by Mitchell Welton, PharmD Candidate 2019
University of Arizona
As with all cause and effect scenarios it is always best to cover the basics. Before we ask if ARBs cause cancer let’s discuss what an ARB actually is. An ARB is a family of medications taken by mouth to lower blood pressure. The acronym stands for angiotensin II receptor blocker (ARB) and its name implies its function. This medication blocks angiotensin II from binding to its respective receptor. When angiotensin II binds to its receptor it causes the blood vessel to contract which increases the blood pressure.1 A patient taking an ARB would have less binding of the receptor and thus no contraction of the blood vessels causing lower blood pressure. Aside from its intended purpose, do ARBs also cause cancer?
Evaluation of Cancer Risk
In 2016 an analysis was done to evaluate the incidence of cancer in patients treated with ARBs for high blood pressure. The review concluded that ARBs had no effect in the incidence of cancer which was consistent with the findings of a similar study conducted in 2011.2 In other words, to say that ARBs as a drug class cause cancer would not be correct. However, in June of 2018 Valsartan, a commonly prescribed ARB, was recalled by the manufacturer citing an impurity found in the medication. The impurity, N-Nitrosodimethylamine (NDMA), is a probable cancer-causing agent.
Since then the United States Food and Drug Administration (FDA) launched an investigation into the affected Valsartan products. That investigation found a second impurity known as N-Nitrosodiethylamine (NDEA) also a probable human carcinogen. Further investigation and testing on other ARBs revealed that some irbesartan and losartan products contained NDEA as well. All affected products have been recalled. Not all ARBs are affected by this recall, however a list of all affected products can be found on the FDA website. It is also important to note that the drugs candesartan, eprosartan, olmesartan, and telmisartan belong to the ARB drug class and have not been identified as containing either of the previously mentioned impurities.3
The Impact of Impurities
The effect that these impurities have on cancer rates is difficult to assign a number to. Professionals at the FDA estimate that there would be one additional case of cancer out of 8,000 people taking valsartan contaminated by NDMA.3 This estimate assumes the patient was taking the highest daily valsartan dose of 320 mg over a period of 4 years. Prescribed dosages of valsartan range from 40 mg to 320 mg daily and lower strength tablets would contain less NDMA respectively than a higher strength tablet.3 This estimate also assumes that every tablet taken over the four-year period contained NDMA. Not all batches affected by the recall actually contained the impurities and over a four year period of refilling the prescription it is unlikely that a patient was exposed to the amount of NDMA calculated in the 1 in 8,000 risk.
With that being said, even if the risk of getting cancer is smaller than 1 in 8,000 it doesn’t take into account the emotional toll this recall can have on a patient that has taken a potentially affected blood pressure medication. NDEA was discovered after NDMA and the FDA does not yet have a risk estimate for the later impurity but will update the information as soon as it becomes available.3
What Should You Do?
If you or someone you know is taking an ARB for the treatment of high blood pressure, check the FDA website regularly. A list of affected medication with their lot and expiration dates can be found for all valsartan, irbesartan, and losartan included in the recall. Again, not all ARBs are affected, and if you are unsure how to match the lot and expiration dates on the medication you picked up from the pharmacy, call and talk to your pharmacist. If you are taking a medication affected in the recall, your pharmacist may be able to recommend or provide you with an unaffected medication by a different manufacturer. The FDA recommends you take your current medication as prescribed until you can get a replacement from your pharmacist or doctor.3
- Ogbru, O. (n.d.). Angiotensin II Receptor Blockers (ARBs) Drug Facts, Side Effects and Dosing. Retrieved from https://www.medicinenet.com/angiotensin_ii_receptor_blockers/article.htm
- Zhao, Y., Li, P., Zhang, J., Wang, L. and Yi, Z. (2018). Angiotensin II Receptor Blockers and Cancer Risk. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4863811/
- Center for Drug Evaluation and Research. (n.d.). Drug Safety and Availability – Questions and Answers: Impurities found in certain generic angiotensin II receptor blocker (ARB) products. Retrieved from https://www.fda.gov/Drugs/DrugSafety/ucm626122.htm