Individual variation in drug response
Prescribers have numerous sources of guidance about how to use drugs appropriately (e.g. dose, route, frequency, duration) for many conditions. However, this advice is based on average dose–response data derived from observations in many individuals. They can never be certain about the actual dose–response relationships for the particular patients that they treat. They can never be certain that their choice will be effective or safe for their individual patient and must recognize the need to monitor the outcome of their prescription. The inter-individual variation from the norm is often predictable and good prescribers are able to anticipate it and adjust their practice accordingly.