Amlodipine + losartan

Oral
Mild to moderate hypertension
Adult: Per tablet contains amlodipine 5 mg and losartan potassium 50 mg: Initial: 1 tablet once daily; may increase to 2 tablets daily if the BP control is inadequate after 1-2 wk.

Known hypersensitivity. Avoid concomitant K supplements. Pregnancy.

Impaired hepatic or renal function, CHF, sick-sinus syndrome, severe ventricular dysfunction, hypertrophic cardiomyopathy. Elderly, children. Lactation. Volume-depleted patients; patients on diuretics and salt restriction; renal artery stenosis. Monitor serum K concentration.

Headache, dizziness, back pain, myalgia, resp tract disorders, asthenia/fatigue; first-dose hypotension; rash, cough, angioedema; neutropaenial GI disturbances; transient elevation of liver enzymes; taste disturbances and hyperkalaemia.
Potentially Fatal: Hypotension, bradycardia, conductive system delay, CCF.

Amlodipine: Increased metabolism with rifampin. Reduced hypotensive effect with calcium. Potentiates effects of thiazide diuretics and ACE inhibitors. Avoid combination with β-blockers in patients with markedly impaired left ventricular function.
Losartan: Concurrent use with NSAIDs may further worsen renal function. Cimetidine may increase the AUC of losartan by about 18%. Phenobarbital and other enzyme inducers may decrease levels of losartan and its active metabolite. Ketoconazole inhibits the conversion of losartan to its active metabolite. Concurrent use with potassium-sparing diuretics or potassium supplements or salt substitutes containing potassium may increase serum potassium levels. Reduces lithium excretion; monitor lithium levels if used together.
Potentially Fatal: Increased cyclosporine levels. Risk of lithium toxicity with losartan. Hypotensive effect of losartan potentiated by diuretics and other antihypertensives. Risk of hyperkalaemia increases with concomitant ACE inhibitors, potassium-sparing diuretics and K supplements.

Amlodipine inhibits the movement of Ca ions across the cell membrane into vascular smooth muscles and myocytes. Action is greater in the arterial resistant vessels causing peripheral vasodilatation and reduction in afterload. Losartan is an angiotensin II receptor (type AT₁) antagonists antihypertensive which acts by blocking the actions of angiotensin II of renin-angiotensin-aldosterone system. The drug and its active metabolite selectively block the vasoconstrictor and aldosterone secreting effects of angiotensin II by selectively antagonising the binding of angiotensin II to AT₁ receptors.
Absorption: Amlodipine: Plasma levels peak 6-12 hr after oral admin; absolute bioavailability is estimated to be 64-90%. Losartan: Well absorbed; undergoes substantial 1st pass metabolism by CYP450 enzymes; systemic bioavailability is about 33%; about 14% of an oral dose is converted to active metabolites.
Distribution: Amlodipine: 93% bound to plasma proteins. Losartan and its active metabolites: Highly bound to plasma proteins, mainly albumin.
Metabolism: Amlodipine: About 90% converted to inactive metabolites hepatically.
Excretion: Amlodipine: 10% of parent compound and 60% of the metabolites are removed in the urine; elimination from the plasma is biphasic with terminal half-life of about 30-50 hr. Losartan and its active metabolites: Biliary excretion; terminal half-life: About 2 hr (losartan) and 6-9 hr (metabolites).

Angiotensin II Antagonists / Calcium Antagonists

C08CA01 - amlodipine ; Belongs to the class of dihydropyridine derivative selective calcium-channel blockers with mainly vascular effects. Used in the treatment of cardiovascular diseases.
C09CA01 - losartan ; Belongs to the class of angiotensin II antagonists. Used in the treatment of cardiovascular disease.