GI Drugs I

Question 1

Acid Neuralizers or antacids -all are used as needed Calcium Carbonate -

Answer 1

reacts very slowly w. hydrochloic acid to form calcium chloride and carbonic acid.

Disadvantage is that it is constipating, therefore,
it is useful to use in combination with magnesium compounds which are laxatives.

Question 2

What are the adverse effects of calcium carbonate?

Answer 2

Milk-alkali syndrome, nephrocalcinosis, “rebound” acidity, digitalis antagonism

Question 3

Sodium Bicarbonate is not used because

Answer 3

it induces systemic alkalosis and it enhances the effects of amphetamines, quinidine and cinchophen. Also has a high sodium content

Question 4

Magnesium Hydroxide/ Carbonate

Answer 4

Most potent is magnesium hydroxide. Like calcium salts, it is absorbed and may cause magnesium intoxication in the presence of renal disease

Question 5

What are the adverse side effects of magnesium hydroxide/magnesium carbonate?

Answer 5

Diarrhea, hypokalemia, hypermagnesemia, complexing

of enteric iron, iron deficiency

Question 6

How does Aluminium Hydroxide work?

Answer 6

Combines with hydrochloric acid to form aluminum chloride and water. Aluminum chloride forms aluminum phosphate lower in the gastrointestinal tract which is not absorbable; therefore, it is not likely to disturb the
serum electrolyte or serum pH

Question 7

Besides neutralizing acid these antacids may also have a

Answer 7

protective effect on the mucosa.

*Useful in RENAL failure patients

Question 8

What are the adverse effects of magnesium hydroxide/mag carbonate antacids?

Answer 8

Constipation; phosphate depletion and sequelae, including weakness, anemia, tetany, apnea; delayed gastric emptying; concretions, including fecaloma, colonic perforation, and stercoral peritonitis; encephalopathy; impaired absorption of many drugs, notably tetracycline, digoxin, INH

Question 9

Which defoaming agent is used?

Answer 9

Simethicone claimed to disperse the antacid and is said to have antiflatulent effects, but this has not been demonstrated in controlled trials.

Question 10

Classes of drugs that decrease acid production and reduce spasm/cramps include

Answer 10

Anticholinergics, histamine, H2, Prostaglandin E analogs, H/K ATPase inhibitors

Question 11

What are the side effects of anticholinergic drugs (probantheline and Atropine?
Why are they no longer used?

Answer 11

dverse effects: dryness of the mouth, blurred vision, atony of the bladder, constipation, drowsiness and mental confusion. They are contraindicated in patients with known pyloric obstruction and in patients with hiatus hernia and peptic esophagitis.

Question 12

What are the H2 blockers? They reduce acid secretion

Answer 12

Cimetidine, Ranitidine, Famotidine, Nizatidine

Question 13

MOA of H2 blockers?

Answer 13

the keep the stomach pH above 3 for 24h - use up to 8 weeks

Question 14

What is important to remember about H2 blockers?

Answer 14

rebound hyperacidity - don’t stop abruptly to downregulate sensitivity

Question 15

Drug interactions of H2 blockers

Answer 15

Cimetidine, and to a lesser extent, ranitidine bind to

cytochrome P450 and interfere with the metabolism of drugs such as theophylline, warfarin,dilatin, or lidocaine

Question 16

Which drugs are block H/K ATPase in the extracellular space?

Answer 16

Omeprazole, Lansoprazole, Pantoprazole….more –prazoles

Question 17

Which ATPase inhibitor is the safest?

Answer 17

pantoprazole (IV)

NEEDS to be activated by low pH (no breakfast and no H2 blockers
They will heal H2 antagonist-resistant ulcers

Question 18

The prostaglandin E analogs are not very effective in decreasing acid production because?

Answer 18

the prostaglandins are already high in duodenal ulcers

Question 19

Which two drugs are mechanical protectors of the mucosa

Answer 19

sucralfate and bismuth salts (Pepto Bismol)

Question 20

Pepto Bismol produces black tarry stool and it is difficult to determine if the person’s stool is black because of it or from a bleed?

Answer 20

So doctors avoid using it–> Sucralfate is better.

Sucralfate is an aluminum hydroxide complex of sucrose, binds to ulcerated tissue, activated in
acid environment

Question 21

Treatment of H. pylori infection

Answer 21

1. Twice a day PPI or ranitidine bismuth citrate triple therapy PLUS 2 antibiotics that can include amoxicilin, clarithromycin, metronidazole
2. Quadruple therapy - a PPI 2x/day along w. Tetracycline, bismuth subsalicylate and metronidazole

Question 22

Antacids aren’t that good because you need to take such low doses.

Give Mg containing for those who do NOT have renal failure

they can’t eliminate it properly

Answer 22

Renal failure pts. give Alumininum antacids