Drugs Used in Treatment of Gastrointestinal Diseases PDF

MODULE: PHARMACOLOGY TRAINER: MR ROMAIN JOHNSON DRUGS USED IN TREATMENT OF GASTROINTESTINAL DISEASES Gastrointestinal disease is a term used to refer to medical conditions affecting the GI tract (mouth to anus). They can be classified in two groups: functional & structural GI diseases. Functional...

MODULE: PHARMACOLOGY TRAINER: MR ROMAIN JOHNSON DRUGS USED IN TREATMENT OF GASTROINTESTINAL DISEASES Gastrointestinal disease is a term used to refer to medical conditions affecting the GI tract (mouth to anus). They can be classified in two groups: functional & structural GI diseases. Functional GI diseases are those in which physical examination shows a normal GI tract but the GI tract is not functioning properly e.g. constipation, diarrhea, gastroesophageal reflux disease (GERD). Structural GI diseases are those that show abnormalities upon examination and the GI tract also doesn’t functional properly e.g. IBD, hemorrhoids, colon cancer. Proton pump Inhibitors (PPIs) M.O.A Work by irreversibly blocking the enzyme system (pump) that controls the production of acid by the stomach. This enzyme system (pump) is located in the parietal cells of the stomach walls and is referred to as the “proton pump”. PPIs block about 70% of the proton pumps resulting in a decrease in the production of acid by the stomach. Since PPIs do not block all the pumps, there is a still a small amount of acid available to facilitate digestion. Examples: Esomeprazole (Nexium) Lansoprazole (Ogastro) Omeprazole (Losec) Pantoprazole (Pantecta) All are available as oral and parenteral preparations except lansoprazole that is only available in oral dosage forms. Administration Best taken half an hour before food; preferably half an hour before breakfast Drug interactions Avoid alcoholic drinks (may irritate gastric lining) Side effects Headache Dizziness Antacids (eg Relcer Gel) M.O.A Neutralize acid in the stomach, relieving symptoms such as burning in the chest. Drug interactions Avoid alcoholic drinks (may irritate gastric lining) Side effects Acid rebound (stomach produces more acid after food consumption). Occurs if antacids are used in high doses for prolonged periods. Histamine-2 receptor blockers (eg famotidine) M.O.A Block histamine-induced gastric acid secretion from parietal cells of the stomach. Administration Best taken half an hour before food Drug interactions Avoid alcoholic drinks; may irritate GI lining Side effects Headache Dizziness Anti-motility agents (eg Loperimide – Imodium) M.O.A. Act by slowing down intestinal contractions and prolong transit time resulting in a reduction in the frequency of bowel movement. Administration May be taken with or without food Side effects Constipation Dizziness Laxatives Bulk-forming agents (eg Metamucil) M.O.A Absorb liquid in the intestines and swell to form soft but bulky stool. The presence of the bulky stool will cause stimulation for natural bowel movement. Lubricants (Mineral Oil) M.O.A Coat the bowel and the stool with a waterproof film that keeps moisture in the stool and keeps it soft Stimulants – (eg Bisacodyl – Dulcolax) M.O.A Increase muscle contractions along the intestinal wall and cause the stool to move along the bowels Emollients (stool softeners) M.O.A Help to mix the liquids in the bowel into the stool to prevent dryness and hardening of the stool. Osmotic agents (eg Lactulose) M.O.A Pulls water into the bowels from surrounding tissues and makes the stool soft as well as increase bowel activity. Antiemetic drugs (eg Dimenhydrinate – Gravol) M.O.A Block neurotransmitter receptors involved in promoting vomiting thereby preventing activity of chemicals in the body that can trigger vomiting. Prokinetic agents (eg Metoclopramide – Moxalon) M.O.A Increase contractions of muscles in the stomach causing the stomach to empty faster than normal. They also strengthen the lower muscles of the esophagus that connects to the stomach hence preventing retrograde movement of stomach acid. Probiotic agents Probiotics are microorganisms that live in the GI tract and offer health benefits to the host. Probiotic agents are drug preparations that are composed of probiotics. M.O.A Prevent binding of pathogens to the cells of the host hence preventing replication of the pathogen. Produce antimicrobial products that have bacteriocidal activity. Stimulate immune response by increasing the secretion of chemicals in the body that fight infections thereby reducing the number of pathogens in the GI tract. Helicobacter pylori(H. pylori) Clarithromycin + PPI + Amoxicillin Clarithromycin + PPI + Metronidazole Bismuth salicylate (Pepto-bismol)