Pharmacogenomics
Scientists believe understanding an individual's genetic makeup is the key to creating personalized drugs with greater efficacy and safety. While widespread application still lies far in the future, pharmacogenomics has the potential to personalize medical therapies because it is based on genetic testing for predisposition to disease or response to therapeutic intervention (i.e. a medication, or radiation therapy).
What is pharmacogenomics?
Pharmacogenomics examines how your genetic makeup affects your response to drugs. Researchers in the field are working on applying human genome knowledge to pharmaceuticals by identifying genes that account for varying drug reactions in different people. Eventually, they hope to be able to customize drug therapies for specific patient populations or even individuals.
Pharmacogenomics combines traditional pharmaceutical sciences such as biochemistry with with an understanding of common DNA variations in the human genome. The most common variations in the human genome are called single nucleotide polymorphisms (SNPs). There is estimated to be approximately 11 million SNPs in the human population, with an average of one every 1,300 base pairs.
An individual's response to a drug is often linked to these common DNA variations. In a similar manner, susceptibility to certain diseases is also influenced by common DNA variations. Currently, much of the research in the field of pharmacogenomics is focused on genes encoding either metabolic enzymes that can alter a drug's activity or defective structural proteins that result in increased susceptibility to disease.
How could pharmacogenomics affect the way medicine is practiced today?
Currently, physicians prescribe medication through a trial-and-error method of matching patients with the right drugs. If the prescribed medication does not work for the patient the first time, the physician will try a different drug or dosage, repeating the process until the patient improves. As pharmacogenomics becomes more advanced, physicians eventually will be able to prescribe medication based on an individual patient’s genotype, maximizing effectiveness while minimizing side effects.
Anticipated benefits of pharmacogenomics
Pharmacogenomics eventually will provide tailored drug therapy based on genetically determined variation in effectiveness and side effects. This will mean:
- More powerful medicines - Pharmaceutical companies will be able to produce therapies more targeted to specific diseases, maximizing therapeutic effects while decreasing damage to nearby healthy cells.
- Better, safer drugs the first time - Recovery time will go down and safety will go up as the likelihood of adverse reactions goes down or is eliminated altogether.
- More accurate methods of determining appropriate drug dosages - Current methods of basing dosages on weight and age will be replaced with dosages based on a person's genetics --how well the body processes the medicine and the time it takes to metabolize it.
- Better vaccines - Vaccines made of genetic material, either DNA or RNA, promise the benefits of existing vaccines without all the risks. They theoretically could activate the immune system but be unable to cause infections.
Practical applications of pharmacogenomics today
Following are links to scientific abstracts that discuss practical applications of pharmacogenomics in cancer, depression, cardiovascular disease and drug metabolism:
- Cancer pharmacogenomics: current and future applications
Watters JW, McLeod HL
Biochim Biophys Acta 2003 Mar 17;1603(2):99-111 - Pharmacogenomics study of statin therapy and cholesterol reduction
Chasman DI, et al.
JAMA 2004; 291(23) 2821-2827. - Role of pharmacogenomics in individualizing treatment with SSRIs
Mancama D, Kerwin RW
CNS Drugs 2003;17(3):143-51 - Cardiovascular pharmacogenomics: current status, future prospects
Anderson JL, Carlquist JF, Horne BD, Muhlestein JB
J Cardiovasc Pharmacol Ther 2003;8(1):71-83 - Pharmacogenomics — Drug disposition, drug targets, and side effects
Evans, WE, and McLeod, HL
NEJM 2003; 348:538-549
Economic issues from molecule to marketplace
Pharmacogenomics eventually can lead to an overall decrease in the cost of health care because of decreases in:
- the number of adverse drug reactions,
- the number of failed drug trials,
- the time it takes to get a drug approved,
- the length of time patients are on medication,
- the number of medications patients must take to find an effective therapy, and
- the effects of a disease on the body (through early detection).
Additional resources
The Department of Energy (DOE) Human Genome Project Information - pharmacogenomics
The Single Nucleotide Polymorphism (SNP) Consortium
Environmental Genome Project (NIEHS)
National Institute of General Medical Science
Listing of federally-sponsored clinical trials in US
Sources
AMA Science
National Institute of Pharmaceutical Education and Research
