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Valsartan is an angiotensin II receptor blockers(ARBs) used to treat high blood pressure and heart failure. In 2018, the U.S. FDA recalled valsartan because of contamination of the carcinogenic chemicals called N-nitrosodimethylamine (NDMA). In Thailand, Thai FDA suspended the sale and collected both ARBs raw materials and finished products. A total of 232 samples which included losartan, valsartan, olmesartan, irbesartan, azilsartan, telmisartan and candesartan were sent to Department of Medical Sciences for the analysis of nitrosamines contamination (NDMA, N-nitrosodiethylamine; NDEA and N-nitroso-N-methyl-4-aminobutyric acid; NMBA, usingliquid chromatography-tandem mass spectrometry. It was found that Losartan rawmaterials are eight samples below the limit and five samples over the limit. Valsartan rawmaterials are three samples over the limit. Losartan finished products are four samples below the limit and forty-two samples over the limit. One-hundred and seventy samples of raw materials and finished products are free fromcontamination. The limits set by ICH for NDMA and NMBA are 96 ng while that of NDEA is 26.5 ng,based on the maximum daily dose. Thai FDA suspended the sale and their production thus patients can use the medicines with confidence and reduce unnecessary carcinogens risk.

Keywords: antihypertensive drug, contamination, N-nitrosodimethylamine