Comparison between various commonly used angiotensin receptor blockers.👀

Angiotensin receptor blockers (ARBs) are commonly used blood pressure
lowering drugs. The more common among them are allisartan, azilsartan, candesartan, irbesartan, losartan, olmesartan, telmisartan, valsartan. What is the difference between them and what is their usage?

Indications.

There are five commonly used antihypertensive drugs: angiotensin-converting enzyme inhibitor (ACEI), angiotensin receptor blocker (ARB), β-blocker, calcium channel blocker (CCB) and diuretics. Although they have the effect of lowering blood pressure, they are used differently in different situations. Depending on the patient's physical condition, risk factors, and comorbidities, there will be different priorities for the selection of antihypertensive drugs.

1. For hypertensive patients with diabetes or chronic kidney disease: ACEI or ARB is the first choice drug. If patients need combination therapy, they should also be based on ACEI or ARB.
2. For patients with hypertension and myocardial infarction: patients should use ACEI or ARB combined with β-blocker.
3. For hypertensive patients with dyslipidemia or atrial fibrillation prophylaxis: ACEI or ARB is the first choice drug.
4. For patients with hypertension and heart failure: ACEI is the first drug of choice. If patients are intolerant to ACEI, ARB can be used instead. Both ACEIs and ARBs can reduce the risk of hospitalization and mortality in patients with Heart Failure with Reduced Ejection Fraction (HFrEF). They can improve the patient's exercise capacity and related symptoms. Unless patients are intolerant to or have contraindications to ACEIs, patients are recommended to use ACEIs first. For patients who cannot use ACEIs, it recommends the use of ARBs with clear evidence of benefit in HFrEF, such as candesartan, losartan, and valsartan. For patients who can tolerate ACEIs or ARBs, it recommends sacubitril/valsartan tablets instead of them. It can further reduce morbidity and mortality in patients with heart failure.

A common adverse reaction of ACEI is cough. If the patient cannot tolerate it, ARB can be used instead.

Among various ARB antihypertensive drugs, losartan is the only one that has the effect of lowering blood pressure and also lowering uric acid. Therefore, it reduces gout attacks.

Dosage.

Allisartan: Its recommended dosage is 240 mg once daily. Food can significantly reduce its absorption. Its bioavailability is reduced by 35.5%. Therefore, it is not recommended to be taken with food and should be taken on an empty stomach.

Azilsartan: Its recommended dosage is 20 to 40 mg once daily. Food does not have a significant effect on its absorption. Therefore, it can be taken with or without food.

Candesartan: Its recommended dosage is 4 to 12 mg once daily. It can be taken with or without food.

Irbesartan: Its recommended dosage is 150 to 300 mg once daily. It can be taken with or without food.

Losartan: Its recommended dosage is 50 to 100 mg once daily. It can be taken with or without food.

Olmesartan: Its recommended dosage is 20 to 40 mg once daily. It can be taken with or without food.

Telmisartan: Its recommended dosage is 40 to 80 mg once daily. Food will slightly reduce its absorption. However, it can be taken with or without food.

Valsartan: Its recommended dosage is 80 to 160 mg once daily. Food reduces its absorption by 48%. However, when it was taken with or without food, there was no significant change in its blood levels after 8 hours. Therefore, it can also be taken with or without food, but it is recommended to take it at the same time each day.

Pharmacokinetics.

Allisartan and losartan are metabolized to the active product EXP-3174 by gastrointestinal esterases and hepatic CYP2C9, respectively. The half-life of EXP-3174 is approximately 10 hours. EXP-3174 has a stronger affinity for angiotensin receptors than they do. However, some studies indicate that only a small amount of losartan can be converted into the active metabolite in a small number of people. The efficacy of losartan may be reduced in these people.

Telmisartan has the longest half-life of these drugs. Its half-life is more than 20 hours. Therefore, an occasional missed dose of telmisartan has little effect on blood pressure.

Affinity to angiotensin receptors:

• Candesartan = Olmesartan > Irbesartan > Telmisartan = Valsartan = EXP-3174 > Losartan

In addition, studies have shown that the maximum dose of azilsartan has a stronger blood pressure lowering ability than the maximum dose of olmesartan and valsartan.

Interaction.

Same points:

1. NSAIDs: In combination with NSAIDs such as etoricoxib and ibuprofen, the antihypertensive ability of ARBs decreases and increases the risk of renal impairment.
2. Diuretics: It may cause severe hypotension in combination with diuretics. If the patient is already taking a diuretic, the ARB should be started at a low dose. In addition, ARBs reduce the secretion of aldosterone. It has the side effect of causing hyperkalemia. Therefore, patients' potassium levels need to be closely monitored when co-administered with potassium-sparing diuretics such as spironolactone.
3. Lithium: The plasma concentration of lithium is increased by ARBs. It may cause lithium poisoning. They should be avoided in combination.

Difference points:

1. Losartan: Although the clinical significance is unclear, studies have shown that fluconazole and rifampicin reduce the metabolism of losartan. They may reduce the blood pressure-lowering effects of losartan. Be careful when using them together.
2. Telmisartan: Since telmisartan will increase the steady state minimal concentration of digoxin by about 20%, the plasma concentration of digoxin should be monitored when it is co-administered with digoxin.