Short answer: Labels generally advise against it. The telmisartan label says combining an ARB with an ACE inhibitor or aliskiren raises the risk of low blood pressure, high potassium and kidney problems. In the ONTARGET trial, telmisartan plus ramipril gave no more benefit than either alone but more kidney problems. A trial in diabetic kidney disease was stopped early for safety.
ARBs (angiotensin receptor blockers, such as telmisartan or losartan) and ACE inhibitors (such as ramipril or lisinopril) both act on the renin-angiotensin system. The telmisartan label calls taking two of these together dual blockade (section 5.6). It says dual blockade is linked to more low blood pressure, high potassium and kidney changes, including acute kidney failure, than one medicine alone.
The label says most people get no added benefit from two such medicines, and that combining them is generally avoided. Blood pressure, kidney function and electrolytes are monitored closely in anyone on telmisartan with another medicine of this kind. Aliskiren is not given with telmisartan in people with diabetes (section 4), and is avoided when GFR is under 60.
ONTARGET randomized 25,620 people aged 55 or older with vascular disease or high-risk diabetes to ramipril 10 mg, telmisartan 80 mg, or both, for a median of 56 months.
| Outcome | Ramipril | Telmisartan | Both |
|---|---|---|---|
| Heart death, heart attack, stroke or heart failure hospital stay | 16.5% | 16.7% | 16.3% |
| Symptoms of low blood pressure | 1.7% | 2.6% | 4.8% |
| Fainting | 0.2% | 0.2% | 0.3% |
| Kidney dysfunction | 10.2% | Not given in the abstract | 13.5% |
| Cough | 4.2% | 1.1% | Not given in the abstract |
The authors concluded that the combination brought more side effects without more benefit. Telmisartan alone was equivalent to ramipril, with less angioedema.
VA NEPHRON-D (Fried 2013) gave losartan 100 mg to 1,448 people with type 2 diabetes and kidney disease with high urine albumin, then added lisinopril or placebo. It was stopped early because of safety concerns after a median of 2.2 years.
There was no benefit in deaths or heart events. See eGFR for how kidney function is measured.
The telmisartan label also says NSAID pain relievers can worsen kidney function in some people and blunt the blood pressure effect (section 7). For potassium with other medicines, see potassium and spironolactone. People seeing more than one prescriber can bring a full medicine list so overlaps show up. Dose Track keeps every medicine in one list with its dose.
Read more on Dose Track: Telmisartan side effects · Telmisartan · eGFR · Blood pressure