Drugs for Lower GI Tract Flashcards
What is the clinical use for lubiprostone?
It is a stimulant laxative used for idiopathic chronic constipation in adults. It is approved for chronic use.
Name the saline laxative and describe its mechanism of action.
Mg(OH)2: It is administered as a hypertonic solution and the osmotic pressure leads to accumulation of fluids in the GI tract and stimulation of peristalsis.
What is the clinical use of Mg(OH)2?
It is used for complete evacuation in under 3 hours for things like colonoscopy prep. Also treats constipation in IBS pts.
In which kind of patient should Mg(OH)2 be used with caution?
A renal insufficient patient. This laxative increases the risk of hypermagnesemia.
Name the anti-diarrheals.
Loperamide (aka Immodium) and Alosetron
Describe the mechanism of action of Loperamide (Immodium).
It is an opioid with low abuse potential d/t poor GI absorption. Slows intestinal transit time by stimulating mu opioid receptors in the intestinal smooth muscle.
*Loperamide- low potential for abuse
In which kind of patient should Loperamide be avoided?
Patients w/ ulcerative colitis or acute bacillary/amoebic dysentery b/c of risk of toxic megacolon
What is the clinical use of Loperamide?
It treats diarrhea in pts w/ IBS
What is the clinical use of Alosetron?
Diarrhea in women, predominantly IBS
What is a rare but serious side effect associated with Alosetron?
Ischemic colitis
Describe the mechanism of action of Alosetron.
It’s a 5-HT3 receptor antagonist. It decreases colonic motility via enteric and CNS blockade of the 5-HT3 receptors.
Name the stimulant laxative and describe its mechanism of action.
Lubiprostone: Cl- channel activator that increases intestinal fluid secretion resulting in increased BMs. Binds to the CIC-2 Cl- channel inducing secretion of Cl- into lumen where Na+ will seek to bind the Cl- for isoelectricity, dragging water with it.
*when stimulated, you use lube ;)
Name the mesalamine and its mechanism of action.
Sulfasalazine: The mechanism is not fully understood but it seems to interfere w/ intermediates in inflammatory pathways. It is only effective topically, not systemically.
What is the clinical use for sulfasalazine?
It is first-line tx for ulcerative colitis
What side effects are associated with sulfasalazine use?
40% of patients can’t tolerate this drug. It can cause n/d, headaches, hypersensitivity, and bone marrow suppression
Name the corticosteroid discussed in lecture and its clinical use.
Prednisone: Used for episodic IBD (**not long-term tx) to rapidly reduce ulceration and cause initial remission by decreasing inflammatory response.
Name the thiopurine anti-metabolite and its clinical use.
Azathioprine: Long-term immunosuppression therapy for IBD.
What are the side effects and drawbacks associated with azathioprine?
It may take 3-6 months to reach maximal effect and polymorphisms can greatly impact efficacy and side effects of this drug. Typical side effects include bone marrow suppression**, pancreatitis, elevated LFTs, rashes, fever, and nausea
Name the TNFa inhibitor and its clinical use.
Infliximab: Approved for use in ulcerative colitis.
Describe the mechanism of infliximab.
It is an antibody to TNF-alpha that binds to TNF-alpha effectively blocking its inflammatory effects at TNF receptors
What side effect is associated with infliximab use?
Increased infections
