Some of us may experience different side-effects from drugs. The way we respond can be due to our genes. With respect to drugs, our unique genetic make-up and our individual response may mean that a drug that is effective and safe for one person may be less effective safe for another person.
Most drugs are broken down (metabolized) in the body by various enzymes. Some people have variable enzyme action. These people may metabolize the drug too quickly or too slowly or not at all — meaning that the drug may not produce its intended effect or it may remain in a person’s system too long and may lead to side effects.
Pharmacogenetics is the study of genetic variability that causes individual responses to medications. By analyzing the genes that produce the specific drug targets or enzymes that metabolize a medication, a doctor may decide to raise or lower the dose or even change to a different drug. The decision about which drug to prescribe may also be influenced by other drugs the person is taking, in order to avoid drug-drug interactions.
Doctors typically prescribe one of several appropriate drugs. Dosages and timing of drugs are usually based upon the anticipated rate of metabolism and clearance from the body in the average person. In general they prescribe a “standard” dose based on average experiences. Clinically, however, each person responds uniquely to treatment and doctors must make adjustments.
In contrast, pharmacogenetics offers doctors now the opportunity to individualize drug therapy based on the individual genetic make-up.