What is pharmacogenomics?
Pharmacogenomics looks at how your DNA affects how you respond to medications. Pharmacogenomics is an important part of precision medicine and can help your physicians be more proactive about the drugs they prescribe to each patient. Your DNA can affect multiple steps of the drug metabolism (drug breakdown) pathway including drug receptors, drug uptake and drug breakdown. Let’s get into a bit more detail about how this works!
Drug Receptors. There are some medications that need to bind to receptors that are found on the outsides of your cells in order to trigger a response. Your DNA can affect the efficacy or ability of your cellular drug receptors to transmit signals which will affect how your body reacts to that medication.
Drug Transporters. There are some medications that don’t need cell surface receptors but instead are absorbed directly into the cell through a drug transporter protein. Your DNA can affect how effective your transport proteins are at allowing medication to pass into the cell.
Drug Breakdown. Once the drug has been taken into the cell, either through receptors or directly, your cell then has to break down or get rid of the medication. Your DNA also plays a major role in this step of the process and that can affect how efficiently you respond to the medication.
How can your DNA affect drug reactions?
We know that your DNA can affect both the transport and uptake of drugs in your body. This is known as drug metabolism. Your DNA can affect the speed of drug metabolism for different medications. Pharmacogenomics DNA testing can classify you into three main types of metabolizers:
- Rapid/ultra rapid metabolizers. In this group, the body is able to break down the medication faster which often means that the medication is less effective since it is leaving the body at a much faster rate than normal.
- Normal metabolizers. In this group, the body is predicted to break down the medication as expected and patients get the intended response.
- Intermediate metabolizer. In this group, the body breaks down medications at a rate that is between a normal metabolizer and a poor metabolizer.
- Poor metabolizers. In this group, the body is unable to break down or breaks down the medication very slowly. This increases the chance for adverse drug events or increased side effects since the medication stays in the body for longer than intended.
What about Prodrugs?
Most drugs are taken in their active state. When the body metabolizes or breaks down a drug, it inactives the drug and flushes it from the body. However, there is another class of medications that are called prodrugs. Prodrugs are taken in their inactive state. When the body metabolizes a prodrug, it is activating the drug to get the intended therapeutic response. In the case of prodrugs, rapid metabolizers will activate the prodrug too quickly, causing increased side effects while poor metabolizers will experience a decrease in therapeutic effect since poor metabolizers are activating the medication too slowly.
Why is this important?
Adverse drug reaction is an unwanted, unintended effect of a medication. Every year there are more than 1.3 million emergency department visits due to adverse drug reactions. Pharmacogenomic testing can help decrease these adverse effects by helping healthcare providers have more information about how their patient may react to certain medications. This can help adjust the dosage or types of medications that they choose to prescribe.
Limitations
Although pharmacogenomics is a powerful tool, there are limitations to what information it can provide for us. It cannot predict exactly what medications to use or what adverse reactions will be caused by certain drugs. As with other fields of genetics, pharmacogenomics is only one piece of the puzzle, there are many other factors that can affect how the body reacts to certain medications.
If you are interested in learning more about the field of pharmacogenomics, please visit the Clinical Pharmacogenomics Implementation Consortium website for the latest developments in the field. If you are interested in getting pharmacogenomics testing you can schedule an appointment with one of our genetic counselors that specializes in pharmacogenomics.
