PHAR1059 GI Drugs 2024-2025 PDF

Gastrointestinal Drugs (Essentials) PHAR1059 – 2024-2025 GI DRUG CATEGORIES Key GI drug categories that you “need to know”” 1. Laxatives 2. Antidiarrheal 3. Anti-emetics 4. Acid Controlling Categories LAXATIVES LAXATIVES Classes of Laxatives 1. Bulk Forming 2. Emollient...

Gastrointestinal Drugs (Essentials) PHAR1059 – 2024-2025 GI DRUG CATEGORIES Key GI drug categories that you “need to know”” 1. Laxatives 2. Antidiarrheal 3. Anti-emetics 4. Acid Controlling Categories LAXATIVES LAXATIVES Classes of Laxatives 1. Bulk Forming 2. Emollient 3. Hyperosmotic 4. Stimulant Indications for use  Prevent constipation  Treatment of constipation  Preparation of GI preoperatively LAXATIVES  Reduce strain of defecation  Removal of toxins from GI  Treatment of parasitic infestation LAXATIVES Bulk Forming 1. Methylcellulose 2. Psyllium Hydrophilic mucilloid (Metamucil) Mechanism of Action  Act like dietary fibre  Pull water into intestines, distends bowel, initiates movement, promotes defecation  Need lots of fluid  Typically, a powder that has to be mixed  Only one recommended for long-term use LAXATIVES Emollients 1. Docusate Sodium (Colace) 2. Mineral Oil Mechanism of action  Lubricate stool by reducing surface tension, more water/fat is absorbed into stool  Lines/coats the intestine, does not let water out  Soften stool, distends bowel, initiates movement, promotes defecation LAXATIVES Hyperosmotic 1. Glycerin 2. Lactulose 3. Polyethylene Glycol 3350 (PEG 3350, GoLYTELY) Mechanism of Action  This class increases the amount of fecal water  Promote distention and movement, aids in defecation Indications  Used extensively for procedure prep where the GI needs to be empty Special notes  Lactulose prevents hepatic encephalopathy by decreasing ammonia  Glycerin PO or suppository LAXATIVES Stimulants 1. Senna (senokot) 2. Bisacodyl (dulcolax) Mechanism of Action  Increases intestinal peristalsis by irritating intestines  Plant based Special notes  Bisacodyl PO or PR as suppository  Most likely to cause dependence  Stimulants work on entire GI tract LAXATIVES General Nursing Considerations  Assess lifestyle, diet, fluid balance, exercise, bowel history  Assess for underlying cause and intervene  Determine most appropriate laxative  Assess for results  Monitor for overuse  Overuse leads to colon stopping its response or large amounts needed for BM ANTIDIARRHEAL ANTIDIARRHEAL Classes of Antidiarrheal Drugs 1. Adsorbents 2. Anticholinergics 3. Opiates 4. Probiotics Goals of antidiarrheal agents:  Decrease stool frequency and symptoms  Avoid fluid and electrolyte loss Antidiarrheal  Prevent weight loss agents  Prevent nutritional deficits from malabsorption  May need to be accompanied by fluid and electrolyte replacement  Antidiarrheal agents are NOT used when infection is suspected ANTIDIARRHEAL Adsorbents 1. Bismuth subsalicylate (Pepto-Bismol, Bismuth) 2. Activated charcoal 3. Aluminum hydroxide 4. Cholestyramine 5. Polycarbophil Mechanism of Action  Coats the walls of GI tract and binds to the causative contaminant (thing causing diarrhea)  Surface allows biding of toxin sand bacteria for elimination. Pharmacokinetics  Onset of action within 30min to 2 hrs, limit 8 does/day 12 ANTIDIARRHEAL Adsorbents Adverse Effects  Increased bleeding  Constipation  Dark stools  Metallic taste  Black tongue  Tinnitus Adverse Events  Bismuth subsalicylate is related to aspirin (ASA)  Can cause Reyes syndrome in children ANTIDIARRHEAL Anticholinergics  Atropine sulphate  Hyoscyamine Mechanism of Action  Antimuscarinic effect on smooth muscle in GI tract  Slows peristalsis by reducing the rhythmic contractions and smooth muscle tone of the GI tract  Also have a drying effect and reduce gastric secretions Adverse Effects  Similar to other anticholinergic drugs done this term  Urinary retention, bradycardia, hypotension ANTIDIARRHEAL Opioids 1. Codeine phosphate 2. Loperamide Hydrochloride (Imodium) 3. Diphenoxylate HCl (Lomotil) Therapeutic Effect  Slow peristalsis by working on opioid receptors (Sem 2)  Reduces pain from rectal spasms  Also slows passage of stool through GI which promote absorption of fluid and nutrients Adverse Effects (opioid effects)  Constipation  Loperamide has only local effects and less adverse effects ANTIDIARRHEAL Probiotics 1. Lactobacillus acidophilus 2. Lactobacillus GG 3. Saccharomyces boulard Mechanism of action  Also called intestinal flora modifiers  Obtained from bacterial cultures such as Lactobacillus  Replace GI normal flora and suppress diarrhea causing flora  Useful for antibiotic related diarrhea ANTIDIARRHEAL Contraindications  Drug allergy  Diarrhea caused by bacterial or parasitic infection  Any major acute GI condition (intestinal obstruction or colitis) Interactions:  Decreases effectiveness of many drugs by decreasing their absorption  Warfarin (bleeding)  Digoxin  Antihyperglycemic agents  Methotrexate  ASA (when given with bismuth) ANTIDIARRHEAL General Nursing Considerations  Do not use if infection is suspected or in children under 6 years (consult HCP)  Do not exceed daily recommended doses  Report fever, malaise or increased abdominal pain/distension or failure of diarrhea to improve  Monitor for dehydration, stool frequency  Increase fluids and electrolytes  Diet- increase bulk, avoid spicy foods, caffeine and those that worsen diarrhea ANTIEMETICS ANTIEMETICS Classes of Antiemetics 1. Antihistamines 2. Anticholinergics 3. Serotonin Blockers 4. Neuroleptics 5. Prokinetics- stimulate movement of gut 6. Tetrahydrocannabinol (medical marijuana) 20 ANTIEMETICS Antihistamines 1. Dimenhydrinate (Gravol®) 2. Diphenhydramine hydrochloride (Benadryl®) Mechanism of Action  H1 blockers that produce an anticholinergic action on the CTZ (Chemoreceptor Trigger Zone)  Have potent Anticholinergic effects which means they decrease secretions and are antispasmodics  These drugs can cause drowsiness ANTIEMETICS Anticholinergics 1. Scopolamine hydrobromide Mechanism of Action  Block ACh receptors in vestibular nuclei to prevent nausea  Blocks transmission of nausea signals to the vomiting centre of the brain  Decrease secretions and smooth muscle motility Not used as much any more because of the adverse effects of anticholinergics ANTIEMETICS Serotonin Blockers 1. Ondansetron hydrochloride dihydrate (Zofran) Mechanism of Action  Block 5-HT3 (serotonin) receptors in GI, chemoreceptor trigger zone, and in vomiting center of the medulla Indications for use  Chemotherapy-induced nausea and vomiting  Postoperative nausea and vomiting  Hyperemesis gravidarum (N&V associated with pregnancy)  Go to drug now for treatment of vomiting in pediatrics because it will not cause drowsiness (very few adverse effects/events) ANTIEMETICS General Nursing Considerations  Monitor for effectiveness  May cause drowsiness, sedation, confusion- avoid driving etc.  Regular scheduled dosing may be needed  Avoid other CNS depressants (i.e. alcohol etc.)  Give 30-60 min before chemotherapy, meals etc. ACID CONTROLLING ACID CONTROLLING DRUGS We will only cover the most common classes 1. Antacids 2. H2 Antagonists (H=Histamine) ACID 3. Proton Pump Inhibitors CONTROLLING DRUGS ACID CONTROLLING DRUGS Antacids 1. Aluminum containing Antacids (Maalox, Mylanta) 2. Calcium containing Antacids (Tums, Rolaids) 3. Magnesium containing Antacids (Milk of Magnesia) 4. Sodium containing Antacids (Alka-Seltzer, Bromo-Seltzer) Mechanism of Action & Effect  This class works to negate or neutralize acid (alkaline) NOT to decrease production of acid  May also stimulate mucous production  Common OTC salt derived drugs  They have little systemic absorption ACID CONTROLLING DRUGS Antacids Cautions  Most of these drugs are very safe but have a high risk of overuse and can lead to adverse effects.  Most common is that they can interact with other drugs in the GI Tract and inactivate them.  Rebound effects  Bloating  Electrolyte imbalances  Calcium containing can cause kidney stones  Renal insufficiency/failure ACID CONTROLLING DRUGS Antacids Nursing Considerations  Chew thoroughly  Take other meds at least 1-2 before or after an antacid is taken  Adequate fluids  Monitor for constipation  Risk of hypercalcemia when taking calcium-containing antacids ACID CONTROLLING DRUGS H2 Antagonists (H=Histamine) 1. Ranitidine (Zantac) 2. Famotidine (Pepcid) Mechanism of Action and Effect  These drugs block H2 receptors in the parietal cells and REDUCE the amount of acid secretion Contraindications  Only contraindicated in liver and renal disease  Otherwise Very safe and have become front line treatment for acid related disorders such as Peptic Ulcers, GERD ACID CONTROLLING DRUGS Proton Pump Inhibitors (PPI’s) 1. Lansoprazole (Prevacid) 2. Omeprazole (Losec) 3. Pantoprazole (Pantaloc) 4. Esomeprazole (Nexium) Mechanism of Action and Effect  This class of drugs is the newest acid reducing drug  PPIs block acid secretion  Bind directly to H-K-ATPase pump mechanism in parietal cells, significantly slow down or stop acid production Indications for use  GERD (that doesn’t respond to an H2), Duodenal & Gastric ulcers  Very few interactions and very safe ACID CONTROLLING DRUGS Miscellaneous Drug SUCRALFATE  Classified as a Mucosal protectant  It coats the GIT lining protecting it against acids – like an acid shield  Good to aid in healing but not preventing  Used for duodenal and gastric ulcers  It is aluminum based (watch for toxicity)  It interacts with many medications, so it is prudent to give other meds 2 hours before sucralfate Recall this was the drug in sem 2 and this term that interacted with several drugs ACID CONTROLLING DRUGS General Nursing Considerations  Assess pattern of pain and other symptoms, exacerbating factors, current meds and pattern of acid reducing drug use  Monitor liver and kidney function test, sodium levels, electrolytes  Best results if H2 Blockers are taken 1 hr before antacids  Timing with regard to administration of other meds  Smoking may decrease effectiveness  Best taken on empty stomach at least 60 min before meals  Long term use of PPI may increase risk of osteoporosis