Pharmacology

• Nucleoside Reverse Transcriptase Inhibitor

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Adverse Effects

General Adverse Effects

• Diarrhea (see Diarrhea)
• Headache (see Headache)
• Nausea/Vomiting (see Nausea and Vomiting)
• Rash

Abacavir Hypersensitivity Reaction

• Epidemiology
  • Relationship to Abacavir Dosing Frequency
    • Hypersensitivity reaction may be more severe with once daily dosing
  • Risk Factors
    • HLA B*5701 -> can screen for this prior to abacavir administration
  • Temporal Relationship to Abacavir Administration
    • During Abacavir Therapy
      • Occurs within few days-6 weeks (median = 11 days) after start of therapy
      • Symptoms usually worsen with continuation of therapy
    • After Re-Introduction of Abacavir
      • Occurs within hours of re-introduction after an interruption in therapy
      • Particularly severe reactions can occur with re-challenge in patients with a previous hypersensitivity reaction
• Physiology
  • Hypersensitivity (immune)-mediated reaction
• Clinical
  • General: 98% of cases have fever or rash or both
    • Fever (80%) (see Fever)
    • Rash (70%)
    • Malaise (40%)
    • Myalgias
    • Arthralgias
    • Lymphadenopathy
  • GI (50%)
    • Nausea/Vomiting (see Nausea and Vomiting)
    • Abdominal Pain (see Abdominal Pain)
    • Diarrhea
    • Liver Failure
  • Pulmonary (18%)
    • Pharyngitis
    • Dyspnea
    • Cough
    • Wheezing (see Obstructive Lung Disease)
  • Renal
    • Acute Kidney Injury (see Acute Kidney Injury)
  • Cardiac
    • Anaphylaxis (see Anaphylaxis)
    • Hypotension (see Hypotension)
  • Neurologic
    • Parasthesias
• Treatment
  • Immediate Withdrawal of Drug: avoid re-challenge with drug in the future if hypersensitivity reaction occurs
  • Supportive Care
• Prognosis
  • Death: may occur in severe cases

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References

• HLA-B*5701 Screening for Hypersensitivity to Abacavir.  N Engl J Med 2008; 358:568-579