Itraconazole: Difference between revisions

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* Wide intersubject variability in levels
* Wide intersubject variability in levels
* Serum half-life is long
* Serum half-life is long
* Metabolized by [[Metabolized by::CYP3A4]] and inhibits [[Inhibits:CYP3A4]]
* Metabolized by [[Metabolized by::CYP3A4]] and inhibits [[Inhibits::CYP3A4]]
* Excreted in urine and feces
* Excreted in urine and feces



Revision as of 14:08, 23 September 2024

Background

Pharmacokinetics

  • Blood concentrations are about 30% higher with oral solution compared to oral capsules
  • Wide intersubject variability in levels
  • Serum half-life is long
  • Metabolized by CYP3A4 and inhibits CYP3A4
  • Excreted in urine and feces

Dosing

  • Preference for oral solution rather than capsules in severe infections (see PK section above)
  • Can consider initial loading doses with IV or p.o
  • Typical dose: 200 mg p.o. twice daily
  • May be used once daily for the treatment of some candidal or dermatophytic infections

Safety

Therapeutic Drug Monitoring

  • Recommended in more serious or severe infections
  • Should be measured 5 to 7 days after starting or changing the dose, or when interacting medications are changed
    • Can likely be collected at any time after steady-state is reached, due to long halflife
  • Target in prophylaxis is a trough level of 0.5 µg/mL
  • Target in treatment is a trough level greater than 0.5 µg/mL, or greater than 0.5 to 1 µg/mL for blastomycosis
  • Toxicity likely increased at trough levels greated than 10 µg/mL

Adverse Drug Reactions

Further Reading

  • Therapeutic drug monitoring (TDM) of antifungal agents: guidelines from the British Society for Medical Mycology. J Antimicrob Chemother. 2014;69(5):1162-1176. doi: 10.1093/jac/dkt508