1 Problems associated with the interpretation of analytical results are often related to the ineffective presentation of reference information. Concentration-response curves overcome many of the problems by presenting all available information concisely and by allowing clear comparisons between drug concentrations associated with different pharmacological responses. Although visual comparison of such curves is possible, it can be advantageous to represent them numerically.
2 Numerical representations are used in the present work to compare sub-therapeutic, optimally therapeutic, toxic (side-effects and severe effects), and fatal blood concentrations of the commonly prescribed antiepileptic drugs.
3 Blood drug concentrations accounting for 50% of the population (EC50) are expressed in relation to the concentrations accounting for 10% (EC10) and 90% (EC 90) of the population in each clinical category.
4 Such EC10 -EC50-EC90 ranges are shown to represent adequately the concentration-response curves. They demonstrate the overlap between drug blood concentrations associated with the various responses and give a good indication of the expected response at any concentration. The concentration ranges are therefore a very useful interpretative aid in therapeutic drug monitoring, emergency toxicology, and forensic toxicology.
