AHRQ report finds unclear value of pretesting autoimmune disorder patients before prescribing thiopurine drugs
Research Activities, March 2011, No. 367
According to the authors of a recently released report from the Agency for Healthcare Research and Quality (AHRQ), there is insufficient evidence to determine whether patients with autoimmune diseases such as Crohn's disease have better outcomes if they are pre-tested for levels of the TPMT enzyme prior to clinicians prescribing a dosage for thiopurine-based medication.
The AHRQ report sought to determine if TPMT pre-testing reduces drug-related adverse effects. Experts have proposed that patients with either intermediate, low, or absent TPMT enzyme activity (reduced detoxifying metabolism) may benefit from lower initial doses of thiopurine drugs, because higher doses may cause toxic reactions such as the reduction of white blood cell and platelet count in the bone marrow. Testing patients' TPMT status prior to starting thiopurine drugs, such as Azasan® and Imuran®, has been recommended. The authors, led by Ronald A. Booth, Ph.D., of the AHRQ-supported University of Ottawa Evidence-based Practice Center in Ottawa, Ontario, said that it is unclear whether pre-testing guides appropriate prescribing.
For more findings and conclusions, go to Assessment of Thiopurine Methyltransferase Activity in Patients Prescribed Azathioprine or Other Thiopurine-based Drugs.