The effect of atovaquone on etoposide pharmacokinetics in children with acute lymphoblastic leukemia.

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van de Poll ME, Relling MV, Schuetz EG, Harrison PL, Hughes W, Flynn PM

The effect of atovaquone on etoposide pharmacokinetics in children with acute lymphoblastic leukemia.

Cancer Chemother Pharmacol. 2001 Jun;47(6):467-72.

PubMed ID

11459198 [ View in PubMed

]

Abstract

PURPOSE: The use of trimethoprim/sulfamethoxazole in the prevention of Pneumocystis carinii pneumonia in patients with acute lymphoblastic leukemia (ALL) may cause undesirable adverse effects: fungal overgrowth, neutropenia, and drug resistance. A possible alternative is atovaquone, a hydroxynaphthoquinone with anti-Pneumocystis carinii activity. However, it is not known if atovaquone alters the disposition or adverse effects of antileukemic drugs. METHODS: Using a crossover study design, we compared the pharmacokinetics of etoposide and its CYP3A4-formed catechol metabolite when given as a 300 mg/m2 i.v. infusion following daily atovaquone versus trimethoprim/sulfamethoxazole in nine patients. RESULTS: The area under the concentration time curve (AUC) of etoposide, etoposide catechol and the catechol to etoposide AUC ratio were slightly higher (a median of 8.6%, 28.4%, and 25.9%) following atovaquone as compared to trimethoprim/sulfamethoxazole (P=0.055, P= 0.031 and P=0.023), respectively. In vitro analysis in human liver microsomes showed modest inhibition of etoposide catechol formation in the presence of atovaquone. Using uptake of 3H-vinblastine in L-MDR1 cells, atovaquone was shown to inhibit P-glycoprotein with an apparent Ki of 95.6 microM. CONCLUSIONS: Although the effect of atovaquone on etoposide disposition was modest, in light of the fact that the risk of etoposide-related secondary acute myeloid leukemia has been linked to minor changes in schedule and concurrent therapy, we suggest caution with the simultaneous administration of atovaquone and etoposide, particularly if used with other CYP3A4/P-glycoprotein substrates.

DrugBank Data that Cites this Article

Drug Transporters

Drug	Transporter	Kind	Organism	Pharmacological Action	Actions
Atovaquone	P-glycoprotein 1	Protein	Humans	No	Inhibitor	Details

Drug Interactions

Drugs	Interaction
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Etoposide Atovaquone	The serum concentration of Etoposide can be increased when it is combined with Atovaquone.