Telmisartan
A long-acting angiotensin receptor blocker used for high blood pressure and to cut cardiovascular risk when ACE inhibitors can't be taken.
Drug card
- How it works
- Blocking angiotensin II's AT1 receptor, so vessels relax
- Used for
- High blood pressure
- Lowering cardiovascular risk if ACE inhibitors can't be used
- Known for
- High potassium (hyperkalemia)
- Harm to the unborn baby (fetal toxicity)
- Its name
- -sartan means an angiotensin II receptor blocker (ARB)
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does telmisartan work?
Telmisartan blocks the AT1 receptor and has a long half-life of about 24 hours. It bypasses the cytochrome P450 enzymes: a small share is conjugated to an inactive glucuronide, and over 97% of a dose leaves unchanged in bile and feces, so liver or bile duct disease slows its clearance.
Like other angiotensin receptor blockers: They block the AT1 receptor, so angiotensin II can no longer narrow arterioles or drive aldosterone release: vessels relax, the kidneys keep less sodium, and potassium can rise. They act at the receptor rather than on ACE, so bradykinin does not build up and cough is far rarer than with ACE inhibitors, though angioedema can still occur.
Uses
What is telmisartan used for?
- High blood pressure
- Lowering cardiovascular risk if ACE inhibitors can't be used
Side effects
Side effects of telmisartan
- High potassium (hyperkalemia)Known forSerious
- Harm to the unborn baby (fetal toxicity)Known forSerious
- Back pain
- Diarrhea
- Dizziness
- Low blood pressure, including on standing
- Kidney injury, more so if combined with ramiprilSerious
- Angioedema (rare, sometimes fatal)Serious
- Abnormal liver functionSerious
- Muscle breakdown (rhabdomyolysis), rareSerious
- Low blood sugar in people with diabetes
- Low sodium (hyponatremia)
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Liver disease or blocked bile ducts: clearance falls, so it is started low.
- Do not combine with ramipril or another ACE inhibitor: more kidney injury, hypotension and hyperkalemia, with no added benefit.
- It raises digoxin levels, so digoxin is monitored.
- It raises lithium levels and can cause lithium toxicity.
Good to know: Cleared almost entirely through the bile rather than the kidneys, with the long half-life of about 24 hours.
Remember it
A way to remember it
Block the lock, not the key-maker.
ACE inhibitors stop the enzyme that makes angiotensin II (the key); ARBs leave that enzyme alone and block the AT1 receptor (the lock). Bradykinin is not built up, so the ACE inhibitor cough is rare, and ARBs are the usual swap when that cough stops an ACE inhibitor.
Written for biofideX
Its name
-sartan means angiotensin II receptor blocker (ARB)
Sartans block the AT1 receptor for angiotensin II. Valsartan is also half of sacubitril/valsartan, which adds a neprilysin inhibitor.
- Every drug name stem
Its class
Angiotensin receptor blockers
Other angiotensin receptor blockers with a card:
Easily mixed up with ACE inhibitors and angiotensin receptor-neprilysin inhibitors.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Blood pressure
Telmisartan is one of 27 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
Start Practicing