Medications for symptom relief in IBS
Anticholinergics/ antispasmodics like Dicyclomine (Bentyl 10 & 20mg), pregnancy category B, Librax pregnancy category C, Donnatal Pregnancy category C, Hyoscyamine (Levsin) category C
Tricyclic antidepressant (TCA), low dose, only improve global well-being. impact not dependent on antidepressant or motility changes.
SSRI like fluoxetine reduces rectal sensitivity in IBS, side effects are diarrhea, cramping, nausea, anxiety. Amongst this group of meds Celexa is highly sedating and cause constipation.
Serotonin agents Alosetrone (Lotronex) a neuroenteric modulator, potent 5HT3 receptor antagonist that selectively blocks receptors of serotonin. it is used in female IBS with severe diarrhea, urgency, abd pain for at least 3 month. dosage 1 mg bid. stop if no better after 4 weeks. MD needs to be registered. pregnancy category B.
Antispasmodics, Anti-flatulents like activated charcoal, chlorophyl, Simethicon, antibiotics like Rifaximin.
Loperamide/Imodium, Cholestyramine/Questran, diphenoxylate/Lomotil, aloserton, D.T.O/deodorized tincture of opium.
In US 63 million have chronic constipation. of those 15.3 million are said to have constipation due to IBS (IBS-C). osmotic agents like 70% sorbitol or PEG solution (miralax) are used in patients with functional constipation. in IBS patients they'll increase bloating and abdominal discomfort. chloride channel activators like lubiproston (Amitiza) or Guanylate cyclase-c agonist linaclotide (Linzess), are more specific for IBS-C
Mesalamine 2.4 g daily has been shown to help post infectious IBS (PI-IBS), following bacterial gastroenteritis. pts are mostly female, past history of anxiety or depression, severe gastroenteritis and a persistent inflammatory response in the colon mucosa & some genetic factors. higher inflammatory cytokines IL-6 and IL-8 has been demonstrated in the blood of IBS patients. Prednison not effective. Mesalamine 2.4 g daily improves general well being but no improvement in pain, bloating and bowel habits.
In 75% of IBS patients bloating symptoms improved with a short course of antibiotics like Xifaxane. Alternative to Xifaxane is antiobiotics like Neomycine or Metronidazole.
Fibers don not imporve symptoms. 55% of patients taking bran will experience more bloating, pain and distension. Only 10% feel better. When fiber is used, start small (one tea spoon full) dose of a soluble fiber and increase the dose gradually over a two weeks period to maximun of 2 table spoon full.