Pharmacology · patient case with 2 questions
Rheumatoid arthritis on a biologic agent
Patient: Female, 35 years old
Chief Complaint: “I need a filling replaced.”
Background: Rheumatoid arthritis of seven years. Adalimumab (Humira) every other week, plus weekly methotrexate with folate. No corticosteroids currently.
Vital Signs: BP 118/74 mmHg · HR 76 bpm · T 98.3°F
Findings: Symmetric swelling of the small joints of the hands with reduced dexterity. Limited opening 34 mm with bilateral TMJ crepitus. Generalized plaque accumulation, moderate gingivitis.
Question 1
What is the mechanism of action of adalimumab?
Show answer and explanation
Correct answer: B. It binds TNF-alpha and blocks its interaction with cell surface receptors
- A. JAK inhibition is the mechanism of the oral agents tofacitinib, baricitinib and upadacitinib — a different class with a different route.
- B. CORRECT. ADALIMUMAB is a fully human monoclonal antibody that binds TUMOUR NECROSIS FACTOR ALPHA and prevents it engaging the p55 and p75 cell surface receptors, interrupting the inflammatory cascade that drives synovitis and joint destruction. The class also includes infliximab, etanercept, golimumab and certolizumab.
- C. That describes METHOTREXATE, the other drug this patient takes. The two are frequently combined, which is why they get confused — but the mechanisms are entirely separate.
- D. CD20-directed B-cell depletion is the mechanism of RITUXIMAB, used in refractory rheumatoid arthritis and in lymphoma.
Note: The dental consequence of TNF-alpha blockade is IMMUNOSUPPRESSION. TNF-alpha is central to granuloma maintenance, so these agents raise the risk of serious infection and of TUBERCULOSIS REACTIVATION — patients are screened before starting. For dentistry: treat oral infection promptly and definitively, expect slower healing after surgery, and discuss timing with the rheumatologist before major procedures. Routine care needs no drug interruption.
Question 2
Beyond the joints, what is the leading cause of excess mortality in rheumatoid arthritis?
Show answer and explanation
Correct answer: A. Cardiovascular disease, particularly myocardial infarction
- A. CORRECT. CARDIOVASCULAR DISEASE accounts for the largest share of excess mortality in rheumatoid arthritis, with roughly a 50% higher risk of myocardial infarction than the general population. The driver is CHRONIC SYSTEMIC INFLAMMATION — persistently elevated cytokines accelerate atherosclerosis independently of the traditional risk factors, and the effect is proportional to disease activity. The parallel with periodontitis and cardiovascular risk is exactly the same mechanism, which is why this appears on a dental examination.
- B. Renal involvement occurs, but more often as a consequence of long-term NSAID use or of secondary amyloidosis than as a leading cause of death.
- C. Hepatic disease is a monitoring concern with methotrexate rather than a feature of the underlying disease.
- D. Interstitial LUNG disease is a recognised extra-articular manifestation and does contribute to mortality, but it does not exceed the cardiovascular burden. COPD is a smoking-related disease, and smoking is a shared risk factor rather than a consequence.
Note: Other extra-articular features worth carrying: rheumatoid nodules, secondary Sjögren syndrome — with the xerostomia and rampant cervical caries that follow — anaemia of chronic disease, scleritis, and Felty syndrome (rheumatoid arthritis with splenomegaly and neutropenia). TMJ involvement affects a large minority and can produce an anterior open bite as the condyles resorb.