Treatment of irritable bowel syndrome

Irritable Bowel Syndrome (IBS) is a common chronic functional disorder characterized by abdominal pain with alterations in bowel habits....
Mahitab Hany, BS Pharm, PGDipClinPharm, PGDipClinNutrition

Introduction

Irritable Bowel Syndrome (IBS) is a common chronic functional disorder characterized by abdominal pain with alterations in bowel habits. Symptoms usually begin in late teens to early twenties. Up to 10% of the adult population have symptoms compatible with irritable bowel syndrome, but most never seek medical attention.

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Clinical findings

Symptoms and signs

Abdominal distention, abdominal pain, intermittent, crampy in the lower abdomen that may be improved or worsened by defecation. Constipation, diarrhea, or alternating constipation and diarrhea. Bloating, flatulence, and diarrhea may be exacerbated in some patients who eat poorly absorbed, fermentable, monosaccharides and short-chain carbohydrates (FODMAPS).

Physical examination

Digital rectal examination should be performed in patients with constipation to screen for paradoxical anal squeezing during attempted straining that may suggest pelvic floor dyssynergia. A pelvic examination is recommended for postmenopausal women with recent onset constipation and lower abdominal pain to screen for gynecologic malignancy. Laboratory Tests INCLUDE complete blood count, erythrocyte sedimentation rate, C-reactive protein, fecal occult blood or fecal immunochemical test. Celiac disease serology (IgA tissue transglutaminase [tTG] antibody) and stool examination for ova and parasites if diarrhea.

Treatment

Abdominal pain and spasm

Antispasmodic (anticholinergic) agents are commonly used despite a lack of good evidence demonstrating efficacy. Dicyclomine, 10–20 mg three or four times daily orally OR Hyoscyamine, 0.125 mg four times daily orally (or sublingually as needed).

Antidepressants can be used, tricyclic and related antidepressants like nortriptyline, desipramine, or imipramine, begin at 10 mg orally every night at bedtime and increase gradually to 25–50 mg orally every night at bedtime as tolerated, or trazodone, beginning at 50 mg orally every night at bedtime, is an alternative but Not recommended for patients with predominant constipation. Serotonin reuptake inhibitor antidepressants such as sertraline (Lustral, Serpass, Moodapex), 25–100 mg once daily orally, fluoxetine (Prozac, Flutin), 10–40 mg once daily orally, citalopram (Cipram), 10–20 mg once daily orally can be safely used for spasm. But not recommended for patients with predominant diarrhea.

Diarrhea

Antidiarrheal agents like loperamide (Imodium, Loperasin), 2 mg three or four times daily orally, cholestyramine (Questran, Cholestran), 2–4 g one to three times daily orally with meals (off-label use) or colesevelam, 625 mg, one to three tablets twice daily orally (off-label use).

Constipation

Fiber supplementation (Bran, psyllium, methylcellulose) may cause increased bloating. Osmotic laxatives such as polyethylene glycol 3350 (MiraLAX, 17–34 g/day) dissolved in fluid orally once daily. Lubiprostone (Lubicont), 8 mcg orally twice daily, linaclotide 290 mcg orally once daily, and plecanatide 3 mg orally once daily. These agent approved for treatment of irritable bowel syndrome with constipation. They stimulate increased intestinal chloride and fluid secretion, resulting in accelerated colonic transit.

Other symptoms

Ondansetron (Zofran), 4–8 mg three times daily, showed overall excellent symptom improvement, including stool frequency, consistency, and urgency. Rifaximin (Gastrobiotic), 550 mg three times daily for 14 days. It may be considered in patients with refractory symptoms, especially bloating. Improvement may be attributable to suppression of bacteria in small intestine or colon.

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References

  1. Ford AC, Moayyedi P, Chey WD, Harris LA, Lacy BE, Saito YA, Quigley EMM; ACG Task Force on Management of Irritable Bowel Syndrome. American College of Gastroenterology Monograph on Management of Irritable Bowel Syndrome. Am J Gastroenterol. 2018 Jun;113(Suppl 2):1-18.
  2. Black CJ, Burr NE, Camilleri M, Earnest DL, Quigley EM, Moayyedi P, Houghton LA, Ford AC. Efficacy of pharmacological therapies in patients with IBS with diarrhoea or mixed stool pattern: systematic review and network meta-analysis. Gut. 2020 Jan;69(1):74-82.
  3. Ford AC, Lacy BE, Harris LA, Quigley EMM, Moayyedi P. Effect of Antidepressants and Psychological Therapies in Irritable Bowel Syndrome: An Updated Systematic Review and Meta-Analysis. Am J Gastroenterol. 2019 Jan;114(1):21-39.