Published in:
01-12-2009 | Case Report
Paralytic ileus possibly associated with interaction between ritonavir/lopinavir and vincristine
Authors:
Dominique Levêque, Raoul Santucci, Julien Pavillet, Raoul Herbrecht, Jean Pierre Bergerat
Published in:
International Journal of Clinical Pharmacy
|
Issue 6/2009
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Abstract
Case description A French Caucasian man aged 39 with HIV infection was treated with abacavir/lamivudine and ritonavir/lopinavir. The patient (normal renal and liver functions) was diagnosed with a Burkitt lymphoma for which he was treated with cyclophosphamide day 1 to 5; doxorubicin day 1; methotrexate day 10; and vincristine day 1 and 8. At day 12, he suffered from abdominal pain associated with constipation. Paralytic ileus was diagnosed by study imaging. Ileus lasted 10 days necessitating parenteral feeding. Later on, a further cycle of chemotherapy with etoposide replacing vincristine was given and was well tolerated. Conclusion We speculate that an interaction between ritonavir/lopinavir and vincristine was responsible for this severe toxicity. Vincristine is transported by P-gp and is metabolized via CYP3A5. Ritonavir is a potent CYP3A5 isoenzyme and P-gp inhibitor. Lopinavir is also a P-gp inhibitor. Ritonavir and lopinavir might have delayed vincristine elimination. Clinicians should be aware of this possible interaction.