The bioavailability of cytarabine in dogs with meningoencephalitis of unknown etiology through iontophoresis and rectal delivery

Abstract

Background: Cytarabine (CA) is used to treat dogs with meningoencephalitis of unknown etiology (MUE) by subcutaneous or intravenous administration.

Aim: The objective was to investigate transdermal iontophoresis and rectal administration as alternative routes of CA delivery.

Methods: Two client-owned dogs with MUE were studied. The ActivaPatch® IONTOGOTM 12.0 iontophoresis drug delivery system delivered 200 mg/m² CA transdermally. Blood samples were collected by sparse sampling technique after initiation of the device. At another visit, 100 mg/m² CA was administered rectally. Blood samples were collected by sparse sampling technique after administration. Plasma CA concentrations were measured by high-pressure liquid chromatography.

Results: The concentration of plasma CA after transdermal and rectal administration was below the limits of quantification (0.1 μg/ml) in all samples suggesting inadequate bioavailability with transdermal and rectal administration.

Conclusion: Transdermal and rectal CA administration are not reasonable alternative routes of delivery.