ScienceDaily (Dec. 31, 2008) — More cisplatin enters the inner ear in an animal model than oxaliplatin. The difference may explain why cisplatin treatment in humans can lead to hearing problems while oxaliplatin rarely does.

The amount of cisplatin a patient can tolerate is often limited by hearing damage induced by the drug, referred to as ototoxicity. Oxaliplatin is not frequently associated with the problem, despite the fact that both drugs are platinum compounds.

To find out why the difference exists, Victoria Hellberg, M.D., at the Karolinska Institutet in Stockholm, and colleagues measured the amount of cisplatin and oxaliplatin that reached the cochlea in guinea pigs following intravenous dosing of each drug.

The total platinum concentration in the cochlea was more than five-fold higher with cisplatin than with oxaliplatin following intravenous injection. The perilymphatic drug concentration was also higher in the cisplatin-treated animals than in those exposed to oxaliplatin.

"The differences in cochlear kinetics and cellular uptake that we found in the hearing end organ are sufficient to explain the difference in ototoxicity between cisplatin and oxaliplatin," the authors conclude.

This research is published in the December 30 issue of the Journal of the National Cancer Institute.

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Adapted from materials provided by Journal of the National Cancer Institute, via EurekAlert!, a service of AAAS.

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