Astrotel H

Uses

Telmisartan and hydrochlorothiazide is used 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 classes to which this drug principally belongs. There are no controlled trials demonstrating risk reduction with Telmisartan and Hydrochlorothiazide.

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 the selection of therapy

Telmisartan and Hydrochlorothiazide is not used for initial therapy for the treatment of hypertension

Telmisartan and Hydrochlorothiazide may be used alone or in combination with other antihypertensive agents.

Astrotel H is also used to associated treatment for these conditions: Acidosis, Renal Tubular, Calcium Nephrolithiasis, Cirrhosis of the Liver, Congestive Heart Failure (CHF), Diabetes Insipidus, Edema, High Blood Pressure (Hypertension), Hypertension,Essential, Hypokalemia caused by diuretics, Nephrotic Syndrome, Premenstrual tension with edema, Sodium retention, Stroke, Prophylaxis of preeclampsiaCardiovascular Events, Diabetic Nephropathy, Heart Failure, High Blood Pressure (Hypertension)

How Astrotel H works

Hydrochlorothiazide is transported from the circulation into epithelial cells of the distal convoluted tubule by the organic anion transporters OAT1, OAT3, and OAT4. From these cells, hydrochlorothiazide is transported to the lumen of the tubule by multidrug resistance associated protein 4 (MRP4).

Normally, sodium is reabsorbed into epithelial cells of the distal convoluted tubule and pumped into the basolateral interstitium by a sodium-potassium ATPase, creating a concentration gradient between the epithelial cell and the distal convoluted tubule that promotes the reabsorption of water.

Hydrochlorothiazide acts on the proximal region of the distal convoluted tubule, inhibiting reabsorption by the sodium-chloride symporter, also known as Solute Carrier Family 12 Member 3 (SLC12A3). Inhibition of SLC12A3 reduces the magnitude of the concentration gradient between the epithelial cell and distal convoluted tubule, reducing the reabsorption of water.

Telmisartan interferes with the binding of angiotensin II to the angiotensin II AT₁-receptor by binding reversibly and selectively to the receptors in vascular smooth muscle and the adrenal gland. As angiotensin II is a vasoconstrictor, which also stimulates the synthesis and release of aldosterone, blockage of its effects results in decreases in systemic vascular resistance. Telmisartan does not inhibit the angiotensin converting enzyme, other hormone receptors, or ion channels. Studies also suggest that telmisartan is a partial agonist of PPARγ, which is an established target for antidiabetic drugs. This suggests that telmisartan can improve carbohydrate and lipid metabolism, as well as control insulin resistance without causing the side effects that are associated with full PPARγ activators.

Dosage

Astrotel H dosage

Initiate a patient whose blood pressure is not adequately controlled with telmisartan monotherapy 80 mg: Telmisartan and hydrochlorothiazide 80 mg/12.5 mg once daily. Dose can be titrated up to 160 mg / 25 mg after 2 to 4 weeks, if necessary.

Initiate a patient whose blood pressure is not adequately controlled by 25 mg once daily of hydrochlorothiazide, or is controlled but who experienceshypokalemiawith this regimen: Telmisartan and hydrochlorothiazide 80 mg / 12.5 mg once daily. Dose can be titrated up to 160 mg / 25 mg after 2 to 4 weeks, if necessary.

Telmisartan and hydrochlorothiazide may be administered with other antihypertensive drugs.

Telmisartan tablets may be administered with other antihypertensive agents with or without food.

Side Effects

Telmisartan: Upper respiratory infection (7%), Urinary tract infection (l%), Back pain (3%), Diarrhea (3%), Myalgia (3%), Fatigue (1%), Sinusitis (3%), Peripheral edema (1%), Chest pain (1 %), Hypertension (1%), Dyspepsia (1%), Headache (1%), Dizziness (1%), Pharyngitis (1%)

Hydrochlorothiazide: Anorexia, Epigastric distress, Hypotension, Orthostatic hypotension, Photosensitivity, Anaphylaxis, Anemia, Confusion, Erythema multiforme, Stevens-Johnson syndrome, Exfoliative dermatitis including toxic epidermal necrolysis, Dizziness, Hypokalemia and/or hypomagnesemia, Hyperuricemia

Toxicity

The oral LD₅₀ of hydrochlorothiazide is >10g/kg in mice and rats.

Patients experiencing an overdose may present with hypokalemia, hypochloremia, and hyponatremia. Treat patients with symptomatic and supportive treatment including fluids and electrolytes. Vasopressors may be administered to treat hypotension and oxygen may be given for respiratory impairment.

Intravenous LD₅₀ in rats is 150-200 mg/kg in males and 200 to 250 mg/kg in females. Acute oral toxicity is low: no deaths and no changes occurred in rats or dogs at 2000 mg/kg, the highest dose tested. Limited data are available with regard to overdosage in humans. The most likely manifestations of overdosage with telmisartan would be hypotension, dizziness and tachycardia; bradycardia could occur from parasympathetic (vagal) stimulation.

Precaution

Hepatic insufficiency, biliary obstruction, renal impairment, renaly artery stenosis. Correct volume depletion before initiating treatment. Monitor serum potassium levels regularly, especially in elderly and renally-impaired patients.

Interaction

Lithium, kaliuretic diuretics, laxatives, corticosteroids, ACTH, amphotericin, carbenoxolone, penicillin G, salicylates, K-sparing diuretics, K supplements, K salt substitutes drugs that cause hyperkalaemia, digitalis glycosides, antiarrhythmic agents, drugs known to induce torsades de pointes, alcohol, barbiturates, narcotics, oral antidiabetics, insulin, anion-exchange resins, NSAIDs, nondepolarising skeletal muscle relaxants, pressor amines, allopurinol, Ca salts, beta-blockers, diazoxide, anticholinergics, amantadine, cytotoxics.

Volume of Distribution

The volume of distribution varies widely from one study to another with values of 0.83-4.19L/kg.

• 500 L

Elimination Route

An oral dose of hydrochlorothiazide is 65-75% bioavailable, with a T_max of 1-5 hours, and a C_max of 70-490ng/mL following doses of 12.5-100mg. When taken with a meal, bioavailability is 10% lower, C_max is 20% lower, and T_max increases from 1.6 to 2.9 hours.

Absolute bioavailability depends on dosage. Food slightly decreases the bioavailability (a decrease of about 6% is seen when the 40-mg dose is administered with food).

Half Life

The plasma half life of hydrochlorothiazide is 5.6-14.8h.

Bi-exponential decay kinetics with a terminal elimination half-life of approximately 24 hours.

Clearance

The renal clearance of hydrochlorothiazide in patients with normal renal function is 285mL/min. Patients with a creatinine clearance of 31-80mL/min have an average hydroxychlorothiazide renal clearance of 75mL/min, and patients with a creatinine clearance of ≤30mL/min have an average hydroxychlorothiazide renal clearance of 17mL/min.

• >800 mL/min

Elimination Route

Hydrochlorothiazide is eliminated in the urine as unchanged hydrochlorothiazide.

Following either intravenous or oral administration of 14C-labeled telmisartan, most of the administered dose (>97%) was eliminated unchanged in feces via biliary excretion; only minute amounts were found in the urine (0.91% and 0.49% of total radioactivity, respectively).

Pregnancy & Breastfeeding use

Pregnancy Category D. Use of drugs that act on the renin-angiotensin system during the second and third trimesters of pregnancy reduces fetal renal function and increases fetal and neonatal morbidity and death. Resulting oligohydramnios can be associated with fetal lung hypoplasia and skeletal deformations. Potential neonatal adverse effects include skull hypoplasia, anuria, hypotension, renal failure, and death. When pregnancy is detected, discontinue Telmisartan and hydrochlorothiazide as soon as possible.

Nursing Mothers: It is not known whether telmisartan is excreted in human milk, but telmisartan was shown to be present in the milk of lactating rats. Thiazides appear in human milk. Because of the potential for adverse effects on the nursing infant, decide whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.

Contraindication

Telmisartan and hydrochlorothiazide is contraindicated:

• In patients who are hypersensitive to any component of this product
• In patients with anuria.
• For co-administration with aliskiren in patients with diabetes

Special Warning

Dose Adjustment For Hepatic Impairment: Initiate patients with biliary obstructive disorders or hepatic insufficiency under close medical supervision using the 40 mg/12.5 mg combination. Telmisartan and hydrochlorothiazide tablets are not recommended for patients with severe hepatic impairment

Use In Patients With Renal Impairment: Safety and effectiveness of Telmisartan and hydrochlorothiazide in patients with severe renal impairment (CrCl ≤ 30 mL/min) have not been established. In patients with severe renal impairment, Telmisartan and hydrochlorothiazide tablets are not recommended. No dose adjustment is required in patients with mild (CrCl 60 to 90 mL/min) or moderate (CrCl 30 to 60 mL/min) renal impairment.

Pediatric Use: Safety and effectiveness in pediatric patients have not been established.

Acute Overdose

Telmisartan: Limited data are available with regard to overdosage of telmisartan in humans. The most likely manifestations of overdosage with telmisartan are hypotension, dizziness, and tachycardia; bradycardia could occur from parasympathetic (vagal) stimulation. If symptomatiazc hypotension should occur, supportive treatment should be instituted. Telmisartan is not removed by hemodialysis.

Hydrochlorothiazide: The most common signs and symptoms observed in patients with a hydrochlorothiazide overdose 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.

Storage Condition

Store at 25° C. Tablets should not be removed from blisters until immediately before administration.

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