Pharmacology: Clearance vs Volume of Distribution

  1. Hi,

    I understand that Volume of Distribution (Vd) = elimination constant (k) * Clearance (Cl), but I can't visualize why clearance would be proportional to volume of distribution. Can someone help explain this to me? I feel like it should be a more complicated relationship. Clearance = Mass Drug eliminated/time/Concentration in Plasma. How are these variables changing with different volumes of distribution?
  2. jcsd
  3. mfb

    Staff: Mentor

    Distribution in a larger volume -> more mass gets absorbed, and clearance is proportional to the eliminated mass.
    I think the elimination constant should be at the other side, or taken as inverse value, otherwise its definition disagrees with the wikipedia article.
  4. Hi thanks you're right the elimination constant should be on the other side. With regards to the eliminated mass, i'm still a bit confused because the rate of elimination of the mass is dependent on the concentration of the drug in the plasma which should be the same between individuals even if they have different volumes of distribution?
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