What is Pharmacogenetics?
Why is it that a drug can help one patient and not another? Geneticists have set their sights on answering that question and their discoveries will revolutionize clinical laboratory medicine. Pharmacogenetics is the study of the hereditary basis for differences in populations’ response to a drug. The same dose of a drug will result in elevated plasma concentrations for some patients and low concentrations for others.
Pharmacogenetics will give clinicians the tools to predetermine response to pharmacotherapy by looking for specific polymorphisms in Cytochrome P450 and other enzymes involved in drug metabolism. Pharmacogenetics also will have an important role in determining or predicting patient response to environmental toxins.
Underdosing, overdosing, and misdosing cost the US more than one hundred billion dollars a year, and can be considered a leading cause of death in this country. Pharmacogenetics can help address why some individuals respond to drugs and others do not. It can also help health care providers understand why some individuals require higher or lower dosing for optimum response to a drug. It could potentially tell health care providers who will respond to a drug and who will have toxic side effects.
The technologies available to assess a person’s polymorphism and likely response to specific drugs can be divided into two approaches—.phenotyping and genotyping. A phenotype is an observable biochemical parameter, usually a biochemical reaction. Phenotyping is straightforward but has the disadvantage that it usually involves an invasive procedure. A genotype is the genetic constitution of an organism, for example, the human genome.
How Payers View Pharmacogenetics
The managed care community will embrace appropriate use pharmacogenetics. In a managed care environment, pharmacogenetics can identify the patients for whom a drug would be safe and effective. A diagnostic product that enables the drug to be selectively prescribed to these patients would provide cost savings to the health care providers. It has the potential to increase drug efficacy, reduce follow-up and doctor visits, eliminate costly ineffective drug alternatives, eliminate prescription by trial-and-error and eliminate possible drug toxicity at "normal" doses in non-metabolizers.
Pharmaceutical companies are already doing trial studies using pharmacogenetics. Probably the best example of how pharmacogenetics will change the future of medicine comes from the treatment of Alzheimer’s disease. One major form of Alzheimer’s disease is called and sporadic. The sporadic form comprises 85% of all cases worldwide, and 50 to 60% of these cases have been linked to the apolipoprotein gene.
It is implicated in synaptic remodeling and regeneration, amyloid metabolism, and appears to modulate Alzheimer’s pathology. There is a clear association with the number of ApoE4 isoforms a person has and the risk of developing the disease, the age of onset, and the accumulation of brain markers of Alzheimer’s disease.
Pharmacogenetics has the potential to both improve the clinical development and, most importantly, improve healthcare, by reducing risk and increasing efficacy. For further information on this topic, go to http://www.healthanddna.com/otherresources.html
Linda J. Hawley, RN, MS, FNP is an FNP Program Coordinator She can be reached at email@example.com