Which antihypertensive drug is the best antihypertensive drug?
Advantages and disadvantages of commonly used antihypertensive drugs!
Mr. Zhang, who was admitted to the hospital this year with complaints of "dizziness and chest tightness for more than a month", was diagnosed with hypertension.
Mr. Zhang's best friend since childhood, Mr. Li, recently developed headache, dizziness, and vomiting, and was also diagnosed with hypertension after being admitted to the hospital.
However, the two men were not taking the same medications, as Mr. Zhang's primary care physician recommended that he take nifedipine controlled-release tablets, while Mr. Li's primary care physician recommended that he take amlodipine benzoate tablets orally.
The two men expressed confusion as to why they were taking different medications for same hypertension and similar symptoms. And aren't nifedipine controlled-release tablets and amlodipine besylate tablets both antihypertensive drugs of the diphenhydramine class?
How do the antihypertensive drugs of the diphenhydramine class lower blood pressure?
It is a selective calcium channel blocking drug, which usually acts selectively on the L-type calcium channel; after binding to the inactivated calcium channel protein binding site on the cell membrane, it blocks the process of channel recovery, thereby inhibiting the inward flow of calcium ions. The inward flow of calcium ions is then inhibited.
In other words, the inward flow of calcium ions is reduced after the administration of diphenhydramine, which can affect the contractile activity of a vascular smooth muscle; the contractile activity of vascular smooth muscle mainly relies on the inward flow of extracellular calcium ions.
In other words, diphenhydramine has a significant vasodilatory effect, mainly on arterial vessels such as coronary arteries, renal arteries, cerebral arteries, and limb arteries, thus causing the pressure in the blood vessels to drop, which has a significant blood pressure lowering effect.
The use of diphenhydramine can also affect the function of the heart, generally producing a "negative muscle force, negative frequency, negative conduction" effect, reducing the blood pumped from the heart to a certain extent, and can also lower blood pressure.
Like vascular smooth muscle, the contractility of the myocardium decreases as calcium ions are reduced in the myocardial cells, resulting in a negative inotropic effect.
In addition, diphenhydramine can affect the 0-phase depolarization process and 4-phase depolarization process of the sinoatrial node and atrioventricular node cell membrane, reducing the autoregulation of cardiac autoregulatory cells and slowing down the heart rate (the frequency of heartbeat per minute), which has a negative frequency effect; and at the same time, it prolongs the atrioventricular conduction time, which prolongs the effective induction period, which has a negative conduction effect.
In short, the antihypertensive effect of diphenhydramine is indisputable! However, since the introduction of antihypertensive drugs, there have been three waves of newer and newer antihypertensive drugs, what are the differences between each generation of antihypertensive drugs? How should hypertensive patients choose them?
The first generation of antihypertensive drugs - mainly nifedipine
Nifedipine, itself active, does not need to go through the liver metabolism to play the role of antihypertensive; that is, rapid antihypertensive, but there are risks, vasodilatation too fast easily leads to patients with rapid heartbeat, facial redness, and other adverse reactions.
In clinical practice, the half-life of the conventional form of nifedipine is short, generally 1.7 to 3.4 hours, so it tends to make blood pressure fluctuate significantly; in addition, the short half-life also means that it needs to be taken several times in a day, which brings inconvenience to patients. Therefore, nifedipine is now generally not used for long-term control, but only for temporary blood pressure lowering.
However, there are different views on whether to swallow the drug directly or sublingually; some scholars believe that sublingual administration should be used because the rich venous plexus in the sublingual mucosa is conducive to the rapid absorption of the drug, which can exert antihypertensive effects within a few minutes, and the antihypertensive effect is obvious.
However, some scholars do not recommend sublingual administration, because the antihypertensive effect of nifedipine is rapid, and sublingual administration is even faster, and it is easy to have insufficient blood supply to the heart and brain vessels due to low blood pressure, dizziness, and other adverse reactions.
Swallowing directly or sublingual is feasible, but sublingual needs to control the dose, small doses of nifedipine sublingual not only good antihypertensive effect but also not too many adverse reactions.
Nifedipine controlled-release tablets and felodipine extended-release tablets are the second generations
Combined with the characteristics of the first generation of nifedipine, the second generation of dihydropyridine calcium antagonists was changed to a slow-release dosage form, which releases the drug slowly to achieve a long-lasting effect of lowering blood pressure.
Nifedipine controlled-release tablets and felodipine extended-release tablets are commonly used. Note that this type of diphenhydramine antihypertensive drug cannot be broken open for use, is easily affected by gastrointestinal function, and does not perform its original efficacy.
Nifedipine controlled-release tablets can well control the morning peak phenomenon of blood pressure, that is, the performance of the rapid rise in blood pressure that occurs between the nighttime blood pressure minimum and the early morning.
Nifedipine controlled-release tablets are long-acting dosage forms with uniform release and zero kinetic release, with no first-pass effect, reaching a stable concentration within 6 hours of administration and maintaining a nearly constant drug concentration for the next 24 hours. Because of this, it can lower blood pressure smoothly, reduce blood pressure fluctuations, and control the morning peak phenomenon of blood pressure.
Felodipine extended-release tablets also belong to medium- and long-acting preparations, with a drug half-life of 10-22 hours, relatively smooth antihypertensive effects, and few adverse reactions, and are more suitable for the control of mild and moderate hypertension.
A study on patients with mild to moderate hypertension showed that after taking felodipine extended-release tablets for 8 weeks, the systolic blood pressure decreased by about 19 mmHg and the diastolic blood pressure decreased by about 14 mmHg, and the patient's blood pressure attainment rate could reach 87.2%; that is, for patients with mild to moderate hypertension, taking felodipine extended-release tablets has a significant effect on lowering blood pressure.
In addition, some scholars compared the antihypertensive effect of nifedipine controlled-release tablets with that of felodipine extended-release tablets, and the efficacy of the two drugs was similar in patients with mild to moderate hypertension; however, for patients with severe hypertension, nifedipine controlled-release tablets were more effective than felodipine extended-release tablets.
However, felodipine extended-release tablets can also be used in patients with renal hypertension, not only for lowering blood pressure but also for protecting the kidneys. The reason why it can protect the kidneys is related to the ability of felodipine extended-release tablets to reduce the intracapsular pressure of the glomerulus and to achieve the expansion of the small arteries into the glomerulus so that the damage to the kidneys can be reduced.
Amlodipine besylate tablets as the third generation
Recently developed third-generation dihydropyridine calcium antagonists have a longer half-life than nifedipine controlled-release tablets and felodipine extended-release tablets; the half-life is more than 30 hours and can even reach 90 hours, mainly represented by amlodipine besylate tablets.
Compared with other dihydropyridine calcium antagonists, amlodipine has the following three main differences.
First, it has the longest half-life, which can ensure effective blood concentration within 24 hours and well control the blood pressure level, which includes nighttime blood pressure and early morning hypertension; meanwhile, maintaining the stability of early morning hypertension is also related to the fact that amlodipine tablets can accelerate the release of endothelial diastolic factor nitric oxide in the patient's organism, which makes the patient's early morning blood pressure lower.
Secondly, it is absorbed slowly after being ingested into the body, and the peak blood concentration fluctuation is small, so the side effects of reflex sympathetic excitation produced by amlodipine are light, and few patients have adverse reactions such as palpitations, headache, and flushing due to rapid vasodilation. Compared with other types of antihypertensive drugs, amlodipine can significantly improve blood pressure variability, providing a smooth lowering of blood pressure and protecting target organs.
In addition, the lesser side effect of reflex sympathetic excitation produced by amlodipine is also related to the fact that amlodipine is an L/N calcium dual channel blocker, which can reduce the patient's sympathetic excitation by producing a blocking effect on the body's N-type calcium channels.
Third, the onset of action is slower than other antihypertensive drugs, and it takes about 7~8 days of continuous administration for the blood concentration of amlodipine to reach a steady state.
Note that amlodipine can be divided into levorotatory and dextrorotatory, of which levorotatory amlodipine is the pharmacologically active amlodipine component, which is 1000 times more effective than dextrorotatory and has significantly fewer adverse effects than dextrorotatory.