When doctors prescribe blood pressure medication, their goal is to reduce the likelihood that a patient with hypertension will develop heart attacks, strokes, kidney damage, eye problems or even Alzheimer’s disease. But some commonly prescribed blood pressure drugs can interact in dangerous, if not deadly, ways with other anti-hypertensive meds or even with antibiotics.
It is not uncommon for health professionals to prescribe two or even three different blood pressure medications to get a patient closer to “normal.” By the way, there is growing evidence that aggressively lowering systolic blood pressure (below 128) with medications in older patients may actually increase the risk for cognitive decline (more about this here).
ARBs and ACEIs: A Dangerous Blood Pressure Mix
Our greater concern is the discovery that certain blood pressure medications may not play well together. Two of the most popular categories of blood pressure medicines are angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs). They both belong to what is called RAS (Renin-Angiotensin System) inhibitors.
At last count more than 160 million prescriptions are filled annually for ACE inhibitor-type drugs. They include benazepril, captopril, enalapril, fosinopril, lisinopril, moexipril, perindopril, quinapril, ramipril and trandolapril. If there is a “PRIL” in the name, you can pretty much assume you are taking an ACE inhibitor.
ARBs include medications such as azilsartan, candesartan, irbesartan, losartan, olmesartan, telmisartan and valsartan. If there is a “SARTAN” in the name, you can pretty much assume you are taking an ARB. Over 80 million prescriptions are written annually for ARBs. While most of the ACE inhibitors are now available generically, that is not true for the ARBs. A minority are available in generic form at this time. Brand names like Atacand, Avapro, Azor, Benicar, Diovan, Exforge, Micardis and Teveten may be more easily recognized than their generic equivalents.
Taken independently, ACE inhibitors or ARBs are reasonably safe and quite effective for controlling high blood pressure. When these categories are combined, however, there can be serious complications. A review of 33 randomized controlled trials in (BMJ, Jan 28, 2013) comparing treatment with one single blood pressure medication to “dual blockade” with both an ARB and an ACE inhibitor together revealed some scary results.
The combination therapy led to an increased risk of a potentially life-threatening condition called hyperkalemia (excessive potassium levels). Too much potassium can lead to cardiac arrest. Other adverse reactions associated with dual therapy included hypotension (very low blood pressure) and kidney failure.
How Serious Are These Side Effects?
When your blood pressure drops too low you can become dizzy and fall. When an older person falls, it can lead to broken bones. A hip fracture is associated not only with disability but also death.
Kidney failure is another life-threatening condition associated with the combination of ACE inhibitors and ARBs.
The conclusion of the researchers was:
“Although dual blockade of the renin-angiotensin system may have seemingly beneficial effects on certain surrogate endpoints, it failed to reduce mortality and was associated with an excessive risk of adverse events such as hyperkalaemia, hypotension, and renal failure when compared with monotherapy. The overall risk to benefit ratio argues against the use of dual therapy.”
Despite this strong admonition to avoid combining ACE inhibitors with ARBs, it is estimated that over one million people are taking the two categories simultaneously. That may be because the FDA does not have a strong warning on the label of such drugs. The advocacy group Public Citizen has petitioned the FDA to include a black box warning about this problem, but to date the FDA has ignored this request.
Public Citizen also warns that the blood pressure drug aliskiren (Tekturna) should not be combined with either ACE inhibitors or ARBs for the same reasons: hyperkalemia, hypotension and kidney failure.
If you are taking an ARB together with an ACE inhibitor or with aliskiren please do NOT stop any drug suddenly. You can make a copy of the BMJ article and give it to your physician for consideration. Hopefully the data in the article will be convincing enough for the prescriber to reevaluate this combination.
Another Potentially Deadly Combination: Antibiotics and ACEIs or ARBS
We have been warning visitors to this website for years that the antibiotic co-trimoxazole (trimethoprim plus sulfamethoxazole, aka Bactrim or Septra and often abbreviated TMP-SMX or TMP-SMZ) could produce a life-threatening reaction if combined with an ARB or an ACEi. This is especially problematic for older people. Despite our efforts and FDA warnings, people continue to die from this combination.
Canadian researchers reported in BMJ (Oct. 30, 2014) that combining an ACE inhibitor or an ARB with co-trimoxazole “is associated with an increased risk of sudden death. Unrecognized severe hyperkalemia may underlie this finding. When appropriate, alternative antibiotics should be considered in such patients.”
These investigators go on to explain that the combination of an ARB or ACEi with the antibiotic co-trimoxazole can lead to very high levels of potassium, which in turn can cause irregular heart rhythms, cardiac arrest and death.
There are more details about this deadly drug interaction at this link.
How To Protect Against Dangerous Drug Combinations
You may be asking yourself how such interactions can occur if they have been thoroughly described in the medical literature. The answer is that busy physicians don’t always check for dangerous drug interactions. They may be harried or preoccupied and when an alert shows up on their smart phone or computer they often override it. Pharmacists are in the same situation.
If you find this hard to believe, you will want to read the chapter titled “Drug Interactions Can Be Deadly” in our book, Top Screwups Doctors Make and How to Avoid Them. You will also find our “Top 11 Tips for Preventing Dangerous Drug Interactions” at the end of the chapter. Although there is much more information in the book, here are the headings:
- Take a list of all your medicines to your appointment.
- Find out how to take your medicine!
- Check about whether any foods or beverages should be avoided.
- Ask your doctor to check for interactions. Before you leave the office, verify that your physician has reviewed your entire list of drugs and dietary supplements to make sure there are no incompatible combinations.
If your doctor is using a computer or handheld device to submit your prescription electronically, ask if there are any drug interaction alerts that you should know about.
- Ask your pharmacist to check for interactions. Do not grab and go when you pick up your prescription.
- Inquire about over- the- counter drugs.
- Go to the Web to check on interactions yourself. The best resource we know of is MediGuard.org.
- Don’t take herbs or dietary supplements without checking for interactions.
- Beware drug-alcohol interactions.
- Inquire about drug-disease interactions. Some medications
can make certain conditions worse.
You will find far more information in the book. We also welcome your comments in the section below called “ADD MY THOUGHTS.” And please vote on this article at the top of the page.