http://www.practicalpainmanagement....chrome-p450-testing-high-dose-opioid-patients
Excerpt:
Excerpt:
P450 Testing In High-dose Opioid Patients
Severe, chronic pain patients who seek opioid dosages above normal standards should now be tested for genetic cytochrome P450 deficiencies.
By Forest Tennant, MD, DrPH
While it is common knowledge that the cytochrome P450 (CYP450) enzyme system is critical for the metabolism of some opioids, genotype testing of pain patients for CYP450 polymorphism has not been generally recommended.1,2 This situation, however, may change as pain specialists begin to recognize that patients who require high doses of opioids may have a genetic defect that may affect their ability to metabolize these agents.
In the past, genotyping for CYP450 polymorphisms was not cost effective or convenient. However, testing technology, commercial availability, third-party reimbursement, and most of all, clinical understanding, have recently coalesced to make CYP450 genetic testing an essential component of high-dose opioid therapy. It is my recommendation, therefore, that patients who require more than 150 mg per day of morphine equivalents be tested for three specific CYP defects—2D6, 2C9, and 2C19.
To study the validity of genotype testing, I prospectively studied 66 patients on high-dose opioids in my pain clinic. The study found that the vast majority of these patients had CYP450 defects...