Pharmacology · patient case question
Which adverse effect of methotrexate is of greatest concern for this dental procedure?
Patient case: Rheumatoid arthritis with a prosthetic mitral valve
Patient: Female, 62 years old
Chief complaint: “I need a tooth taken out.”
History: Rheumatic fever in childhood. Mechanical mitral valve replacement six years ago. Rheumatoid arthritis managed with weekly methotrexate. Warfarin, stable.
Findings: Non-restorable tooth #14 with a chronic apical abscess. No acute swelling. Reduced grip strength and limited manual dexterity.
Show answer and explanation
Correct answer: C. Increased susceptibility to infection from bone marrow suppression
- A. Osteonecrosis of the jaw is associated with antiresorptives — bisphosphonates and denosumab — and with antiangiogenics, not with methotrexate.
- B. Xerostomia is caused by anticholinergics, tricyclic antidepressants, antihistamines, diuretics and many antihypertensives. It is not a leading methotrexate effect.
- C. CORRECT. Methotrexate is a folate antagonist that suppresses the bone marrow. The consequences that matter dentally are LEUKOPENIA, raising infection risk and impairing healing after surgery; THROMBOCYTOPENIA, adding to bleeding risk on top of the warfarin; and ORAL ULCERATION and MUCOSITIS from the antifolate effect on rapidly dividing mucosal cells. A recent complete blood count with differential should be reviewed before extraction.
- D. Gingival enlargement is caused by phenytoin, cyclosporine and dihydropyridine calcium channel blockers such as nifedipine and amlodipine — not methotrexate.
Note: Do not give this patient an NSAID: NSAIDs reduce renal clearance of methotrexate and can precipitate methotrexate toxicity. Folate supplementation is standard alongside weekly dosing.