Necessary actions have been taken to stop the supply or remove products that contain nitrosamine impurities above the acceptable levels from the Singapore market. To ensure patients’ continued access to essential medicines, we have also temporarily allowed continued supply of certain medicines that may contain trace amount of nitrosamine impurities above acceptable levels while companies make the necessary changes to eliminate or reduce the nitrosamines to acceptable levels. The list of medicines impacted are in Tables 1 and 2 below.
There is no immediate risk associated with the use of medicines containing trace levels of nitrosamine impurities. Nitrosamine impurities are probable carcinogens based on animal studies where they have been reported to cause cancer only if consumed in very high amounts over a long period of time. The potential risk of cancer is with long-term exposure to unacceptable levels of the impurities.
A very conservative approach is used to set limits for these impurities in medicines, based on what is considered as reasonably safe if a patient continues to take the affected medicine every day for a lifetime of 70 years.
Patients are advised to speak to their doctor or healthcare professional if they have concerns about this issue and should not stop the medicines which has been prescribed to them for their medical conditions on their own. Sudden stopping of the medicines may pose a greater and more immediate health risk than the potential exposure to nitrosamine impurities.
Table 1: Medicines recalled due to nitrosamine impurities
Medicine
|
Use
|
Link to product recall information – Recall date
|
Acyclovir
|
Chickenpox, shingles, herpes simplex virus infection
|
27 Apr 2022
1 Aug 2022
16 Aug 2023
|
Amitriptyline
|
Depression
|
6 Feb 2023
16 Aug 2023
|
Angiotensin II receptor blockers (ARBs) (e.g., candesartan, irbesartan, losartan, olmesartan, valsartan)
|
High blood pressure
|
28 Mar 2019
|
Fluoxetine
|
Depression, bulimia, obsessive-compulsive disorder
|
27 Sep 2023
|
Metformin
|
Type 2 diabetes mellitus
|
4 Dec 2019
|
Ranitidine
|
Indigestion, heartburn, gastric ulcers
|
16 Sep 2019
|
Salbutamol
|
Asthma, chronic bronchitis, emphysema
|
9 Dec 2021
|
Sitagliptin
|
Type 2 diabetes mellitus
|
13 Dec 2022
|
Varenicline
|
Smoking cessation
|
16 Nov 2021
|
Table 2: Medicines that may contain nitrosamine impurities above acceptable levels temporarily allowed for supply
Medicine
|
Use
|
Publication date
|
Rifampicin
|
Tuberculosis
|
23 Apr 2021
|
Sitagliptin
|
Type 2 diabetes mellitus
|
2 Nov 2022
|
Ropinirole
|
Parkinson’s disease
|
14 Jun 2023
|