Irbesartan (Avapro - Sanofi/Bristol-Myers Squibb) is the third angiotensin II receptor antagonist to become available in the USA for oral treatment of hypertension. Losartan (Cozaar) and valsartan (Diovan) were marketed earlier. Eprosartan (Teveten - SmithKline Beecham) has been approved by the FDA but not marketed.

The angiotensin receptor blocker (ARB) azilsartan medoxomil (Edarbi – Takeda) was recently approved by the FDA for oral treatment of hypertension, either alone or combined with other drugs. It is the eighth ARB approved for this indication.

Valsartan (Diovan - Novartis), a non-peptide tetrazole, is the second angiotensin II receptor antagonist approved for oral treatment of hypertension by the US Food and Drug Administration. The first was losartan (Cozaar - Medical Letter, 37:57, 1995).

Losartan potassium (Cozaar - Merck), the first angiotensin II receptor antagonist, has been approved for oral treatment of hypertension by the US Food and Drug Administration. It will be marketed both alone and in a fixed-dose combination with the diuretic hydrochlorothiazide (Hyzaar).

Candesartan cilexetil (Atacand - Astra) is the fourth angiotensin II receptor antagonist to become available in the USA for oral treatment of hypertension.

Eplerenone (e pler' en one; Inspra - Pharmacia), an aldosterone receptor antagonist similar to spironolactone (Aldactone, and others), has been approved by the FDA, but not yet marketed, for treatment of hypertension. It has also been tried for treatment of heart failure.

Perindopril, the tenth angiotensin converting enzyme (ACE) inhibitor to be marketed in the USA, and telmisartan and eprosartan, the fifth and sixth angiotensin receptor blockers, have recently become available for treatment of hypertension.

Angiotensin receptor blockers (ARBs) are widely used as an alternative to angiotensin converting enzyme (ACE) inhibitors for treatment of hypertension because they lower blood pressure without inducing a cough. It has not been established that they provide the same cardiac benefits as ACE inhibitors. Recently, an editorial in the British Medical Journal suggested that ARBs may increase the risk of myocardial infarction.

Changes caused by one drug in the absorption, distribution, metabolism or excretion of another may lead to a pharmacokinetic adverse drug interaction (DN Juurlink et al, JAMA 2003; 289:1652). Additive drug interactions, such as vasodilation caused by both sildenafil (Viagra) and nitrates, can also have adverse effects.

The FDA has approved Entresto (Novartis), an oral fixed-dose combination of the neprilysin inhibitor sacubitril and the angiotensin receptor blocker (ARB) valsartan, to reduce the risk of cardiovascular death and heart failure hospitalization in patients with heart failure with reduced ejection fraction. Sacubitril is the first neprilysin inhibitor to become available in the US.