Genetic screening to avoid adverse drug reactions from medication use and approach patients' better outcomes: A lesson learn from the report of the Queen Savang Vadhana Memorial Hospital.

Background and Aims: The polymerase chain reaction (PCR) technique is adopted for pharmacogenetic testing and adverse drug reaction (ADR) analysis. Methods: PCR was used for testing of pharmacogenetic markers for HLA and non-HLA polymorphism related to specific drugs.

Results: Among 76 cases that underwent genetic screening, 7.7%, 11.1%, and 2.7% of the patients were found to be genetically positive for allopurinol, carbamazepine, and abacavir, respectively. Two cases were genetically positive for interferon, and two cases of extensive metabolizers were positive for clopidogrel. One case of a NAT2 slow acetylator for isoniazid was found. Among the 74 cases with complete outcomes, 39.2% showed improvements and 18.9% reported a deterioration. Although no serious ADR was observed, two HLA-B*5701-negative cases reported ADRs (2.7%). All patients positive for IL28B were improved. One patient receiving clopidogrel showed improvements, but another showed deterioration. Finally, the outcome of slow acetylation NAT2 was worse without ADR.

Conclusion: PCR-based pharmacogenetic testing is critical for ADR monitoring in a cost-effective manner.