Losartan

Products

Losartan is commercially available in the form of film-coated tablets (Cosaar, generics). It has been approved in many countries since 1994 and was the first agent in the sartan group. Losartan is also combined with the diuretic hydrochlorothiazide (Cosaar Plus, generic).

Structure and properties

Losartan (C₂₂H₂₃ClN₆O, M_r = 422.9 g/mol) is a biphenyl, imidazole, and tetrazole derivative. It is present in drugs as losartan potassium, a white crystalline powder that is soluble in water. Losartan is a prodrug and is enzymatically converted in the body by CYP2C9 and CYP3A4 to an active carboxylic acid metabolite by oxidation of the hydroxymethyl side chain. Losartan also binds to the receptor, but with a lower affinity.

Effects

Losartan (ATC C09CA01) has antihypertensive and renoprotective properties. The effects are due to selective abrogation of the physiologic effects of angiotensin II at the AT1 receptor. Angiotensin II is a peptide hormone directly involved in the development of hypertension. It has potent vasoconstrictor effects and increases aldosterone release, which in turn causes increased water and sodium retention.

Indications

Treatment of essential hypertension
Reduction of stroke risk in hypertensive patients with left ventricular hypertrophy.
Heart failure (combination therapy).
Diabetic nephropathy in hypertensive type II diabetic patients with an elevated serum creatinine and proteinuria.

Dosage

According to the professional information. The drug is administered once a day, regardless of meals.

Contraindications

Hypersensitivity
Severe hepatic insufficiency
Hereditary angioedema and previous angioedema on ACE inhibitors or sartans.
2nd and 3rd trimester of pregnancy.
Combination with aliskiren in patients with diabetes mellitus or impaired renal function.

Full details of precautions and interactions can be found in the drug label.

Adverse effects

The most common possible adverse effects include headache, dizziness, sleep disturbances, upper respiratory tract infections, indigestion, low blood pressure, palpable heartbeats, rapid pulse, back pain, muscle cramps, edema, and fatigue. Like other sartans and ACE inhibitors, losartan can cause hyperkalemia.