Triplixam Mechanism of Action

Pharmacology: Pharmacodynamics: Perindopril arginine + Indapamide + Amlodipine (TRIPLIXAM) is a combination of three antihypertensive components with complementary mechanisms to control blood pressure in patient with hypertension. Perindopril arginine salt is an angiotensin converting enzyme inhibitor, indapamide, a chlorosulphamoyl diuretic and amlodipine, a calcium ion flux inhibitor of the dihydropyridine group.
The pharmacological properties of Perindopril arginine + Indapamide + Amlodipine (TRIPLIXAM) are derived from those of each of the components taken separately. In addition, the combination of perindopril/indapamide produces an additive synergy of the antihypertensive effects of the two components.
Mechanism of action: Perindopril: Perindopril is an inhibitor of the angiotensin converting enzyme (ACE inhibitor) which converts angiotensin I to angiotensin II, a vasoconstricting substance; in addition the enzyme stimulates the secretion of aldosterone by the adrenal cortex and stimulates the degradation of bradykinin, a vasodilatory substance, into inactive heptapeptides.
This results in: a reduction in aldosterone secretion; an increase in plasma renin activity, since aldosterone no longer exercises negative feedback; a reduction in total peripheral resistance with a preferential action on the vascular bed in muscle and the kidney, with no accompanying salt and water retention or reflex tachycardia, with chronic treatment.
The antihypertensive action of perindopril also occurs in patients with low or normal renin concentrations.
Perindopril acts through its active metabolite, perindoprilat. The other metabolites are inactive.
Perindopril reduces the work of the heart: by a vasodilatory effect on veins, probably caused by changes in the metabolism of prostaglandins: reduction in pre-load; by reduction of the total peripheral resistance: reduction in afterload.
Studies carried out on patients with cardiac insufficiency have shown: a reduction in left and right ventricular filling pressures; a reduction in total peripheral vascular resistance; an increase in cardiac output and an improvement in the cardiac index; an increase in regional blood flow in muscle.
Exercise test results also showed improvement.
Indapamide: Indapamide is a sulfonamide derivative with an indole ring, pharmacologically related to the thiazide group of diuretics. Indapamide inhibits the reabsorption of sodium in the cortical dilution segment. It increases the urinary excretion of sodium and chlorides and, to a lesser extent, the excretion of potassium and magnesium, thereby increasing urine output and having an antihypertensive action.
Amlodipine: Amlodipine is a calcium ion influx inhibitor of the dihydropyridine group (slow channel blocker or calcium ion antagonist) and inhibits the transmembrane influx of calcium ions into cardiac and vascular smooth muscle.
Pharmacodynamic effects: Perindopril/indapamide: In hypertensive patients regardless of age, the perindopril/indapamide combination exerts a dose-dependent antihypertensive effect on diastolic and systolic arterial pressure whilst supine or standing. During clinical trials, the concomitant administration of perindopril and indapamide produced antihypertensive effects of a synergic nature in relation to each of the products administered alone.
Perindopril: Perindopril is active in all grades of hypertension: mild to moderate or severe. A reduction in systolic and diastolic arterial pressure is observed in the lying and standing position.
The antihypertensive activity after a single dose is maximal at between 4 and 6 hours and is maintained over 24 hours.
There is a high degree of residual blocking of angiotensin converting enzyme at 24 hours, approximately 80%.
In patients who respond, normalised blood pressure is reached after one month and is maintained without tachyphylaxis.
Withdrawal of treatment has no rebound effect on hypertension.
Perindopril has vasodilatory properties and restores elasticity of the main arterial trunks, corrects histomorphometric changes in resistance arteries and produces a reduction in left ventricular hypertrophy.
If necessary, the addition of a thiazide diuretic leads to an additive synergy.
The combination of an angiotensin converting enzyme inhibitor with a thiazide diuretic decreases the hypokalemia risk associated with the diuretic alone.
Indapamide: Indapamide, as monotherapy, has an antihypertensive effect which lasts for 24 hours. This effect occurs at doses at which the diuretic properties are minimal.
Its antihypertensive action is proportional to an improvement in arterial compliance and a reduction in total and arteriolar peripheral vascular resistance.
Indapamide reduces left ventricular hypertrophy.
When a dose of thiazide diuretic and thiazide-related diuretics is exceeded, the antihypertensive effect reaches a plateau, whereas the adverse effects continue to increase. If the treatment is ineffective, the dose should not be increased.
Furthermore, it has been shown that in the short-term, mid-term and long-term in hypertensive patients, indapamide: has no effect on lipid metabolism: triglycerides, LDL-cholesterol and HDL-cholesterol; has no effect on carbohydrate metabolism, even in diabetic hypertensive patients.
Amlodipine: The mechanism of the antihypertensive action of amlodipine is due to a direct relaxant effect on vascular smooth muscle. The precise mechanism by which amlodipine relieves angina has not been fully determined but amlodipine reduces total ischemic burden by the following two actions: Amlodipine dilates peripheral arterioles and thus, reduces the total peripheral resistance (afterload) against which the heart works. Since the heart rate remains stable, this unloading of the heart reduces myocardial energy consumption and oxygen requirements.
The mechanism of action of amlodipine also probably involves dilatation of the main coronary arteries and coronary arterioles, both in normal and ischemic regions. This dilatation increases myocardial oxygen delivery in patients with coronary artery spasm (Prinzmetal's or variant angina).
In patients with hypertension, once daily dosing provides clinically significant reductions of blood pressure in both the supine and standing positions throughout the 24-hour interval. Due to the slow onset of action, acute hypotension is not a feature of amlodipine administration.
Amlodipine has not been associated with any adverse metabolic effects or changes in plasma lipids and is suitable for use in patients with asthma, diabetes, and gout.
Pharmacokinetics: Perindopril arginine + Indapamide + Amlodipine (TRIPLIXAM): The co-administration of perindopril/indapamide and amlodipine does not change their pharmacokinetic properties by comparison to separate administration.
Perindopril: Absorption and bioavailability: After oral administration, the absorption of perindopril is rapid and the peak concentration is achieved within 1 hour (perindopril is a prodrug and perindoprilat the active metabolite). The plasma half-life of perindopril is equal to 1 hour. As ingestion of food decreases conversion to perindoprilat, hence bioavailability, perindopril arginine should be administered orally in a single daily dose in the morning before a meal.
Distribution: The volume of distribution is approximately 0.2 L/kg for unbound perindoprilat. Protein binding of perindoprilat to plasma proteins is 20%, principally to angiotensin converting enzyme, but is concentration-dependent.
Biotransformation: Perindopril is a prodrug. Twenty-seven percent of the administered perindopril dose reaches the bloodstream as the active metabolite perindoprilat. In addition to active perindoprilat, perindopril yields five metabolites, all inactive. The peak plasma concentration of perindoprilat is achieved within 3 to 4 hours.
Elimination: Perindoprilat is eliminated in the urine and the terminal half-life of the unbound fraction is approximately 17 hours, resulting in steady-state within 4 days.
Linearity/non-linearity: It has been demonstrated a linear relationship between the dose of perindopril and its plasma exposure.
Special Populations: Elderly: Elimination of perindoprilat is decreased in the elderly, and also in patients with heart or renal failure.
Renal impairment: Dosage adjustment in renal insufficiency is desirable depending on the degree of impairment (creatinine clearance).
In case of dialysis: clearance of perindoprilat is equal to 70 mL/min.
In patients with cirrhosis: Perindopril pharmacokinetics is modified; hepatic clearance of the parent molecule is reduced by half. However, the quantity of perindoprilat formed is not reduced and therefore no dosage adjustment is required.
Indapamide: Absorption: Indapamide is rapidly and completely absorbed from the digestive tract.
The peak plasma level is reached in humans approximately one hour after oral administration of the product.
Distribution: Plasma protein binding is 79%.
Metabolism and Elimination: The elimination half-life is between 14 and 24 hours (average 18 hours). Repeated administration does not produce accumulation.
Elimination is mainly in the urine (70% of the dose) and feces (22%) in the form of inactive metabolites.
Special populations: The pharmacokinetics is unchanged in patients with renal insufficiency.
Amlodipine: Absorption and Bioavailability: After oral administration of therapeutic doses, amlodipine is well absorbed with peak blood levels between 6-12 hours post dose. Absolute bioavailability has been estimated to be between 64 and 80%.
The bioavailability of amlodipine is not affected by food intake.
Distribution: The volume of distribution is approximately 21 L/kg. In vitro studies have shown that approximately 97.5% of circulating amlodipine is bound to plasma proteins.
Metabolism: Amlodipine is extensively metabolised by the liver to inactive metabolites with 10% of the parent compound and 60% of metabolites excreted in the urine.
Elimination: The terminal plasma elimination half-life is about 35-50 hours and is consistent with once daily dosing.
Special populations: Use in the elderly: the time to reach peak plasma concentrations of amlodipine is similar in elderly and younger subjects. Amlodipine clearance tends to be decreased with resulting increases in AUC and elimination half-life in elderly patients. Increases in AUC and elimination half-life in patients with congestive heart failure were as expected for the patient age group studied.
Use in patients with impaired hepatic function: Very limited clinical data are available regarding amlodipine administration in patients with hepatic impairment. Patients with hepatic insufficiency have decreased clearance of amlodipine resulting in a longer half-life and an increase in AUC of approximately 40-60%.