Clinical Pharmacokinetics

, Volume 19, Issue 2, pp 167–169 | Cite as

Allopurinol Influences Aminophenazone Elimination

  • Michael Barry
  • John Feely
Pharmacokinetic Case Report


The authors observed an interaction between allopurinol and both theophylline and warfarin in 2 patients. To determine the possible effect of allopurinol on hepatic oxidative metabolism a [14C]-aminophenazone (aminopyrine) breath test was performed before and during treatment with allopurinol 100mg daily in 5 patients with hyperuricaemia. Allopurinol prolonged the [14CO2]-aminophenazone half-life from 72 ± 13 to 104 ± 16 minutes (mean ± SEM, p < 0.05). It is possible that allopurinol may produce clinically significant drug interactions through an inhibitory effect not only on xanthine oxidase metabolism but also on oxidative metabolism.


Warfarin Theophylline Xanthine Oxidase Allopurinol Mercaptopurine 
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Copyright information

© Adis International Limited 1990

Authors and Affiliations

  • Michael Barry
    • 1
    • 2
  • John Feely
    • 1
  1. 1.Department of Pharmacology and Therapeutics, Trinity College Medical SchoolSt Jame’s HospitalDublinIreland
  2. 2.Department of Pharmacology and TherapeuticsUniversity of LiverpoolLiverpoolEngland

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