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  • Posted by Ehdaa Hatem on December 9, 2022 at 3:34 pm

    Good evening,if any one knows which equation should I use here

    1) A drug is given at the dose of 1g IV Q12H to a patient. The desired therapeutic level of the drug in the blood is 15 – 20 mg/L. When blood drawn just before the next dose, the concentration was found 10.57 mg/L. What is the appropriate dose of the drug so that the desired therapeutic level is maintained?

    a) 1250 mg IV Q12H

    *b) 1500 mg IV Q12H*

    c) 1750 mg IV Q12H

    d) 2500 mg IV Q12H

    e) 1125 mg IV Q12H

    R.Ph. Shams replied 1 year, 6 months ago 2 Members · 1 Reply
  • 1 Reply
  • R.Ph. Shams

    December 30, 2022 at 11:57 am

    At first, let’s analyze the question: R0=1g | T=12h | Ctrough (desired)=15mg/L | Cpeak (desired)=20mg/L | Ctrough=10.57mg/L.

    Think outside the formulas because you don’t have time in the exam:

    1000mg → 10.57mg/L (focus on units)
    ? → 15mg/L

    ? = 1,419mg/L, so the answer is B.

    We can’t use a formula here because we need at least Cpeak to calculate Vd and K; remember that exam questions will not ask you to do more than two steps.

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