An active substance has been classified as "a probable human carcinogen"
A recall has been issued for film coated tablets which contain Valsartan.
Valsartan is prescription medicine used in several different products.
It is used to treat high blood pressure and heart failure. It is also sometimes prescribed after a heart attack.
The Health Products Regulatory Authority (HPRA) says some of the products have a "quality defect".
"An impurity has been identified in the Valsartan active substance used in the listed medicinal products; this impurity is N-nitrosodimethylamine (NDMA) and it has been classified as a probable human carcinogen."
The HPRA says there is no evidence that this has caused any harm to patients.
However the recall is being undertaken "as a precautionary measure".
The active substance manufacturer - Zhejiang Huahai Pharmaceuticals, located in China - has reported that the impurity is linked to changes made to the manufacturing process.
The HPRA adds: "At present, the risk is theoretical and there is no direct evidence of harm having been caused".
It is actively involved with the European Medicines Agency and other regulators to determine any possible impact on patients who have been taking these medicines.
Work is currently ongoing at a European level to better understand the potential impact of this impurity.
Patients taking the affected medicines (listed below) have been advised not to stop taking their Valsartan medicine abruptly.
Patients should contact their pharmacist for further advice.
This issue only applies to Valsartan medicines listed above. Those who are not sure can consult their pharmacist.
A recall letter was issued on July 5th to all pharmacies and pharmacists in Ireland.
It is being e-mailed at the HPRA’s request by the Pharmaceutical Society of Ireland (PSI).