Avapro - General Information
Avapro is an angiotensin II receptor antagonist used mainly for the treatment of hypertension.
Pharmacology of Avapro
Avapro is a specific competitive antagonist of AT1 receptors with a much greater affinity (more than 8500-fold) for the AT1 receptor than for the AT2 receptor and no agonist activity.
Avapro for patients
Pregnancy: Female patients of childbearing age should be told about the consequences of second- and third-trimester exposure to drugs that act on the renin-angiotensin system, and they should also be told that these consequences do not appear to have resulted from intrauterine drug exposure that has been limited to the first trimester. These patients should be asked to report pregnancies to their physicians as soon as possible.
No significant drug-drug pharmacokinetic (or pharmacodynamic) interactions have been found in interaction studies with hydrochlorothiazide, digoxin, warfarin, and nifedipine.
In vitro studies show significant inhibition of the formation of oxidized irbesartan metabolites with the known cytochrome CYP 2C9 substrates/inhibitors sulphenazole, tolbutamide and nifedipine. However, in clinical studies the consequences of concomitant irbesartan on the pharmacodynamics of warfarin were negligible. Based on in vitro data, no interaction would be expected with drugs whose metabolism is dependent upon cytochrome P450 isozymes 1A1, 1A2,2A6,2B6,2D6,2E1,or 3A4.
In separate studies of patients receiving maintenance doses of warfarin, hydrochlorothiazide, or digoxin, irbesartan administration for 7 days had no effect on the pharmacodynamics of warfarin (prothrombin time) or pharmacokinetics of digoxin. The pharmacokinetics of irbesartan were not affected by coadministration of nifedipine or hydrochlorothiazide.
AVAPRO is contraindicated in patients who are hypersensitive to any component of this product.
Additional information about Avapro
Avapro Indication: For the treatment of hypertension, and for the treatment of diabetic nephropathy with an elevated serum creatinine and proteinuria (>300 mg/day) in patients with type 2 diabetes and hypertension.
Mechanism Of Action: Avapro is a nonpeptide angiotensin II antagonist that selectively blocks the binding of angiotensin II to the AT1 receptor. In the renin-angiotensin system, angiotensin I is converted by angiotensin-converting enzyme (ACE) to form angiotensin II. Angiotensin II stimulates the adrenal cortex to synthesize and secrete aldosterone, which decreases the excretion of sodium and increases the excretion of potassium. Angiotensin II also acts as a vasoconstrictor in vascular smooth muscle. Avapro, by blocking the binding of angiotensin II to the AT1 receptor, promotes vasodilation and decreases the effects of aldosterone. The negative feedback regulation of angiotensin II on renin secretion also is inhibited, but the resulting rise in plasma renin concentrations and consequent rise in angiotensin II plasma concentrations do not counteract the blood pressure–lowering effect that occurs.
Drug Interactions: Amiloride Increased risk of hyperkaliemia
Drospirenone Increased risk of hyperkaliemia
Spironolactone Increased risk of hyperkaliemia
Potassium Increased risk of hyperkaliemia
Lithium The ARB increases serum levels of lithium
Triamterene Increased risk of hyperkaliemia
Food Interactions: Take without regard to meals.
Generic Name: Irbesartan
Synonyms: Not Available
Drug Category: Antihypertensive Agents; Angiotensin II Receptor Antagonists
Drug Type: Small Molecule; Approved
Other Brand Names containing Irbesartan: Avalide; Avapro; Irbesarran; Irbesartan [Usan-Inn]; Lrbesartan;
Absorption: Rapid and complete with an average absolute bioavailability of 60-80%. Food has no affect on bioavailability.
Toxicity (Overdose): Hypotension and tachycardia; bradycardia might also occur from overdose, LD50=mg/kg(orally in rat)
Protein Binding: 90% bound to serum proteins (primarily albumin and a1-acid glycoprotein) with negligible binding to cellular components of blood.
Biotransformation: Hepatic. Irbesartan is metabolized via glucuronide conjugation and oxidation. In vitro studies of irbesartan oxidation by cytochrome P450 isoenzymes indicated irbesartan was oxidized primarily by 2C9; metabolism by 3A4 was negligible.
Half Life: 11-15 hours
Dosage Forms of Avapro: Tablet Oral
Chemical IUPAC Name: 2-butyl-3-[[4-[2-(2H-tetrazol-5-yl)phenyl]phenyl]methyl]-1,3-diazaspiro[4.4]non-1-en-4-one
Chemical Formula: C25H28N6O
Irbesartan on Wikipedia: http://en.wikipedia.org/wiki/Irbesartan
Organisms Affected: Humans and other mammals