Nitrosamine impurity 1-methyl-4-nitrosopiperazine (MNP) found in rifampicin products

The Health Sciences Authority (HSA) would like to inform healthcare professionals about the recent findings of a newly discovered nitrosamine impurity, 1-methyl-4-nitrosopiperazine (MNP), in rifampicin products. HSA has tested and found that all the rifampicin products in the Singapore market contain trace amounts of MNP. However, in consultation with local infectious diseases experts, HSA has assessed that the benefit of rifampicin, being an essential medicine for active and latent tuberculosis and its role in curtailing the spread of tuberculosis, far outweighs the theoretical long-term risk posed by MNP. In consideration of this, HSA will temporarily allow the supply of rifampicin products with trace amounts of MNP so that patients can have continued access to this essential medicine. Please refer to the letter for details.
Healthcare professional, Industry member, Therapeutic Products

Dear Healthcare Professional Letters

23 Apr 2021

Only abstracts of the Dear Healthcare Professional Letters (DHCPL) are provided on this website. Details of the letters can be found on the MOH Alert System, which is accessible via the Health Professionals Portal (HPP). HPP is a one-stop portal for all healthcare professionals in Singapore. Dentists, medical doctors and pharmacists may access HPP at, and follow the procedures below to access the MOH Alert system.

Step 1: On the top navigation ribbon of webpage, select 'For Healthcare Professionals' followed by 'Health Professionals Portal' and click on the choice of profession. User will be redirected to the specific HPP webpage for the selected profession.

Step 2: Click on the Restricted Content icon on the left panel of webpage and login via SingPass.

Step 3: Click on the MOH Alert icon under ‘Applications’ section

Step 4: Click on the Drug Alert tab to view the DHCPLs.