PHA 5127

Problem Set "Pharmacokinetics After Oral Administration"

 

An 80 kg patient was given a tablet containing 400 mg of a drug. The drug is completely absorbed. Plasma and urine was assayed:

 

Plasma
Time [hrs] Cp[mg/ml]
  • 0.1
    •
  • 1.5
    •
  • 0.2
    •
  • 3.2
    •
  • 0.4
    •
  • 4.3
    •
  • 0.6
    •
  • 5.1
    •
  • 0.8
    •
  • 5.4
    •
  • 1.0
    •
  • 5.2
    •
  • 1.2
    •
  • 5.0
    •
  • 1.4
    •
  • 4.8
    •
  • 2.0
    •
  • 4.0
    •
  • 3.0
    •
  • 2.5
    •
  • 4.0
    •
  • 1.5
    •
  • 5.0
    •
  • 1.0
    •
  • 6.0
    •
  • 0.62
    •
  • 7.0
    •
  • 0.40
    •
  • 8.0
    •
  • 0.25
    •
  • 10.0
    •
  • 0.10
    •

     

     

    1. Determine the constant k1 and k2 for absorption and elimination by feathering. Can you tell from the above data which is the absorption and which is the elimination rate constant? If not how could you?

    2. Determine the total body clearance.

    3. Two tablet forms of the same drug having the same bioavailability (f = 1) were given to the same group of volunteers and plasma concentrations were measured. For both tablets ka is much larger than ke. Find two errors in the graph and explain briefly.

     

     

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