Generic Name: olmesartan medoxomil, amlodipine besylate and hydrochlorothiazide
Dosage Form: tablet, film coated
FULL PRESCRIBING INFORMATION
When pregnancy is detected, discontinue Tribenzor as soon as possible. Drugs that act directly on the renin-angiotensin system can cause injury and even death to the developing fetus [see Warning and Precautions (5.1)].
Indications and Usage for Tribenzor
Tribenzor (olmesartan medoxomil, amlodipine, hydrochlorothiazide) is indicated for the treatment of hypertension, to lower blood pressure. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions. These benefits have been seen in controlled trials of antihypertensive drugs from a wide variety of pharmacologic classes including the class to which this drug principally belongs. There are no controlled trials demonstrating risk reduction with Tribenzor.
Control of high blood pressure should be part of comprehensive cardiovascular risk management, including, as appropriate, lipid control, diabetes management, antithrombotic therapy, smoking cessation, exercise, and limited sodium intake. Many patients will require more than one drug to achieve blood pressure goals. For specific advice on goals and management, see published guidelines, such as those of the National High Blood Pressure Education Program’s Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC).
Numerous antihypertensive drugs, from a variety of pharmacologic classes and with different mechanisms of action, have been shown in randomized controlled trials to reduce cardiovascular morbidity and mortality, and it can be concluded that it is blood pressure reduction, and not some other pharmacologic property of the drugs, that is largely responsible for those benefits. The largest and most consistent cardiovascular outcome benefit has been a reduction in the risk of stroke, but reductions in myocardial infarction and cardiovascular mortality also have been seen regularly.
Elevated systolic or diastolic pressure causes increased cardiovascular risk, and the absolute risk increase per mmHg is greater at higher blood pressures, so that even modest reductions of severe hypertension can provide substantial benefit. Relative risk reduction from blood pressure reduction is similar across populations with varying absolute risk, so the absolute benefit is greater in patients who are at higher risk independent of their hypertension (for example, patients with diabetes or hyperlipidemia), and such patients would be expected to benefit from more aggressive treatment to a lower blood pressure goal.
Some antihypertensive drugs have smaller blood pressure effects (as monotherapy) in black patients, and many antihypertensive drugs have additional approved indications and effects (e.g., on angina, heart failure, or diabetic kidney disease). These considerations may guide selection of therapy.
This fixed combination drug is not indicated for the initial therapy of hypertension[see Dosage and Administration (2)].
Tribenzor Dosage and Administration
General Considerations
Dose once daily.
Dosage may be increased after 2 weeks. The full blood pressure lowering effects are attained within 2 weeks after a change in dose. The maximum recommended dose of Tribenzor is 40/10/25 mg. Tribenzor may be taken with or without food.
Renal Impairment
The usual regimens of therapy with Tribenzor may be followed if the patient’s creatinine clearance is >30 mL/min. In patients with more severe renal impairment, loop diuretics are preferred to thiazides, so avoid use of Tribenzor [see Warnings and Precautions (5.4)].
Elderly
Patients ≥ 75 years of age should start amlodipine at 2.5 mg, which is not available with Tribenzor.
Hepatic Impairment
Patients with severe hepatic impairment should start amlodipine at 2.5 mg, which is not available with Tribenzor [see Warnings and Precautions (5.5)].
Replacement Therapy
Tribenzor may be substituted for its individually titrated components.
Add-on/Switch Therapy
Tribenzor may be used to provide additional blood pressure lowering for patients not adequately controlled on maximally tolerated, labeled, or usual doses of any two of the following antihypertensive classes: angiotensin receptor blockers (ARB), calcium channel blockers (CCB), and diuretics.
A patient who experiences dose-limiting adverse reactions to an individual component while on any dual combination of the components of Tribenzor may be switched to Tribenzor containing a lower dose of that component to achieve similar blood pressure reductions.
Dosage Forms and Strengths
Tribenzor tablets are formulated for oral administration in the following strength combinations: (olmesartan medoxomil/amlodipine/hydrochlorothiazide) 20 /5 /12.5 mg, 40 /5 / 12.5 mg, 40 /5 /25 mg, 40 /10 /12.5 mg, and 40 /10 /25 mg.
Contraindications
Because of the hydrochlorothiazide component, Tribenzor is contraindicated in patients with anuria or hypersensitivity to other sulfonamide-derived drugs.
Warnings and Precautions
Fetal/Neonatal Morbidity and Mortality
Drugs that act directly on the renin-angiotensin system like olmesartan medoxomil can cause fetal and neonatal morbidity and death when administered to pregnant women. Several dozen cases have been reported in the world literature of patients who were taking angiotensin converting enzyme (ACE) inhibitors. When pregnancy is detected, discontinue Tribenzor as soon as possible.
The use of drugs that act directly on the renin-angiotensin system during the second and third trimesters of pregnancy has been associated with fetal and neonatal injury, including hypotension, neonatal skull hypoplasia, anuria, reversible or irreversible renal failure, and death. Oligohydramnios has also been reported, presumably resulting from decreased fetal renal function; oligohydramnios in this setting has been associated with fetal limb contractures, craniofacial deformation, and hypoplastic lung development. Prematurity, intrauterine growth retardation, and patent ductus arteriosus have also been reported, although it is not clear whether these occurrences were due to exposure to the drug.
These adverse effects do not appear to have resulted from intrauterine drug exposure that has been limited to the first trimester. Mothers whose embryos and fetuses are exposed to an angiotensin II receptor antagonist only during the first trimester should be so informed. Nonetheless, when patients become pregnant, physicians should have the patient discontinue the use of Tribenzor as soon as possible [see Use in Specific Populations (8.1)].
Rarely (probably less often than once in every thousand pregnancies), no alternative to a drug acting on the renin-angiotensin system is available. In these rare cases, the mother should be apprised of the potential hazards to the fetus and serial ultrasound examinations should be performed to assess the intra-amniotic environment.
If oligohydramnios is observed, Tribenzor should be discontinued unless it is considered life-saving for the mother. Contraction stress testing, a nonstress test or biophysical profiling may be appropriate, depending upon the week of pregnancy. Patients and physicians should be aware, however, that oligohydramnios may not appear until after the fetus has sustained irreversible injury.
Infants with histories of in utero exposure to an angiotensin II receptor antagonist should be closely observed for hypotension, oliguria, and hyperkalemia. If oliguria occurs, attention should be directed toward support of blood pressure and renal perfusion. Exchange transfusion or dialysis may be required as a means of reversing hypotension and/or substituting for impaired renal function.
Hypotension in Volume- or Salt-Depleted Patients
Olmesartan medoxomil. Symptomatic hypotension may be anticipated after initiation of treatment with olmesartan medoxomil. Patients with an activated renin-angiotensin system, such as volume- and/or salt-depleted patients (e.g., those being treated with high doses of diuretics) may be particularly vulnerable. Initiate treatment with Tribenzor under close medical supervision. If hypotension does occur, place the patient in the supine position and, if necessary, give an intravenous infusion of normal saline. A transient hypotensive response is not a contraindication to further treatment, which usually can be continued without difficulty once the blood pressure has stabilized.
Increased Angina and/or Myocardial Infarction
Amlodipine. Patients, particularly those with severe obstructive coronary artery disease, may develop increased frequency, duration, or severity of angina or acute myocardial infarction upon starting calcium channel blocker therapy or at the time of dosage increase. The mechanism of this effect has not been elucidated.
Impaired Renal Function
Tribenzor. Tribenzor has not been studied in patients with impaired renal function. Avoid use in patients with severe renal impairment (creatinine clearance ≤30 ml/min) [see Dosage and Administration (2)].
An adverse event of impaired renal function was reported in 2.1% of subjects receiving Tribenzor compared to 0.2% to 1.3% of subjects receiving dual combination therapy.
If progressive renal impairment becomes evident consider withholding or discontinuing either diuretic or angiotensin receptor blocker therapies.
Olmesartan medoxomil. Changes in renal function occur in some individuals treated with olmesartan medoxomil as a consequence of inhibiting the renin-angiotensin-aldosterone system. In patients whose renal function may depend upon the activity of the renin-angiotensin-aldosterone system (e.g., patients with severe congestive heart failure), treatment with ACE inhibitors and angiotensin receptor antagonists has been associated with oliguria or progressive azotemia and (rarely) with acute renal failure and/or death. Similar effects may occur in patients treated with Tribenzor due to the olmesartan medoxomil component [see Clinical Pharmacology (12.3)].
In studies of ACE inhibitors in patients with unilateral or bilateral renal artery stenosis, increases in serum creatinine or blood urea nitrogen (BUN) have been reported. There has been no long-term use of olmesartan medoxomil in patients with unilateral or bilateral renal artery stenosis, but similar effects would be expected with Tribenzor because of the olmesartan medoxomil component.
Hydrochlorothiazide. Thiazides may precipitate azotemia in patients with renal disease. Cumulative effects of the drug may develop in patients with impaired renal function.
Hepatic Impairment
Amlodipine. Amlodipine is extensively metabolized by the liver and the plasma elimination half-life (t1/2) is 56 hours in patients with severely impaired hepatic function [see Dosage and Administration (2)].
Hydrochlorothiazide. Minor alterations of fluid and electrolyte balance may precipitate hepatic coma.
Electrolyte and Metabolic Imbalances
Hydrochlorothiazide. Perform periodic determinations of serum electrolytes to detect possible electrolyte imbalance. Observe patients receiving thiazide therapy for clinical signs of fluid or electrolyte imbalance: hyponatremia, hypochloremic alkalosis, and hypokalemia. Serum and urine electrolyte determinations are important when the patient is vomiting excessively or receiving parental fluids. Warning signs or symptoms of fluid and electrolyte imbalance, irrespective of cause, include dryness of mouth, thirst, weakness, lethargy, drowsiness, restlessness, confusion, seizures, muscle pains or cramps, muscular fatigue, hypotension, oliguria, tachycardia, and gastrointestinal disturbances such as nausea and vomiting.
Hypokalemia may develop, especially during brisk diuresis, when severe cirrhosis is present, or after prolonged therapy.
Interference with adequate oral electrolyte intake will also contribute to hypokalemia. Hypokalemia may cause cardiac arrhythmia and may also sensitize or exaggerate the response of the heart to the toxic effects of digitalis (e.g., increased ventricular irritability).
Metabolic acidosis may occur. Although a chloride deficit in a particular patient is generally mild and usually does not require specific treatment, except under extraordinary circumstances (as in liver disease or renal disease), chloride replacement may be required in the treatment of metabolic alkalosis.
Dilutional hyponatremia may occur in edematous patients in hot weather; appropriate therapy is water restriction, rather than administration of salt, except in rare instances when the hyponatremia is life-threatening. In actual salt depletion, appropriate replacement is the therapy of choice.
Hyperuricemia may occur or frank gout may be precipitated in certain patients receiving thiazide therapy.
In diabetic patients dosage adjustments of insulin or oral hypoglycemic agents may be required. Hyperglycemia may occur with thiazide diuretics. Thus, latent diabetes mellitus may become manifest during thiazide therapy.
The antihypertensive effects of the drug may be enhanced in the post-sympathectomy patient.
Thiazides have been shown to increase the urinary excretion of magnesium; this may result in hypomagnesemia.
Thiazides may decrease urinary calcium excretion. Thiazides may cause intermittent and slight elevation of serum calcium in the absence of known disorders of calcium metabolism. Marked hypercalcemia may be evidence of hyperparathyroidism. Tribenzor should be discontinued before carrying out tests for parathyroid function.
Hypersensitivity Reaction
Hydrochlorothiazide. Hypersensitivity reactions to hydrochlorothiazide may occur in patients with or without a history of allergy or bronchial asthma, but are more likely in patients with such a history.
Systemic Lupus Erythematosus
Hydrochlorothiazide. Thiazide diuretics have been reported to cause exacerbation or activation of systemic lupus erythematosus.
Acute Myopia and Secondary Angle-Closure Glaucoma
Hydrochlorothiazide, a sulfonamide, can cause an idiosyncratic reaction, resulting in acute transient myopia and acute angle-closure glaucoma. Symptoms include acute onset of decreased visual acuity or ocular pain and typically occur within hours to weeks of drug initiation. Untreated acute angle-closure glaucoma can lead to permanent vision loss. The primary treatment is to discontinue hydrochlorothiazide as rapidly as possible. Prompt medical or surgical treatments may need to be considered if the intraocular pressure remains uncontrolled. Risk factors for developing acute angle-closure glaucoma may include a history of sulfonamide or penicillin allergy.
Vasodilation
Amlodipine. Although vasodilation attributable to amlodipine is generally gradual in onset, acute hypotension has rarely been reported after oral administration. Patients with severe aortic stenosis may be at particular risk.
Heart Failure
Tribenzor. Tribenzor has not been studied in patients with heart failure.
Amlodipine. Amlodipine (5-10 mg per day) has been studied in a placebo-controlled trial of 1153 patients with New York Heart Association (NYHA) Class III or IV heart failure on stable doses of ACE inhibitor, digoxin, and diuretics. Follow-up was at least 6 months, with a mean of about 14 months. There was no overall adverse effect on survival or cardiac morbidity (as defined by life threatening arrhythmia, acute myocardial infarction, or hospitalization for worsened heart failure). Amlodipine has been compared to placebo in four 8-12 week studies of patients with NYHA Class II/III heart failure, involving a total of 697 patients. In these studies, there was no evidence of worsening of heart failure based on measures of exercise tolerance, NYHA classification, symptoms, or left ventricular ejection fraction.
Lithium Interaction
Hydrochlorothiazide. Lithium generally should not be given with thiazides [see Drug Interactions (7.4)].
Laboratory Tests
Olmesartan medoxomil. In post-marketing experience, increased blood creatinine levels and hyperkalemia have been reported.
Amlodipine. In post-marketing experience, hepatic enzyme elevations have been reported [see Adverse Reactions (6.2)].
Hydrochlorothiazide. Increases in cholesterol and triglyceride levels may be associated with thiazide diuretic therapy.
Adverse Reactions
Clinical Trials Experience
Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rates observed in practice.
Tribenzor
In the controlled trial of Tribenzor, patients were randomized to Tribenzor (olmesartan medoxomil/amlodipine/hydrochlorothiazide 40/10/25 mg), olmesartan medoxomil/amlodipine 40/10 mg, olmesartan medoxomil/hydrochlorothiazide 40/25 mg, or amlodipine/hydrochlorothiazide 10/25 mg. Subjects who received triple combination therapy were treated between two and four weeks with one of the three dual combination therapies. Safety data from this study were obtained in 574 patients with hypertension who received Tribenzor for 8 weeks.
The frequency of adverse reactions was similar between men and women, patients <65 years of age and patients ≥65 years of age, patients with and without diabetes, and Black and non-Black patients. Discontinuations because of adverse events occurred in 4% of patients treated with Tribenzor 40/10/25 mg compared to 1% of patients treated with olmesartan medoxomil/amlodipine 40/10 mg, 2% of patients treated with olmesartan medoxomil/hydrochlorothiazide 40/25 mg, and 2% of patients treated with amlodipine/hydrochlorothiazide 10/25 mg. The most common reason for discontinuation with Tribenzor was dizziness (1%).
Dizziness was one of the most frequently reported adverse reactions with incidence of 1.4% to 3.6% in subjects continuing on dual combination therapy compared to 5.8% to 8.9% in subjects who switched to Tribenzor.
The other most frequent adverse reactions that occurred in at least 2% of subjects are presented in the table below:
Table 1
| Adverse Reaction | OM40/ AML10/ HCTZ25 mg (N = 574) n (%) | OM40/ AML10 mg (N = 596) n (%) | OM40/ HCTZ25mg (N = 580) n (%) | AML10/ HCTZ25 mg (N = 552) n (%) |
| Edema peripheral | 44 (7.7) | 42 (7.0) | 6 (1.0) | 46 (8.3) |
| Headache | 37 (6.4) | 42 (7.0) | 38 (6.6) | 33 (6.0) |
| Fatigue | 24 (4.2) | 34 (5.7) | 31 (5.3) | 36 (6.5) |
| Nasopharyngitis | 20 (3.5) | 11 (1.8) | 20 (3.4) | 16 (2.9) |
| Muscle spasms | 18 (3.1) | 12 (2.0) | 14 (2.4) | 13 (2.4) |
| Nausea | 17 (3.0) | 12 (2.0) | 22 (3.8) | 12 (2.2) |
| Upper respiratory tract infection | 16 (2.8) | 26 (4.4) | 18 (3.1) | 14 (2.5) |
| Diarrhea | 15 (2.6) | 14 (2.3) | 12 (2.1) | 9 (1.6) |
| Urinary tract infection | 14 (2.4) | 8 (1.3) | 6 (1.0) | 7 (1.3) |
| Joint swelling | 12 (2.1) | 17 (2.9) | 2 (0.3) | 16 (2.9) |
Syncope was reported by 1% of Tribenzor subjects compared to 0.5% or less for the other treatment groups.
Olmesartan medoxomil
Olmesartan medoxomil has been evaluated for safety in more than 3825 patients/subjects, including more than 3275 patients treated for hypertension in controlled trials. This experience included about 900 patients treated for at least 6 months and more than 525 treated for at least 1 year. Treatment with olmesartan medoxomil was well tolerated, with an incidence of adverse reactions similar to that seen with placebo. Adverse reactions were generally mild, transient, and without relationship to the dose of olmesartan medoxomil.
Amlodipine
Amlodipine has been evaluated for safety in more than 11,000 patients in U.S. and foreign clinical trials.
The following adverse reactions occurred in <1% but >0.1% of patients in controlled clinical trials under conditions of open trials or marketing experience where a causal relationship is uncertain; they are listed to alert physicians to a possible relationship:
Cardiovascular: arrhythmia (including ventricular tachycardia and atrial fibrillation), bradycardia, chest pain, hypotension, peripheral ischemia, syncope, tachycardia, postural dizziness, postural hypotension, vasculitis
Central and Peripheral Nervous System: hypoesthesia, neuropathy peripheral, paresthesia, tremor, vertigo
Gastrointestinal: anorexia, constipation, dyspepsia*, dysphagia, diarrhea, flatulence, pancreatitis, vomiting, gingival hyperplasia
General: allergic reaction, asthenia*, back pain, hot flushes, malaise, pain, rigors, weight gain, weight decrease
Musculoskeletal System: arthralgia, arthrosis, muscle cramps*, myalgia
Psychiatric: sexual dysfunction (male* and female), insomnia, nervousness, depression, abnormal dreams, anxiety, depersonalization
Respiratory: dyspnea*, epistaxis
Skin and Appendages: angioedema, erythema multiforme, pruritus*, rash*, rash erythematous, rash maculopapular
Special Senses: abnormal vision, conjunctivitis, diplopia, eye pain, tinnitus
Urinary System: micturition frequency, micturition disorder, nocturia
Autonomic Nervous System: dry mouth, sweating increased
Metabolic and Nutritional: hyperglycemia, thirst
Hemopoietic: leukopenia, purpura, thrombocytopenia
* = events that occurred in less than 1% in placebo-controlled trials, but the incidence of these side effects was between 1% and 2% in all multiple dose studies.
The following adverse reactions occurred in <0.1% of patients: cardiac failure, pulse irregularity, extrasystoles, skin discoloration, urticaria, skin dryness, alopecia, dermatitis, muscle weakness, twitching, ataxia, hypertonia, migraine, cold and clammy skin, apathy, agitation, amnesia, gastritis, increased appetite, loose stools, coughing, rhinitis, dysuria, polyuria, parosmia, taste perversion, abnormal visual accommodation, and xerophthalmia.
Hydrochlorothiazide
Other adverse reactions that have been reported with hydrochlorothiazide, without regard to causality, are listed below:
Body as a Whole: weakness
Digestive: pancreatitis, jaundice (intrahepatic cholestatic jaundice), sialadenitis, cramping, gastric irritation
Hematologic: aplastic anemia, agranulocytosis, leukopenia, hemolytic anemia, thrombocytopenia
Hypersensitivity: purpura, photosensitivity, urticaria, necrotizing angiitis (vasculitis and cutaneous vasculitis), fever, respiratory distress including pneumonitis and pulmonary edema, anaphylactic reactions
Metabolic: hyperglycemia, glycosuria, hyperuricemia
Musculoskeletal: muscle spasm
Nervous System/Psychiatric: restlessness
Renal: renal failure, renal dysfunction, interstitial nephritis
Skin: erythema multiforme including Stevens-Johnson syndrome, exfoliative dermatitis including toxic epidermal necrolysis
Special Senses: transient blurred vision, xanthopsia
Post-Marketing Experience
The following adverse reactions have been identified during post-approval use of the individual components of Tribenzor. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Olmesartan medoxomil. The following adverse reactions have been reported in post marketing experience:
Body as a Whole: asthenia, angioedema, anaphylactic reactions, peripheral edema
Gastrointestinal: vomiting, diarrhea
Musculoskeletal: rhabdomyolysis
Urogenital System: acute renal failure
Skin and Appendages: alopecia, pruritus, urticaria
Amlodipine. The following post-marketing event has been reported infrequently where a causal relationship is uncertain: gynecomastia. In post-marketing experience, jaundice and hepatic enzyme elevations (mostly consistent with cholestasis or hepatitis), in some cases severe enough to require hospitalization, have been reported in association with use of amlodipine.
Drug Interactions
Drug Interactions with Tribenzor
The pharmacokinetics of olmesartan medoxomil, amlodipine, and hydrochlorothiazide are not altered when the drugs are co-administered.
No drug interaction studies have been conducted with other drugs and Tribenzor, although studies have been conducted with the olmesartan medoxomil, amlodipine, and hydrochlorothiazide components of Tribenzor, as described below.
Drug Interactions with Olmesartan Medoxomil
No significant drug interactions were reported in studies in which olmesartan medoxomil was co-administered with digoxin or warfarin in healthy volunteers.
The bioavailability of olmesartan medoxomil was not significantly altered by the co-administration of antacids [Al(OH)3/Mg(OH)2].
Olmesartan medoxomil is not metabolized by the cytochrome P450 system and has no effects on P450 enzymes; thus, interactions with drugs that inhibit, induce, or are metabolized by those enzymes are not expected.
Non-Steroidal Anti-Inflammatory Agents including Selective Cyclooxygenase-2 Inhibitors (COX-2 Inhibitors)
In patients who are elderly, volume-depleted (including those on diuretic therapy), or with compromised renal function, co-administration of NSAIDs, including selective COX-2 inhibitors, with angiotensin II receptor antagonists, including olmesartan medoxomil, may result in deterioration of renal function, including possible acute renal failure. These effects are usually reversible. Monitor renal function periodically in patients receiving olmesartan medoxomil and NSAID therapy.
The antihypertensive effect of angiotensin II receptor antagonists, including olmesartan medoxomil may be attenuated by NSAIDs including selective COX-2 inhibitors.
Drug Interactions with Amlodipine
In vitro data indicate that amlodipine has no effect on the human plasma protein binding of digoxin, phenytoin, warfarin, and indomethacin.
Effect of Other Agents on Amlodipine
Cimetidine: Co-administration of amlodipine with cimetidine did not alter the pharmacokinetics of amlodipine.
Grapefruit juice: Co-administration of 240 mL of grapefruit juice with a single oral dose of amlodipine 10 mg in 20 healthy volunteers had no significant effect on the pharmacokinetics of amlodipine.
Maalox® (antacid): Co-administration of the antacid Maalox with a single dose of amlodipine had no significant effect on the pharmacokinetics of amlodipine.
Sildenafil: A single 100 mg dose of sildenafil in patients with essential hypertension had no effect on the pharmacokinetic parameters of amlodipine. When amlodipine and sildenafil were used in combination, each agent independently exerted its own blood pressure lowering effect.
Effect of Amlodipine on Other Agents
Atorvastatin: Co-administration of multiple 10 mg doses of amlodipine with 80 mg of atorvastatin resulted in no significant change in the steady state pharmacokinetic parameters of atorvastatin.
Digoxin: Co-administration of amlodipine with digoxin did not change serum digoxin levels or digoxin renal clearance in normal volunteers.
Ethanol (alcohol): Single and multiple 10 mg doses of amlodipine had no significant effect on the pharmacokinetics of ethanol.
Warfarin: Co-administration of amlodipine with warfarin did not change the warfarin prothrombin response time.
In clinical trials, amlodipine has been safely administered with thiazide diuretics, beta blockers, ACE inhibitors, long-acting nitrates, sublingual nitroglycerin, digoxin, warfarin, non-steroidal anti-inflammatory drugs, antibiotics, and oral hypoglycemic drugs.
Drug Interactions with Hydrochlorothiazide
When administered concurrently the following drugs may interact with thiazide diuretics:
Alcohol, Barbiturates, or Narcotics: Potentiation of orthostatic hypotension may occur.
Antidiabetic Drugs (oral agents and insulin): Dosage adjustment of the antidiabetic drug may be required.
Other Antihypertensive Drugs: Additive effect or potentiation.
Cholestyramine and Colestipol Resins: Absorption of hydrochlorothiazide is impaired in the presence of anionic exchange resins. Single dose of either cholestyramine or colestipol resins bind the hydrochlorothiazide and reduce its absorption from the gastrointestinal tract by up to 85% and 43%, respectively.
Corticosteroids, ACTH: Intensified electrolyte depletion, particularly hypokalemia.
Pressor Amines (e.g., Norepinephrine): Possible decreased response to pressor amines but not sufficient to preclude their use.
Skeletal Muscle Relaxants, Non-depolarizing (e.g., Tubocurarine): Possible increased responsiveness to the muscle relaxant.
Lithium: Should not be given with diuretics. Diuretic agents reduce the renal clearance of lithium and add a high risk of lithium toxicity. Refer to the package insert for lithium preparations before use of such preparations with hydrochlorothiazide.
Non-steroidal Anti-inflammatory Drugs: In some patients the administration of a non-steroidal anti-inflammatory agent can reduce the diuretic, natriuretic, and antihypertensive effects of loop, potassium-sparing and thiazide diuretics. Therefore, when hydrochlorothiazide tablets and non-steroidal anti-inflammatory agents are used concomitantly, the patients should be observed closely to determine if the desired effect of the diuretic is obtained.
USE IN SPECIFIC POPULATIONS
Pregnancy
Tribenzor. Pregnancy Categories C (first trimester) and D (second and third trimesters) [see Warnings and Precautions (5.1)].
Drugs that act directly on the renin-angiotensin system like olmesartan medoxomil can cause fetal and neonatal morbidity and death when administered to pregnant women. There have been several dozen cases reported in the world literature of patients who were taking angiotensin converting enzyme inhibitors. When pregnancy is detected, discontinue Tribenzor as soon as possible.
Healthcare professionals who prescribe drugs acting directly on the renin angiotensin aldosterone system should counsel women of childbearing potential about the risks of these agents during pregnancy [see Nonclinical Toxicology (13.3)].
Nursing Mothers
It is not known whether amlodipine or olmesartan are excreted in human milk, but thiazides appear in human milk and olmesartan is secreted at low concentration in the milk of lactating rats. Because of the potential for adverse effects on the nursing infant, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
Pediatric Use
The safety and effectiveness of Tribenzor in pediatric patients have not been established.
Geriatric Use
Tribenzor. In a controlled clinical trial, 123 hypertensive patients treated with Tribenzor were ≥65 years of age and 18 patients were ≥75 years of age. No overall differences in the efficacy or safety of Tribenzor were observed in these patient populations; however, greater sensitivity of some older individuals cannot be ruled out.
Hepatic Impairment
There are no studies of Tribenzor in patients with hepatic insufficiency, but both amlodipine and olmesartan medoxomil show moderate increases in exposure in patients with severe hepatic impairment. Initiate amlodipine at 2.5 mg in patients with severe hepatic impairment.
Olmesartan medoxomil. Increases in AUC0-∞ and peak plasma concentration (Cmax) for olmesartan were observed with moderate hepatic impairment compared to those in matched controls with an increase in AUC of about 60%.
Hydrochlorothiazide. In patients with impaired hepatic function or progressive liver disease, minor alterations of fluid and electrolyte balance may precipitate hepatic coma.
Renal Impairment
There are no studies of Tribenzor in patients with renal impairment. Avoid use in patients with severe renal impairment (creatinine clearance <30 mL/min).
Olmesartan medoxomil. Patients with renal insufficiency have elevated serum concentrations of olmesartan compared with patients with normal renal function. After repeated dosing, AUC was approximately tripled in patients with severe renal impairment (creatinine clearance <20 mL/min). No initial dosage adjustment is recommended for patients with moderate to marked renal impairment (creatinine clearance <40 mL/min). The pharmacokinetics of olmesartan in patients undergoing hemodialysis has not been studied.
Amlodipine. The pharmacokinetics of amlodipine are not significantly influenced by renal impairment.
Hydrochlorothiazide. Thiazide should be used with caution in patients with severe renal disease. In patients with renal disease, thiazides may precipitate azotemia. Cumulative effects of the drug may develop in patients with impaired renal function.
Black Patients
Of the total number of patients who received Tribenzor in a randomized trial, 29% (184/627) were black. Tribenzor was effective in lowering both systolic and diastolic blood pressure in black patients (usually a low-renin population) to the same extent as in non-black patients.
Overdosage
There is no information on overdosage with Tribenzor in humans.
Olmesartan medoxomil. Limited data are available related to overdosage in humans. The most likely manifestations of overdosage would be hypotension and tachycardia; bradycardia could be encountered if parasympathetic (vagal) stimulation occurs. If symptomatic hypotension should occur, supportive treatment should be initiated. The dialyzability of olmesartan is unknown.
Amlodipine. Single oral doses of amlodipine maleate equivalent to 40 mg amlodipine/kg and 100 mg amlodipine/kg in mice and rats, respectively, caused deaths. Single oral amlodipine maleate doses equivalent to 4 or more mg amlodipine/kg or higher in dogs (11 or more times the maximum recommended human dose on a mg/m2 basis) caused a marked peripheral vasodilation and hypotension.
Overdosage might be expected to cause excessive peripheral vasodilation with marked hypotension and possibly a reflex tachycardia. In humans, experience with intentional overdosage of amlodipine is limited.
If massive overdose should occur, active cardiac and respiratory monitoring should be instituted. Frequent blood pressure measurements are essential. Should hypotension occur, cardiovascular support including elevation of the extremities and the judicious administration of fluids should be initiated. If hypotension remains unresponsive to these conservative measures, administration of vasopressors (such as phenylephrine) should be considered with attention to circulating volume and urine output. Intravenous calcium gluconate may help to reverse the effects of calcium entry blockade. As amlodipine is highly protein bound, hemodialysis is not likely to be of benefit.
Hydrochlorothiazide. The most common signs and symptoms of overdose observed in humans are those caused by electrolyte depletion (hypokalemia, hypochloremia, hyponatremia) and dehydration resulting from excessive diuresis. If digitalis has also been administered, hypokalemia may accentuate cardiac arrhythmias. The degree to which hydrochlorothiazide is removed by hemodialysis has not been established. The oral LD50 of hydrochlorothiazide is greater than 10 g/kg in both mice and rats, more than 1000-fold the highest recommended human dose.
Tribenzor Description
Tribenzor is a fixed combination of olmesartan medoxomil (ARB), amlodipine (CCB), and hydrochlorothiazide (thiazide diuretic).
Olmesartan medoxomil, a prodrug, is hydrolyzed to olmesartan during absorption from the gastrointestinal tract.
The olmesartan medoxomil component of Tribenzor is chemically described as 2,3-dihydroxy-2-butenyl 4-(1-hydroxy-1-methylethyl)-2-propyl-1-[p-(o-1H-tetrazol-5-ylphenyl)benzyl]imidazole-5-carboxylate, cyclic 2,3-carbonate. Its empirical formula is C29H30N6O6.
The amlodipine besylate component of Tribenzor is chemically described as 3-ethyl-5-methyl (±) - 2 - [(2 - aminoethoxy)methyl] - 4 - (2 - chlorophenyl) - 1,4 - dihydro - 6 - methyl - 3,5 - pyridinedicarboxylate, monobenzenesulphonate. Its empirical formula is C20H25CIN2O5•C6H6O3S.
The hydrochlorothiazide component of Tribenzor is chemically described as 6-chloro-3,4-dihydro-2H-1,2,4-benzo-thiazidiazine-7-sulfonamide 1,1-dioxide. Its empirical formula is C7H8CIN3O4S2.
The structural formula for olmesartan medoxomil is:
The structural formula for amlodipine besylate is:
The structural formula for hydrochlorothiazide is:
Tribenzor contains olmesartan medoxomil, a white to light yellowish-white powder or crystalline powder, amlodipine besylate, a white to off-white crystalline powder, and hydrochlorothiazide, a white or practically white, crystalline powder. The molecular weights of olmesartan medoxomil, amlodipine besylate, and hydrochlorothiazide are 558.6, 567.1, and 297.7, respectively. Olmesartan medoxomil is practically insoluble in water and sparingly soluble in methanol. Amlodipine besylate is slightly soluble in water and sparingly soluble in ethanol. Hydrochlorothiazide is slightly soluble in water but freely soluble in sodium hydroxide solution.
Each tablet of Tribenzor also contains the following inactive ingredients: silicified microcrystalline cellulose, pregelatinized starch, croscarmellose sodium, and magnesium stearate. The color coating contains polyvinyl alcohol, macrogol/polyethylene glycol 3350, titanium dioxide, talc, iron oxide yellow (20 /5 /12.5 mg, 40 /5 /12.5 mg, 40 /5 /25 mg, 40 /10 /12.5 mg, and 40 /10 /25 mg tablets), iron oxide red (20 /5 /12.5 mg, 40 /10 /12.5 mg, and 40 /10 /25 mg tablets), and iron oxide black (20 /5 /12.5 mg tablets).
Tribenzor - Clinical Pharmacology
Mechanism of Action
The active ingredients of Tribenzor target three separate mechanisms involved in blood pressure regulation. Specifically, amlodipine blocks the contractile effects of calcium on cardiac and vascular smooth muscle cells; olmesartan medoxomil blocks the vasoconstriction and sodium retaining effects of angiotensin II on cardiac, vascular smooth muscle, adrenal and renal cells; and hydrochlorothiazide directly promotes the excretion of sodium and chloride in the kidney leading to reductions in intravascular volume. For a more detailed description of the mechanisms of action for each individual component, see below.
Olmesartan medoxomil. Angiotensin II is formed from angiotensin I in a reaction catalyzed by ACE, kininase II. Angiotensin II is the principal 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. Olmesartan blocks the vasoconstrictor effects of angiotensin II by selectively blocking the binding of angiotensin II to the AT1 receptor in vascular smooth muscle. Its action is, therefore, independent of the pathways for angiotensin II synthesis.
An AT2 receptor is found also in many tissues, but this receptor is not known to be associated with cardiovascular homeostasis. Olmesartan has more than a 12,500-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 a mechanism of many drugs used to treat hypertension. Angiotensin-converting enzyme inhibitors also inhibit the degradation of bradykinin, a reaction also catalyzed by ACE. Because olmesartan does not inhibit ACE (kininase II), it does not affect the response to bradykinin. Whether this difference has clinical relevance is not yet known.
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 circulating angiotensin II levels do not overcome the effect of olmesartan on blood pressure.
Amlodipine. Amlodipine is a dihydropyridine calcium channel blocker that inhibits the transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle. Experimental data suggests that amlodipine binds to both dihydropyridine and nonhydropyridine binding sites. The contractile processes of cardiac muscle and vascular smooth muscle are dependent upon the movement of extracellular calcium ions into these cells through specific ion channels. Amlodipine inhibits calcium ion influx across cell membranes selectively, with a greater effect on vascular smooth muscle cells than on cardiac muscle cells. Negative inotropic effects can be detected in vitro but such effects have not been seen in intact animals at therapeutic doses. Serum calcium concentration is not affected by amlodipine. Within the physiologic pH range, amlodipine is an ionized compound (pKa=8.6), and its kinetic interaction with the calcium channel receptor is characterized by a gradual rate of association and dissociation with the receptor binding site, resulting in a gradual onset of effect.
Amlodipine is a peripheral arterial vasodilator that acts directly on vascular smooth muscle to cause a reduction in peripheral vascular resistance and reduction in blood pressure.
Hydrochlorothiazide. Hydrochlorothiazide is a thiazide diuretic. Thiazides affect the renal tubular mechanisms of electrolyte reabsorption, directly increasing excretion of sodium and chloride in approximately equivalent amounts. Indirectly, the diuretic action of hydrochlorothiazide reduces plasma volume, with consequent increases in plasma renin activity, increases in aldosterone secretion, increases in urinary potassium loss, and decreases in serum potassium. The renin-aldosterone link is mediated by angiotensin II, so co-administration of an angiotensin II receptor antagonist tends to reverse the potassium loss associated with these diuretics.
The mechanism of the antihypertensive effect of thiazides is not fully understood.
Pharmacodynamics
Tribenzor has been shown to be effective in lowering blood pressure. The three components of Tribenzor (olmesartan medoxomil, amlodipine, and hydrochlorothiazide) lower the blood pressure through complementary mechanisms, each working at a separate site and blocking different effects or pathways. The pharmacodynamics of each individual component is described below.
Olmesartan medoxomil. Olmesartan medoxomil doses of 2.5 to 40 mg inhibit the pressor effects of angiotensin I infusion. The duration of the inhibitory effect was related to dose, with doses of olmesartan medoxomil >40 mg giving >90% inhibition at 24 hours.
Plasma concentrations of angiotensin I and angiotensin II and plasma renin activity (PRA) increase after single and repeated administration of olmesartan medoxomil to healthy subjects and hypertensive patients. Repeated administration of up to 80 mg olmesartan medoxomil had minimal influence on aldosterone levels and no effect on serum potassium.
Amlodipine. Following administration of therapeutic doses to patients with hypertension, amlodipine produces vasodilation resulting in a reduction of supine and standing blood pressures
