time (AUC) was found to be 27.72 mg × h/L. Calculate the initial plasma concentration after administration of the drug.


Click on the button below to see the answer and explanations


Notice: Undefined variable: input_value1 in /home/jshzub/web/rxcal.org/public_html/practice/practice/includes/body.php on line 220
lb equals 3.41 mg/L kg

    We know that, AUC may be calculated from dose (`X_{0}`) and clearance (`Cl`) OR initial concentration (`C_{0}`) and the elimination rate constant (`K`).

    ` AUC = (X_{0})/(Cl) = (C_{0})/K`.

    By rearranging the equation, we find:

    `C_{0}=AUC × K`

    `C_{0}=(27.72 \quad mg × h)/L × 0.123 \quad h^{-1} = 3.41 \quad (mg)/L`. Ans.


Notice: Undefined index: TOTALTRY in /home/jshzub/web/rxcal.org/public_html/practice/practice/includes/body.php on line 675