PY 420 - Med. Chem. I

Case Study #1


Read the following case then answer the six (6) questions that follow concerning this case. When you have answered the questions to your satisfaction, click on the {SUBMIT} button at the bottom of the page to Email your responses to Dr. Riley. Your answers must be submitted no later that October 7, 1996 for you to receive credit.


You are talking with patient BRP about his purchase of Advil® (ibuprofen) in your community pharmacy. BRP is an athletic individual who is taking the Advil® for an inflamed knee related to his training for a local marathon run. He complains that, even though he has drastically reduced his running, he experiences mild pain in his knee between doses. Upon questioning the patient further, you find that he consumes approximately 1 gallon of a popular sports drink containing a high concentration of sodium citrate (which alkalinizes the urine) per day. BRP has a urinary pH of 7.5 and the pKa of ibuprofen is 4.5


1. With respect to acid-base character, ibuprofen is: (Select your response from the pull-down menu.)

Acidic - a carboxylic acid (COOH) derivative

2. Select the acid-base property that best describes sodium citrate.
(Select your response from the pull-down menu.)

Salt of a weak acid and a strong base

3. What would be the ratio of ionized to unionized forms of ibuprofen in BRP's urine?
(Select your response from the pull-down menu.)

1,000 parts anion to 1 part unionized.

4. The pH of a 1 molar solution of sodium citrate in H2O will be: (Select your response to each of the questions below from the pull-down menu.)

Alkaline (pH >7)

5. How do you explain the inadequate therapeutic response of BRP to Advil® therapy?

The urinary elimination of ibuprofen is being hastened by BRP's alkaline urine which promotes extensive ionization of the drug which favors excretion (shortens duration of action) rather than reabsorption (involved in normal half-life of the drug).

6. What advice would you offer to BRP concerning his sports drink intake? Suppose he asks, "How is the sports drink affecting the analgesic activity of Advil®? How would you answer this question?

He should be advised to replace the current sports drink with a beverage that does not shift urine pH, e.g. water or one lacking large amounts of alkaline salts. You should explain the by consuming large amounts of the sports drink, BRP is increasing the elimination (dcreasing the effectiveness) of Advil from his body and that the use of some other drink (e.g. water) will all the analgesic to work normally.


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