Pharmacogenomics is the study of how an individual’s genetic make-up affects the body’s response to drugs. Pharmacogenomics holds the potential for drugs to be tailored to an individual’s genetic make-up, sometimes referred to as “personalized medicine.” Environment, diet, age, lifestyle, and health status all can influence a person’s response to medicines, but understanding an individual’s genetic makeup is thought to be the key to creating personalized drugs with greater efficacy and safety.

The impact of an individual’s genetic make-up on drug response and outcome has actually been known since the 1950’s but has been re-ignited by the sequencing of the human genome. Genetic variation in drug targets or genes involved in drug disposition can result in a different drug responses and outcomes for a given group of patients treated with the same drug. At this early stage of pharmacogenomics research, the development of clinical tests and targeted drugs is slow due to the limited knowledge of which genes are involved with each drug response. Since many genes are likely to influence responses, obtaining the big picture on the impact of gene variations is highly time-consuming and complicated.

The cytochrome (CYP) P450 family of liver enzymes is responsible for breaking down more than 30 different classes of drugs. DNA variations in genes that code for these enzymes can influence their ability to metabolize certain drugs. Less active or inactive forms of CYP enzymes that are unable to break down and efficiently eliminate drugs from the body can lead to drug toxicity.

It is hoped that new findings from genetic studies will facilitate drug discovery and allow drug makers to produce treatments better targeted to the cause of specific diseases. This accuracy not only will maximize therapeutic effects but also decrease damage to nearby healthy cells. In addition, physicians will be able to analyze a patient’s genetic profile and prescribe the best available drug therapy from the beginning rather than relying on the traditional trial-and-error method of matching patients with the right drugs. Pharmacogenomics aims to improve the likelihood of an improved outcome and reduce risk of serious adverse responses.

Pharmacogenomics has the potential to dramatically reduce health care costs associated with the more than 2 million hospitalizations each year in the U.S. as a result of adverse drug response and multiple drug prescriptions and patient visits.