Pharmacotherapy Case Study 9: Irritable Bowel Syndrome (IBS) By: Dr. Nehad Ahmed

 

 

Pharmacotherapy Case Study 9: Irritable Bowel Syndrome (IBS) By: Dr. Nehad Ahmed

 

Chief Complaint:

A 29-year-old female presents with intermittent abdominal discomfort, bloating, and changes in bowel movements for the past 6 months. She reports alternating episodes of diarrhea and constipation, with the symptoms exacerbating during periods of stress.

Subjective Data:

History of Present Illness (HPI):

·        The patient reports a 6-month history of abdominal discomfort and bloating, which tends to be relieved by bowel movements. The pain is described as crampy and is located in the lower abdomen, particularly on the left side.

·        She notes that her symptoms fluctuate between diarrhea (typically after meals) and constipation (typically in the morning). She does not experience blood in the stools.

·        The diarrhea episodes are characterized by frequent, loose stools, and the constipation episodes are marked by hard, infrequent stools with straining. These alternating patterns have led to significant discomfort and frustration.

·        The symptoms have become more frequent and severe during stressful periods, such as at work, and are generally relieved during weekends or vacation time when stress levels are lower.

·        The patient denies any weight loss, blood in the stool, or night sweats. She reports a normal appetite, although her diet often includes high-fat, low-fiber foods, and she drinks 2-3 cups of coffee daily.

·        The patient has tried over-the-counter antacids and laxatives, which provided temporary relief but did not fully address her symptoms. She has avoided immodium due to concerns about constipation during flare-ups.

Past Medical History (PMH):

·        No significant past medical history.

·        No history of gastrointestinal disorders (e.g., Crohn's disease, celiac disease).

Medications:

·        Multivitamin daily.

·        Occasional use of over-the-counter antacids (ranitidine or Tums).

·        Occasional use of laxatives (e.g., docusate sodium or polyethylene glycol) when constipated.

Allergies:

·        No known drug allergies (NKDA).

Social History:

·        Non-smoker.

·        Drinks alcohol socially (about 2-3 drinks per week).

·        Works as a marketing coordinator in a high-pressure environment with deadlines and multiple projects, contributing to stress.

·        Regularly exercises (walking, yoga) but has reported that stress impacts her ability to maintain consistent physical activity.

·        Diet is high in processed foods and low in fiber, with occasional fast food meals.

Family History:

·        Mother with a history of irritable bowel syndrome (IBS) and gastroesophageal reflux disease (GERD).

·        Father with type 2 diabetes.

·        No family history of gastrointestinal cancers, celiac disease, or inflammatory bowel disease.

 

 

Review of Systems (ROS):

·        Gastrointestinal: Abdominal bloating, crampy lower abdominal pain, alternating diarrhea and constipation. No blood in stools or recent changes in bowel habits. Occasional nausea after meals.

·        Cardiovascular: No chest pain, palpitations, or edema.

·        Respiratory: No shortness of breath or cough.

·        Neurological: No dizziness, headaches, or visual changes.

·        Musculoskeletal: No joint pain or discomfort.

Objective Data:

Vital Signs:

·        Blood Pressure: 118/75 mmHg

·        Heart Rate: 76 bpm

·        Respiratory Rate: 16 breaths/min

·        Temperature: 98.6°F (37.0°C)

·        Weight: 142 lbs (64.4 kg)

·        Height: 5'5" (165 cm)

Physical Exam:

·        General: Alert and oriented, in no acute distress. Appears well-nourished but mildly anxious.

·        Abdomen: Soft, non-distended. Mild tenderness to palpation in the lower abdomen, particularly on the left side, but no rebound tenderness or guarding. Bowel sounds are normal.

·        Cardiovascular: Regular rate and rhythm, no murmurs or gallops.

·        Respiratory: Clear to auscultation bilaterally.

·        Neurological: Alert and oriented, no focal deficits.

·        Skin: No rashes or jaundice.

 

Labs and Imaging:

·        Complete Blood Count (CBC):

o   Hemoglobin: 13.8 g/dL (normal)

o   Hematocrit: 41% (normal)

o   White Blood Cell Count: 6,000/mm³ (normal)

o   Platelets: 210,000/mm³ (normal)

·        Basic Metabolic Panel (BMP):

o   Sodium: 139 mEq/L (normal)

o   Potassium: 4.0 mEq/L (normal)

o   Chloride: 102 mEq/L (normal)

o   Bicarbonate: 23 mEq/L (normal)

o   Blood Urea Nitrogen (BUN): 15 mg/dL (normal)

o   Creatinine: 0.9 mg/dL (normal)

o   Glucose: 94 mg/dL (normal)

·        Liver Function Tests (LFTs):

o   Normal.

·        Thyroid Stimulating Hormone (TSH): Normal (2.2 µU/mL).

·        Stool Culture: Negative for pathogenic bacteria (e.g., Salmonella, E. coli, Shigella, Campylobacter).

·        Celiac Disease Panel: Negative for antibodies (e.g., anti-tTG, anti-endomysial antibodies).

·        Colonoscopy: Normal findings, no evidence of inflammation, polyps, or malignancy.

Assessment:

The patient's symptoms, including intermittent abdominal discomfort, bloating, and alternating diarrhea and constipation, along with a family history of IBS, are highly suggestive of Irritable Bowel Syndrome (IBS). Given the normal colonoscopy findings and negative stool cultures, there is no evidence of organic gastrointestinal disease. The patient's symptoms appear to be exacerbated by stress, which is common in IBS.

The most likely subtype of IBS in this patient is IBS-Mixed (IBS-M), characterized by both diarrhea and constipation, given the alternating bowel patterns.

Plan:

Pharmacologic Treatment:

1.     Antispasmodics:

o   Hyoscyamine 0.125 mg orally every 4-6 hours as needed for relief of crampy abdominal pain. Adjust dose if necessary to manage symptoms.

2.     Laxatives (for constipation episodes):

o   Polyethylene glycol (MiraLAX) 17 g in 8 oz of water daily as needed during episodes of constipation.

3.     Antidiarrheals (for diarrhea episodes):

o   Loperamide 2 mg orally after each loose stool, up to a maximum of 8 mg per day. This may be used during episodes of diarrhea.

4.     Probiotics:

o   Lactobacillus GG 1 capsule (250 mg) daily to help normalize gut flora and alleviate symptoms.

5.     Low-dose Tricyclic Antidepressant (TCA) for visceral pain and mood stabilization:

o   Amitriptyline 10 mg orally at bedtime, which can help reduce pain and improve bowel regularity due to its anticholinergic properties and effects on serotonin.

Non-Pharmacologic Treatment:

·        Dietary Modifications:

o   Recommend a low FODMAP diet, as this has been shown to reduce symptoms in patients with IBS. Encourage the patient to avoid high-fat, processed foods and increase fiber intake gradually.

o   Keep a food diary to track potential triggers and identify patterns between diet and symptoms.

 

 

·        Stress Management:

o   Recommend cognitive-behavioral therapy (CBT) or mindfulness-based stress reduction (MBSR) to help the patient manage work-related stress and its impact on gastrointestinal symptoms.

o   Encourage the patient to engage in regular physical activity, such as yoga or walking, to help reduce stress and promote bowel function.

·        Hydration:

o   Ensure adequate fluid intake, particularly water, to help manage constipation and support gastrointestinal health.

Monitoring and Follow-Up:

·        Follow-up in 4 weeks to evaluate the effectiveness of pharmacologic and non-pharmacologic interventions. If the patient’s symptoms have not improved, consider increasing the dose of Amitriptyline or exploring alternative treatments such as Rifaximin for IBS-related bloating.

·        If symptoms persist or worsen despite treatment, further diagnostic evaluation, including breath tests for lactose intolerance or SIBO (small intestinal bacterial overgrowth), may be considered.

Patient Education:

·        Explain the nature of IBS as a functional gastrointestinal disorder and the importance of lifestyle modifications (diet, stress management).

·        Educate the patient on the appropriate use of laxatives and antidiarrheals, emphasizing not to overuse them.

·        Discuss the low FODMAP diet and its potential benefits in managing IBS symptoms, as well as the role of probiotics in supporting gut health.

 

Referral:

·        If symptoms remain poorly controlled or if other underlying conditions are suspected, referral to a gastroenterologist may be warranted for further evaluation, including testing for lactose intolerance or small intestinal bacterial overgrowth (SIBO).

Long-Term Management:

·        Encourage ongoing lifestyle modifications, including stress management techniques, a balanced diet, and regular exercise to minimize symptom flare-ups.