RiteMED Mefenamic Acid Overdosage

Symptoms following acute overdose of NSAIDs, such as mefenamic acid, are usually limited to lethargy (fatigue), drowsiness, nausea, vomiting and epigastric pain. Gastrointestinal bleeding can occur. Hypertension, acute kidney failure, respiratory depression and coma may also occur. Anaphylactoid reactions have been reported with recommended doses of NSAIDs, and may occur following an overdose.
250 mg: What to do when the patient has taken more than the recommended dosage: If more than the recommended dosage has been given, consult a doctor or contact a Poison Control Center right away.
500 mg: In humans who reportedly ingested 1.5 to 50 g of mefenamic acid, those with plasma drug concentrations ranging from 11 to 211 mcg/mL experienced tonic-clonic seizures, muscle twitching, vomiting, and diarrhea. Several other cases of seizures following ingestion of 5 to 50 g of mefenamic acid have also been reported.
Patients should be managed by symptomatic and supportive care after an NSAID overdose. There are no specific antidotes. In the event of overdose, emesis and/or activated charcoal (60 to 100 g in adults, 1 to 2 g/kg in children) and/or an osmotic cathartic may be indicated in patients seen within 4 hours of ingestion with symptoms or following a large overdose (5 to 10 times the usual dose). Since mefenamic acid is highly bound to plasma proteins, forced diuresis, alkalinization of urine, hemodialysis, or hemoperfusion may not be useful due to high protein binding.