Mathematical analysis of concentration-response relationships. Method for the evaluation of the ED50 and the number of binding sites per receptor molecule using the logit transformation.

The mathematical analysis of concentration-response relationships is performed by means of the mass law and the drug-receptor theory. It is demonstrated that the calculation of the median effective dose (ED50), which is decisive for the pharmacological characterisation of a certain drug, may only be effected by means of the logit transformation. In addition, it is shown that this transformation is most suitable to evaluate in a mathematically simple way the number of drug binding sites of the receptor molecule.