Exposure-Response Relationship

Exposure-response relationships characterise dependencies between drug concentration or dose and observed effects including efficacy and toxicity. Pharmacokinetic-pharmacodynamic modelling quantitatively defines these relationships enabling dose optimisation. Linear, nonlinear, and sigmoidal relationships variously describe different drug-effect systems. Threshold concentrations identify minimum exposures necessary for therapeutic effect; conversely, ceiling concentrations define maximum tolerated exposure levels.

Population exposure-response analysis incorporates heterogeneous patient populations identifying covariates influencing drug response. Genetic polymorphisms in metabolising enzymes or target receptors explain individual variability in exposure-response relationships. Therapeutic drug monitoring guides dose individualisation based on measured concentrations. Regulatory submissions incorporate exposure-response analysis supporting dose selection and labelling. Exposure-response relationships prove particularly informative for narrow therapeutic index drugs requiring precise exposure control. Advanced modelling techniques including Bayesian forecasting enable patient-specific exposure predictions optimising treatment outcomes.