Azoren Mechanism of Action

Pharmacotherapeutic group: Angiotensin II antagonists and calcium channel blockers. ATC code: C09DB02.
Pharmacology: Pharmacodynamics: Mechanism of action: Azoren is a combination of an angiotensin II receptor antagonist, olmesartan medoxomil, and a calcium channel blocker, amlodipine besylate. The combination of these active ingredients has an additive antihypertensive effect, reducing blood pressure to a greater degree than either component alone.
Clinical efficacy and safety: Azoren: In an 8-week, double-blind, randomised, placebo-controlled factorial design study in 1940 patients (71% Caucasian and 29% non-Caucasian patients), treatment with each combination dose of Azoren resulted in significantly greater reductions in diastolic and systolic blood pressures than the respective monotherapy components. The mean change in systolic/diastolic blood pressure was dose-dependent: -24/-14 mmHg (20 mg/5 mg combination), -25/-16 mmHg (40 mg/5 mg combination) and -30/-19 mmHg (40 mg/10 mg combination).
Azoren 40 mg/5 mg reduced seated systolic/diastolic blood pressure by an additional 2.5/1.7 mmHg over Azoren 20 mg/5 mg. Similarly Azoren 40 mg/10 mg reduced seated systolic/diastolic blood pressure by an additional 4.7/3.5 mmHg over Azoren 40 mg/5 mg.
The proportions of patients reaching blood pressure goal (<140/90 mmHg for non-diabetic patients and <130/80 mmHg for diabetic patients) were 42.5%, 51.0% and 49.1% for Azoren 20 mg/5 mg, 40 mg/5 mg and 40 mg/10 mg respectively.
The majority of the antihypertensive effect of Azoren was generally achieved within the first 2 weeks of therapy.
A second double-blind, randomised, placebo-controlled study evaluated the effectiveness of adding amlodipine to the treatment in Caucasian patients whose blood pressure was inadequately controlled by 8 weeks of monotherapy with 20 mg olmesartan medoxomil.
In patients who continued to receive only 20 mg olmesartan medoxomil, systolic/diastolic blood pressure was reduced by -10.6/-7.8 mmHg after a further 8 weeks. The addition of 5 mg amlodipine for 8 weeks resulted in a reduction in systolic/diastolic blood pressure of -16.2/-10.6 mmHg (p=0.0006).
The proportion of patients reaching blood pressure goal (<140/90 mmHg for non-diabetic patients and <130/80 mmHg for diabetic patients) was 44.5% for the 20 mg/5 mg combination compared to 28.5% for 20 mg olmesartan medoxomil.
A further study evaluated the addition of various doses of olmesartan medoxomil in Caucasian patients whose blood pressure was not adequately controlled by 8 weeks of monotherapy with 5 mg amlodipine.
In patients who continued to receive only 5 mg amlodipine, systolic/diastolic blood pressure was reduced by -9.9/-5.7 mmHg after a further 8 weeks. The addition of 20 mg olmesartan medoxomil resulted in a reduction in systolic/diastolic blood pressure of -15.3/-9.3 mmHg and the addition of 40 mg olmesartan medoxomil resulted in a reduction in systolic/diastolic blood pressure of -16.7/-9.5 mmHg (p<0.0001).
The proportions of patients reaching blood pressure goal (<140/90 mmHg for non-diabetic patients and <130/80 mmHg for diabetic patients) was 29.9% for the group who continued to receive 5 mg amlodipine alone, 53.5% for Azoren 20 mg/5 mg and 50.5% for Azoren 40 mg/5 mg.
Randomised data in uncontrolled hypertensive patients, comparing the use of medium dose Azoren combination therapy versus escalation to top dose monotherapy of amlodipine or olmesartan, are not available.
The three studies performed confirmed that the blood pressure lowering effect of Azoren once daily was maintained throughout the 24-hour dose interval, with trough-to-peak ratios of 71% to 82% for systolic and diastolic response and with 24-hour effectiveness being confirmed by ambulatory blood pressure monitoring.
The antihypertensive effect of Azoren was similar irrespective of age and gender, and was similar in patients with and without diabetes.
In two open-label, non-randomised extension studies, sustained efficacy using Azoren 40 mg/5 mg was demonstrated at one year for 49% - 67% of patients.
Olmesartan Medoxomil (active ingredient of Azoren): The olmesartan medoxomil component of Azoren is a selective angiotensin II type 1 (AT1) receptor antagonist. Olmesartan medoxomil is rapidly converted to the pharmacologically active metabolite, olmesartan. Angiotensin II is the primary vasoactive hormone of the renin-angiotensin-aldosterone system, and plays a significant role in the pathophysiology of hypertension. The effects of angiotensin II include vasoconstriction, stimulation of the synthesis and release of aldosterone, cardiac stimulation, and renal reabsorption of sodium. Olmesartan blocks the vasoconstrictor and aldosterone-secreting effects of angiotensin II by blocking its binding to the AT1 receptor in tissues, including vascular smooth muscle and the adrenal gland. The action of olmesartan is independent of the source or route of synthesis of angiotensin II. The selective antagonism of the angiotensin II (AT1) receptors by olmesartan results in increases in plasma renin levels and angiotensin I and II concentrations, and some decrease in plasma aldosterone concentrations.
In hypertension, olmesartan medoxomil causes a dose-dependent, long-lasting reduction in arterial blood pressure. There has been no evidence of first-dose hypotension, of tachyphylaxis during long-term treatment, or of rebound hypertension after abrupt cessation of therapy.
Following once daily administration to patients with hypertension, olmesartan medoxomil produces an effective and smooth reduction in blood pressure over the 24-hour dose interval. Once daily dosing produced similar decreases in blood pressure as twice daily dosing at the same total daily dose.
With continuous treatment, maximum reductions in blood pressure are achieved by 8 weeks after the initiation of therapy; although, a substantial proportion of the blood pressure lowering effect is already observed after 2 weeks of treatment.
The effect of olmesartan medoxomil on mortality and morbidity is not yet known.
The Randomised Olmesartan and Diabetes Microalbuminuria Prevention (ROADMAP) study in 4447 patients with type 2 diabetes, normo-albuminuria and at least one additional cardiovascular risk factor, investigated whether treatment with olmesartan could delay the onset of microalbuminuria. During the median follow-up duration of 3.2 years, patients received either olmesartan or placebo in addition to other antihypertensive agents, except ACE inhibitors or ARBs.
For the primary endpoint, the study demonstrated a significant risk reduction in the time to onset of microalbuminuria, in favour of olmesartan. After adjustment for BP differences, this risk reduction was no longer statistically significant. 8.2% (178 of 2160) of the patients in the olmesartan group and 9.8% (210 of 2139) in the placebo group developed microalbuminuria.
For the secondary endpoints, cardiovascular events occurred in 96 patients (4.3%) with olmesartan and in 94 patients (4.2%) with placebo. The incidence of cardiovascular mortality was higher with olmesartan compared to placebo treatment (15 patients (0.7%) vs. 3 patients (0.1%)), despite similar rates for non-fatal stroke (14 patients (0.6%) vs. 8 patients (0.4%)), non-fatal myocardial infarction (17 patients (0.8%) vs. 26 patients (1.2%)) and non-cardiovascular mortality (11 patients (0.5%) vs. 12 patients (0.5%)). Overall mortality with olmesartan was numerically increased (26 patients (1.2%) vs. 15 patients (0.7%)), which was mainly driven by a higher number of fatal cardiovascular events.
The Olmesartan Reducing Incidence of End-stage Renal Disease in Diabetic Nephropathy Trial (ORIENT) investigated the effects of olmesartan on renal and cardiovascular outcomes in 577 randomized Japanese and Chinese type 2 diabetic patients with overt nephropathy. During a median follow-up of 3.1 years, patients received either olmesartan or placebo in addition to other antihypertensive agents including ACE inhibitors.
The primary composite endpoint (time to first event of the doubling of serum creatinine, end-stage renal disease, all-cause death) occurred in 116 patients in the olmesartan group (41.1%) and 129 patients in the placebo group (45.4%) (HR 0.97 (95% CI 0.75 to 1.24); p=0.791). The composite secondary cardiovascular endpoint occurred in 40 olmesartan-treated patients (14.2%) and 53 placebo-treated patients (18.7%). This composite cardiovascular endpoint included cardiovascular death in 10 (3.5%) patients receiving olmesartan versus 3 (1.1%) receiving placebo, overall mortality 19 (6.7%) versus 20 (7.0%), non-fatal stroke 8 (2.8%) versus 11 (3.9%) and non-fatal myocardial infarction 3 (1.1%) versus 7 (2.5%), respectively.
Amlodipine (active ingredient of Azoren): The amlodipine component of Azoren is a calcium channel blocker that inhibits the transmembrane influx of calcium ions through the potential-dependent L-type channels into the heart and smooth muscle. Experimental data indicate that amlodipine binds to both dihydropyridine and non-dihydropyridine binding sites. Amlodipine is relatively vessel-selective, with a greater effect on vascular smooth muscle cells than on cardiac muscle cells. The antihypertensive effect of amlodipine derives from a direct relaxant effect on arterial smooth muscle, which leads to a lowering of peripheral resistance and hence, of blood pressure.
In hypertensive patients, amlodipine causes a dose-dependent, long-lasting reduction in arterial blood pressure. There has been no evidence of first-dose hypotension, of tachyphylaxis during long-term treatment, or of rebound hypertension after abrupt cessation of therapy.
Following administration of therapeutic doses to patients with hypertension, amlodipine produces an effective reduction in blood pressure in the supine, sitting, and standing positions. Chronic use of amlodipine is not associated with significant changes in heart rate or plasma catecholamine levels. In hypertensive patients with normal renal function, therapeutic doses of amlodipine reduce renal vascular resistance and increase glomerular filtration rate and effective renal plasma flow, without changing filtration fraction or proteinuria.
In haemodynamic studies in patients with heart failure and in clinical studies based on exercise tests in patients with NYHA class II-IV heart failure, amlodipine was found not to cause any clinical deterioration, as measured by exercise tolerance, left ventricular ejection fraction and clinical signs and symptoms.
A placebo-controlled study (PRAISE) designed to evaluate patients with NYHA class III-IV heart failure receiving digoxin, diuretics and ACE inhibitors has shown that amlodipine did not lead to an increase in risk of mortality or combined mortality and morbidity in patients with heart failure.
In a follow-up, long-term, placebo controlled study (PRAISE-2) of amlodipine in patients with NYHA III and IV heart failure without clinical symptoms or objective findings suggestive of underlying ischaemic disease, on stable doses of ACE inhibitors, digitalis, and diuretics, amlodipine had no effect on total or cardiovascular mortality. In this same population, amlodipine was associated with increased reports of pulmonary oedema despite no significant difference in the incidence of worsening heart failure as compared to placebo.
Treatment to prevent heart attack trial (ALLHAT): A randomized double-blind morbidity-mortality study called the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) was performed to compare newer drug therapies: amlodipine 2.5-10 mg/d (calcium channel blocker) or lisinopril 10-40 mg/d (ACE-inhibitor) as first-line therapies to that of the thiazide-diuretic, chlorthalidone 12.5-25 mg/d in mild to moderate hypertension. A total of 33,357 hypertensive patients aged 55 or older were randomized and followed for a mean of 4.9 years. The patients had at least one additional CHD risk factor, including: previous myocardial infarction or stroke (>6 months prior to enrollment) or documentation of other atherosclerotic CVD (overall 51.5%), type 2 diabetes (36.1%), HDL-C<35 mg/dL (11.6%), left ventricular hypertrophy diagnosed by electrocardiogram or echocardiography (20.9%), current cigarette smoking (21.9%).
The primary endpoint was a composite of fatal CHD or non-fatal myocardial infarction. There was no significant difference in the primary endpoint between amlodipine-based therapy and chlorthalidone-based therapy: RR 0.98, 95% CI (0.90-1.07) p=0.65. Among secondary endpoints, the incidence of heart failure (component of a composite combined cardiovascular endpoint) was significantly higher in the amlodipine group as compared to the chlorthalidone group (10.2% vs. 7.7%, RR 1.38, 95% CI [1.25-1.52] p<0.001). However, there was no significant difference in all-cause mortality between amlodipine-based therapy and chlorthalidone-based therapy (RR 0.96, 95% CI [0.89-1.02] p=0.20).
Other information: Two large randomised, controlled trials (ONTARGET (ONgoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial) and VA NEPHRON-D (The Veterans Affairs Nephropathy in Diabetes)) have examined the use of the combination of an ACE-inhibitor with an angiotensin II receptor blocker.
ONTARGET was a study conducted in patients with a history of cardiovascular or cerebrovascular disease, or type 2 diabetes mellitus accompanied by evidence of end-organ damage. VA NEPHRON-D was a study in patients with type 2 diabetes mellitus and diabetic nephropathy.
These studies have shown no significant beneficial effect on renal and/or cardiovascular outcomes and mortality, while an increased risk of hyperkalaemia, acute kidney injury and/or hypotension as compared to monotherapy was observed. Given their similar pharmacodynamic properties, these results are also relevant for other ACE-inhibitors and angiotensin II receptor blockers.
ACE-inhibitors and angiotensin II receptor blockers should therefore not be used concomitantly in patients with diabetic nephropathy.
ALTITUDE (Aliskiren Trial in Type 2 Diabetes Using Cardiovascular and Renal Disease Endpoints) was a study designed to test the benefit of adding aliskiren to a standard therapy of an ACE-inhibitor or an angiotensin II receptor blocker in patients with type 2 diabetes mellitus and chronic kidney disease, cardiovascular disease, or both. The study was terminated early because of an increased risk of adverse outcomes. Cardiovascular death and stroke were both numerically more frequent in the aliskiren group than in the placebo group and adverse events and serious adverse events of interest (hyperkalaemia, hypotension and renal dysfunction) were more frequently reported in the aliskiren group than in the placebo group.
Pharmacokinetics: Azoren: Following oral intake of Azoren, peak plasma concentrations of olmesartan and amlodipine are reached at 1.5 - 2 hours and 6 - 8 hours, respectively. The rate and extent of absorption of the two active substances from Azoren are equivalent to the rate and extent of absorption following intake of the two components as separate tablets. Food does not affect the bioavailability of olmesartan and amlodipine from Azoren.
Olmesartan medoxomil (active ingredient of Azoren): Absorption and distribution: Olmesartan medoxomil is a prodrug. It is rapidly converted to the pharmacologically active metabolite, olmesartan, by esterases in the gut mucosa and in portal blood during absorption from the gastrointestinal tract. No intact olmesartan medoxomil or intact side chain medoxomil moiety have been detected in plasma or excreta. The mean absolute bioavailability of olmesartan from a tablet formulation was 25.6%.
The mean peak plasma concentration (C_max) of olmesartan is reached within about 2 hours after oral dosing with olmesartan medoxomil, and olmesartan plasma concentrations increase approximately linearly with increasing single oral doses up to about 80 mg.
Food had minimal effect on the bioavailability of olmesartan and therefore, olmesartan medoxomil may be administered with or without food.
No clinically relevant gender-related differences in the pharmacokinetics of olmesartan have been observed.
Olmesartan is highly bound to plasma protein (99.7%), but the potential for clinically significant protein binding displacement interactions between olmesartan and other highly bound co-administered active substances is low (as confirmed by the lack of a clinically significant interaction between olmesartan medoxomil and warfarin). The binding of olmesartan to blood cells is negligible. The mean volume of distribution after intravenous dosing is low (16 - 29 L).
Biotransformation and elimination: Total plasma clearance of olmesartan was typically 1.3 L/h (CV, 19%) and was relatively slow compared to hepatic blood flow (ca 90 L/h). Following a single oral dose of 14C-labelled olmesartan medoxomil, 10% - 16% of the administered radioactivity was excreted in the urine (the vast majority within 24 hours of dose administration) and the remainder of the recovered radioactivity was excreted in the faeces. Based on the systemic availability of 25.6%, it can be calculated that absorbed olmesartan is cleared by both renal excretion (ca 40%) and hepato-biliary excretion (ca 60%). All recovered radioactivity was identified as olmesartan. No other significant metabolite was detected. Enterohepatic recycling of olmesartan is minimal. Since a large proportion of olmesartan is excreted via the biliary route, use in patients with biliary obstruction is contraindicated (see Contraindications).
The terminal elimination half-life of olmesartan is between 10 and 15 hours after multiple oral dosing. Steady-state is reached after the first few doses and no further accumulation is evident after 14 days of repeated dosing. Renal clearance is approximately 0.5 - 0.7 L/h and is independent of dose.
Drug interactions: Bile acid sequestering agent colesevelam: Concomitant administration of 40 mg olmesartan medoxomil and 3750 mg colesevelam hydrochloride in healthy subjects resulted in 28% reduction in C_max and 39% reduction in AUC of olmesartan. Lesser effects, 4% and 15% reduction in C_max and AUC respectively, were observed when olmesartan medoxomil was administered 4 hours prior to colesevelam hydrochloride. Elimination half-life of olmesartan was reduced by 50 - 52% irrespectively of whether administered concomitantly or 4 hours prior to colesevelam hydrochloride (see Interactions).
Amlodipine (active ingredient of Azoren): Absorption and distribution: 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 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. The absorption of amlodipine is unaffected by the concomitant intake of food.
Biotransformation and elimination: The terminal plasma elimination half-life is about 35 - 50 hours and is consistent with once daily dosing. Amlodipine is extensively metabolized by the liver to inactive metabolites with 10% of the parent compound and 60% of metabolites excreted in the urine.
Olmesartan medoxomil and amlodipine (active ingredients of Azoren): Special populations: Paediatric population (age below 18 years): No pharmacokinetic data in paediatric patients are available.
Elderly (age 65 years or over): In hypertensive patients, the olmesartan AUC at steady-state is increased by ca 35% in elderly people (65 - 75 years old) and by ca 44% in very elderly people (>75 years old) compared with the younger age group (see Dosage & Administration). This may be at least in part related to a mean decrease in renal function in this group of patients. The recommended dosage regimen for elderly people is, however, the same, although caution should be exercised when increasing the dosage.
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 people. Increases in AUC and elimination half-life in patients with congestive heart failure were as expected for the patient age group in this study (see Precautions).
Renal impairment: In renally impaired patients, the olmesartan AUC at steady state increased by 62%, 82% and 179% in patients with mild, moderate and severe renal impairment, respectively, compared to healthy controls (see Dosage & Administration and Precautions).
Amlodipine is extensively metabolised to inactive metabolites. Ten percent of the substance is excreted unchanged in the urine. Changes in amlodipine plasma concentration are not correlated with the degree of renal impairment. In these patients, amlodipine may be administered at the normal dosage. Amlodipine is not dialysable.
Hepatic impairment: After single oral administration, olmesartan AUC values are 6% and 65% higher in mildly and moderately hepatically impaired patients, respectively, than in their corresponding matched healthy controls. The unbound fraction of olmesartan at 2 hours post-dose in healthy subjects, in patients with mild hepatic impairment and in patients with moderate hepatic impairment is 0.26%, 0.34% and 0.41%, respectively. Following repeated dosing in patients with moderate hepatic impairment, olmesartan mean AUC is again about 65% higher than in matched healthy controls. Olmesartan mean C_max values are similar in hepatically-impaired and healthy subjects. Olmesartan medoxomil has not been evaluated in patients with severe hepatic impairment (see Dosage & Administration and Precautions).
Very limited clinical data are available regarding amlodipine administration in patients with hepatic impairment. The clearance of amlodipine is decreased and the half-life is prolonged in patients with impaired hepatic function, resulting in an increase in AUC of about 40% - 60% (see Dosage & Administration and Precautions).
Toxicology: Preclinical safety data: Based on the non-clinical toxicity profile of each substance, no exacerbation of toxicities for the combination is expected, because each substance has different targets, i.e. the kidneys for olmesartan medoxomil and the heart for amlodipine.
In a 3-month, repeat-dose toxicity study of orally administered olmesartan medoxomil/amlodipine in combination in rats the following alterations were observed: decreases in red blood cell count-related parameters and kidney changes both of which might be induced by the olmesartan medoxomil component; alterations in the intestines (luminal dilatation and diffuse mucosal thickening of the ileum and colon), the adrenals (hypertrophy of the glomerular cortical cells and vacuolation of the fascicular cortical cells), and hypertrophy of the ducts in the mammary glands which might be induced by the amlodipine component. These alterations neither augmented any of the previously reported and existing toxicity of the individual agents nor induced any new toxicity, and no toxicologically synergistic effects were observed.
Olmesartan medoxomil (active ingredient of Azoren): In chronic toxicity studies in rats and dogs, olmesartan medoxomil showed similar effects to other AT1 receptor antagonists and ACE inhibitors: raised blood urea (BUN) and creatinine; reduction in heart weight; reduction of red cell parameters (erythrocytes, haemoglobin, haematocrit); histological indications of renal damage (regenerative lesions of the renal epithelium, thickening of the basal membrane, dilatation of the tubules). These adverse effects caused by the pharmacological action of olmesartan medoxomil have also occurred in preclinical trials on other AT1 receptor antagonists and ACE inhibitors and can be reduced by simultaneous oral administration of sodium chloride. In both species, increased plasma renin activity and hypertrophy/hyperplasia of the juxtaglomerular cells of the kidney were observed. These changes, which are a typical effect of the class of ACE inhibitors and other AT1 receptor antagonists, would appear to have no clinical relevance.
Like other AT1 receptor antagonists, olmesartan medoxomil was found to increase the incidence of chromosome breaks in cell cultures in vitro. No relevant effects were observed in several in vivo studies using olmesartan medoxomil at very high oral doses of up to 2000 mg/kg. The overall data of a comprehensive genotoxicity testing program suggest that olmesartan is very unlikely to exert genotoxic effects under conditions of clinical use.
Olmesartan medoxomil was not carcinogenic, in a 2-year study in rats nor in two 6-month carcinogenicity studies in transgenic mice.
In reproductive studies in rats, olmesartan medoxomil did not affect fertility and there was no evidence of a teratogenic effect. In common with other angiotensin II antagonists, survival of offspring was reduced following exposure to olmesartan medoxomil and pelvic dilatation of the kidney was seen after exposure of the dams in late pregnancy and lactation. In common with other antihypertensive agents, olmesartan medoxomil was shown to be more toxic to pregnant rabbits than to pregnant rats, however, there was no indication of a fetotoxic effect.
Amlodipine (active ingredient of Azoren): Reproductive toxicology: Reproductive studies in rats and mice have shown delayed date of delivery, prolonged duration of labour and decreased pup survival at dosages approximately 50 times greater than the maximum recommended dosage for humans based on mg/kg.
Impairment of fertility: There was no effect on the fertility of rats treated with amlodipine (males for 64 days and females 14 days prior to mating) at doses up to 10 mg/kg/day (8 times* the maximum recommended human dose of 10 mg on a mg/m² basis). In another rat study in which male rats were treated with amlodipine besylate for 30 days at a dose comparable with the human dose based on mg/kg, decreased plasma follicle-stimulating hormone and testosterone were found as well as decreases in sperm density and in the number of mature spermatids and Sertoli cells.
Carcinogenesis, mutagenesis: Rats and mice treated with amlodipine in the diet for two years, at concentrations calculated to provide daily dosage levels of 0.5, 1.25, and 2.5 mg/kg/day showed no evidence of carcinogenicity. The highest dose (for mice, similar to, and for rats twice* the maximum recommended clinical dose of 10 mg on a mg/m² basis) was close to the maximum tolerated dose for mice but not for rats.
Mutagenicity studies revealed no drug related effects at either the gene or chromosome levels.
* Based on patient weight of 50 kg.