Final Diagnosis -- Phenylbutazone Toxicity




  1. PHENYLBUTAZONE: is a NSAID which was discontinued for human use because of its harmful side effects. It is currently used in veterinary medicine as a pain killer. The girl had access to the drug and had used it in working with livestock. She had recently expressed a desire to kill herself and there was a history of suicidal overdose in the family. When the patient became conscious she admitted that she ingested about 7 grams of PHENYLBUTAZONE as a suicide attempt.

    Phenylbutazone is readily absorbed from the gastrointestinal tract with peak plasma concentrations occurring about 2 hours after ingestion. It is also readily absorbed when administered rectally. Phenylbutazone is widely distributed throughout body fluids and tissues; it diffuses into the synovial fluid, crosses the placenta, and small amounts enter the CNS and breast milk. It is 98% bound to plasma proteins. It is extensively metabolised in the liver by oxidation and by conjugation with glucuronic acid. Oxyphenbutazone, gamma-hydroxyphenbutazone, and p,gamma-dihydroxyphenylbutazone are formed by oxidation but only small amounts appear in urine, the remainder being further metabolised. It is mainly excreted in the urine as metabolites although about a quarter of a dose may be excreted in the faeces. The plasma elimination half-life is about 70 hours but it is subject to large interindividual variations.


  3. Diphenhydramine:
  4. Nicotine Metabolite

Hospital Course and Discussion

This patient developed the following sings and symptoms of PHENYLBUTAZONE toxicity:

  1. Thrombocytopenia.
  2. CNS effects: Convulsions and coma.
  3. Hepatotoxicity: High Liver Enzymes.
  4. Renal Toxicity:
  5. The patient stayed in coma for 6 days and gradually improved after an exchange Transfusion.
  6. Liver and renal function tests improved gradually with plasmapheresis.
  7. She was started on Antidepressants and discharged after about 10 days.

  1. Prescott LF. Clinical features and management of analgesic poisoning. [Journal Article] Human Toxicology. 3 Suppl:75S-84S, 1984 Aug.
  2. Okonek S. Reinecke HJ. Acute toxicity of pyrazolones. [Review] [26 refs] [Journal Article. Review] American Journal of Medicine. 75:94-8, 1983 Nov 14.

Contributed by Hazim Najjar, M.D.

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