There are many similarities between ACEI and ARB in terms of antihypertensive mechanism and organ protection, and although there are different pathways to inhibit RAS activation, they do share a common effect of inhibiting RAS activation. It has not been used as an initial agent for active use. In fact, ARBs are different from ACEIs in many ways. Basic research has found that ARB activates AT2 receptors by inhibiting AT1 receptors, and that AT2 receptor activation can mediate the production of the vasodilator nitric oxide (NO) through the release of endothelium-derived bradykinin and prostaglandins. It has been clearly found that activation of AT2 receptors can produce antiproliferative effects after endothelial damage and in coronary vascular endothelial cells. In general, the higher the selectivity of ARBs, the greater the selectivity for AT 1 receptors and the greater the degree of activation of AT2. ARB drugs differ in their selectivity. The affinity for AT 1 receptors is approximately 1000-fold higher for cloxacin than for AT 2 receptors, the affinity for AT 1 receptors is approximately 3000-fold higher for telmisartan than for AT 2 receptors, the difference in affinity between the two receptors is more than 8500-fold for irbesartan, 10,000-fold for candesartan, and 30,000-fold for valsartan, which has the highest affinity for AT 1 receptors. There is no dose-dependent decrease in blood pressure with cloxacin, while the antihypertensive efficacy of irbesartan, candesartan, and valsartan increases with increasing dose, a characteristic that should be taken into account in the clinical treatment of hypertension. ACEI has a better antihypertensive effect by blocking ACE enzymes and promoting bradykinin production, which leads to an increase in NO. ACEI has only the affinity for tissues to determine the antihypertensive efficacy, but not the affinity for receptors. In the clinical study, it was also found that the compliance of ARB treatment is 64%, while the compliance of ACEI treatment is only 52%, ARB has better compliance than ACEI. Therefore, the specific characteristics of ARB determine its clinical antihypertensive effect. ARB is a long-acting, stable and potent antihypertensive drug in the treatment of hypertension in line with the characteristics of chronotherapeutics. Most of the current studies show that the onset of hypertension, myocardial ischemia, ventricular arrhythmias, angina pectoris and sudden cardiac death show a diurnal rhythm. The peak onset of these diseases is between 6:00 a.m. and 12:00 p.m., and physiological factors (e.g., blood pressure, heart rate, platelet coagulation, catecholamine release) also follow a rhythm. Human blood pressure varies rhythmically over a 24-hour period: it rises rapidly to a peak within a few hours of awakening in the early morning and falls to a trough between midnight and early morning. Usually the nighttime drop in blood pressure is greater than 10% of the daytime drop in blood pressure, which follows an aryeplate curve. Most patients with hypertension have a pattern of blood pressure fluctuations similar to that of normal people, with only the average blood pressure level being higher than that of normal people, and some patients have a nighttime blood pressure drop of less than 10% of the daytime blood pressure, showing a non-ascending curve. Therefore, understanding the rhythmical pattern of blood pressure and its relationship with cardiovascular events is an important guide to the clinical treatment of hypertension. As a clinician, you should master these rhythmic changes in the process of diagnosis and treatment, and combine them with the pharmacokinetic and pharmacodynamic changes of drugs to develop the best treatment plan and to administer drugs at the right time, which will help to improve the efficacy of drugs and reduce the occurrence of adverse drug reactions. The ideal antihypertensive drug should be able to lower blood pressure smoothly within 24 hours and reduce the overall blood pressure level; significantly reduce the patient’s early morning blood pressure and deter early morning sleepiness. The ideal antihypertensive drug should be able to lower the overall blood pressure level within 24 hours, significantly reduce the early morning blood pressure of patients, stop the sudden rise of blood pressure in the morning after waking up, and enable hypertensive patients to safely pass the time of high cardiovascular and cerebrovascular events. ARB has such long-lasting, smooth and efficient antihypertensive characteristics, which can be confirmed from three aspects. From the ARBs currently on the market, the trough/peak (T/P) ratio, which reflects the long-lasting efficacy of antihypertensive, is >50%. The T/P value of telmisartan can be over 95%. As demonstrated in two randomized, double-blind, placebo-controlled clinical trials conducted abroad with amlodipine and coxsartan, respectively, temisartan not only restored the “normal” blood pressure pattern in hypertensive patients when administered in the morning, but also had a better antihypertensive effect than amlodipine and coxsartan, especially in the last 4 hours of the dosing interval, i.e., the early morning danger time for hypertensive patients. ARB drugs have a better T/P value, therefore, the clinical use of hypertension treatment has the characteristic of high blood pressure rate. 2, reflecting the smoothness of antihypertensive index – smoothing index (SI) ARB of telmisartan, irbesartan, and valsartan and candesartan have a high smoothing index, indicating a smooth antihypertensive, long-term application to avoid the transitional fluctuations of blood pressure and excessive variability caused by organ damage. 3, reflecting the antihypertensive potency of the index – blood pressure reduction ARB in different hypertensive patients, its antihypertensive magnitude varies, a study found that the ARB valsartan 80mg antihypertensive magnitude at 8 weeks of treatment is equivalent to enalapril 4 times the dose (20mg) of antihypertensive magnitude, temisartan 80mg and valsartan Temisartan 80mg and valsartan 80mg were superior to amlodipine 5mg-10mg for both systolic and diastolic blood pressure averaged over 24 hours. The fixed combination of ARB and hydrochlorothiazide plays an important role in lowering blood pressure. Since hypertension is a disease with multiple mechanisms, and antihypertensive drugs often have a single mechanism for lowering blood pressure, the use of a single drug is not sufficient to fully control blood pressure to the desired level in many patients during the process of lowering blood pressure, thus the principle of combination drug therapy is proposed. The US JNC7 states: monotherapy at level 1 hypertension and combination therapy at level 2 hypertension; the 2004 hypertension guidelines also suggest that combination therapy can be considered in high-risk hypertensive patients and hypertensive patients at level 2. The higher the blood pressure level, the greater the proportion of combination drugs. There are 2 types of drug combinations, one is a temporary combination of prescriptions and the other is a fixed combination of small doses in a fixed compound. A reasonable combination of drugs has synergistic antihypertensive properties, low side effects and high attainment rate. The time to onset of antihypertensive effect of valsartan 50mg/hydrochlorothiazide 12.5mg was advanced from 3 weeks to 1 week for the original valsartan (single drug), and the T/P ratio increased from 67% to 85% for the original single drug, and the magnitude of antihypertensive effect also increased significantly. Irbesartan 150mg/Hydrochlorothiazide 12.5mg (Ambronol) was brought forward from 2 weeks to 1 week for the original single agent (Irbesartan). The T/P ratio was >80% and blood pressure was reduced to