Drug Information: Irbesartan
Irbesartan is an angiotensin II receptor blocker (ARB) used primarily in the treatment of hypertension. It works by blocking the action of angiotensin II, a hormone that causes blood vessels to constrict. By blocking angiotensin II, Irbesartan helps to relax blood vessels, which lowers blood pressure and improves blood flow. It is also used to protect the kidneys in patients with type 2 diabetes who also have high blood pressure.
Category
Antihypertensive
Mechanism of Action
Irbesartan is an angiotensin II receptor blocker (ARB). Angiotensin II is a potent vasoconstrictor, meaning it causes blood vessels to narrow, which increases blood pressure. It also stimulates the release of aldosterone, a hormone that causes the kidneys to retain sodium and water, further increasing blood volume and pressure. Irbesartan selectively blocks the AT1 receptor, one of the main receptors for angiotensin II. By blocking this receptor, Irbesartan prevents angiotensin II from binding and exerting its effects. This results in vasodilation (relaxation of blood vessels), decreased aldosterone secretion, and reduced sodium and water retention, ultimately leading to a decrease in blood pressure. Unlike ACE inhibitors, ARBs like Irbesartan do not inhibit the breakdown of bradykinin, a substance that can cause a dry cough. Therefore, ARBs are often prescribed to patients who cannot tolerate ACE inhibitors due to this side effect.
Clinical Uses
Irbesartan is primarily used in the treatment of hypertension (high blood pressure). Lowering blood pressure helps prevent strokes, heart attacks, and kidney problems. It is also used to treat diabetic nephropathy (kidney disease caused by diabetes), particularly in patients with type 2 diabetes who have high blood pressure. Irbesartan can help slow the progression of kidney damage in these patients. It may also be used off-label for other conditions where blocking the effects of angiotensin II is beneficial, such as heart failure and prevention of migraine headaches, though its primary and approved use remains in hypertension and diabetic nephropathy.
Dosage
Adults: The usual starting dose for hypertension is 150 mg once daily. The dose may be increased to 300 mg once daily as needed to control blood pressure. For patients with depletion of intravascular volume (e.g., patients treated with diuretics), a starting dose of 75 mg once daily may be considered. For the treatment of nephropathy in type 2 diabetic patients, the usual dose is 300 mg once daily.
Pediatric: For children 6 to 16 years of age, the starting dose is typically 75 mg once daily. The dosage may be adjusted based on blood pressure response, up to a maximum of 150 mg daily for patients weighing less than 50 kg, and up to 300 mg daily for patients weighing 50 kg or more.
Route of Administration: Irbesartan is administered orally, typically as a tablet taken once daily. It can be taken with or without food.
Indications
* Hypertension (high blood pressure)
* Diabetic nephropathy (kidney disease in type 2 diabetics with hypertension)
Contraindications
* Hypersensitivity to Irbesartan or any of its components.
* Pregnancy: Irbesartan can cause fetal harm or death when administered to a pregnant woman.
* Use with Aliskiren in patients with diabetes: Avoid concomitant use of irbesartan with aliskiren in patients with diabetes.
FAQ
Q: What is Irbesartan used for?
A: Irbesartan is used to treat high blood pressure (hypertension) and to help protect the kidneys in patients with type 2 diabetes who also have high blood pressure.
Q: How does Irbesartan work?
A: Irbesartan is an angiotensin II receptor blocker (ARB). It works by blocking the action of angiotensin II, a substance in the body that causes blood vessels to tighten. By blocking angiotensin II, Irbesartan allows blood vessels to relax, which lowers blood pressure.
Q: What are the common side effects of Irbesartan?
A: Common side effects may include dizziness, lightheadedness, fatigue, and diarrhea. Less common but more serious side effects can include allergic reactions and kidney problems. Consult your doctor if you experience any unusual symptoms.
Q: Can I take Irbesartan if I am pregnant?
A: No, Irbesartan is contraindicated in pregnancy as it can cause serious harm or death to the developing fetus. It is crucial to inform your doctor if you are pregnant or planning to become pregnant.
Q: Can I take Irbesartan with other medications?
A: Irbesartan can interact with other medications, so it’s important to inform your doctor about all the medications you are currently taking, including over-the-counter drugs and herbal supplements. Specific medications of concern include other blood pressure medications, diuretics, and nonsteroidal anti-inflammatory drugs (NSAIDs).
Q: How long does it take for Irbesartan to start working?
A: It may take several weeks for Irbesartan to reach its full effect on blood pressure. It is important to continue taking the medication as prescribed, even if you don’t feel an immediate difference.
Q: What should I do if I miss a dose of Irbesartan?
A: If you miss a dose, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not double the dose to catch up.
Q: Does Irbesartan cause a cough like some other blood pressure medications?
A: Irbesartan, being an ARB, is less likely to cause a cough compared to ACE inhibitors. ACE inhibitors can increase bradykinin levels, leading to a dry cough in some patients.
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