Repace A

Uses

Patients with mild to moderate hypertension (alone or in combination with other antihypertensives).

The treatment of chronic stable and vasospastic angina.

Raynaud\'s disease.

Losartan is an angiotensin II receptor blocker (ARB) used for:

• Treatment of hypertension, to lower blood pressure in adults and children greater than 6 years old. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions.
• Reduction of the risk of stroke in patients with hypertension and left ventricular hypertrophy. There is evidence that this benefit does not apply to Black patients.
• Treatment of diabetic nephropathy with an elevated serum creatinine and proteinuria in patients with type 2 diabetes and a history of hypertension.

Repace A is also used to associated treatment for these conditions: Anginal Pain, Cardiovascular Events, Chronic Stable Angina Pectoris, Coronary Artery Disease (CAD), High Blood Pressure (Hypertension), Homozygous Familial Hypercholesterolemia, Hypertension,Essential, Mixed Dyslipidemias, Primary Hypercholesterolemia, Vasospastic AnginaDiabetic Nephropathy, Heart Failure, High Blood Pressure (Hypertension), Marfan Syndrome, Stroke

How Repace A works

Mechanism of action on blood pressure

Amlodipine is considered a peripheral arterial vasodilator that exerts its action directly on vascular smooth muscle to lead to a reduction in peripheral vascular resistance, causing a decrease in blood pressure. Amlodipine is a dihydropyridine calcium antagonist (calcium ion antagonist or slow-channel blocker) that inhibits the influx of calcium ions into both vascular smooth muscle and cardiac muscle. Experimental studies imply that amlodipine binds to both dihydropyridine and nondihydropyridine binding sites, located on cell membranes. The contraction of cardiac muscle and vascular smooth muscle are dependent on the movement of extracellular calcium ions into these cells by specific ion channels. Amlodipine blocks calcium ion influx across cell membranes with selectivity. A stronger effect of amlodipine is exerted on vascular smooth muscle cells than on cardiac muscle cells . Direct actions of amlodipine on vascular smooth muscle result in reduced blood pressure .

Mechanism of action in angina

The exact mechanism by which amlodipine relieves the symptoms of angina have not been fully elucidated to this date, however, the mechanism of action is likely twofold:

Amlodipine has a dilating effect on peripheral arterioles, reducing the total peripheral resistance (afterload) against which the cardiac muscle functions. Since the heart rate remains stable during amlodipine administration, the reduced work of the heart reduces both myocardial energy use and oxygen requirements .

Dilatation of the main coronary arteries and coronary arterioles, both in healthy and ischemic areas, is another possible mechanism of amlodipine reduction of blood pressure. The dilatation causes an increase in myocardial oxygen delivery in patients experiencing coronary artery spasm (Prinzmetal's or variant angina) and reduces coronary vasoconstriction caused by smoking .

Losartan reversibly and competitively prevents angiotensin II binding to the AT₁ receptor in tissues like vascular smooth muscle and the adrenal gland. Losartan and its active metabolite bind the AT₁ receptor with 1000 times more affinity than they bind to the AT₂ receptor. The active metabolite of losartan is 10-40 times more potent by weight than unmetabolized losartan as an inhibitor of AT₁ and is a non-competitive inhibitor. Losartan's prevention of angiotensin II binding causes vascular smooth muscle relaxation, lowering blood pressure.

Angiotensin II would otherwise bind to the AT₁ receptor and induce vasoconstriction, raising blood pressure.

Dosage

Repace A dosage

For treatment of both hypertension and angina pectoris, the usual initial dose is 5 mg once daily. If the desired therapeutic effect cannot be achieved within 2-4 weeks, the dose may be increased to a maximum dose of 10 mg once daily. Amlodipine 10 mg once daily provides symptomatic improvement in patients with Raynaud's disease.

Use in children: Use of Amlodipine in children (under 12 years of age) is not recommended.

Hypertension:

• Usual adult dose: 50 mg once daily.
• Usual pediatric starting dose: 0.7 mg per kg once daily (up to 50 mg).

Hypertensive Patients with Left Ventricular Hypertrophy:

• Usual starting dose: 50 mg once daily.
• Add hydrochlorothiazide 12.5 mg and/or increase Losartan to 100 mg followed by an increase to hydrochlorothiazide 25 mg if further blood pressure response is needed.

Nephropathy in Type 2 Diabetic Patients:

• Usual dose: 50 mg once daily.
• Increase dose to 100 mg once daily if further blood pressure response is needed.

Use in elderly:

• Patients up to 75 years: No initial dosage adjustment is necessary for this group of patients.
• Patients over 75 years: A lower starting dose of 25 mg once daily is recommended.

Side Effects

Amlodipine is generally well tolerated. The most commonly observed side effects are headache, peripheral oedema, palpitations, flushing, dizziness, nausea, abdominal pain.

In controlled clinical trials in patients with essential hypertension, dizziness was the only side effect reported that occurred with an incidence greater than placebo in 1% or more of patients treated with Losartan. Rarely, rash was reported although the incidence in controlled clinical trials was less than placebo. Angioedema, involving swelling of the face, lips and/or tongue has been reported rarely in patients treated with Losartan. Serious hypotension (particularly on initiating treatment in salt-depleted patients) or renal failure (mainly in patients with renal artery stenosis) may be encountered during Losartan treatment.

Toxicity

Acute oral toxicity (LD50): 37 mg/kg (mouse) .

Overdose

An overdose of amlodipine could result in a high degree of peripheral vasodilatation with a possibility of reflex tachycardia. Significant and prolonged hypotension leading to shock and fatal outcomes have been reported .

Carcinogenesis, mutagenesis, impairment of fertility

Rats and mice treated with amlodipine maleate in the diet on a long-term basis for up to 2 years demonstrated no evidence of a carcinogenic effect of the drug. For the mouse, the highest dose was comparable to the maximum recommended human dose of 10 mg amlodipine per day. For the rat, the highest dose was measured to be about twice the maximum recommended human dose .

Mutagenicity studies using amlodipine maleate showed no drug-related gene or chromosomal effects .

There was no impact on the fertility of rats given oral amlodipine maleate (males for 64 days and females for 14 days before mating) at doses up to 10 mg amlodipine/kg/day (8 times the maximum recommended human dose) .

Use in pregnancy

The safety of amlodipine in human pregnancy or lactation has not been proven. Amlodipine is therefore considered a pregnancy category C drug . Use amlodipine only if the potential benefit justifies the potential risk .

Use in nursing

Discontinue when administering amlodipine .

The oral TDLO in mice is 1000mg/kg and in rats is 2000mg/kg. In humans the TDLO for men is 10mg/kg/2W and for women is 1mg/kg/1D.

Symptoms of overdose are likely to include hypotension, tachycardia, or bradycardia due to vagal stimulation. Supportive treatment should be instituted for symptomatic hypotension. Hemodialysis will not remove losartan or its active metabolite due to their high rates of protein binding.

Precaution

Hypotension: Since the vasodilUse in renal failure

Although Amlodipine is excreted primarily via kidney, mild renal impairment does not appear to have an effect on the plasma concentrations. Severe renal impairment may however require a dosage reduction. Amlodipine is not dialyzable.

Use in patients with impaired hepatic function

Amlodipine half-life is prolonged in patient with impaired hepatic function. Amlodipine should therefore be administered at lower (5mg) initial dose in these patients.

Use in heart failure

An increased number of pulmonary oedema has been reported.atation induced by Amlodipine is gradual in onset, acute hypotension has rarely been reported after oral administration of Amlodipine. Nonetheless, caution should be exercised when administering the drug with any other peripheral vasodilator particularly in patients with severe aortic stenosis.

Cardiac failure: Patients with heart failure should be treated with caution. Calcium channel blockers, including Amlodipine, should be usedwith caution in patients with congestive heart failure, as they may increase the risk of future cardiovascular events and mortality.

Beta blocker withdrawal: Amlodipine gives no protection against the danger of abrupt beta blocker withdrawal; any such withdrawal should be gradualreduction of the dose of beta blocker.

Hepatic failure: The half-life of amlodipine is prolonged and AUC values are higher in patients with impaired liver function. Amlodipine should therefore be initiated at the lower end of the dosing range and caution should be used, both on initial treatment and when increasing the dose. Slow dose titration and careful monitoring may be required in patients with severe hepatic impairment.

A lower dose should be considered for patients with a history of hepatic and renal impairment. Losartan should not be used with potassium-sparing diuretic

Interaction

Use of Amlodipine together with thiazide diuretics or angiotensin-converting-enzyme inhibitors in the treatment of hypertension is additive. There are no hazardous interaction of Amlodipine with Digoxin, Cimetidine, Warfarin and food.

No drug interaction of clinical significance has been identified. Compounds which have been studied in clinical pharmacokinetic trials include hydrochlorothiazide, digoxin, warfarin, cimetidine, ketoconazole and phenobarbital.

Volume of Distribution

21 L/kg , .

The volume of distribution of losartan is 34.4±17.9L and 10.3±1.1L for the active metabolite (E-3174).

Elimination Route

Amlodipine absorbed slowly and almost completely from the gastrointestinal tract. Peak plasma concentrations are achieved 6-12 hours after oral administration. The estimated bioavailability of amlodipine is 64-90%. Steady-state plasma amlodipine levels are achieved after 7-8 days of consecutive daily dosing. Absorption is not affected by food .

Losartan is approximately 33% orally bioavailable. Losartan has a T_max of 1 hour and the active metabolite has a T_max of 3-4 hours. Taking losartan with food decreases the C_max but does only results in a 10% decrease in the AUC of losartan and its active metabolite. A 50-80mg oral dose of losartan leads to a C_max of 200-250ng/mL.

Half Life

The terminal elimination half-life of about 30–50 hours .

Plasma elimination half-life is 56 hours in patients with impaired hepatic function, titrate slowly when administering this drug to patients with severe hepatic impairment .

The terminal elimination half life of losartan is 1.5-2.5 hours while the active metabolite has a half life of 6-9 hours.

Clearance

Total body clearance (CL) has been calculated as 7 ± 1.3 ml/min/kg (0.42 ± 0.078 L/ h/kg) in healthy volunteers , .

Elderly patients show a reduced clearance of amlodipine with an AUC (area under the curve) increase of about 40–60%, and a lower initial dose may be required .

Losartan has a total plasma clearance of 600mL/min and a renal clearance of 75mL/min. E-3174, the active metabolite, has a total plasma clearance of 50mL/min and a renal clearance of 25mL/min.

Elimination Route

Elimination from the plasma occurs in a biphasic with a terminal elimination half-life of about 30–50 hours. Steady-state plasma levels of amlodipine are reached after 7-8 days of consecutive daily dosing . Amlodipine is 10% excreted as unchanged drug in the urine. Amlodipine can be initiated at normal doses in patients diagnosed with renal failure , .

A single oral dose of losartan leads to 4% recovery in the urine as unchanged losartan, 6% in the urine as the active metabolite. Oral radiolabelled losartan is 35% recovered in urine and 60% in feces. Intravenous radiolabelled losartan is 45% recovered in urine and 50% in feces.

Pregnancy & Breastfeeding use

Pregnancy: Safety in pregnancy has not been established.

Lactation: It is not known whether Amlodipine is excreted in breast milk. It is advised to stop breastfeeding during treatment with Amlodipine.

Although there is no experience with the use of Losartan in pregnant women, animal studies with Losartan potassium have demonstrated fetal and neonatal injury and death, the mechanism of which is believed to be pharmacologically mediated through effects on the renin angiotensinaldosterone system. Losartan should not be used in pregnancy and if pregnancy is detected Losartan should be discontinued as soon as possible.

It is not known whether Losartan is excreted in human breast milk. However, significant level of Losartan found in rat milk which suggests that the drug should not be used in lactating mother.

Contraindication

Amlodipine is contraindicated in patients with-

• Hypersensitivity to amlodipine, dihydropyridine derivatives or any of the excipients
• Shock (including cardiogenic shock)
• Obstruction of the outflow-tract of the left ventricle (e.g. high grade aortic stenosis)
• Unstable angina
• Hemodynamically unstable heart failure after acute myocardial infarction (during the first 28 days)
• Severe hypotension

It is also contraindicated to patients who are hypersensitive to any component of this product. In patients who are intravenously volume depleted (e.g. those treated with high dose diuretics), symptomatic hypotension may occur. These conditions Losartan potassium should be corrected prior to administer Losartan or a lower starting dose (usually 25 mg) should be used.

Special Warning

Children with hypertension from 6 years to 17 years of age: 2.5 mg once daily as a starting dose, up-titrated to 5 mg once daily if blood pressure goal is not achieved after 4 weeks. Doses in excess of 5 mg daily have not been studied in pediatric patients.

Children under 6 years old: The effect of amlodipine on blood pressure in patients less than 6 years of age is not known.

Elderly: Amlodipine used at similar doses in elderly or younger patients is equally well tolerated. Normal dosage regimens are recommended in the elderly, but increase of the dosage should take place with care.

Renal impairment: Changes in amlodipine plasma concentrations are not correlated with degree of renal impairment, therefore the normal dosage is recommended. Amlodipine is not dialysable.

Hepatic impairment: Dosage recommendations have not been established in patients with mild to moderate hepatic impairment; therefore dose selection should be cautions and should start at the lower end of the dosing range. The pharmacokinetics of Amlodipine have not been studied in severe hepatic impairment. Amlodipine should be initiated at the lowest dose (2.5 mg once daily) and titrated slowly in patients with severe hepatic impairment.

No initial dosage adjustment is necessary in patients with mild renal impairment (CrCl 20-50 ml/min). For patients with moderate to severe renal impairment (CrCl <20 ml/min) or patients on dialysis, a lower starting dose of 25 mg is recommended.

Acute Overdose

There is no well documented experience with Amlodipine overdosage. In case of clinically significant hypotension due to Amlodipine over dosage, calls for active cardiovascular support including monitoring of cardiac and respiratory function, elevation of extremities and attention to circulating fluid volume and urine output. Since Amlodipine is highly protein-bound, dialysis is unlikely to be of benefit.

Limited data are available regarding overdose in humans. The most likely manifestation of overdose would be hypotension and tachycardia; bradycardia could occur from parasympathetic (vagal) stimulation. Supportive treatment should include repletion of the intravascular volume. Neither Losartan nor the active metabolite can be removed by hemodialysis.

Storage Condition

Keep out of the reach of children. Store below 30° C. Keep in the original package in a cool & dry place in order to protect from light and moisture.

Store between 15-30°C

Innovators Monograph

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