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May 18, 2015 at 10:49 AMComments: 1 Faves: 1

Pharmacogenomics: When A Treatment Fails To Deliver, A Cheek-Swab DNA Test May Reveal the Solution!

By Jeffrey VanWingen M.D. More Blogs by This Author

As a doctor, I prescribe medications to patients every day, and it's something that I take very seriously. After all, a substance taken in the body walks a fine line in yielding benefit. The alternative, a significant possibility, is that it will have unwanted side effects. It can be incredibly frustrating when intentions go wrong in taking a medication. 

This blog will highlight new technology aimed at taking guesswork out and better directing medical therapy by examining genetic make-up.

Archery

Sometimes I use the analogy of archery when explaining the art of prescribing medication to patients. Just like shooting an arrow, I grab the best looking arrow and take aim utilizing all my expertise, practice and know-how. When satisfied that all factors are aligned to their best, the bow-string is released and the arrow allowed to fly. As an experienced archer, in most cases, the arrow falls reasonably close to the bulls eye. Despite the best calculations and unseen factors, however, there are times that the mark is missed. In these instances, it is my job as the marksman to make adjustments, learning from the former result. Prescribing medications is very similar.

As a doctor/prescriber, it is my job to know everything about the medication I am giving to my patient to help their condition - its chemical make-up, potency, route, frequency, duration, side-effects, precautions, etc. If the medication does not work or has an unexpected effect, this may provide important information for a plan B option.

Why Negative Side-Effects Happen

Various issues can pre-dispose a person to a negative outcome when it comes to taking a medication.

Allergy: Allergy to a medication is usually a random occurrence brought on by the body's immune system. With an initial experience in the body, the immune system mounts a defense against the medication recognizing it as an invader. In general, subsequent experiences with the medication yield more sever results. While an initial symptom may present as a rash or hives, another exposure could lead to the condition of anaphylaxis which can be fatal. As a general rule, once allergic to a medication, always allergic.

Non-Compliance: In general, a medication works best when it is taken and taken according to instructions. For instance, taking a medication and suddenly stopping it may lead to a rebound or withdrawal. Taking the medication sporadically may reduce its ability to work.

Expected Side -Effect:  Some medications, in order benefit one problem, may through their intended effect cause a negative effect in another realm. For instance, nitroglycerine can save a life in the face of a heart attack by lowering the force of the blood flowing to the heart and reducing strain on the heart. By this function, however, it can also cause a headache or dizziness as it has the same effect on other areas of the body.

Unexpected Side- Effect: Some medications, with no certain predictability, can cause side effects in those who take them. These effects are generally not considered a consequence of their successful functioning. These are the most frustrating side effects. They are unintended and for the most part unexplained. Why would a cholesterol medication cause muscle pain?  Why would a pain medication be short-lived? Why would an antidepressant not only fail to work but cause unusual symptoms? Many times these situations are due to the different ways that medications are metabolized by a body.

Precision Prescription

Our unique genetic make-up codes for various enzymes in our body and these enzymes regulate various chemical reactions in our day-to-day metabolism. However, different medications interfere with these enzymes in various ways.

Sometimes the enzymes are responsible for metabolizing the medication and in people genetically-disposed to low levels of enzymes may receive an increased potency of the medications as a result. In turn, high levels of a medication meant to produce a certain effect may actually cause an opposite effect to take place. Or sometimes low levels of certain enzymes can yield negative effects when more than one drug that relies on the enzyme for turnover and removal from the body is prescribed . 

Another example of how genetics may influence drug efficiency - overactive metabolism which can reduce the intended effect of the drug. 

No though, these unexpected side effects which don't follow logical explanations can now perhaps now be helped by examining the genetic make-up responsible for metabolism and processing of medications. This field of study is now called "pharmacogenomics."  

Pharmacogenomics

Pharmacogenomics helps to crack codes and answer questions as to why a patient may not be getting intended medication effects and streamlines choices for getting the best medication, minimizing trial and error.

In the case of breast cancer for example, pharmacogenomic testing can direct cancer treatment to see if cancer cells are producing certain proteins which predict success with a certain medication. Many such scenarios exist and the list is growing.

Even better? Most pharmacogenomic testing can occur right in a doctor's office with a swab of cheek cells. The swab collects sloughed cells that contain DNA and that sample is then sent to a lab for testing.  Many insurances are now covering pharmacogenomic testing provided that the test is justified.

Could a Cheek-Swab DNA Test Help Me?

The most common type of drugs for which pharmacogenomics testing can offer benefit are listed below:

  • Heart rhythm drugs
  • Blood pressure drugs
  • Diabetes drugs
  • Cholesterol drugs
  • Drugs for blood clotting disorders
  • Attention Deficiency drugs
  • Alzheimer's Disease drugs
  • Depression drugs and other drugs for mental illness
  • Epilepsy drugs
  • Pain drugs

If you have had difficulties with medications and feel like you are struggling tolerating certain medications, talk to your doctor about pharmacogenomics testing.  As this testing is quite new check with your insurance carrier about stipulations for coverage.

Live, and live well!

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1 Comment

  • I am allergic to many of synthetic meds.

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