If you take blood pressure medicine, you’ll want to double-check your bottle. Torrent Pharmaceuticals Ltd. has expanded its recall of losartan potassium and losartan potassium/hydrochlorothiazide tablets. Tests found trace amounts of a potentially cancer-causing impurity called N-methylnitrosobutyric acid in some of these drugs. The company is recalling 36 additional lots, it said Thursday. A full list of recalled drugs is available on the US Food and Drug Administration website. The company hasn’t had any reports of users getting sick, but the impurity level in these pills is above what the FDA considers an acceptable daily intake level. Doctors prescribe losartan for patients with high blood pressure and for Type 2 diabetics who have nephropathy. The FDA advises patients who take these drugs – even the ones that have been recalled – to continue taking them but to talk to their doctor or pharmacist immediately about alternative treatment. This latest recall is related to the valsartan recall that has been expanded multiple times since July. The FDA put the Chinese company Zhejiang Huahai Pharmaceutical on an import alert after it learned that the company made the tainted ingredient that is at the heart of most of these recalls. The impurity is a chemical that is used in gasoline as a stabilizer and as a lubricant additive. The FDA started testing all heart drugs called angiotensin II receptor blockers for these impurities. Also known as ARBs, they block a potent chemical in the blood called angiotensin that causes muscles surrounding blood vessels to contract. When the chemical binds, it narrows the vessels, and that can cause high blood pressure. It’s unclear exactly what the cancer risk is if you take the contaminated pills; the FDA believed that the risk was low with the valsartan recall. It estimated that if 8,000 people took the highest dose of valsartan (320 milligrams) containing the impurity, N-nitrosodimethylamine or NDMA, from these recalled batches daily for four years, there may be one additional case of cancer over the total lifetimes. Many patients take a much lower dose of valsartan, and therefore their risks are theoretically much lower. The FDA said it will continue to test all products containing valsartan and similar drugs for the presence of impurities.