The interval-force relationship: a technique for evaluating the cardiac toxicity of anthracycline analogs.

The most serious side effect of the anthracycline derivatives is dose-related cardiac toxicity induced during repeated administration. An in vitro method is described which assesses the interval-force relationship in evaluating the contractility of the rat and rabbit heart. Repeated administration of Adriamycin resulted in a progressive decrease in contractility which correlated closely with the cumulative dose administered. This model offers a reliable method to evaluate the effect of new anthracycline analogs on the heart and to study the potential of other drugs or agents to protect against cardiac toxicity.