What is the appropriate dosage and usage of Neo Ponstan Forte (mefenamic acid) for an adult patient with pain or inflammation, considering impaired renal function and gastrointestinal history?

Neo Ponstan Forte (Mefenamic Acid) Dosing and Management

For adult patients with pain or inflammation, Neo Ponstan Forte (mefenamic acid) should be dosed at 500 mg three times daily with a maximum of 1500 mg per day, but this medication requires significant caution in patients with renal impairment and should be avoided entirely in those with creatinine clearance <30 mL/min or any history of gastrointestinal bleeding. 1

Standard Dosing for Adults

• Initial dose: 500 mg orally three times daily (total 1500 mg/day maximum) 1
• Treatment duration should be limited to 5-7 days for acute pain, as prolonged use increases risk of serious adverse effects 1
• Take with food to minimize gastrointestinal irritation 1

Critical Renal Function Considerations

Mefenamic acid poses significant nephrotoxicity risk and requires careful assessment:

• Contraindicated in creatinine clearance <30 mL/min - select alternative analgesic entirely 1
• For creatinine clearance 30-50 mL/min: reduce dose to 250 mg three times daily and monitor renal function every 2-3 days 1
• Monitor serum creatinine and electrolytes if treatment extends beyond 3-5 days in any patient with renal compromise 2, 3
• Mefenamic acid can cause acute interstitial nephritis with severe, non-oliguric renal failure, though typically reversible with discontinuation 4

Gastrointestinal History Assessment

Before prescribing, specifically evaluate for these high-risk factors:

• Active or history of peptic ulcer disease - absolute contraindication 2, 3
• Previous gastrointestinal bleeding - absolute contraindication 5, 2
• Age ≥75 years, concurrent anticoagulant/antiplatelet use, SSRI use, or glucocorticoid therapy - all require mandatory gastroprotection 5

If any high-risk factors present:

• Co-prescribe proton pump inhibitor (omeprazole 20 mg daily or equivalent) 5, 2
• Consider alternative analgesic if multiple risk factors present 5

Gastrointestinal Adverse Effects Unique to Mefenamic Acid

Mefenamic acid (a fenamate-class NSAID) has distinctive GI toxicity beyond typical NSAIDs:

• Can cause severe diarrhea and steatorrhea through blocking intestinal fluid absorption 6
• May produce enteropathy mimicking celiac disease with severe intestinal damage 7
• Discontinue immediately if severe diarrhea, steatorrhea, or malabsorption symptoms develop 6, 7

Hepatotoxicity Monitoring

Mefenamic acid carries significant hepatotoxicity risk:

• Can cause dose-dependent hepatocellular necrosis and inflammation 8
• Baseline liver function tests required before initiating therapy 8
• Monitor ALT/AST at 2 weeks if treatment continues beyond acute use 8
• Discontinue if transaminases exceed 3× upper limit of normal 3

Cardiovascular Precautions

• Avoid in severe heart failure - NSAIDs cause fluid retention and cardiac decompensation 2, 3
• Use extreme caution in any cardiovascular disease due to increased ischemic event risk 5
• Monitor blood pressure if treatment extends beyond 5 days 5

Anticoagulant Interactions

Concurrent anticoagulant use dramatically increases bleeding risk:

• Avoid combination with warfarin, DOACs, or heparin whenever possible 5, 2
• If combination unavoidable: reduce mefenamic acid dose, increase INR monitoring frequency, and use gastroprotection 5, 2
• INR may increase up to 15% with NSAID addition 2

Treatment Response Evaluation

• Assess efficacy at 2-4 weeks for chronic inflammatory conditions 3
• If insufficient response after 2-4 weeks at maximum tolerated dose, switch to alternative NSAID or analgesic strategy 5, 3
• Do not exceed 4 weeks of continuous use without reassessing need and risk-benefit ratio 1

When to Discontinue Immediately

Stop mefenamic acid and do not rechallenge if:

• Severe diarrhea or steatorrhea develops 6, 7
• Signs of GI bleeding (melena, hematemesis, severe abdominal pain) 5, 2
• Serum creatinine doubles from baseline 5
• Transaminases exceed 3× upper limit normal 3
• New or worsening hypertension 5

Practical Algorithm for Safe Prescribing

1. Screen for absolute contraindications: active PUD, GI bleeding history, CrCl <30 mL/min, severe heart failure, liver failure 2, 3
2. If contraindications present: select alternative analgesic (acetaminophen, tramadol, or topical NSAIDs) 1
3. Assess GI risk factors: age ≥75, anticoagulants, antiplatelets, SSRIs, steroids 5
4. If high GI risk: add PPI prophylaxis mandatory 5, 2
5. Check baseline: creatinine, electrolytes, liver enzymes 1, 8
6. Prescribe: 500 mg TID with food, maximum 7 days for acute pain 1
7. Monitor: if >5 days use, recheck creatinine/electrolytes at 1-2 weeks 2, 3