GIT Nursing PDF

SYSTEMIC PHARMACOLOGY Dr. Kabiru Abubakar (B. Pharm., MSc., PhD) Associate Professor (Pharmacology) Gastrointestinal & Biliary System GASTROINTESTINAL TRACT (GIT) PHARMACOLOGY Gastro intestinal (GI) disorders account for minor, day to day complains as well as major health problems. In...

SYSTEMIC PHARMACOLOGY Dr. Kabiru Abubakar (B. Pharm., MSc., PhD) Associate Professor (Pharmacology) Gastrointestinal & Biliary System GASTROINTESTINAL TRACT (GIT) PHARMACOLOGY Gastro intestinal (GI) disorders account for minor, day to day complains as well as major health problems. In most cases, dietary interventions can improve symptoms that are caused, for example, by poor eating habits, but if these measures are not successful, pharmacological interventions have to be employed. Major diseases of the GIT includes but not limited to Peptic ulcer disease (PUD), diarrhoea and constipation. GASTROINTESTINAL TRACT (GIT) PHARMACOLOGY Diarrhoeal disease causes fluid and electrolyte imbalance, and are usually treated with correction of the imbalance by oral or intravenous fluid and electrolyte replacement therapy. Constipation on the other hand is usually treated by use of Laxatives or Purgatives Laxatives include Al, Mg and sodium salts, while Purgatives include mineral oils such as Liquid paraffin, castor oil and stimulant purgatives such as Bisacodyl.  PEPTIC ULCER DISEASE (PUD) The term peptic ulcer refers to any ulcer in an area where the mucosa is bathed with HCL and pepsin of gastric juice (ie the stomach and upper part of the duodenum). Damage to the mucosa and deeper tissue exposed to acid and pepsin is known as peptic ulcer. Drugs that are effective in peptic ulcer either reduce gastric acid secretion or increase mucosal resistance to acid-pepsin attack. Peptic ulcers however healed will always reoccur without continuous administration of drugs.  Causes of Ulcer Causes of Ulcer: H. pylori, NSAID use, Stress Chronic infection of the stomach with Helicobacteria pylori is an important aetiological factor in peptic ulcer formation H. pylori is implicated in about 95% of duodenal ulcers and 70% of stomach ulcers H. pylori infection causes hypergastrinaemia, which in turn causes increased acid production.  Classification of the drugs used in peptic ulcer Drugs that inhibit gastric acid secretion 1. Proton pump inhibitors: omeprazole, esomeprazole, lansoprazole, pantoprazole, rabeprazole. 2. H2-receptor antagonists: cimetidine, ranitidine, famotidine, roxatidine,nizatidine 3. Antimuscarinic agents (anticholinergics): blocks the Muscarinic (M1 cholinergic receptors).They include Pirenzepine, Telenzepine 4. Prostaglandin analogs: misoprostol, enprostil.  Anti-peptic ulcer drugs Ulcer protective sucralfate, and bismuth subcitrate (CBS) Drugs that neutralize gastric acid (antacids) a) Systemic antacids: sodium bicarbonate and sodium citrate. b) Non systemic antacids: magnesium hydroxide, magnesium trisilicate, aluminum hydroxide, and calcium carbonate. Anti-peptic ulcer drug Anti- H. pylori drugs Amoxicillin, tetracycline, clarithromycin, metronidazole, tinidazole, bismuth subsalicylate, H2-antagonists and PPIs.  Proton pump inhibitors Proton pump, K+-ATPase membrane bound enzyme play an important role in the final step of gastric acid secretion (basal and stimulated). Omeprazole is the prototype drug: these are prodrugs and activated to sulfonamide at acidic pH. Activated form binds covalently with SH group of H+ pump and irreversibly inactivates it. PPIs administered orally 30 min. before meal. Half life short (1.5 hr), acid secretion suppressed for up to 24 hr. Proton Pump Inhibitors Indications: Single daily administration can inhibit acid secretion 100% Effective in Reflux, duodenal and gastric ulcer, Multiple endocrine neoplasia (MEN) and Zollinger-Ellison syndrome. S/E Well tolerated but have been reported to cause diarhea  H2-Receptor antagonists Mechanism of action: Competitively block H2 receptors on parietal cells; Suppress all phases of acid secretion. Most effective in suppressing nocturnal acid Secretion and less potent than PPIs. S/E: Reversible gynaecomastia, elevated serum prolactin levels and altered oestrogen level in men. Inhibition of cytochrome P450 metabolism.  Prostaglandin analogues Misoprostol effective orally for prevention and treatment of NSAID-induced duodenal and gastric ulcers. Misoprostol is a Prostaglandin E1 analogue that stimulates production of mucus and other protective factors such as bicarbonate. Common side effects: Diarrhoea and abdominal cramps. Containdicated in pregnancy  Ulcer protective Sucralfate : it is complex aluminum hydroxide and sulphated sucrose. Form Physical barrier against acid- pepsin. Polymerized to form sticky gel that adheres to the ulcer base and protects it. Warning: Sucralfate should not be taken simultaneously with PPI or H2 blockers because the drug needs an acid PH for its action.  Bismuth containing preparation Bismuth salicylates and colloidal Bismuth subcitrate. Moa: similar to sucralfate, React with protein in the base of ulcer and protect it from peptic digestion. Stimulates secretion of PGE2, mucus and bicarbonate. 98% ulcer healing reported when combined with Anti-microbial agents due to increase effects against H. pylori.  Drugs that neutralized gastric acid Antacids: Antacids are bases that raises the gastric PH by neutralizing gastric acids, they provide effective treatment for many dyspepsia and symptomatic relief for many peptic ulcers and oesophageal reflux. Types of antacids Systemic: Sodium bicarbonate and Sodium citrate Non systemic: magnesium hydroxide, magnesium trisilicate, aluminum hydroxide gel and calcium carbonate  Anti H. pylori agents Gram negative, rod shaped bacteria associated with gastritis, duodenal ulcer, gastric ulcer and gastric carcinoma. Cause mucosal inflammation Ammonia produced by urease activity damage cells. Combination therapy (Use of multiple antibiotics for synergism) To prevent or delay development of resistant organism. Prevent relapse Promote rapid ulcer healing Eradicate H. pylori infection Treatment for 1 or 2 weeks required Triple therapy x 14 days Lansoprazole 30 mg BD+ clarithromycin 500 mg BD + Amoxicillin 1 g BD Quadruple therapy x 14 days Lansoprazole 30 mg BD + Bismuth subsalicylate 525 mg QID + Tetracycline 500 mg QID + Metronidazole 500 TDS After completion of above regimen, PPIs should be continued for six more weeks.  ANTI EMETICS They include drugs like: Antihistamines- H1 blockers such as Diphenhydramine Phenothiazines- Promethazine, prochloperazine 5-HT3 inhibitors- ondansetron INDICATIONS: Any condition that is inducing emesis such as chemotherapy, and GI infection.  LAXATIVES Agents use to soften stool and relieve indigestion, classified based on their MOA as 1. Bulk Forming; They are nonabsorbable agents that increase water retention and stool bulk, which distends the bowel and increase peristalsis. They are normally insoluble during the digestive process such as: Hydrophilic colloids (from indigestible parts of fruits and vegetables), Agar, Methycellulose, Bran, Lactulose, sorbitol and saline cathartics (Magnesium citrate and Magnesium hydroxide) 2. Stimulant: Castor oil, Bisacodyl(Dulcolax), Senna and Phenophtalein  Stool softeners These agents emulsifies the stool and make it soft and easy to pass Examples include: Mineral oil (glycerin) Suppositories and detergent eg Dioctyl sodium sulfosuccinate (Docusate)