Featured Test: Genetic Testing

Pharmacogenetic tests can help physicians personalize therapy by choosing the most suitable medications and possibly adjusting standard dosage recommendations. 

Cytochrome P450 2D6, 2C19, 3A4, & 3A5

Cytochrome P450 is a family of enzymes involved in the rate and extent of drug metabolism. Some patients being treated with pain medication may not experience expected pain relief if they are ultra –rapid or poor metabolizers. Cytochrome P450 may also be inhibited or induced by drugs, resulting in drug-drug interactions and leading to unanticipated, adverse drug reactions.

DNA strands

Patients can exhibit inconsistent responses to drug therapies which are influenced by variations in DNA coding of the Cytochrome P450 enzyme family. These enzymes affect the extent of drug metabolism, and understanding patient metabolism rate can help physicians determine accurate dosage of proper pain management medication.Identifying CYP450 polymorphisms in 2D6, 2C19, 3A4 and 3A5 will indicate the rate at which patients can be expected to metabolize a drug.  These tests can classify a patient as an ultra-rapid metabolizer, extensive (normal) metabolizer, intermediate metabolizer or poor metabolizer.

Patients who are poor metabolizers may have an increased risk of drug-induced side effects, or may experience inadequate pain relief. Patients characterized as poor metabolizers or ultra-rapid metabolizers may need adjustments in dosage depending on the drug. Cytochrome P450 test results may help you develop a treatment strategy for patients using pain management medication.   These tests can also help explain inconsistencies in urine drug testing results

Quest Diagnostics has provided genetic testing since the 1970’s, and has a wealth of experience covering all genetics areas. Our experts, which include board-certified geneticists, medical directors and genetic counselors, provide clinical support in prenatal, molecular and biochemical genetics, as well as cytogenetics and oncology-related genetics.

The test makes it possible to identify four types of patients:drug metabolism chart

  • Poor metabolizer with two non-functional alleles
  • Intermediate metabolizer with one functional allele and one non-functional allele
  • Extensive metabolizer with two functional alleles
  • Ultra-rapid metabolizer with more than one increased functional allele

Knowledge of your patient’s metabolizing rate will allow you to better predict how your patient might respond to certain prescription pain medications. 

Full more information on the tests available at Quest Diagnostics click here