Pharmacogenetics: Assessing Medication Tolerance

Medical research has worked to make psychiatric drugs more effective, but the “trial and error” approach to prescribing has long frustrated the mental health community.

One example that still bothers Dr. Cheryl Clark, VP and chief medical/chief clinical officer at the Mental Health Center of Denver, is a young Denver woman in particular.

Dr. Cheryl Clark

The woman experienced her first psychotic episode and was in and out of counseling and psychiatric clinics throughout Denver. She was prescribed a powerful anti-psychotic medication, but the medication didn’t alter her symptoms. And the side effects were severe, as potent psychiatric formulas often can be.

The woman ended up in the hospital with urine retention as a side effect. Not only was it a delay in finding an effective drug, it was a setback to her confidence in the treatment system – and created an expensive hospital bill.

She was then referred to the Mental Health Center of Denver where she was genetically tested for drug compatibility. Her genetic markers meant she couldn’t metabolize the first medication prescribed.

“The one she was on was exactly the one she never should have been on,” Dr. Clark said. “Had they known that from the beginning, we could have saved this young woman a lot of adverse side effects.”

What is Pharmacogenetics?

The relatively new science of pharmacogenetics in mental health treatment is a fancy word for “had they known.” Simple genetic testing – one swab of a Q-tip – can tell the prescribing psychiatrist if the patient has genetic markers showing they won’t metabolize some medications well. The worst side effects can be avoided, and the right drug can be matched with the person’s metabolism.

The Mental Health Center of Denver is expanding the number of new patients who are genetically tested for medication tolerance. It’s optional, but no patients have said “no” so far once they understand it can speed up choosing the right prescription, Dr. Clark said.

So, How Does it Work?

The genetic markers come back in a handy green-yellow-and-red light format. It lists prescriptions that will be tolerated well, those that are uncertain, and those that could cause big problems. The reports also check any new drug’s potential interactions with the person’s other medications.

“We think this reduces weeks and weeks of trial and error,” Dr. Clark said. “Finding effective medications that people are willing to stay on is very difficult. Some of the psychosis drugs have very strong side effects. So if the drug’s not working, it’s very discouraging, and that wastes a good deal of time, and patient energy and willingness to try.”

Genetic coding can tell scientists how a person’s brain receptors are coded compared to others, and may help tell whether an antidepressant drug or a non-antidepressant drug would be most effective.

“In medicine, what we all want is a silver bullet,” said Dr. Clark, who presents updates on genetic science to her medical staff at monthly meetings. “What’s the perfect medicine for this person? The wave of the future is getting closer to that. It will change the face of medicine in the future, not just in psychiatry, but in everything.”