Laxatives, Ant-Diarrheals, IBD Flashcards
Metoclopramide (D2 antagonist) MOA
Inhibits smooth muscle stimulation
Uses: GERD, impaired gastric emptying, postpartum lactation stimulation
Macrolides MOA
Directly stimulate motilin receptors on GI smooth muscle though tolerance develops quickly
Docusate MOA
(Stool surfactant agent/softener) Reduces surface tension of oil-water interface of stool resulting in enhanced incorporation of water and fat
Generally well tolerated
Short term use for treatment of constipation is generally safe in pregnancy!
Osmotic Laxatives MOA
soluble but nonabsorbable compounds resulting in increased stool liquidity due to obligate increase in fecal fluid
Osmotic Laxatives (drug list)
Magnesium hydroxide
magnesium citrate, sulfate solution
Sodium phosphate
Magnesium hydroxide
(milk of magnesia)
not for prolonged periods in renal insufficiency due to hypermagnesemia
Magnesium citrate, sulfate solution
Purgatives to treat acute constipation or clear bowel prior to procedure
MAINTAIN HYDRATION!
Sodium phosphate
Can precipitate arrhythmias or acute renal failure esp in elderly or renal or cardiac disease
Polyethylene glycol
Osmotic laxative
Used for complete colonic cleansing before endoscopy
Designed so no significant intravascular fluid or electrolyte shifts occur (SAFE!)
Stimulant Laxatives MOA
Induce bowel movements through poorly understood mechanisms; direct stimulation of enteric nervous system & colonic electrolyte & fluid secretion
Stimulant Laxatives (drug list)
Aloe
Senna
Bisacodyl
Senna (Senokot)
Stimulant laxative
Poorly absorbed and produces bowel movement 6-12 hrs after PO and 2 hrs after PR
Chronic use leads to brown pigment of colon
Bisacodyl (Dulcolax)
Stimulant laxative
Treatment of acute chronic constipation
Minimal systemic absorption & safe for acute & long term use!
Lubiprostone (Amitiza) MOA
Stimulates type 2 chloride channel in small intestine
Methynaltrexone (Relistor)
Opioid receptor antagonist
Doesn’t cross BBB so doesn’t impact analgesic effects in CNS but inhibits peripheral mu-opioid receptors
Loperamide (Imodium) OTC
MOA: opioid agonist
Doesn’t cross BBB!
Diphenoxylate/Atropine (Lomotil)
MOA: opioid agonist
No analgesic properties in standard dose but higher doses have CNS effects
Prolonged use can lead to dependence
Atropine added to discourage overdose & may contribute to antidiarrheal action!
Bismuth subsalicylate (Pepto-Bismol) MOA
Reduce stool frequency & liquidity due to salicylate inhibition of intestinal prostaglandin & chloride secretion
Has direct antimicrobial effects & binds to enterotoxins
Prevents and treats traveler’s diarrhea!
Bile Salt Binding Resins (drug list)
Cholestyramine
Colestipol
Colesevelam
Aminosalicylates MOA
Thought to modulate inflammatory mediators derived from cyclooxygenase and lipooxygenase pathways interfering with production of inflammatory cytokines
Aminosalicylates
Effectiveness depends on achieving high concentrations and site of active disease
Sulfasalazine (Azulfidine) class
Aminosalicylate: Azo Compound
Sulfasalazine Adverse Effects
High incidence associated with sulfapyridine molecule
GI upset, nausea, headache, arthralgias, myalgias, bone marrow suppression, hypersensitivity
Impairs folate absorption & processing (need supplement)
Pentasa
Aminosalicylate: Mesalamine compound
Contains timed release microgranules
Purine Analogs (drug list)
Azathioprine (Imuran)
6-mercaptopurine (6-MP)
Purine Analogs MOA
Purine antimetabolites with immunosuppressive properties
Purine Analogs Adverse Effects
Nausea, vomiting, bone marrow depression, hepatic toxicity
Interactions: allopurinol!
They are inactivated by xanthine oxidase and allopurinol is xanthine oxidase inhibitor!
Methotrexate MOA
Inhibits dihydrofolate reductase
High doses inhibit cellular proliferation but lower doses not so much
Methotrexate ADE
Bone marrow suppression
Megaloblastic anemia
Mucositis
Need folate supplement!
Antitumor Necrosis Factor (drug list)
Infliximab (Remicade)
Adalimumab (Humira)
Infliximab and adalimumab
Approved for acute and chronic moderate to severe Crohn’s disease with inadequate response to conventional therapies
