Mefenamic Acid for Toothache Pain
Mefenamic acid 500 mg is an effective NSAID option for acute toothache pain, with proven efficacy in dental pain management, though it offers no clear advantage over other NSAIDs like ibuprofen and carries a higher risk of gastrointestinal toxicity. 1, 2
Efficacy for Dental Pain
Mefenamic acid 500 mg provides at least 50% pain relief in acute postoperative pain with an NNT of 4.0 (95% CI: 2.7-7.1) over 6 hours, based on data that included dental extraction pain. 3
The drug demonstrates analgesic efficacy through COX-1 and COX-2 inhibition, reducing prostaglandin synthesis that sensitizes pain nerves. 4
Peak plasma levels of 10-20 mcg/mL are reached within 2-4 hours after oral administration, providing relatively rapid pain relief. 4
Dosing Recommendations
Standard dosing is 500 mg capsules, with a maximum daily dose of 2000 mg (4 × 500 mg). 1
The elimination half-life is approximately 2 hours, requiring dosing every 6-8 hours for sustained pain control. 4
Mefenamic acid is rapidly absorbed after oral administration, with steady-state concentrations achieved quickly due to the short half-life. 4
Safety Concerns and Comparative Profile
Mefenamic acid has a less favorable safety profile compared to other NSAIDs, with higher rates of upper gastrointestinal lesions and renal insufficiency, particularly with prolonged use. 2
Systemic toxicity can occur at relatively low doses above the maximum daily dose compared to other NSAIDs. 2
Like all NSAIDs, use with caution in patients at high risk for renal, GI, or cardiac toxicities, particularly those over 60 years, with peptic ulcer history, or on anticoagulants. 1
Rare but serious central nervous system toxicity has been reported, including altered mental status and metabolic acidosis, even with therapeutic dosing. 5
Clinical Positioning
There is no evidence that mefenamic acid is more effective than other NSAIDs for dental pain, and current literature does not support preferring it over alternatives like ibuprofen or naproxen. 2
For toothache pain specifically, ibuprofen 400-600 mg every 6 hours (maximum 2400-3200 mg/day) remains a safer first-line option with comparable efficacy. 1
Consider mefenamic acid only if the patient has previously tolerated it well or has contraindications to other NSAIDs. 1
Monitoring Requirements
Baseline assessment of renal function (BUN, creatinine), liver function, and blood pressure is prudent, especially for use beyond 3-5 days. 1
Discontinue if BUN or creatinine doubles, liver function tests exceed 3 times upper limit of normal, or gastrointestinal bleeding occurs. 1
Key Contraindications
Active peptic ulcer disease, severe heart failure, liver failure, or history of GI bleeding are absolute contraindications. 1
Avoid in patients with significant renal impairment, as mefenamic acid is primarily renally excreted (52% as glucuronide metabolites). 4
Use extreme caution with concomitant anticoagulants, as bleeding risk increases 3-6 fold. 1