Research Papers: Assay of the Curative Action of Neoarsphenamine by Time-Mortality Data

The commonest current methods employed for testing the action of neoarsphenamine are those in which the drug is injected into mice or rats already lightly or heavily infected with Trypanosoma equiperdum on a previous day. Blood specimens removed from every animal are examined daily, involving the counting of many squares of the counting-chamber, before deciding whether or not the animals are cured. These methods are laborious and time-consuming, and for this reason, and because of other disadvantages, Bülbring and Burn1 proposed that the activity of a preparation should be estimated from the survival times of mice infected and treated on the same day. In the present work, this method has been extended and examined statistically.

Toxicity, the Therapeutic Index, and the Ranking of Drugs

The therapeutic index is often used to rank the net effectiveness of drugs and to provide a guide for choosing the best among several drugs. This can be a misleading guide since we show that drugs with the same therapeutic index can have unequal "worth." A substitute ranking measure for the therapeutic index is proposed that would be based on minimizing the losses from the failure to cure plus the losses due to toxicity. This measure would specify a "best" dose over a wide range of conditions, which the therapeutic index does not do. An example is given in which the minimum loss approach produces a ranking of drugs different from that produced by the therapeutic index. In this example the different rankings hold, with minor shifts, over a wide range.