This article is from "Nankai Sun Pharmacist", which is used for medical science popularization for reference. Can you take half a tablet of irbesartan?Is it to protect the kidneys or to hurt the kidneys?How is it different from valsartan?Can it be used in combination with amlodipine?
Irbesartan is the first-line antihypertensive drug for essential hypertension, belonging to angiotensin II receptor antagonist, mainly acting on the renin-angiotensin-aldosterone system, by antagonizing the vasoconstriction effect of angiotensin II, inhibiting the release of aldosterone, reducing water and sodium retention and lowering blood pressure, its antihypertensive effect is slow, but stable and long-lasting, suitable for patients with mild, moderate and severe hypertension, and is the preferred antihypertensive drug for the initiation and maintenance of hypertension. In addition, irbesartan also has a good cardiovascular protective effect, can reverse left ventricular hypertrophy, anti-atherosclerosis, inhibit fibroblast proliferation and atrial fibrillation electrical remodeling, and can improve glucose and lipid metabolism, reduce urine protein excretion, especially suitable for hypertension patients with left ventricular hypertrophy, cardiac insufficiency, atrial fibrillation, coronary heart disease, diabetic nephropathy, microalbuminuria or proteinuria, metabolic syndrome (hyperlipidemia, diabetes, obesity or hyperuricemia). In addition, enalapril, benazepril and other pril antihypertensive drugs can cause adverse reactions such as dry cough and angioedema, and for patients who cannot tolerate it, sartan antihypertensive drugs such as irbesartan can be selected.
At present, there are two main specifications of irbesartan in clinical use: 150mg tablets and 300mg tablets, the general initial dose and maintenance dose are 150mg per day, and if irbesartan 150mg once a day cannot effectively control blood pressure, the dose can be increased to 300mg. For hypertensive patients with type 2 diabetes, the initial dose of irbesartan should be 150 mg once daily and can be gradually increased to 300 mg once daily as a maintenance dose for diabetic nephropathy.
There are two specifications of irbesartan, which are very convenient to use clinically, and it is not recommended to break open and take half a tablet, mainly for three reasons: first, because the drug dose is determined through rigorous human clinical trials, and the safety and efficacy are ***, and second, because 150mg once a day can better control blood pressure for 24 hours than 75mg, which is more conducive to stable blood pressure. The third reason is that hypertension is a polygenic hereditary disease, which is not very clear at present, only the long-term blood pressure target can effectively prevent the occurrence of cardiovascular and cerebrovascular events, and the blood pressure target is based on the long-term regular use of antihypertensive drugs.
Of course, in some special cases, irbesartan can take half a tablet, such as hemodialysis and patients over 75 years old, the initial dose can be considered 75mg, this is because irbesartan is excreted through the urine through the kidneys, renal insufficiency is easy to cause drug accumulation, increasing the risk of adverse reactions, and the elderly are more sensitive to drugs, and they are also high-risk groups for adverse reactions. In addition, if the blood pressure control is achieved and has been very stable for six months to one year, you can take 75 mg of irbesartan under the guidance of a doctor, and you should strictly adhere to a healthy lifestyle during the dose reduction process, and at the same time monitor the blood pressure changes more closely.
Irbesartan itself is not nephrotoxic, will not cause kidney damage, and can reduce renal vascular damage, reduce urine protein, and protect kidney function by antagonizing a variety of physiological effects of angiotensin II, although irbesartan will not cause kidney damage, but it can be excreted through the kidneys, patients with renal impairment use of irbesartan is easy to cause an increase in blood creatinine and blood potassium levels, the process of medication should be closely monitored, once the blood creatinine level increases by more than 30%, the drug dose should be reduced, and the blood creatinine level increases by 50% The above should be stopped immediately, and it can generally return to normal after stopping the drug.
Irbesartan differs from valsartan in that:
1.Antihypertensive effect: irbesartan and valsartan both have phenylimidazole rings, but the modification of imidazole rings varies, resulting in different physical and chemical properties, such as fat solubility, tissue penetration, Irbesartan is modified by aromatic heterocyclic, which has strong lipid solubility and tissue penetration, higher affinity with AT1 receptors, stronger antagonism to angiotensin II, good oral absorption, and higher bioavailability, so its antihypertensive effect is better than valsartan.
2.Antihypertensive stability: Compared with valsartan, irbesartan has a higher antihypertensive trough-to-peak ratio, has a hypotensive effect throughout the medication period, has small blood pressure fluctuations, and has better antihypertensive stability.
3.Duration of action: irbesartan has strong lipid solubility and tissue penetration, is more widely distributed in the body, binds more firmly to AT1 receptors, and dissociates slowly, therefore, its half-life is longer, which can reach 15 hours, while valsartan has a half-life of only 6 hours, therefore, irbesartan has a longer antihypertensive effect.
4.Dosage: The usual dose range of irbesartan is 150-300mg (1-2 tablets), eating will not significantly affect its bioavailability, it can be taken before or after meals, the usual dose range of valsartan is 80-160mg (1-2 tablets), eating will affect the absorption of valsartan, it is recommended to take it on an empty stomach.
Amlodipine has the effect of directly dilating the arteries, irbesartan dilates the arteries and veins, the combination of the two drugs has a synergistic antihypertensive effect, and can protect vascular endothelial function, anti-atherosclerosis, reverse left ventricular hypertrophy, reduce albuminuria, protect renal function, improve the protective effect of target organs, amlodipine common adverse reactions of ankle edema, can be reduced or offset by irbesartan, studies have confirmed that low-dose application of amlodipine combined with irbesartan for the initial ** of hypertensive patients, the blood pressure control rate and compliance rate can be significantly improved. Finally, irbesartan can also partially block the adverse effects of amlodipine-induced increased reflex**sensory tone and increased heart rate. Therefore, the combination of the two drugs is the preferred combination drug regimen recommended in the latest version of the Chinese Guidelines for the Prevention and Treatment of Hypertension.