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Nurses turn to DNA testing to help patients being treated with psychotropic drugs

Monday August 27, 2012
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Linda Gable-Gaston, APN
Six months ago, psychiatric nurse practitioner Laura Leahy decided to try a little-used kind of testing to help a patient who had suffered from profound depression for more than 30 years.

Leahy, RN, MSN, APN, PMHNP/CNS-BC said the patient cried daily, had regular migraines and fatigue, didnít want to get out of bed and had lost the will and energy to enjoy life.

She had tried numerous therapists, multiple medications and 18 electroconvulsive therapy treatments.

So Leahy, who has a private practice called APNSolutions in Vineland, N.J., sent a saliva sample to Genomind in Chalfont, Pa., for a genetic test to check the patientís DNA for clues.

Two "aha" moments followed.

One was for Leahy, who discovered the patientís genetic makeup indicated the way she metabolized psychotropic drugs meant her current treatments were likely to fail. The second was for the patient, who finally knew "it wasnít all in her head," Leahy said.

Leahy lowered the dose of the antidepressant and added a psychostimulant, and now "sheís a new woman," said Leahy, who said that in late July, the patient related her latest night out. "She was supposed to meet a friend to do karaoke. Her friend ended up not showing, and she spent four hours doing karaoke by herself."

How a patient metabolizes drugs
Using a personís DNA to predict how they will react to psychotropic drugs takes some of the trial and error out of determining which drug is best for which patient.

Pharmacogenetic testing involves a swab or a blood or saliva sample sent to a lab that analyzes patientsí DNA — specifically cytochrome P450, the enzymes that metabolize medication — to find out how they metabolize a certain drug. That can influence which drugs are prescribed and in what amounts.

The testing is not yet widely used among hospitals. Physicians and nurses familiar with the testing say this is because hospital systems arenít generally convinced the tests are cost-effective or are not familiar enough with the procedure to make that determination.

At Zucker Hillside Hospital in Glen Oaks, N.Y., research nurse Brian Cantley, RN, is part of a team studying whether genetic testing can help in treating schizophrenic patients who use one of the most widely prescribed atypical antipsychotic agents, risperidone (Risperdal).

Researchers theorize that poor metabolizers who are treated with a low dose and slow titration of risperidone will better tolerate its side effects and show more clinical improvement compared with those treated with usual dose and titration.

The interest in the test came after large-scale clinical trials had shown a substantial percentage of patients with schizophrenia stop taking their antipsychotic medicines because they see them as ineffective or they canít tolerate the side effects.

Cantley said side effects of antipsychotic drugs can include akathisia, a restlessness often described as feeling like youíre crawling out of your skin; myoclonus, or quick involuntary muscle twitches; dystonia, or muscle contractions that cause uncontrollable twisting; and weight gain.

There can be sexual side effects as well, Cantley said. "In men, they (can be) unable to get an erection or to ejaculate." Women may see a drop in estrogen and may have irregular or absent periods, infertility, breast discharge and menopausal symptoms.

Though risperidone is probably the most popular treatment for schizophrenia, there are other medication options, Cantley said.

In addition to costs for the tests, he said, the time it takes to get DNA testing results — two to three days in his case — may be a negative for hospitals.

"Itís not a quick thing," Cantley said.

Leahy said it typically takes a week to get the results from Genomind.

Test often follows multiple trials
Linda Gable-Gaston, APN, MSN, said she has used the tests for many patients in her private practice, Introspection Mind, Body & Spirit Center, in Bloomfield, N.J.

Gable-Gaston does an evaluation to gather patient history and medication history. If she thinks the genetic testing would be beneficial, she sends a DNA swab to the lab. When results come back, she and the patient go over them and Gable-Gaston makes a recommendation for medications.

Both Cantley and Gable-Gaston said they use AssureRx Health lab. Gable-Gaston said she chose that company partially because they make results easy for the patient to understand.

Genetic testing usually comes after multiple trials for psychotropic drugs havenít produced the desired results.

"Not everybody is a candidate for this," Gable-Gaston said. "I reserve it for people who have been on multiple medications, continue to struggle or may have breakthrough symptoms, such as visual or auditory hallucinations."

She said in her experience, the test is not only worth the cost, but can prevent bigger costs.

Gable-Gaston and Leahy said their patients usually end up paying only a copay for the service. Some, whose income falls below the poverty level, can get the copay waived, they said.

Gable-Gaston said in her experience, "Itís covered by private insurance, and itís also covered by Medicare but not Medicaid."

The test is one tool used in combination with patient history and lifestyle indicators to determine which drug will be best, Gable-Gaston said. For instance, smoking can interfere with a medicationís effectiveness.

Leahy said the test can tell her how a certain type of drug might interact with a womanís birth control pills or a personís blood pressure medication, based on the genetic profile of their liver enzymes.

Research at Mayo
Mayo Clinic in Rochester, Minn., is a pioneer for genetic tests in psychiatry. There, David Mrazek, MD, chair of the department of psychiatry and psychology, developed a federally funded psychiatric pharmacogenomics research program and implemented clinical psychiatric pharmacogenomics services.

Daniel Hall-Flavin, MD, a consultant in the department, said in his experience the costs of the tests run from $1,000 to $2,000, but noted those costs are likely to come down as technology advances.

When testing is more widespread, nurses will play important roles in working with physicians to assess whether patients could benefit from the tests, he said.

"It is the nursing staff that are able to spend the most time with patients," he said. "With this in mind, monitoring patientsí response for effectiveness and untoward effects, helping the physician to assess the benefits and risk both proactively and retroactively in planning additional care, bringing new information to the physician that may not have been previously available, and working in research to better understand the applications of new interventions are all roles that nursing can play."

Marcia Frellick is a freelance writer.


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