Pharmacokinetics and dynamics in action
Pharmacokinetics is the study of what the body does to a drug: the movement of it into, through and out of the body and the processes in between. One "PK" test looks for different alleles of the cytochrome P450 superfamily of drug metabolising enzymes. The results can be used to guide the clinician in which drugs and at what dosage they should prescribe.
Pharmacodynamics is the study of what a drug does to the body, how it binds to cell receptors and the chemical reactions it produces.
A topical example is the drug Herceptin, used to fight breast cancer. Herceptin is a "monoclonal" antibody; one that only recognises one specific molecule, in this case the human epidermal growth factor receptor type 2 or HER2. Overexpression of HER2 occurs in 20-30% of invasive breast cancers (malignant tumours) and drives tumour development. Herceptin binds to HER2 and stops it from forming its active state, which inhibits this form of tumour growth and proliferation.
Tests are carried out on breast cancer patients to see whether they overexpress the HER2 receptor, this reveals whether or not the patient will benefit from herceptin therapy.
These tests are the beginning of personalised medicine. In the future your doctor will be able to decide which drug and how much of it suits your individual body based on which genes you have inherited.
Researchers are beginning to map out what they have found about genes, diseases and drug reactions and are sharing this knowledge in databases such as the
Pharmacogenomics Knowledge Base.
Some people think they should charge for this information. What do you think?
What should we do with the genetic knowledge revealed by pharmacogenetic tests?