1. Laxatives
1.1. Bulk-forming laxatives
1.1.1. Methylcellulose
1.1.1.1. MOA
1.1.1.1.1. Increased bacterial mass causes distension in colon
1.1.1.2. Use
1.1.1.2.1. Acute or chronic constipation (better for chronic)
1.1.1.2.2. Effect w/in 12-24 hrs
1.1.1.3. SE
1.1.1.3.1. Flatulence and bloating d/t bacteria
1.2. Osmotic Laxatives
1.2.1. Saline laxatives
1.2.1.1. Magnesium citrate
1.2.1.1.1. Use
1.2.1.1.2. SE
1.2.1.2. Sodium phosphate
1.2.1.2.1. Enema works very quickly (2-15 minutes)
1.2.1.2.2. Oral
1.2.2. Non-digestible sugars & alcohols
1.2.2.1. Lactulose
1.2.2.1.1. Use
1.2.2.1.2. SE
1.2.3. Polyethylene glycol (PEG)
1.2.3.1. Use
1.2.3.1.1. Constipation (A&C)
1.2.3.1.2. Bowel prep
1.2.4. MOA
1.2.4.1. Create osmotic gradient that increases intra-luminal volume and pressure in small intestine and/or colon
1.3. Stimulant Laxatives
1.3.1. Bisacodyl
1.3.1.1. MOA
1.3.1.1.1. Acts as irritant
1.3.1.1.2. Increase H2O and electrolytes in lumen
1.3.1.2. Use
1.3.1.2.1. A&C constipation
1.3.1.2.2. Bowel prep: Used in combo w/ PEG
1.4. Stool softeners
1.4.1. Docusate sodium
1.4.1.1. MOA
1.4.1.1.1. Anionic surfactants allow water and lipid penetration into stool
1.4.1.2. Use
1.4.1.2.1. Don't help w/ constipation!
1.4.1.2.2. Post surgery if given opiod
1.5. Lubiprostone
1.5.1. MOA
1.5.1.1. Selective type 2 Cl channel activator
1.5.1.2. Increases intestinal fluid secretion and motility
1.5.2. Use
1.5.2.1. Chronic constipation
1.5.2.2. Constipation predominant IBS
1.5.3. SE
1.5.3.1. Nausea, diarrhea
1.5.3.2. Cost
2. Antidiarrheals
2.1. Antimotility/Antisecretory Agents
2.1.1. Opioids
2.1.1.1. Diphenoxylate + Atropine
2.1.1.1.1. LD atropine prevents drug abuse (get cholernergic Sx if dose too high)
2.1.1.2. Loperamide
2.1.1.3. These two have the greatest ratio of intestinal to CNS activity!
2.1.2. MOA
2.1.2.1. Antagonist Mu and delta receptors in enteric neurons/muscle
2.1.2.1.1. Reduced peristalsis and intestinal secretions
2.1.3. Use
2.1.3.1. Control diarrhea d/t almost any cause
2.2. Intraluminal agents
2.2.1. Bismuth Subsalicylate
2.2.1.1. MOA
2.2.1.1.1. Bismuth: binds enterotoxins to prevent traveler's diarrhea
2.2.1.1.2. Salicylate: Inhibits production of PGs to deacreas intestinal secretions
2.2.1.2. Not as good as Loperamide!
3. IBS Drugs
3.1. IBS characterized by altered bowel habits + abdominal pain
3.1.1. Tx has high placebo effect!
3.2. Tx
3.2.1. Constipation - OTC laxatives
3.2.2. Diarrhea - Loperamide
3.2.3. Pain - Anticholinergics/antidepressants
3.3. IBS w/ constipation (IBS-C)
3.3.1. Bulk-forming laxatives
3.3.2. Lubiprostone
3.3.2.1. affects serotonin receptors
3.3.2.1.1. Big gun!!!
3.4. IBS w/ diarrhea
3.4.1. Loperamide
3.4.2. Cholestyramine reduces bile and colonic secretion