Optimum antitumor drugs

Thus, the conclusions from equation (27) are that the two activities cannot be separated, but for optimum hypotensive activity the lipophilicity of the compounds should be around 1.5. Such analogs can readily cross the blood-brain barrier and their central effect will override the peripheral effect. All other attempts to find chemically related analogs with improved selectivity must fail. Thus, no more syntheses and testing of compounds within this series need to be performed. Several other examples are known where desired activities have been compared with toxicides, especially for antitumor drugs. In some cases the syntheses of further analogs were stopped because no better therapeutic indices could be expected. " ... 

Schacht and coworkers in Belgium201-212 used pellets of a polyphosphazene with both ethyl glycinate and ethyl phenylalanate side groups for the controlled release of the antitumor agent, mitomycin-C. A 100% ethyl glycinato polymer released the drug too rapidly, but mixed-substituent polymers with 50-65% phenylalanine ester released the drug at an optimum rate. 

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