Complexities of personalized medicine: how genes, drug-drug interactions, dosing schedules, and other factors can combine to produce clinically meaningful differences in a drug's effect.

Given increased knowledge from molecular biology and pharmacology, it is apparent that multiple factors can interact to produce clinically meaningful differences in a drug's effect in specific individuals (i.e., personalized medicine). This topic is discussed in this column using iloperidone as an example. The variables discussed include dose, dosing schedule, genes, drug-drug interactions, and other medical factors. How such variables can combine to alter a drug's effect is illustrated with a case example and the results of a thorough QTc study of iloperidone.