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DRUGS ACTION TO GIT, Mechanism of action
5HT3 Antagonists: They block…
DRUGS ACTION TO GIT
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Antacids
Mechanism of action
- They achieve their effects by neutralizing gastric acid, inhibiting gastric acid secretion or protect gastric mucosa.
Drug example and doses
- Sodium bi carbonate 1-5 gram orally
- Magnesium hydroxide 0.5-1gm
- Aluminum Hydroxide Up to 1gm daily
- Magnesium carbonate 250-500 mg orally
- Calcium carbonate Up to 1.5gm daily
Indications / Uses
- Indigestion.
- Reflux esophagitis,
- Pain and burning with peptic ulcer.
- Peptic ulcer.
Contraindication / Precautions
- Abdominal pain of unknown origin.
- Caution in renal failure because they contain magnesium.
- Heart patient.
Adverse effects
- Constipation (Aluminum Hydroxide).
- Hypophosphatemia (with Aluminum Hydroxide).
- Hypomagnesemia (with Magnesium Hydroxide).
- Increase sodium can cause edema and CHF. (Sodium bi carbonate).
- Diarrhea (Magnesium Hydroxide)
Proton pump inhibitors
Mechanism of Action
It acts by inhibiting proton pump which is final common step in gastric acid secretion. It also have antisecretory action.
Example of drugs and doses
- Omeprazole 20mg daily
- Lansoprazole 30 mg OD.
- Pantoprazole 40mg
- Rabeprazole 20mg
Contraindication / Precautions
- Hypersensitivity.
- Special precaution in pregnant and breast feeding mothers.
Adverse effects
- Headache.
- Abdominal pain.
- Chest pain.
- Diarrhea.
- Dizziness.
- Nausea / Vomiting.
Indications / Uses
- Peptic ulcer.
- Reflux esophagitis.
- Zollinger – elision syndrome.
- Prevent and treat NSAID’s related to gastric ulcer.
Antidiarrheals
Drug example and doses
- Loperamide 2-4mg
- Diphenoxylate 5-10mg
- Octreotide 100-250 mcg TID
- Polycarbophil 1-4 times daily
- Bismuth subsalicylate 60 ml
6 hourly suspension
Indications / Uses
- To treat underlying cause of diarrhea.
- To control the relive symptoms of acute and chronic diarrhea.
Adverse effects
- Constipation.
- Abdominal pain.
- Pain at the injection site.
- Nausea.
- Gall stones.(with octreotide)
- Drowsiness.(with diphenoxylate, and loperamide).
Contraindication / Precautions
- Contraindicated in abdominal pain of unknown pathology.
- There is an increase risk of megacolon in clients with inflammatory bowel disorders. This could lead to a serious complication such as perforation of bowel.
Mechanism of action
- Antidiarrheals active opioids receptor in G.I. tract to decrease intestinal motility and to increase the absorption of fluid and sodium in the intestine.
Emetics
Mechanism of action
- They stimulate the chemoreceptor trigger zone and gastric mucosa to induce vomiting.
Example of drugs and doses
- Apomorphine 5mg IM
- Copper sulfate - Given in water every 5 min. until emesis occur.
- Sodium chloride (NaCl) 2 table spoon of NaCl in glass of warm water
- Ipecac syrup 15-30ml (followed by 200ml of water).
Contraindication / Precautions
- History of seizures.
- Semi comatose or unconscious patient.
- Ingested caustic substance or petroleum products.
Adverse effects
- Arrhythmias
- Cardiotoxicity.
- Diarrhea.
- Drowsiness.
Laxatives/Purgatives
Mechanism of action
- Osmotic laxatives (Magnesium hydroxide) draw water into the intestine to increase the mass of stool, stretching musculature which results in peristalsis.
- Stimulant laxatives result in stimulation of intestinal peristalsis.
- Lubricant laxatives increase water retention in the stool, prevent water absorption from the stool, and lubricate as well as soften intestinal contents.
- Stool softener allow more fluid are fat to penetrate the faeces, producing a softer fecal mass.
Drug example and doses
- Bilk forming laxatives (Methyl Cellulose) 2 tablets 1000mg orally with 8oz of liquid up to 6 times a day.
- Lubricant laxatives include mineral oil (Kondremal, Fleet mineral oil enema.15-45ml/days
- Hyperosmotic laxatives include lactulose. 10mg BD
- Stimulant laxatives (Bisacodyl, Castor oil) 5-10 mg sodium Pico sulfate 15-20 ml
- Stool softener (Docusate Calcium, Docusate potassium) 240mg 50-400mg orally,1 to 4 equally divided dose each day.
Contraindication / Precautions
- Contraindicated if patient with parasites.
Or severe abdominal pain of unknown cause
Indications / Uses
- To treat or prevent constipation.
- To prepare the bowel for radiologic or endoscopic procedures.
- Short term treatment of constipation caused high dose of opioid use.
- Osmotic laxatives are used to rapid evacuation of the bowel after ingestion of poison or following anti-helminthic therapy to rid of the body from dead parasites.
- Methyl cellulose and psyllium are used to many chronic diarrhea.
Adverse effects
- GI irritation.
- Rectal burning sensation.
- Osmotic laxatives may causes dehydration.
- Long term use and abuse of laxatives may cause permanent loss of colonic motility. Laxative dependence and electrolyte imbalances.
- Nutritional deficiencies (with lubricant laxatives).
- Belching (with osmotic laxatives)
- Electrolyte imbalance. (with saline laxatives)
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Mechanism of action
- 5HT3 Antagonists: They block serotonin receptors in CNS and Gastrointestinal tract So they can be used to treat post operative and cytotoxic (Chemotherapy) drugs nausea/ vomiting.
- Prokinetics (Dopamine Antagonists): They block the dopamine neurotransmitter also they promote gastrointestinal motility & quicken gastric emptying.
- Antihistamines: They block the histamine neurotransmitter and they act by an effect on vomiting center and by producing sedation.
- Anticholinergics: An Anticholinergic agents block the neurotransmitter Acetyl choline in central and peripheral nervous system.
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classification
- 5HT3 receptor antagonist
- Prokinetics / Dopamine Antagonists
- Antihistamines
- Anticholinergics
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Example of drugs and doses
- Hyoscine 200-600mg (SC)
- Diclomine 40mg 6hourly
- Cyclizine 50mg 4-6 hour
- Meclizine 25mg/day.
- Metoclopramide 10mg
- Domperidone 10-20 mg 4-6hours
- Ondansetron 8-16mg
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Indications / Uses
- 5HT3 antagonists are used in management of nausea vomiting associated with chemotherapy. •
- Antihistamine such as diphen hydramine is used for motion sickness and morning sickness.
- Metoclopramide is used for gastric emptying in patient’s receiving tube feeding.
- Anticholinergic such as hyoscine, Dicyclomine are useful in travel sickness.
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Contraindication / Precautions •
- Diphenhydramine is contraindicated in hypertensive patients.
- Metoclopramide is contraindicated in suspected gastrointestinal problem.
- Use cautiously and reduced dose in renal impairment conditions.
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Adverse effects
- Hypotension.
- Constipation.
- Dryness of mouth.
- Blurred vision.
- Pain in IM injection site.
- Drowsiness.
- Rectal irritation.
- Photo sensitivity reaction.
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Indications / Uses
- To induce vomiting.
- To treat poisoning.
- Treatment of overdose of drug.
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These drugs are combinedly knows as purgatives, which includes laxatives and cathartics these drugs are used to overcome the constipation and proper evacuation of bowels.
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They are also called as H2 antagonists. These agents block the action of histamine, thus it reduce the amount of acid released into the stomach. They also promote ulcer healing.
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NURFATIN LIYANA AQILAH BINTI BAHARUDDIN
012020091220
ASSIGNMENT 2
CLINICAL PHARMACOLOGY II
(KPC10202)
FEBRUARY 2022