[Pharmacokinetics of bendamustin (Cytostasan) in B6D2F1-mice]

The pharmacokinetics of bendamustine, (1; Cytostasan), an alkylating antineoplastic agent of the N-lost group, was investigated in B6D2F1 mice. After i.v. injection of the maximally tolerated dose of 50 mg/kg a rapid decrease of the unchanged drug in plasma (MRT 21.9 min) and slowly decreasing levels of mono-, dihydroxy and beta-hydroxy-1 were observed. Variations of the age of the animals as well as of the dose administered did not alter the short MRT of 1. 1 is excreted via the kidneys to a considerable extent showing a similar metabolite pattern in urine as in plasma. The absorption of the drug from the gastrointestinal tract is incomplete resulting in an absolute bioavailability of about 40%.