Drug General Information (ID: DDIMARDVO1)
  Drug Name Allopurinol Drug Info Benazepril Drug Info
  Drug Type Small molecule Small molecule
  Therapeutic Class Antimetabolites Antihypertensive Agents
  Structure

 Mechanism of Allopurinol-Benazepril Interaction (Severity Level: Major)
     Increased risk of angioedema/anaphylactoid reactions Click to Show/Hide Mechanism Graph
Could Not Find 2D Structure
      Drug Name Allopurinol Benazepril
      Mechanism Anaphylactoid reactions Anaphylactoid reactions
      Key Mechanism Factor 1
Factor Name Angioedema/anaphylactoid reactions
Factor Description Anaphylactoid reaction is a condition in which symptoms similar to an allergic reaction occur, but no immune sensitization is detected. Most commonly, the syndrome begins with skin involvement, usually pruritus, flushing, urticaria, or angioedema. Angioedema is a reaction to a trigger that causes swelling of the tissue below the inner layer of the skin, called the dermis or submucosa, and the swelling can occur on the face, throat, or around the genitals.
      Mechanism Description
  • Increased risk of angioedema by the combination of Allopurinol and Benazepril 

Recommended Action
      Management Caution is advised if allopurinol is prescribed in combination with an ACE inhibitor, particularly in the elderly and patients with renal impairment. Periodic monitoring of white blood cell counts is recommended. Patients should be advised to promptly discontinue these medications and seek medical attention if they develop dyspnea throat constriction swelling of the face, lips, or tongue urticaria rash fever arthralgia or myalgia. Patients should also contact their physician if they notice signs of infection or experience fever, chills, sore throat, lethargy, body aches, or other flu-like symptoms.

References
1 Duchin KL, McKinstry DN, Cohen AI, Migdalof BH "Pharmacokinetics of captopril in healthy subjects and in patients with cardiovascular diseases." Clin Pharmacokinet 14 (1988): 241-59.[PMID: 3292102]
2 Pennell DJ, Nunan TO, O'Doherty MJ, Croft DN "Fatal Stevens-Johnson syndrome in a patient on captopril and allopurinol." Lancet 1 (1984): 463.[PMID: 6142201]
3 Product Information. Zyloprim capsules (allopurinol). Glaxo Wellcome, Research Triangle Park, NC.