title: Central nervous system toxicity of mefenamic acid overdose compared with other NSAIDs: an analysis of cases reported to the United Kingdom National Poisons Information Service.
abstract: Case reports and small case series suggest increased central nervous system (CNS) toxicity, especially convulsions, after overdose of mefenamic acid, compared with other nonsteroidal anti-inflammatory drugs (NSAIDs), although comparative epidemiological studies have not been conducted. The current study compared rates of CNS toxicity after overdose between mefenamic acid, ibuprofen, diclofenac and naproxen, as reported in telephone enquiries to the UK National Poisons Information Service (NPIS).
  
  
  
  NPIS telephone enquiries related to the four NSAIDs, received between January 2007 and December 2013, were analysed, comparing the frequency of reported CNS toxicity (convulsions, altered conscious level, agitation or aggression, confusion or disorientation) using multivariable logistic regression.
  
  
  
  Of 22 937 patient-specific telephone enquiries, 10 398 did not involve co-ingestion of other substances (mefenamic acid 461, ibuprofen 8090, diclofenac 1300, naproxen 547). Patients taking mefenamic acid were younger and more commonly female than those using other NSAIDs. Those ingesting mefenamic acid were more likely to experience CNS toxicity than those ingesting the other NSAIDs combined [adjusted odds ratio (OR) 7.77, 95% confidence interval (CI) 5.68, 10.62], especially convulsions (adjusted OR 81.5, 95% CI 27.8, 238.8). Predictors of CNS toxicity included reported dose and age, but not gender.
  
  
  
  Mefenamic acid overdose is associated with a much larger and dose-related risk of CNS toxicity, especially convulsions, compared with overdose of other NSAIDs. The benefit-risk profile of mefenamic acid should now be re-evaluated in light of effective and less toxic alternatives.
authors: National Poisons Information Service, Newcastle Unit, Newcastle upon Tyne Hospitals NHS Foundation Trust, Wolfson Unit, Claremont Place, Newcastle upon Tyne, NE2 4HH, UK.
authors: Ashraf
authors: A
authors: Kamour
authors: Department of Primary Care and Public Health, King's College London, Capital House, London, SE1 3QD, UK.
authors: Siobhan
authors: S
authors: Crichton
authors: National Poisons Information Service, Cardiff Unit, University Hospital Llandough, Penlan Road, Penarth, Vale of Glamorgan, CF64 2XX, UK.
authors: Gill
authors: G
authors: Cooper
authors: National Poisons Information Service, Edinburgh Unit, Royal Infirmary of Edinburgh, 51 Little France Crescent, Old Dalkeith Road, Edinburgh, EH16 4SA, UK.
authors: David J
authors: DJ
authors: Lupton
authors: National Poisons Information Service, Edinburgh Unit, Royal Infirmary of Edinburgh, 51 Little France Crescent, Old Dalkeith Road, Edinburgh, EH16 4SA, UK.|Pharmacology, Toxicology and Therapeutics, University/BHF Centre for Cardiovascular Science, University of Edinburgh, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK.
authors: Michael
authors: M
authors: Eddleston
authors: National Poisons Information Service, Birmingham Unit, City Hospital, Dudley Road, Birmingham, B18 7QH, UK.
authors: J Allister
authors: JA
authors: Vale
authors: National Poisons Information Service, Cardiff Unit, University Hospital Llandough, Penlan Road, Penarth, Vale of Glamorgan, CF64 2XX, UK.
authors: John P
authors: JP
authors: Thompson
authors: National Poisons Information Service, Newcastle Unit, Newcastle upon Tyne Hospitals NHS Foundation Trust, Wolfson Unit, Claremont Place, Newcastle upon Tyne, NE2 4HH, UK.|Medical Toxicology Centre, Institute of Cellular Medicine, Wolfson Building, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
authors: Simon H L
authors: SH
authors: Thomas
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000506:poisoning*; D002648:Child; D002675:Child, Preschool; D004008:Diclofenac / Q000008:administration & dosage / Q000506:poisoning; D004305:Dose-Response Relationship, Drug; D062787:Drug Overdose; D005260:Female; D006801:Humans; D007052:Ibuprofen / Q000008:administration & dosage / Q000506:poisoning; D007223:Infant; D007231:Infant, Newborn; D016015:Logistic Models; D008297:Male; D008528:Mefenamic Acid / Q000008:administration & dosage / Q000506:poisoning*; D008875:Middle Aged; D015999:Multivariate Analysis; D009288:Naproxen / Q000008:administration & dosage / Q000506:poisoning; D020258:Neurotoxicity Syndromes / Q000453:epidemiology / Q000209:etiology*; D011039:Poison Control Centers; D012737:Sex Factors; D006113:United Kingdom / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D004008:Diclofenac; D008528:Mefenamic Acid; D009288:Naproxen; D007052:Ibuprofen
keywords: CNS toxicity; convulsions; mefenamic acid; nonsteroidal anti-inflammatory drug; overdose; poisoning