Singapore's health authority on Thursday announced recall of three brands of high blood pressure medicine containing losartan, an active ingredient manufactured by an Indian pharma company, which contained higher than acceptable levels of a potentially harmful impurity.
The affected products are the 50mg and 100mg tablets from the brands Losartas, Losagen and Hyperten and distributed by local suppliers Apotheca Marketing, Medicell Pharmaceutical and Goldplus Universal, respectively.
Losartas is prescribed in public healthcare institutions, while Losagen, Hyperten and Losartas are prescribed at private healthcare institutions, according to a report by the Channel News Asia.
Announcing the recall, the Health Sciences Authority (HSA) said that these drugs contain the active ingredient losartan potassium, manufactured by Indian pharmaceutical company Hetero Labs.
The recalled products were found to contain trace amount, above the internationally accepted levels, of nitrosamine impurity, N-nitro-N-methyl-4-aminobutyric acid (NMBA), the HSA said.
The exposure to nitrosamines, beyond permissible levels, over a long-term period may potentially increase the risk of cancer.
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For example, the added cancer risk from an additional six-month exposure is estimated to be less than 0.0002 per cent.
"The risks of trace amounts of the NMBA are associated with long term exposure," the HSA said, and advised patients not to stop treatment on their own as there is no immediate health risk and sudden stopping of the drugs can pose greater immediate risk to their health.
"The sudden stopping of the medicines can pose greater and more immediate risk to patient's health. We have advised healthcare professionals to review the medicine and treatment plans of their patients," the HSA said, adding that several losartan medicines have been recalled overseas since end-February due to the presence of NMBA.
According to the Ministry of Health, about 137,000 patients in Singapore are using the three recalled brands of losartan medicine.
The HSA tested all the locally marketed losartan products for the presence of the NMBA impurity and in March found the three brands contained trace amounts of NMBA above acceptable levels.
The other seven brands of losartan medicines marketed in Singapore are not affected by this impurity.
According to National Heart Centre Singapore Cardiologist Professor Ding Zee Pin there is no immediate health risk associated with taking the affected medicines and that patients are advised not to stop or change treatment on their own.
"As losartan is used to treat high blood pressure, stopping the medicine without replacement of other equivalent medication can increase the risk of poor control of blood pressure," said Ding, who is also on the HSA's Expert Panel on Nitrosamines.
Consumers who are taking the affected medication are advised to discuss their treatment plan with their healthcare provider.
"Do not stop taking the medicines on your own until you have been provided with a replacement brand of losartan or a different medicine by your healthcare provider," the HSA said.