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Difficulty: HardPharmacologic Interventions

A 68-year-old man is evaluated in the outpatient clinic for a 1-day history of severe right great toe pain, swelling, and redness. He reports the pain woke him from sleep and is so exquisite that he cannot bear the weight of a bedsheet on his foot. Medical history is notable for hypertension, type 2 diabetes mellitus, and chronic kidney disease stage 3b. One week ago, he was diagnosed with a peptic ulcer associated with Helicobacter pylori and was started on a 14-day eradication regimen. Current medications include lisinopril, amlodipine, clarithromycin, amoxicillin, and omeprazole. Vital signs are temperature 37.3°C (99.1°F), blood pressure 138/82 mmHg, and pulse 88/min. Physical examination shows a swollen, erythematous, and exquisitely tender right first metatarsophalangeal joint. Arthrocentesis is performed, and synovial fluid analysis reveals a leukocyte count of 25,000/mm³ and negatively birefringent, needle-shaped crystals. Gram stain is negative. Laboratory studies show:

TestResult
Leukocyte count11,200/mm³
Serum uric acid5.4 mg/dL
Serum creatinine1.7 mg/dL (baseline 1.6 mg/dL)

Which of the following is the most appropriate next step in pharmacologic management for this patient?

  1. Intra-articular triamcinoloneAnswer
  2. B
    Oral colchicine
  3. C
    Oral indomethacin
  4. D
    Oral allopurinol
  5. E
    Intravenous ceftriaxone

Answer

Intra-articular triamcinolone is the most appropriate pharmacologic intervention.
The patient is experiencing an acute gout flare, definitively diagnosed by the presence of negatively birefringent monosodium urate crystals in the synovial fluid. Standard first-line systemic therapies for acute gout include nonsteroidal anti-inflammatory drugs (NSAIDs) and colchicine. However, in this patient, NSAIDs (e.g., indomethacin) are contraindicated due to his underlying chronic kidney disease and concurrent use of an angiotensin-converting enzyme (ACE) inhibitor (lisinopril), a combination that carries a high risk of precipitating acute renal failure. Colchicine is also strictly contraindicated because the patient is taking clarithromycin for Helicobacter pylori eradication. Clarithromycin is a potent inhibitor of both cytochrome P450 3A4 (CYP3A4) and P-glycoprotein; coadministration with colchicine can lead to fatal colchicine toxicity (neuromyopathy, cytopenias), particularly in patients with baseline renal impairment. Therefore, a localized intra-articular glucocorticoid injection (e.g., triamcinolone) is the safest and most effective targeted intervention. It provides rapid local symptom relief for monoarticular gout while completely bypassing the risks of systemic drug-drug interactions and nephrotoxicity.

Step-by-Step Solution

1
Analyze the synovial fluid and laboratory results.
Negatively birefringent crystals definitively confirm an acute gout flare, ruling out septic arthritis despite the normal serum uric acid level.
Establishing the correct diagnosis is the necessary first step before selecting pharmacotherapy.
2
Evaluate the safety of NSAIDs for this specific patient.
Indomethacin is contraindicated.
The patient has chronic kidney disease and is taking an ACE inhibitor; NSAIDs can precipitate severe acute renal failure in this setting.
3
Evaluate the safety of colchicine for this specific patient.
Colchicine is contraindicated.
The patient is taking clarithromycin, a strong CYP3A4 and P-glycoprotein inhibitor, which would cause fatal colchicine toxicity.
4
Select the optimal alternative therapy.
Intra-articular triamcinolone is chosen.
Localized glucocorticoid injection provides rapid anti-inflammatory relief for monoarticular gout without systemic drug interactions or nephrotoxicity.

Key Concept

Pharmacologic management of acute gout in patients with complex comorbidities and critical drug-drug interactions.
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Topics

Pharmacologic Interventions

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