Edarbyclor (Page 4 of 7)

8.6 Renal Impairment

Edarbyclor

Safety and effectiveness of Edarbyclor in patients with severe renal impairment (eGFR <30 mL/min/1.73 m2) have not been established. No dose adjustment is required in patients with mild (eGFR 60-90 mL/min/1.73 m2) or moderate (eGFR 30-60 mL/min/1.73 m2) renal impairment.

Chlorthalidone

Chlorthalidone may precipitate azotemia.

8.7 Hepatic Impairment

Azilsartan medoxomil

No dose adjustment is necessary for subjects with mild or moderate hepatic impairment. Azilsartan medoxomil has not been studied in patients with severe hepatic impairment [see Clinical Pharmacology (12.3)].

Chlorthalidone

Minor alterations of fluid and electrolyte balance may precipitate hepatic coma in patients with impaired hepatic function or progressive liver disease.

10 OVERDOSAGE

Limited data are available related to overdosage in humans.

Azilsartan medoxomil

Limited data are available related to overdosage in humans. During controlled clinical trials in healthy subjects, once daily doses up to 320 mg of azilsartan medoxomil were administered for 7 days and were well tolerated. In the event of an overdose, supportive therapy should be instituted as dictated by the patient’s clinical status. Azilsartan is not dialyzable.

Chlorthalidone

Symptoms of acute overdosage include nausea, weakness, dizziness, and disturbances of electrolyte balance. The oral LD50 of the drug in the mouse and the rat is more than 25,000 mg/kg body weight. The minimum lethal dose (MLD) in humans has not been established. There is no specific antidote, but gastric lavage is recommended, followed by supportive treatment. Where necessary, this may include intravenous dextrose-saline with potassium, administered with caution.

11 DESCRIPTION

Edarbyclor is a combination of azilsartan medoxomil (angiotensin II receptor blocker; as its potassium salt) and chlorthalidone (thiazide-like diuretic).

Azilsartan medoxomil, a prodrug, is hydrolyzed to azilsartan in the gastrointestinal tract during absorption. Azilsartan is an angiotensin II receptor blocker. Chlorthalidone is a monosulfamyl thiazide-like diuretic that differs chemically from thiazide diuretics by the lack of a benzothiadiazine structure.

The potassium salt of azilsartan medoxomil, azilsartan kamedoxomil, is chemically described as (5-Methyl-2-oxo-1,3-dioxol-4-yl)methyl 2-ethoxy-1-{[2'-(5-oxo-4,5-dihydro-1,2,4-oxadiazol-3-yl)biphenyl-4-yl]methyl}-1H -benzimidazole-7-carboxylate monopotassium salt. Its empirical formula is C30 H23 KN4 O8.

Chlorthalidone is chemically described as 2-chloro-5(1-hydroxy-3-oxo-1- isoindolinyl) benzenesulfonamide. Its empirical formula is C14 H11 ClN2 O4 S.

The structural formula for azilsartan medoxomil is

Chemical Structure
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The structural formula for chlorthalidone is

Chemical Structure
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Azilsartan kamedoxomil is a white to nearly white powder with a molecular weight of 606.62. It is practically insoluble in water and freely soluble in methanol.

Chlorthalidone is a white to yellowish white powder with a molecular weight of 338.76. Chlorthalidone is practically insoluble in water, in ether, and in chloroform; soluble in methanol; slightly soluble in ethanol.

Edarbyclor is available for oral use as tablets. The tablets have a characteristic odor. Each Edarbyclor tablet contains 42.68 mg of azilsartan kamedoxomil, which is equivalent to containing azilsartan medoxomil 40 mg plus 12.5 or 25 mg of chlorthalidone. Each tablet of Edarbyclor also contains the following inactive ingredients: mannitol, microcrystalline cellulose, fumaric acid, sodium hydroxide, hydroxypropyl cellulose, crospovidone, magnesium stearate, hypromellose 2910, talc, titanium dioxide, ferric oxide red, polyethylene glycol 8000, and printing ink gray F1.

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action

The active ingredients of Edarbyclor target two separate mechanisms involved in blood pressure regulation.

Azilsartan medoxomil

Angiotensin II is formed from angiotensin I in a reaction catalyzed by angiotensin-converting enzymes (ACE, kinase II). Angiotensin II is the principle pressor agent of the renin-angiotensin system, with effects that include vasoconstriction, stimulation of synthesis and release of aldosterone, cardiac stimulation, and renal reabsorption of sodium. Azilsartan medoxomil is an orally administered prodrug that is rapidly converted by esterases during absorption to the active moiety, azilsartan. Azilsartan blocks the vasoconstrictor and aldosterone-secreting effects of angiotensin II by selectively blocking the binding of angiotensin II to the AT1 receptor in many tissues, such as vascular smooth muscle and the adrenal gland. Its action is, therefore, independent of the pathway for angiotensin II synthesis.

An AT2 receptor is also found in many tissues, but this receptor is not known to be associated with cardiovascular homeostasis. Azilsartan has more than a 10,000-fold greater affinity for the AT1 receptor than for the AT2 receptor.

Blockade of the renin-angiotensin system with ACE inhibitors, which inhibit the biosynthesis of angiotensin II from angiotensin I, is widely used in the treatment of hypertension. ACE inhibitors also inhibit the degradation of bradykinin, a reaction catalyzed by ACE. Because azilsartan does not inhibit ACE (kinase II), it should not affect bradykinin levels. Whether this difference has clinical relevance is not yet known. Azilsartan does not bind to or block other receptors or ion channels known to be important in cardiovascular regulation.

Blockade of the angiotensin II receptor inhibits the negative regulatory feedback of angiotensin II on renin secretion, but the resulting increased plasma renin activity and angiotensin II circulating levels do not overcome the effect of azilsartan on blood pressure.

Chlorthalidone

Chlorthalidone produces diuresis with increased excretion of sodium and chloride. The site of action appears to be the distal renal tubule (early convoluted part), inhibiting NaCl reabsorption (by antagonizing the Na+-Cl-cotransporter) and promoting Ca++ reabsorption (by an unknown mechanism). The enhanced delivery of Na+ and water to the cortical collecting tubule and/or the increased flow rate leads to increased secretion and elimination of K+ and H+. The diuretic effects of chlorthalildone lead to decreased extracellular fluid volume, plasma volume, cardiac output, total exchangeable sodium, glomerular filtration rate, and renal plasma flow. Although the mechanism of action of chlorthalidone and related drugs is not wholly clear, sodium and water depletion appear to provide a basis for its antihypertensive effect.

12.2 Pharmacodynamics

Edarbyclor

Edarbyclor tablets have been shown to be effective in lowering blood pressure. Both azilsartan medoxomil and chlorthalidone lower blood pressure by reducing peripheral resistance but through complementary mechanisms.

Azilsartan medoxomil

Azilsartan inhibits the pressor effects of an angiotensin II infusion in a dose-related manner. An azilsartan single dose equivalent to 32 mg azilsartan medoxomil inhibited the maximal pressor effect by approximately 90% at peak, and approximately 60% at 24 hours. Plasma angiotensin I and II concentrations and plasma renin activity increased while plasma aldosterone concentrations decreased after single and repeated administration of azilsartan medoxomil to healthy subjects; no clinically significant effects on serum potassium or sodium were observed.

Chlorthalidone

The diuretic effect of chlorthalidone occurs in approximately 2.6 hours and continues for up to 72 hours.

12.3 Pharmacokinetics

Edarbyclor

Following oral administration of Edarbyclor, peak plasma concentrations of azilsartan and chlorthalidone are reached at 3 and 1 hours, respectively. The rate (Cmax and Tmax ) and extent (AUC) of absorption of azilsartan are similar when it is administered alone or with chlorthalidone. The extent (AUC) of absorption of chlorthalidone is similar when it is administered alone or with azilsartan medoxomil; however, the Cmax of chlorthalidone from Edarbyclor was 45-47% higher.

There is no clinically significant effect of food on the bioavailability of azilsartan or chlorthalidone following administration of Edarbyclor.

Azilsartan medoxomil

Absorption: Azilsartan medoxomil is an orally administered prodrug that is rapidly converted by esterases during absorption to the active moiety, azilsartan. Azilsartan medoxomil is not detected in plasma after oral administration. Dose proportionality in exposure was established for azilsartan in the azilsartan medoxomil dose range of 20 mg to 320 mg after single or multiple dosing.

The estimated absolute bioavailability of azilsartan following administration of azilsartan medoxomil is approximately 60%. After oral administration of azilsartan medoxomil, peak plasma concentrations (Cmax ) of azilsartan are reached within 1.5 to 3 hours. Food does not affect the bioavailability of azilsartan.

Distribution

Azilsartan medoxomil: The volume of distribution of azilsartan is approximately 16L. Azilsartan is highly bound to human plasma proteins (>99%), mainly serum albumin. Protein binding is constant at azilsartan plasma concentrations well above the range achieved with recommended doses.

In rats, minimal azilsartan-associated radioactivity crossed the blood-brain barrier. Azilsartan passed across the placental barrier in pregnant rats and was distributed to the fetus.

Chlorthalidone: In whole blood, chlorthalidone is predominantly bound to erythrocyte carbonic anhydrase. In the plasma, approximately 75% of chlorthalidone is bound to plasma proteins, 58% of the drug being bound to albumin. Chlorthalidone crosses the placental barrier and passes into breast milk. When mothers were treated before and after birth with 50 mg chlorthalidone daily, chlorthalidone levels in fetal whole blood were around 15% of those found in maternal blood. Chlorthalidone concentrations in amniotic fluid and breast milk are approximately 4% of those found in maternal blood.

Metabolism and Elimination

Azilsartan medoxomil: Azilsartan medoxomil, when administered alone or in combination with chlorthalidone is eliminated from plasma with an elimination half-life of 11-13 hours. Azilsartan is metabolized to two primary metabolites. The major metabolite in plasma is formed by O -dealkylation, referred to as metabolite M-II, and the minor metabolite is formed by decarboxylation, referred to as metabolite M-I. Systemic exposures to the major and minor metabolites in humans were approximately 50% and less than 1% of azilsartan, respectively. M-I and M-II do not contribute to the pharmacologic activity of azilsartan medoxomil. The major enzyme responsible for azilsartan metabolism is CYP2C9.

Following an oral dose of 14 C-labeled azilsartan medoxomil, approximately 55% of radioactivity was recovered in feces and approximately 42% in urine, with 15% of the dose excreted in urine as azilsartan. The elimination half-life of azilsartan is approximately 11 hours and renal clearance is approximately 2.3 mL/min. Steady-state levels of azilsartan are achieved within 5 days and no accumulation in plasma occurs with repeated once-daily dosing.

Chlorthalidone: Chlorthalidone when administered alone or in combination with azilsartan medoxomil is eliminated from plasma with an elimination half-life of 42-45 hours. The elimination half-life is unaltered following repeat dosing. The majority of an absorbed quantity of chlorthalidone is excreted by the kidneys with a mean renal clearance of 46-70 mL/min. By contrast, metabolism and excretion via the liver and bile play a minor role in the elimination of the substance. Approximately 60%-70% of chlorthalidone is excreted in the urine and feces within 120 hours, mainly in unchanged form.

Specific Populations

Azilsartan medoxomil: The effect of demographic and functional factors on the pharmacokinetics of azilsartan was studied in single and multiple dose studies. Pharmacokinetic measures indicating the magnitude of the effect on azilsartan are presented in Figure 2 as change relative to reference (test/reference).

Figure 2. Impact of intrinsic factors on the pharmacokinetics of azilsartan
Figure 2
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Drug Interactions

Azilsartan medoxomil

No clinically significant drug interactions have been observed in studies of azilsartan medoxomil or azilsartan given with amlodipine, antacids, chlorthalidone, digoxin, fluconazole, glyburide, ketoconazole, metformin, pioglitazone, and warfarin. Therefore, azilsartan medoxomil may be used concomitantly with these medications.

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