PEBC MCQ study guide: Gastrointestinal & Hepatic Disorders

Providing Care – Clinical Care

GERD, peptic ulcer disease/H. pylori, IBD, and hepatic dosing considerations.

GERD & Peptic Ulcer Disease

Proton pump inhibitors (PPIs) are first-line for GERD and PUD, generally dosed once daily before breakfast for maximal acid-suppression effect (proton pumps are most active postprandially). An 8-week trial is standard for erosive esophagitis; long-term/chronic use should be reassessed periodically given associations with C. difficile infection, fracture risk, hypomagnesemia, and B12 deficiency with prolonged use — deprescribing to the lowest effective dose or on-demand therapy is appropriate once symptoms are controlled.

H. pylori eradication (when identified, e.g., in PUD) uses triple or quadruple therapy — a common regimen is a PPI + amoxicillin + clarithromycin x14 days (triple), or bismuth quadruple therapy (bismuth + metronidazole + tetracycline + PPI) especially where clarithromycin resistance is a concern or with penicillin allergy.

Key interaction: PPIs reduce absorption of drugs requiring an acidic stomach for dissolution (e.g., certain HIV antivirals, itraconazole capsules) and PPIs can reduce clopidogrel's antiplatelet activation via CYP2C19 competition — pantoprazole is often preferred over omeprazole when a PPI must be co-administered with clopidogrel.

Inflammatory Bowel Disease

Mild-to-moderate ulcerative colitis is managed with 5-aminosalicylates (mesalamine, sulfasalazine) as first-line induction and maintenance therapy. Crohn's disease does not respond well to 5-ASAs and instead relies on corticosteroids for induction with biologics (anti-TNF agents like infliximab/adalimumab, or newer classes) for steroid-sparing maintenance in moderate-to-severe disease.

Corticosteroids (budesonide, prednisone) induce remission but are not appropriate for long-term maintenance in either UC or Crohn's due to cumulative toxicity — "bridge, don't maintain" is the guiding principle.

Hepatic Impairment — Dosing Considerations

Hepatic impairment primarily affects drugs cleared by CYP450 metabolism and drugs with high first-pass hepatic extraction (these show increased bioavailability/effect in liver disease due to reduced first-pass clearance). Child-Pugh scoring stratifies severity and guides dose adjustment for many hepatically-cleared drugs.

Practical exam-relevant points: acetaminophen should be dose-reduced/limited in chronic liver disease (though it is not absolutely contraindicated at therapeutic doses); NSAIDs are best avoided in cirrhosis (bleeding risk from coagulopathy, renal risk from hepatorenal physiology, GI bleed risk from varices); opioids requiring hepatic activation (e.g., codeine → morphine via CYP2D6) may have unpredictable effect, and doses of hepatically-cleared sedatives/opioids are generally reduced and intervals extended.

High-yield points

PPIs dosed once daily BEFORE breakfast for maximal effect; reassess/deprescribe long-term use given C. diff, fracture, and B12/Mg risks.
Pantoprazole preferred over omeprazole when co-administering a PPI with clopidogrel (less CYP2C19 interaction).
5-ASAs work for ulcerative colitis, NOT reliably for Crohn's disease.
Corticosteroids induce remission in IBD but are never long-term maintenance therapy.
NSAIDs are best avoided in cirrhosis — bleeding, renal, and GI-bleed risk all compound.

Guideline references

Canadian Association of Gastroenterology Clinical Practice Guidelines
Choosing Wisely Canada — PPI Deprescribing