Unit 5 Beavis Gi Drugs: Anti-Ulcer Meds

Front 1

Cimetidine

Back 1

H2 BLOCKER
The most important side effect of cimetidine is inhibition of P450 -
mediated (CYP1A2, CYP2C9, CYP3A4) metabolism of drugs such as
warfarin, phenytoin, theophylline, phenobarbital, diazepam, propranolol, and
imipramine. Hence, if coadministered with cimetidine, the doses of these
drugs may have to be decreased.
ENDOCRINE EFFECTS
Cimetidine blocks androgen receptors and when taken in high doses
for long periods, e.g., for treatment of Zollinger-Ellison Syndrome, can lead to
gynecomastia and impotence in men and galactorrhea in women.
CNS EFFECTS
These are rare but slurred speech, delirium, confusional states have
been reported especially in elderly patients.

Front 2

Omeprazole

Back 2

PROTON PUMP INHIBITOR
irreversibly blocks the H+/K+ proton pump.
Gastrin levels rise due to increase in gastric pH. This leads to hyperplasia of
ECL cells and ECL tumors in rats treated with the drug for long periods (2
years).
 High pH allows bacterial growth in stomach -- it has been suggested that
nitroso-compounds synthesized from nitrites may lead to gastric cancer.
Interactions due to INCREASED GASTRIC pH
e.g. Decreased bioavailability of
 Ketoconazole, itraconazole
 Fe2+ salts
 Ampicillin esters
 Digoxin

Front 3

Misoprostol

Back 3

analog of prostaglandin E1
 Inhibits acid secretion
 Stimulates HCO3
- and mucus secretion
 Promotes gastric blood flow
SIDE EFFECTS
 Diarrhea due to increased intestinal motility and secretion
 Abdominal cramping
 Uterine contraction can cause abortion of pregnancy
Pregnancy termination in combination with mifepristone (RU486, Mifeprex®)
or methotrexate

Front 4

Sucralfate

Back 4

 If pH < 4, sucralfate polymerizes to form a thick, sticky gel which adheres to
proteins in the ulcer crater.
SE some drug interactions, e.g., decreases absorption of cimetidine.

Front 5

Bismuth Subsalicylate

Back 5

 Act much like sucralfate, but may also kill H. pylori
 Often used in conjunction with antibiotics and H2-blockers or proton pump inhibitors.

Front 6

Mg(OH)2, Al(OH)3,

Back 6

Antacids
Mg2+ increases motor activity, accelerates gastric emptying  diarrhea.
Al3+ decreases motor activity, slows gastric emptying  constipation.
3. Systemic antacids alkalinize blood/urine
4. Drug Interactions Al3+ and Mg2+ e.g., tetracycline

Front 7

Tetracycline, metronidazole

Back 7

Antibiotics
The main advantage of eradicating H. pylori is the very low rate of
recurrence of the ulcer after cessation of treatment,
H. pylori rapidly becomes resistant to the antibiotics metronidazole and
clarithromycin, therefore, these drugs are not used alone, but in combination with
other antibiotics.