Hello, welcome back to the "Hypertension Medical Course." I'm Jessica.
For treating hypertension, although lifestyle adjustments are
effective, they are demanding, and many people find them difficult to
maintain. Additionally, many people discover their hypertension when it
is already irreversible. However, this is not a major concern, as we
have the most effective weapon against high blood pressure—medication.
Antihypertensive drugs are currently the most numerous and best-selling
drugs for a single disease, with about 13 major categories and more
than 70 types. Combined with different brand names and dosages, there
are more than 300 on the Chinese market alone.
Can doctors understand every single one? Frankly, no. So the question
arises, if even doctors can't keep track, how should we choose? How can
we take them with confidence? In this lecture, I will guide you through
the principles of drug selection by unraveling the mechanisms of
antihypertensive drugs.
As mentioned earlier, there are only two main mechanisms that lead to
high blood pressure: vasoconstriction and increased blood volume. As
the saying goes, "All things, in their myriad forms, return to their
root." The vast array of antihypertensive drugs on the market are all
inspired by these two mechanisms.
The First Major Category: Reducing Blood Volume
This is an old but enduring class of drugs called diuretics, which,
as the name suggests, make you urinate more. Urination means expelling
water and sodium from the body. When the water and sodium in the blood
vessels decrease, blood pressure naturally drops.
For nearly seventy years since their invention, these sodium-excreting
drugs have been first-line antihypertensives. The most common one is
hydrochlorothiazide. To avoid the appearance of advertising, the drugs
I mention below will be by their chemical names, not brand names. You
might find them a bit unfamiliar, but don't worry, I've attached a
table at the end of the manuscript that cross-references drug
categories, chemical names, and brand names for your reference.
The biggest advantage of this type of antihypertensive drug is its low
cost, just a few yuan for a bottle of one hundred tablets. In terms of
blood pressure-lowering effect alone, it is no different from other
drugs that are dozens of times more expensive, and it is equally
outstanding in reducing the future incidence of cardiovascular
diseases.
However, everything has two sides. This class of drugs also has some
side effects: it may cause orthostatic hypotension, which is dizziness
upon standing up suddenly, so you need to move slowly; it may also lead
to hypokalemia, requiring potassium supplementation; and there is a
small chance it may cause hyperuricemia and hyperglycemia, so it is not
suitable for people with abnormal uric acid or blood sugar levels, or
those who are overweight and prone to developing diabetes in the
future.
The Second Major Category: Directly Dilating Blood Vessels
If diuretics lower blood pressure by reducing blood volume, then the
second, third, and fourth major categories of antihypertensive drugs
work on the blood vessels.
Among them, the second category directly dilates blood vessels, such
as calcium channel blockers, or CCBs for short. This class of drugs
prevents calcium ions from entering cells. The "gates" for these cells
are located on the muscle cell membranes of the blood vessel walls. If
calcium ions cannot enter, the muscle cells cannot contract, meaning
the blood vessels cannot constrict. If the blood vessels cannot
constrict, blood pressure naturally decreases.
The most classic drugs in this category are the "-dipines," such as
nifedipine and amlodipine. Their biggest advantage is their wide
applicability; they are suitable for almost everyone. In China, nearly
half of all hypertensive patients use them.
Furthermore, pharmaceutical companies have developed many
sustained-release and controlled-release formulations to make their
effects last longer. Even if you occasionally forget to take a dose, it
doesn't matter much, as blood pressure fluctuations will remain small.
For a drug that is taken almost for life, it's hard to avoid missing a
dose now and then, so this advantage is very important.
Based on these two advantages, it is not only a first-line medication
for hypertension but also one of the top recommendations by doctors.
Of course, this class of drugs also has some side effects. Due to their
potent vasodilating effect, no more than 10% of people may experience
flushing, edema, headache, and dizziness after taking them. These
symptoms usually subside after a while, but some people cannot tolerate
them and need to switch medications.
The Third Major Category: Reducing Vasoconstriction
Of course, besides dilating blood vessels to lower blood pressure, one
can also take the opposite approach: reducing vasoconstriction. This
line of thinking has also led to the development of antihypertensive
drugs—either by reducing the substances in body fluids that constrict
blood vessels or by reducing the nerve reflexes that cause
vasoconstriction, i.e., lowering sympathetic nerve excitement. These
are what we refer to as the third and fourth major categories of
antihypertensive drugs.
Let's first talk about the third major category, which lowers blood
pressure by reducing the substances in body fluids that constrict blood
vessels.
What are the substances in the human body that constrict blood vessels?
Through medical research, scientists have identified a potent
vasoconstrictor in the human body called angiotensin. By controlling it
and preventing vasoconstriction, blood pressure can be lowered. This
approach has led to two different strategies—
One is the use of angiotensin-converting enzyme inhibitors, or ACEIs
for short. They inhibit the synthesis of angiotensin. With less
angiotensin, there is less vasoconstriction, and thus, blood pressure
is lowered. These drugs are often called "-prils," such as benazepril
and enalapril.
The other is the use of angiotensin receptor blockers, or ARBs for
short. They bind to the angiotensin receptors first. This way, when
angiotensin tries to bind to its receptors, it finds that all the spots
are already taken by these "decoys." Consequently, no matter how much
angiotensin there is, it has no effect. These drugs are often called
"-sartans," such as losartan and valsartan.
Drugs produced along these two lines are currently the most commonly
used class of all antihypertensive medications.
Why is that? Because in addition to lowering blood pressure, they have
been found to have other amazing therapeutic effects.
This is common in the history of drug discovery. The full range of
reactions and effects a newly synthesized drug will have on the human
body can only be discovered over time. Over a long enough period, some
drugs may find expanded uses beyond their original purpose, while
others may be discontinued due to unexpected side effects.
Clearly, ACEIs and ARBs belong to the fortunate category. Besides
lowering blood pressure, they have three other important effects:
first, they prevent coronary heart disease; second, they protect kidney
function and reduce kidney damage from diabetes; and third, they
prevent further heart damage in patients with heart failure. Coronary
heart disease, diabetes, and heart failure are all problems that people
with hypertension are very likely to face in the future. Therefore,
this class of drugs has not only become a first-line antihypertensive
but also a top recommendation in most guidelines.
Of course, this class of drugs is not perfect. They are not suitable
for people who are pregnant, have high potassium levels, angioedema, or
bilateral renal artery stenosis.
The Fourth Major Category: Reducing Sympathetic Nerve Excitation
The last major category of antihypertensive drugs reduces
vasoconstriction by lowering sympathetic nerve excitement, with
beta-blockers being a typical example.
In the human body, sympathetic nerve excitement leads to the release of
catecholamines, which bind to beta-receptors on blood vessels and the
heart, causing vasoconstriction. Thus, medical scientists designed
beta-blockers. If the binding is blocked, vasoconstriction and the
resulting rise in blood pressure are prevented. These drugs are
generally called "-lols," such as metoprolol and propranolol.
It certainly can lower blood pressure, but in recent years, more and
more clinical studies have found that it has some safety issues—first,
it may cause bradycardia, arrhythmia, and asthma; second, it may
increase the incidence of diabetes; and third, it has a certain impact
on sexual function.
Therefore, it has gradually been withdrawn from the list of first-line
antihypertensive drugs.
Principles for Choosing Antihypertensive Medications
At this point, I have outlined the main antihypertensive drugs and
their mechanisms. You might say, "It's too much, I can't remember it
all!" Don't worry, I will share with you the principles that doctors
use to select antihypertensive drugs. Just remember these general
principles—
First, effectiveness is paramount.
All the harm from hypertension stems from the elevated blood pressure
itself. The most important thing is to lower the blood pressure to
below the target value. From this perspective, if you have no other
health problems besides hypertension, there is no difference in
choosing diuretics, calcium channel blockers, ACE inhibitors, or
angiotensin receptor blockers.
Second, choose different major categories for different diseases.
For example, if you have high blood sugar, high uric acid, or a family
history of diabetes, diuretics are not suitable. As another example, if
you also have high cholesterol or a high future risk of cardiovascular
disease, ACE inhibitors or angiotensin receptor blockers are more
suitable for you.
Third, don't sweat the small stuff.
When choosing antihypertensive drugs, only distinguish between the
major categories; you don't need to look at which specific brand or
type it is. For example, among calcium channel blockers, the difference
between one "-dipine" and another is very small.
Fourth, convenience is king.
Because the differences in effects and side effects among
antihypertensive drugs are not significant, and the medication needs to
be taken for a lifetime, it is best to choose one that is taken once a
day, one that is easy for you to obtain, and one that you can afford.
Don't worry about the rest.
Fifth, time is the standard for testing truth.
Choosing a medication is not about innovation. It's best to use drugs
that have been widely used by many people for many years. The adverse
reactions of these drugs have long been verified by others, and their
safety is more guaranteed.
Next Section Preview
In this lecture, we talked about how to choose antihypertensive drugs.
However, even if you choose the right drug, if you don't take it
correctly, it will still be difficult to achieve the desired effect. So
in the next lecture, we will talk in detail about "the self-discipline
of taking antihypertensive drugs."
Key Points
1. The core and most commonly used antihypertensive drugs are the four
major classes, the "five golden flowers": diuretics, calcium channel
blockers (CCBs), angiotensin-converting enzyme inhibitors (ACEIs),
angiotensin receptor blockers (ARBs), and beta-blockers.
2. For specific selection, please remember five principles:
effectiveness is paramount; choose different major categories for
different diseases; don't sweat the small stuff; convenience is king;
and time is the standard for testing truth.
3. There is no such thing as a good or bad antihypertensive drug. As
long as it can lower your blood pressure to the target value and does
not have significant side effects for you, it is a good drug for you.
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