IBS-D and global symptom medications

Loperamide (imodium)

• acts only peripherally

• MOA: antisecretory, inhibits the Ca binding protein calmodulin and controls chloride secretion

• usual adult dose: 4 mg orally followed by 2 mg after each loose stool, up to 16 mg/day

• side effects: dizziness and constipation

Eluxadoline (Viberzi)

• MOA: mixed mu-opioid receptor agonist, delta opioid receptor antagonist, and kappa opioid receptor agonist which acts locally to reduce abdominal pain and diarrhea

• use: indicated for adults in treatment of IBS-D

• Dose: 100mg BID or 75 mg BID

• ADR: constipation, nausea, abdominal pain

• reserve use for pts with a gallbladder who do not consume >3 alcoholic beverages per day or have a history of alcohol use disorder

alosetron (lotronex)

• MOA: selective serotonin 5-HT3 antagonist

• Use: IBS-D in women who are refractory to usual therapy

• Dose: 0.5mg BID

• available under the REMS program because of increased risk of ischemic colitis and serious constipation. Patients should contact their physician if they experience: abdominal pain and tenderness, rectal bleeding, or bloody diarrhea.

• has been shown to be superior to placebo for treatment of abdominal pain, urgency, global symptoms, and diarrhea-related symtpms

• box warning: discontinue immediately in patients who develop constipation

antispasmodics

• MOA: have anticholinergic effects and decrease spontaneous activity of intestinal smooth muscle

• should generally be on a PRN basis and/or in anticipation of triggers which lead to abdominal pain

• typical doses:

  • dicyclomine 20mg orally QID PRN

  • hyoscyamine 0.125 to 0.25 mg orally or SL TID to QID prn. Sustained release hyoscyamine 0.375 to 0.75 mg orally every 12 hours

• ADRs: dizziness, nausea, blurred vision, xerostomia (dry mouth), use antispasmodics with caution in elderly

• onset: 4-8 hours

Rifaximin

• MOA: inhibits bacterial RNA synthesis by binding to bacterial DNA-dependent RNA polymerase

• Use: useful in patients with moderate to severe IBS without constipation particularly those with bloating

• doses: oral: 550 mg 3 times daily for 14 days

  • may retreat every 3-4 months prn, if symptoms recur

• ADRs: nausea, increase in alanine aminotransferase (ALT)

• onset: 2 weeks

antidepressants (tricyclics)

• for treatment of abdominal pain in IBS, antidepressants should be started at low doses

• initial dose should be adjusted based upon tolerance and response

• due to the delayed onset of action of antidepressants, three to four weeks of therapy should be attempted before increase the dose

• amitriptyline, nortriptyline, desipramine, imipramine can be started at a dose of 10mg-25mg at bedtime

• if the patient is intolerant of one TCA, another may be tried

• onset 4-6 weeks

peppermint oil

• mechanism: ant inflammatory, smooth muscle relaxant

• 0.2ml po TID or 180mg TID

• onset: usually less than 1 week