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.

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

Olmesartan medoxomil (Benicar - Sankyo), a substituted imidazole, is the seventh oral angiotensin II receptor blocker (ARB) approved by the FDA for treatment of hypertension.

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.

The FDA has approved a fixed-dose combination of the angiotensin receptor blocker (ARB) azilsartan and the thiazide-like diuretic chlorthalidone as Edarbyclor (Takeda) for treatment of hypertension

Aliskiren (Tekturna - Novartis), the first direct renin inhibitor for treatment of hypertension, has been approved for use in a fixed-dose combination with the diuretic hydrochlorothiazide (Tekturna HCT - Novartis). Many angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) are also available in fixed-dose combinations with hydrochlorothiazide (HCTZ).

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.

Aliskiren (ah LIS ker in; Tekturna - Novartis), the first direct renin inhibitor, has been approved by the FDA for treatment of hypertension. It is indicated for oral use either as monotherapy or in combination with other antihypertensive agents.

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.