Many hypertensive friends need to take sartan antihypertensive drugs for a long time, and many people may have questions. It is said that drugs have three poisons, which do not harm the liver but also the kidney. Can losartan, valsartan, irbesartan, candesartan and telmisartan still protect the kidneys? What is the truth? This has to start with their mechanism of action.
The kidney has afferent arterioles and efferent arterioles. Angiotensin Ⅱ plays an important role in regulating renal artery blood flow and glomerular filtration rate through its 1 receptor. When hypertension or heart failure occurs, the angiotensin system is overactive, producing too much angiotensin II, which can contract the renal efferent arteriole.
This is equivalent to blocking the water outlet, thus increasing the glomerular filtration pressure, improving the glomerular filtration rate of plasma and promoting the reabsorption of water and sodium by renal tubules. The reabsorption of water and sodium will lead to water and sodium retention, which will further aggravate hypertension and heart failure. The increase of glomerular filtration rate, coupled with glomerular damage, will cause protein in blood to leak out of the glomerulus and enter urine, eventually forming proteinuria.
In addition, angiotensin ⅱ can contract to glomerular arterioles, reducing renal blood flow and urine volume, which is the physiological function of angiotensin ⅱ. Sartans are antagonists of angiotensin Ⅱ receptor, which are used to antagonize the adverse effects of angiotensin Ⅱ. Therefore, it can relax the efferent arterioles of the kidney, reduce the perfusion pressure of glomerulus (also known as intracapsular pressure) and reduce the glomerular filtration rate.
Because the increase of intraglomerular pressure often leads to the damage of glomerulus and renal function, especially in diabetic patients, diabetic nephropathy is often complicated. 1 type diabetes or type 2 diabetes with or without hypertension can improve or prevent the deterioration of renal function. In addition, it can protect nephropathy, glomerulonephritis and interstitial nephritis caused by hypertension, reduce proteinuria and improve creatinine clearance rate.
For example, commonly used losartan, irbesartan and candesartan are good choices for patients with hypertension complicated with nephropathy, diabetes complicated with nephropathy and hypertension complicated with diabetes. Their protective effect on kidney has nothing to do with hypotensive effect, but is the result of relaxing renal efferent arterioles. In addition, it can relax the afferent arterioles of the kidney and increase the renal blood flow. Therefore, it can be said that the antihypertensive drugs of sartan protect the kidney, not damage it.
However, patients with bilateral renal vascular disease caused by renal artery stenosis (occlusion) and renal atherosclerosis cannot use it. Because under normal circumstances, angiotensin ⅱ maintains renal perfusion pressure by contracting renal efferent arterioles, the blood flow after renal artery stenosis (occlusion) and renal atherosclerosis is very small. In addition, sartans can relax renal efferent arterioles and reduce renal perfusion pressure, which will further reduce renal filtration rate and renal function, aggravate renal function damage, increase creatinine concentration, and even produce azotemia, which can be recovered after drug withdrawal.
Therefore, the majority of hypertensive friends do not have to worry about the damage of sartan antihypertensive drugs to the kidney. On the contrary, it can effectively protect the kidney, reduce proteinuria, improve creatinine clearance rate and improve or delay the deterioration of renal function. Similarly, patients with diabetic nephropathy can use it even if they do not have high blood pressure. If it is a patient with hypertension and diabetes, it is more suitable.