Module 8 questions - Extreme volumes (Clinical challenge)
  1. What physiologic and biochemical change or changes result in increased hepatic clearance associated with enzyme induction?

    More copies of the metabolizing enzyme means a greater hepatic efficiency (more phenobarbital can be removed from each ml of blood that passes through the liver.

  2. What physiologic and biochemical change or changes result in decreased hepatic clearance associated with hepatic failure?

    The number of cells capable of metabolising the drug is reduced (efficiency drops) AND hepatic failure can be accompanied by reductions in blood flow (hepatic flow drops).

  3. Does the change in the fraction of an oral dose absorbed add to the effect of altered clearance or does it counter the effect?

    It adds to the effect.

  4. For which of the following dogs should the dosage of phenobarbital be adjusted (immediately)?
    1. A dog whose seizures are well controlled at 120 days but with a phenobarbital Cave 10% lower than during the second week.
    2. A dog whose seizures are not well controlled during the second week and whose phenobarbital Cave is 30 μg/ml.