L22- GIT Drugs I (antacids)

Question 1

Antacids:

• (1) definition
• (2) mechanism

Answer 1

1- weak bases (no Rx)

2- Antacid + HCl —> salt + H2O

Question 2

Antacid time of onset and duration of action

Answer 2

Onset- 5 mins

Duration 1/2-1 hr

Question 3

list the classic antacid formulations

Answer 3

AlOH, aluminum hydroxide

MgOH, magnesium hydroxide

CaCO3, calcium carbonate (Tums)

Question 4

Indicate the antacid associated with the following:

• (1) osmotic diarrhea
• (2) constipation
• (3) CO2 causes belching leading to (4)

Answer 4

1- MgOH
2- AlOH
Note- MgOH, AlOH can be combined to net no changes in BMs

3- calcium carbonate
4- metabolic acidosis // milk alkali syndrome

Question 5

discuss the main adverse effect of antacids

Answer 5

Dec absorption of co-administered drugs:

• includes tetracylcines, fluoroquinolones, itraconazole, iron
• result of binding / chelation to many drugs
• inc gastric pH –> alters weakly charged drugs