Doxorubicin must be given within what timeframe relative to the start of the dexrazoxane infusion?

• A. Within 60 minutes from the beginning of the dexrazoxane infusion
• B. Within 60 minutes from the completion of the dexrazoxane infusion
• C. Within 30 minutes from the completion of the dexrazoxane infusion
• D. Within 30 minutes from the beginning of the dexrazoxane infusion

Answer: (D)

The key idea is the timing of dexrazoxane to maximize protection against doxorubicin’s heart-toxic effects. Dexrazoxane is given first to prepare the heart by chelating iron and scavenging free radicals that doxorubicin can release. To ensure these protective mechanisms are active when doxorubicin is given, the infusion of doxorubicin should start within a short window after the dexrazoxane infusion begins. If you wait longer than about 30 minutes from the start of the dexrazoxane infusion, dexrazoxane levels may fall and the protective effect wanes, increasing the risk of cardiotoxicity. Therefore, starting doxorubicin within 30 minutes of the beginning of the dexrazoxane infusion is the correct, best timing.