Antidiarrheals and Laxatives PDF

Antidiarrheals (Ch 84) and Laxatives (Ch 83) Objectives Understand the causes of alterations of secretions and motility in lower intestines leading to diarrhea and constipation Describe the groups of agents used to treat diarrhea Describe the groups of agents used to treat constipation...

Antidiarrheals (Ch 84) and Laxatives (Ch 83) Objectives Understand the causes of alterations of secretions and motility in lower intestines leading to diarrhea and constipation Describe the groups of agents used to treat diarrhea Describe the groups of agents used to treat constipation Develop understanding of related client care GI Drugs Drugs that alter the motility of the gastrointestinal tract include: Antidiarrhoeal drugs and antispasmodic drugs decrease motility or which decrease smooth muscle tone Laxatives/Purgatives accelerate the passage of food through the intestine Antidiarrheal Drugs Diarrhea Abnormal passage of stools increased frequency fluidity, and weight increased stool water excretion Bristol Stool Chart Diarrhea Acute diarrhea Sudden onset in a previously healthy person Lasts from 3 days to 2 weeks Self-limiting Resolves without sequelae Causes of acute diarrhea Microbial Drug-induced Nutritional Diarrhea Chronic diarrhea Lasts for more than 3 weeks Associated with recurring passage of diarrheal stools, fever, loss of appetite, nausea, vomiting, weight loss, and chronic weakness Causes of chronic diarrhea Tumours Diabetes Hormonal (hyperthyroidism, Addison’s disease) Irritable bowel syndrome Antidiarrheal Drugs Opioids Adsorbents Anticholinergics (antispasmodic) Opioids: Mechanism of Action Activating opioid receptors in GI tract: 1. Decrease bowel motility Increase bowel transit time allows more time for water and electrolytes to be absorbed 2. Decrease secretions & increase fluid absorption Opioids loperamide (Imodium) poorly absorbed poor access to CNS Others: diphenoxylate, paregoric, opium tincture Opioids: Adverse Effects Excessive doses can lead to typical opioid drug effects: Drowsiness, sedation, dizziness, lethargy Nausea, vomiting, anorexia, constipation Respiratory depression Bradycardia, palpitations, hypotension Urinary retention Flushing, rash, urticaria Adsorbents Coat the walls of the GI tract (??) Bind to the causative bacteria or toxin, which is then eliminated through the stool (?perhaps?) Inhibit intestinal secretions (??) Examples: bismuth subsalicylate (Pepto- bismol), activated charcoal Adsorbents Bismuth subsalicylate also used for relief of stomach acid symptoms Bismuth adverse effects: Constipation Dark stools and tongue Metallic taste, blue gums Client Care: Antidiarrheal Agents DO NOT give bismuth subsalicylate to children younger than age 16 or teenagers with viral infections (eg chicken pox) Reye’s syndrome Anticholinergics: Mechanism of Action Antagonist at cholinergic receptors Decrease diarrheal muscle cramping Examples: atropine, scopolamine (hyoscine) typical undesirable anticholinergic effects Anticholinergics: Adverse Effects Typical Anticholinergic Effects CNS excitation- dizziness, confusion, anxiety Blurred vision, photophobia, increased intraocular pressure Dry mouth, dry skin CV (tachycardia) Constipation Urinary retention, hesitancy Laxatives Constipation Abnormally infrequent and difficult passage of feces through the lower GI tract Symptom, not a disease What is the cause? Diet? Disease? Drugs? Disorder of movement through intestines and/or rectum Constipation Constipation Complications of constipation hemorrhoids (enlarged rectal veins) anal fissure (cracks in anal lining) fecal impaction (manual removal?) rectal prolapse (rectal tissue pushed out) “lazy bowel” Laxatives: Mechanism of Action Bulk forming (1-3 days) Osmotic (Hyperosmotic; dose dependent) Fecal softener (Emollient; 1-3 days) Stimulant (6-12 hours) Some available as enema/suppositories All laxatives lead to softer stools onset and extent of action varies Laxative Use DO NOT use if bowel obstruction Overuse/abuse Atonic colon – reduced muscular activity “lazy bowel” Require more laxatives Dependency (of sorts!) Laxatives: Bulk Forming Bulk forming High fibre substances (non-digestable material) Absorbs water present in lumen to increase bulk Distends bowel to initiate reflex bowel activity Examples: methylcellulose (Citrucel) psyllium (Metamucil) Polycarbophil Also relief of diarrhea Laxatives Osmotic Laxatives (next 2 slides) Non-absorbable compounds or salt solutions that draw water into intestinal lumen Hyperosmotic compounds Salines (salt solutions) can cause substantial water loss = dehydration Laxatives: Mechanism of Action Hyperosmotic compounds Increase fecal water content bowel distention, increased peristalsis, and evacuation Examples: Lactulose polyethyleneglycol (Restoralax) sorbitol glycerin (enema/suppository) Laxatives: Mechanism of Action Salines Increase osmotic pressure within the intestinal tract, causing more water to enter the intestines bowel distention, increased peristalsis, and evacuation Saline laxative examples: magnesium sulfate magnesium hydroxide magnesium citrate sodium phosphate enema (Fleet) Laxatives – Osmotic Constipation low doses - 6-12 h Diagnostic and surgical preps high doses eg watery stool in 2-6 h for a 'squeaky clean' colon PEG + Na/Mg salines Laxatives: Mechanism of Action Fecal Softeners (= emollients or surfactants) Stool softeners and lubricants Promote more water and fat in the stools Lubricate the fecal material and intestinal walls Examples: Stool softeners: docusate sodium (enema) Lubricants: mineral oil emema options Laxatives: Mechanism of Action Stimulant Increases peristalsis via intestinal nerve stimulation Increase fluid secretion into intestine Examples: Senna (enema/suppository options) cascara bisacodyl (synthetic; enema/suppository options) castor oil (only for rapid GI cleansing) Laxatives Remember opioids cause constipation…. Stimulants and fecal softener used to prevent this + Client Care: Laxatives Clients should take bulk-forming laxatives with at least 240 mL of water (full glass) prevents esophageal obstruction Client Care: Laxatives A healthy, high-fibre diet, increased fluid intake and exercise should be encouraged as an alternative to laxative use Long-term use of laxatives often results in decreased bowel tone and may lead to dependency Clients should not take laxatives if they are experiencing nausea, vomiting, and/or abdominal pain