This document discusses various classes of drugs used to treat gastrointestinal disorders. It describes the mechanisms of action, indications, examples, side effects and counseling points for histamine H2 receptor blockers, proton pump inhibitors, mucosal protectants, prostaglandins, antacids, antiemetics, antidiarrheals, laxatives and antispasmodics.

1. By: Mahmooda lecturer
ION,DUHs

3.  Histamine H2 receptor blockers
 Proton pump inhibitors
 Mucosal Protactants
 Prostaglandin E
 Antacids

4.  Antiemetic
 Antidiarrheal
 Laxatives
 Antispasmodic

5. Histamine H2-antagonist directly inhibits
histamine action on H2-receptor to decrease
acid production.

6. Block H2 receptor (located on gastric parital cell)

Prevent gastrin secretion (Gastrin is
responsible for local release of histamine)

es Stimulation of HCL and pepsin production

7.  Active gastric or duodenal ulcers, GERD, PUD,
stress ulcers and gastritis
Examples include:Cemitidine (Tagamet),
ranitidine (zantac) etc

8.  The most common side effect is diarrhea,
constipation, blurred vision, headache,
dizziness, fatigue, confusion, bradycardia and
hypotension

9.  Cimetidine should be avoided in people taking
Warfarin, Phenytoin and other antiepileptic drugs,
Theophylline or Aminophylline, NSAID and some
drugs for abnormal heart rhythms.
 Educate the patient:
 To avoid alcohol, smoking, coffee, spicy and fatty
food.
 To eat 5- 6 small meals instead of 3 large meals.
 H2 receptors blocker can be taken without regard
to meal

10.  PPI act by blocking the enzyme (hydrogen
potassium ATpase H+/K+ -ATpase)
responsible for HCL secretion in the
stomach.

11.  Oesophagitis, deudenal ulcers, treatment of
hypersecreatory conditions , GERD, and PUD
Examples:
 Omeprazole (prilosec),esomeprazole
(Nexium),rabeprazole(Aciphex)

12.  Headache, dizziness, diarrhea and flatulence
are most common. Others are cough, stiffy
nose, hoarseness, and epistaxis.

13.  Instruct patient to avoid opening, chewing, or
crushing capsules. These medications should be
swallowed whole for therapeutic effect.
 With long term use liver function should be
periodically monitored along with serum gastrin.
 PPI should be taken 30 minutes prior to eating,
usually before breakfast.
 Inform health care provider of significant
diarrhea.
 Avoid smoking, alcohol use, and food that cause
gastric discomfort.

14.  React with gastric acid at the ulcer site to
farm a thick paste  covers and stick to
ulcer site  Helps protect the ulcer from
gasric acid, pepsin and bile (act locally)

15. Indications
 Prevent or treat ulcer disease, injury from
hyper acidity.
Examples: Sucralfate
Adverse effect:
 Most common is constipation.

16.  Administer sucralfate on empty stomach (1
hour before meals and at bed times).
 Administer other oral medications 2 hour
before giving sucralfate to prevent drug
interaction. Because sucralfate provide
protective barrier to the GI mucosa.
 Administration with other drug may interfere
with absorption and decrease the action of
other drug.

17. Action
Prostaglandin E, decrease gastric acid secretion
and helps to protect GI mucosa
Indication:
 To prevent NSAID-induced gastric ulcers in
patient.
Example: Misoprostol
Adverse Effect:
 Most common is diarrhea and abdominal
pain.

18.  Avoid administering misoprostol with
magnesium-containing antacid, which my
increase the incidence and severity of
diarrhea.
 Administer misoprostol at mealtime and at
bedtime with food to prevent GI discomfort.
 Monitor for GI distress, the number and
consistency of stool, and sign and symptoms
of dehydration.

19. Are alkaline substance that neutralizes acid.
Indication:
 Used to prevent or treat mild GERD, PUD,
stress ulcers, pyrosis (heart burn), and
gastritis
Examples:
 Aluminum Hydroxide, Aluminum and
Magnesium Hydroxide (Mylanta), Calcium
Carbonate, Magnesium Gluconate, and
Magnesium Hydroxide (Milk of Magnesia)

20.  Calcium: Constipation, reduced iron
absorption, renal stones and hypocalcaemia
 Magnesium: Diarrhea, hypermagnesemia
(especially with renal impairment)
 Aluminum: Constipation, phosphate
depletion, and neuroixicity
 Sodium: Water retention, risk of edema,
ascitis, HTN, HF

21.  Antacids, high in sodium, should not be used by
those on sodium-restricted diet.
 Administer other medication at least 1 to 2 hours
before antacids.
 Educate the patient:
 For chewable tablets, chew them thoroughly and
follow with a glass of water or milk. For oral
suspension, shake well before use.

22.  Symptomatic relief typically occurs within 5 to 15
minutes after taking an antacid; however, duration of
this relief may only last for 1 to 3 hours. Therefore,
multiple doses may be needed throughout the day for
adequate symptom control.
 Do not use antacids for more than 2 weeks as a self-
prescribed treatment.
 If symptoms do not improve after taking antacids
consult health care provider

23. Phenothiazine
 Mechanism of action:
◦ Block dopamine receptor in the in the brain
(responsible for activation of vomiting)
◦ Also block neurotransmitters acetylcholine,
histamine, and nor epinephrine which results in
interrupts the impulse to vomit, resulting in an
antiemetic effect.

24. Indications:
 Used to prevent or treat nausea and vomiting
associated with surgery, pain, motion sickness,
and chemotherapy etc
Examples:
Promethazine (Phenergan), Prochlorperazine
(Stemitil)
Adverse Effect:
 Common side effects are drowsiness,
hypotension and ant cholinergic effect (dry
mouth, flushing, blurred vision, tachycardia, and
photosensitivity

25.  Administer Phenothiazine cautiously in
children with viral illnesses, patients on
antihypertensive drugs and in pregnant
women.
 Monitor the patient for drug adverse effect.
 Encourage adequate fluid intake.
 Be aware that phenothiazines may depress
the cough reflux and cause thickened
secretion placing the patient at risk for
aspiration.

26. Most diarrheas are self limiting when diarrhea
is severe, restoring and maintaining fluid and
electrolyte balance is of prime importance.

27. Opioides and opiates derivative
 Depresses the nervous system thus results in
slowing of intestinal movements.
 Examples are Diphenoxylate with atropine
(Lomotil), Liperamide (Imodium).
 Contraindicated in acute infective diarrhea.
Adsorbents: absorbs microorganisms and prevent
their contact with intestine.
 Examples are Kaolin and pectin mixture
(Kaopectate)

28. Indications:
 Severe or prolong diarrheas, chronic inflammatory
disease of bowl such as ulcerative colitis and
Crohn’s disease
 Used in conditions that requires decrease fluidity
and volume of stool such as illeostomy.
Side effects:
 Constipation, bloating and fullness (adsorbents)
 Tinnitus (Bismuth subsalicylate)
 Skin rash, drowsiness, dizziness, tiredness, and
dry mouth (Loperamide)

29.  Determine the underlying cause of diarrhea.
 Administer fluids to rectify electrolyte
imbalance.
 Suggest non pharmacological measures to
prevent diarrhea.

30. Classification
 Bulk Forming Laxatives: eg psyllium,Ispaghol
 Osmotic Laxatives: Lactolose
 Stimulant Laxatives: senna, bisacodyl
 Emollient Laxatives: Oils

32. Indications:
 To relieve constipation.
 To prevent straining at stool.
 To empty the bowel.
 To accelerate elimination.
 To prevent absorption.
Contraindications: Undiagnosed abdominal
pain, intestinal obstruction, and fecal
impaction

33.  Laxatives should only be used for short
periods of time, until normal bowel
movements are re-established.
 Educate patient to avoid laxatives abuse.