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Pharmacology · patient case with 2 questions

Adverse drug reactions in two patients

Patient: Two patients presenting the same day

Chief complaint: Patient A: “My front tooth chipped.” Patient B: “I have a really bad infection.”

History: Patient A: 52-year-old male with chronic migraines, taking amitriptyline. Patient B: 19-year-old male, asthma, smoker, documented penicillin allergy, taking albuterol.

Findings: Patient A: Ellis class I fracture of tooth #9. Patient B: acute apical abscess on tooth #3.

Question 1

What is a DIRECT side effect of Patient A's medication?

  1. Xerostomia
  2. Burning mouth syndrome
  3. Gingival hyperplasia
  4. Candidiasis
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Correct answer: A. Xerostomia

  • A. CORRECT. Amitriptyline is a TRICYCLIC ANTIDEPRESSANT with strong ANTIMUSCARINIC activity. Blocking muscarinic receptors on salivary acinar cells directly reduces salivary secretion, and xerostomia is among its most common adverse effects. The dental consequences follow predictably — rampant cervical and root caries, candidiasis, and difficulty wearing a prosthesis.
  • B. Burning mouth syndrome is a chronic idiopathic pain condition. Interestingly, low-dose tricyclics are used to TREAT it rather than cause it.
  • C. Gingival hyperplasia is caused by phenytoin, cyclosporine and dihydropyridine calcium channel blockers, through fibroblast proliferation. Tricyclics do not cause it.
  • D. Candidiasis can occur SECONDARY to the xerostomia, since reduced salivary flow removes antimicrobial proteins and mechanical clearance — but it is a downstream consequence, not the direct pharmacological effect the question asks for.

Note: The other reason amitriptyline matters in the operatory: its antimuscarinic and alpha-blocking effects mean epinephrine-containing local anaesthetic can produce an exaggerated pressor response. Limit the dose and aspirate. Orthostatic hypotension on standing from the chair is also common.

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Question 2

Which symptom would most likely confirm a diagnosis of penicillin allergy in Patient B?

  1. Maculopapular rash
  2. Vomiting
  3. Diarrhoea
  4. Nausea
Show answer and explanation

Correct answer: A. Maculopapular rash

  • A. CORRECT. A MACULOPAPULAR RASH is an immunologically mediated hypersensitivity reaction and is the most common true allergic manifestation of penicillin. Cutaneous findings — rash, urticaria, angioedema, pruritus — are what distinguish genuine allergy from intolerance, and they are what should be documented in the record.
  • B. Vomiting is likewise an adverse gastrointestinal effect rather than hypersensitivity.
  • C. Diarrhoea results from disruption of gut flora, and in its severe form indicates C. difficile colitis — a serious adverse effect, but not an allergic one.
  • D. Nausea is a gastrointestinal INTOLERANCE, not an immune reaction. Recording it as an allergy is one of the commonest causes of unnecessary lifelong penicillin avoidance.

Note: This distinction has real consequences. Roughly 10 percent of people report a penicillin allergy but fewer than 1 percent have a genuine IgE-mediated one, and most who did as children lose it within a decade. Mislabelling drives patients to broader, costlier and more toxic alternatives — clindamycin among them, with its C. difficile risk. Take a proper history: what happened, how soon, and what treatment was needed.

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