Preliminary studies on the validity of in vitro measurement of drug toxicity using HeLa cells. IV. Therapeutic effects and side effects of 50 drugs related to the HeLa toxicity of the therapeutic concentrations.

As a measure of the relevance to human drug effects of drug cytotoxicity in vitro, calculated and actual therapeutic blood concentrations of 50 drugs were divided by their 50% inhibitory concentrations for HeLa cells in vitro to make up three types of cytotoxic quotients (CQTv, CQTd, and CQTr). When the various quotients were compared with known cytotoxic effects of the drugs the parameters correlated well. While most drugs at single dosage reached concentrations with low quotients (CQTv and CQTd) corresponding to few reported cytotoxic effects and side effects, a substantial number of drugs at repeated dosage reached concentrations with high quotients (CQTr) corresponding to known or suspected cytotoxic action in man.