Combination antiretroviral therapy (cART) component ritonavir significantly alters docetaxel exposure

Michelle A. Rudek, Cathy Y. Chang, Kenneth Steadman, Michael D. Johnson, Naveen Desai, John F. Deeken

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Purpose: Non-AIDS-defining cancers (NADCs) now exceed rates of AIDS-defining cancers in HIV-positive patients. Treatment of NADCs may be complicated by drug-drug interactions between antiretrovirals and chemotherapy. Docetaxel is a widely used anticancer agent that is primarily metabolized by CYP3A4 enzymes and used to treat NADCs. A preclinical in vivo assessment was performed to gain a better understanding of CYP3-mediated drug-drug interactions between antiretrovirals and docetaxel, as well as to assess any alterations in gene expression with these combinations. Methods: Docetaxel (20 mg/kg i.v.) was administered to male FVB mice in the presence and absence of dexamethasone (10 mg/kg p.o. ×4d), efavirenz (25 mg/kg p.o. ×4d), ketoconazole (50 mg/kg p.o.), or ritonavir (12.5 mg/kg p.o.). At various time points, plasma and liver tissue were harvested. Docetaxel concentrations were determined by LC/MS/MS. Pharmacokinetic parameters were calculated. Liver tissue RNA was used to evaluate alterations in Cyp3a11 and Abcb1a gene expression. Results: Docetaxel exposure was altered by CYP3A4 inhibitors but not by inducers. The CYP3A4 inducers efavirenz and dexamethasone did not have a significant effect on docetaxel exposure (AUC). However, the CYP3A4 inhibitors ritonavir and ketoconazole resulted in a 6.9- and 3.1-fold increase in AUC, respectively. Alterations in gene expression did not account for the altered docetaxel exposure. Conclusions: Docetaxel exposure was significantly altered by CYP3A4 inhibitors. Until a definitive clinical trial is performed, docetaxel should be used with caution in patients on a ritonavir-containing antiretroviral regimen or an alternative antineoplastic therapy or antiretroviral regimen should be considered.

Original languageEnglish (US)
Pages (from-to)729-736
Number of pages8
JournalCancer Chemotherapy and Pharmacology
Issue number4
StatePublished - Apr 2014


  • Antiretrovirals
  • Docetaxel
  • Drug interaction
  • HIV
  • Pharmacokinetics

ASJC Scopus subject areas

  • Oncology
  • Toxicology
  • Pharmacology
  • Cancer Research
  • Pharmacology (medical)


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