RiteMED Irbesartan Special Precautions

Fetal Toxicity: Use of drugs that act on the renin-angiotensin-aldosterone 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 irbesartan as soon as possible. These adverse outcomes are usually associated with the use of these drugs in the second and third trimester of pregnancy. Most epidemiologic studies examining fetal abnormalities after exposure to antihypertensive use in the first trimester have not distinguished drugs affecting the renin-angiotensin-aldosterone system from other antihypertensive agents. Appropriate management of maternal hypertension during pregnancy is important to optimize outcomes for both mother and fetus.
In the unusual case that there is no appropriate alternative to therapy with drugs affecting the renin-angiotensin-aldosterone system for a particular patient, the mother should be informed of the potential risk to the fetus. Perform serial ultrasound examinations to assess the intra-amniotic environment. If oligohydramnios is observed, discontinue irbesartan, unless it is considered lifesaving for the mother. Fetal testing may be appropriate, based on the week of pregnancy. However, patients and physicians should be aware that oligohydramnios may not appear until after the fetus has sustained irreversible injury.
Infants with history of in utero exposure to irbesartan should be closely observed for hypotension, oliguria and hyperkalemia. If oliguria or hypotension occurs, attention should be directed toward support of blood pressure and renal perfusion. Exchange transfusion or dialysis may be required as means of reversing hypotension and/or substituting for disordered renal function.
Hypotension in Volume- or Salt-depleted Patients: Symptomatic hypotension may be observed in patients who are intravascularly volume- or sodium-depleted (e.g., those treated with high-dose diuretics). These conditions should be corrected before starting irbesartan therapy, or a lower starting dose should be used.
Hyperkalemia: Hyperkalemia may occur during irbesartan treatment, especially in the presence of renal impairment, overt proteinuria due to diabetic renal disease, and/or heart failure. Monitor closely serum potassium in patients at risk.
Aortic and Mitral Valve Stenosis, Obstructive Hypertrophic Cardiomyopathy: As with other vasodilators, special caution is indicated in patients suffering from aortic or mitral valve stenosis, or obstructive hypertrophic cardiomyopathy.
Primary Aldosteronism: Generally, patients with primary aldosteronism will not respond to antihypertensive agents acting through inhibition of the renin-angiotensin-aldosterone system; thus, irbesartan use is not recommended.
General: Treatment with drugs that affect the renin-angiotensin-aldosterone system has been associated with acute hypotension, azotemia, oliguria or, rarely, acute renal failure in patients whose vascular tone and renal function depend predominantly on the activity of this system (e.g., patients with severe congestive heart failure or underlying renal disease, including renal artery stenosis). As with any antihypertensive agent, excessive hypotension in patients with ischemic cardiopathy or ischemic cardiovascular disease could result in a myocardial infarction or stroke.
Effect on Ability to Drive and Use Machines: No studies on the effects on the ability to drive and use machines have been performed. However, dizziness or fatigue may occasionally occur when taking antihypertensive therapy. Exercise caution when driving vehicles or operating machinery.
Renal Impairment and Kidney Transplantation: There is an increased risk of severe hypotension and renal insufficiency when patients with unilateral or bilateral renal artery stenosis are treated with drugs that affect the renin-angiotensin-aldosterone system. Increases in blood urea nitrogen (BUN) and serum creatinine may occur in these patients.
Periodic monitoring of potassium and creatinine serum levels is recommended when irbesartan is used in patients with impaired renal function.
There is no experience regarding the use of irbesartan in patients with recent kidney transplantation.
Use in Children: Irbesartan 4.5 mg/kg/day, once daily, did not appear to decrease blood pressure effectively in children 6 to 16 years old. Irbesartan has not been studied in children less than 6 years old.
Use in the Elderly: There were no age-related differences in efficacy or safety profile of irbesartan, but greater sensitivity of some older individuals cannot be ruled out.