The FDA has made the decision to relabel Coumadin to include the importance of genetic testing. PGXL Laboratories was the first CLIA certified laboratory to provide clinical pharmacogenetic testing, and offers the warfarin test, with unparalleled expertise and service.
Our laboratory is equipped to apply a mathematical model , which makes our lab capable of estimating the most appropriate maintenance dose based in part on diagnostic testing of CYP2C9 and the VKORC1 genetic variants, thereby limiting the potential for un-intentional overdose. PGXL Laboratories was the first CLIA certified laboratory to provide Pharmacogenetic testing, and the first to market the warfarin test.
Warfarin is a racemic mixture of R – and S- warfarin. The S-warfarin enantiomer is considered to be the primary active principle. S-warfarin is cleared by metabolism via the cytochrome P4502C9 enzyme (CYP2C9). Approximately 30 to 40% of individuals inherit one or more alleles that lead to decreased CYP2C9 activity. Decreased CYP2C9 is unequivocally associated with increased risk of severe bleeding and increased time to stable therapy. The anti-coagulation effects of S-warfarin result from inhibiting the vitamin K epoxide reductase. Recently, inherited genetic variation in the expression of vitamin K epoxide reductase component protein 1 (VKORC1) has been clearly associated with decreased maintenance dose requirement, and increased risk of bleeding when standard dosages are administered.
The feasibility of this approach for limiting the risk of above range INR’s and bleeding events, and in decreasing the time required to titrate patients toward stable therapy, has been acknowledged by the Clinical Pharmacology Advisory Committee reporting to the FDA.
The manufacturer of Coumadin has included this information in the Coumadin product label.
The knowledge that a patient has a deficiency in the metabolism of this medication can help you interpret the meaning of INR measurements, and allow you to develop a monitoring strategy that takes this delay into account. This process can facilitate more consistent care for the patient.
Therefore, screening patients gives you insight into their metabolic capacity during the early phase of warfarin therapy, and it can provide you with fundamental information supported by classical principles of pharmacology. This can improve both the lives of your patients, and the effectiveness of your practice.
Please contact PGXL Laboratories at 502-569-1584 Ext:4, for more information on how to order the test.