Question

41. Aspirin (acetylsalicylic acid) has a pKa of 3.5. (1) Calculate the ratio of ionized/unionized of the drug in the stomach where pH is 1. (i) Calculate the ratio of ionized/unionized in the intestine where pH is 6. (iii) Based on these calculations- where is aspirin absorbed within the body? (15 points) 42. What is oral daily dose for each family member? (10 points) Amount of Amount of Total Body Media Consumed Benzene Consumed Benzene Weight Water Fish Soil Water Fish Soil Consumed (kg) (1) (mg) (mg) (Hg) (mg) (mg) (vg) 80 3 500 50 15 0.00015 1015.15 60 2 300 0.6 0.00003 610.03 25 200 5 0.4 0.0006 405.6 1 Dad Mom Child 10 10 1 200

Answer 1

41. Aspirin or acetylsalicyclic acid is a drug prescribed forheadaches, fever, inflammation, etc. It acts as inhibitor of COX (cyclooxxygenase). This leads to lowered production of prostaglandins and thromboxanes.

The Henderseon Hasselbalch equation can used to calculate the ration of ionized to unionized form,

salt ionized pH = pka + log; or pka + log: acid unionized

At pH =1,

ionized 1 = 3.5 + log unionized log, ionized unionized -2.5-→ ionized unionized antilog (-2.5) = 0.00316

This means that the drug is mostly in its unionized form.

At pH =6,

ionized 6 = 3.5 + log unionized log, ionized unionized 2.5-→ ionized unionized antilog (2.5) = 316.28

This means that the drug is mostly in its ionized form.

Thus more of it would be absorbed at lower pH. So, its absorbed in the stomach in the body.

In the stomach the pH is quite low, and acetylsalicylic acid being a weal acidic is very less ionized. This allows it to get abosrbed. As the pH increases in the small intestine it gets ionized and very less is now able to get absorbed.

As per Chegg guidelines I can answer only 1 question, if you want answers to all the questions please send them separately.