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Pharmacology · patient case with 1 question

Odontogenic infection in a patient with hepatic impairment

Patient: Male, 59 years old

Chief Complaint: “My tooth is throbbing and the gum is swollen.”

Background: Alcohol-related cirrhosis with a recent decompensation. No drug allergies. Not on anticoagulants.

Vital Signs: BP 118/72 mmHg · HR 92 bpm · T 100.4°F · INR 1.6 · platelets 96,000/µL · albumin low

Findings: Localized vestibular swelling adjacent to tooth #30 with a periapical radiolucency. No trismus, no airway compromise.

Question 1

Which antibiotic is the most appropriate first choice for this patient?

  1. Penicillin V potassium
  2. Clindamycin
  3. Metronidazole
  4. Erythromycin
Show answer and explanation

Correct answer: A. Penicillin V potassium

  • A. CORRECT. PENICILLIN V is renally excreted largely unchanged, needs no adjustment for hepatic impairment, remains first-line for odontogenic infection, and has the narrowest useful spectrum of the four. In a patient whose liver is already the limiting organ, the drug that bypasses it is the right drug.
  • B. Clindamycin is hepatically metabolised and carries the highest risk of Clostridioides difficile colitis of the common dental antibiotics — a particular concern in a patient with cirrhosis and impaired immune function. It is reserved for genuine beta-lactam allergy.
  • C. Metronidazole undergoes extensive HEPATIC metabolism and accumulates in hepatic impairment, with dose reduction required. It also gives a disulfiram-like reaction with alcohol, which matters directly in this patient.
  • D. Erythromycin is hepatically metabolised, is itself associated with cholestatic hepatitis, and is a potent CYP3A4 inhibitor. It is a poor choice here on every count.

Note: Analgesia matters as much as the antibiotic here. AVOID NSAIDs — they raise the bleeding risk on top of thrombocytopenia and a prolonged INR, and they can precipitate hepatorenal syndrome. Paracetamol/acetaminophen is acceptable in cirrhosis but at a REDUCED ceiling, usually 2 g per day and lower with continued alcohol use. Definitive management remains drainage or extraction; the antibiotic is adjunctive.

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