Antihypertensive Drugs: Diuretics in a Nutshell

When talking about heart conductivity, the first thing that comes to mind is the rate in which the heart contracts – either too much or too little. If the heart is contracting at an increased, irregular, and uncontrollable speed, then what we usually give is a rate-control drug.

Rate-control drugs are your:

  • Beta-blockers
  • Calcium-channel blockers

These drugs affect the electro-excitability within the heart. Diuretics, on the other hand, do not work like that.

What are Diuretics?

In the simplest sense, diuretics are medications that primarily decrease the heart’s workload. Diuretics are medications that are designed specifically to eliminate increased amounts of salt and water inside the body by passing it out as urine. Diuretics that are mainly used for high blood pressure reduces the amount of fluid from the blood vessels which significantly decreases pressure within the vessels. While they are usually prescribed for high blood pressure, there are other conditions that diuretics can treat as well.

Antihypertensive Medications

When talking about diuretics for the heart, there is some pertinent information that you need to know. It can be quite confusing to identify the different kinds of antihypertensive medications. But, there is an easier way to pinpoint which is which; just do the ABCD; those letters stand for the following:

  • A – Ace Inhibitors, Angiotensin Receptor Blockers (ARBs)
  • B – Beta-blockers (rate-control drug)
  • C – Calcium-channel blockers (inhibit electrical stimulations)
  • D – Diuretics (bring down the volume)

Classifications of Diuretics

Think of it this way: diuretics causes diarrhea of the kidneys and the bladder. You are basically diuresing contents out of the body. So what are the different kinds of diuretics?

  1. Loop Diuretics (Furosemide, popularly known as Lasix)
  2. Thiazide Diuretics (Hydrochlorothiazide)
  3. Potassium-Sparing Diuretics (Spironolactone, Aldactone, “-tone”)
  4. Osmotic Diuretics (Mannitol)

To easily ascertain what kind of diuretics you’re encountering, just try to relate to the different suffixes mentioned since these are the most commonly used diuretics in a hospital setting:

  • Loop = Furosemide

Considered as the “big guns” when decreasing workload, loop diuretics are potassium-wasting diuretics; they are fast-acting and effectively take off fluid out of the vascular spaces into the potty and not the body.

  • Thiazide = Hydrochlorothiazide

Thiazides are the second string of potassium-wasting diuretics; think of it as the backup quarterback. This medication is quite effective but not as good as loop diuretics.

  • Potassium-Sparing = Spironolactone, Aldactone

Potassium-sparing diuretics block aldosterone which you can think of as Aldos “Tyrone”). So, Aldostyrone is a nightclub bouncer that stands at the door of your kidneys. He is that bouncer that prevents sodium from going out of the kidneys. Holding back sodium inside the kidneys will attract more water. Blocking Aldostyrone will allow sodium to leave the kidneys and water will instantaneously follow.

Since this type of diuretic is potassium-sparing, there is no need to educate your client about potassium-rich foods. Unlike your loop and thiazide diuretics that you are required to emphasize the need for increased potassium intake because they waste potassium out of the body.

  • Osmotic = Mannitol

Osmotic diuretics are your last line of drugs and are rarely given in hospital settings just because Furosemide is more popular and fast-acting. However, osmotic diuretics can also be provided to decrease blood pressure and volume inside the vascular system.

There you go, a very informative, concise, and useful way of identifying and remembering your antihypertensive diuretics. For other relevant nursing topics, you can head on to our website, simplenursing.com.

Antihypertensive Medication: Calcium Channel Blockers – Part 2

Calcium channel blockers are antihypertensive medications that technically reduce hypertension or blood pressure; thus, relieving stress from the heart.

How does one quickly spot a calcium channel blocker?

More often than not, calcium channel blockers end in “-pine.” Not to be confused with another antihypertensive medication known as beta-blockers that end in “-lol.” The most popular calcium channel blocker used in a hospital setting, which doesn’t end in “-pine” is Cardizem (Diltiazem). Cardizem drip is given to clients who have significantly high blood pressure and suffers chronic stable angina or chest pain.

Anatomy of the Heart

How do calcium channel blockers relieve the pressure on the heart that results to smooth contraction? All your questions will be answered momentarily but first, let’s do quick anatomy and physiology of the heart.

The heart’s primary responsibility is to pump blood. Think of the heart as a pumping station that pumps fuel to a car, the car is your body. Blood is composed of nutrients as well as oxygen. If the heart is dysfunctional, blood will not be sufficiently pumped, and the organs will malfunction which leads to the deterioration of the system.

Now, the veins vacuum deoxygenated blood into the heart to be re-oxygenated while the arteries send oxygenated blood away from the body. So remember:

  • Veins – Vacuum
  • Arteries – Away

The left ventricle, one of the main chambers of the heart, is the chamber that is mainly responsible for pumping oxygenated blood throughout the entire body. For this reason, the left ventricle is the thickest and the largest chamber of the heart.

If the peripheral vessels (arteries) are stiff, this causes the left ventricle to push hard against the resistance. If this happens, a lot more energy is required, and the left ventricle exerts more stress to pump more blood into the system.

If there was less resistance, the heart does not suffer. The tendency is for the heart to push as much as it can just to suffice different parts of the body with the blood it needs to function correctly. To lessen the strain on the heart and bring the blood pressure down, you need your calcium channel blockers.

How does calcium works inside the body?

Blood vessels are composed of epithelial cells. Imagine that every cell operates as a city – it has walls, a city hall, a cleaning or trash department, a post office, and gates. The central area that we will be focusing on is the city gates which are known as “channels” of the cell. The primary functions of these barriers are:

  • Break down enzymes
  • Allow enzymes into the cell
  • Releases enzymes from the cell

One of the main channels that you want to block in cases of hypertension is calcium. Why do you want to prevent calcium from coming inside the cell? This is because calcium is a mineral that contributes to the following:

  • Cellular connection
  • Blood clot
  • Muscle contraction
  • Nerve function
  • Teeth and bone strength

Calcium hardens the cells which then makes the arteries rigid. Increased cardiac output and stroke volume are two identifiers that the left ventricle is putting a lot of effort to pump blood into the stiff vessels.

Mechanisms of calcium channel blockers

This is where calcium channel blockers come in. Calcium channel blockers prevent calcium from entering the cells which lessens the cell’s hardness thereby making the blood vessels or the highways of the heart more flexible. It is now easier for the left ventricle to push blood out of the heart and into the vessels resulting to lower blood pressure.

For those who haven’t had a copy of the Pathophysiology Bible, get yourself a copy now. It contains more 70 concept maps that you can utilize for your clinical days. Concept maps vary from nursing outcomes, interventions, signs and symptoms, and pathophysiology of the Top 70 diagnoses of common admissions inside the hospital. With the Pathophysiology Bible, your study time will be cut by 200%.

For our next discussion, we will be tackling Nitroglycerin and vasodilators. See you on our next lecture!

 

Antihypertensive Drugs: A Closer Look at Beta-Blockers

Beta-blockers are, in the simplest sense, heart medications for clients with hypertension that is mainly focused on the conduction system of the heart.

Just to refresh your memory, there are two ways to lower blood pressure.

  1. Relieving pressure from the pipes by decreasing fluid volume. These are your ACE inhibitors and diuretics.
  2. Decrease rate of conduction in the heart. These are your beta-blockers and calcium channel blockers.

Mechanism of beta-blockers

Beta-blockers are negative, chronotropic drugs that block that SA node from contracting excessively. Beta-blockers block the beta-adrenergic receptor also known beta-1 and beta-2. Beta-1 are receptors in the heart stimulates increased heart contraction. If stimulated, these beta receptors can cause contraction at higher rates. Similarly, this concept applies to beta-2 in the lungs.

Study tip: Beta-2 is for the lungs (since you have two lungs) and beta-1 is for the heart (since you have one heart)

Beta-2 agonist causes bronchial dilation. One typical example is albuterol. Dosing someone with albuterol will antagonize beta-2. However, it will also affect beta-1 which means that there will be a noticeable rise in your heart rate. This is the reason why treatment of beta-2 causes tachycardia in clients.

Beta-blockers block beta. Beta excited the heart. When the beta is blocked, the heart rate decreases. It’s as simple as that. Cool!

Beta-blockers make you LOL

According to the FDA, identification of these types of drugs must be through their suffix. One of the easiest ways to identify your beta-blockers is to know, by heart, that it can make you laugh out loud (LOL). Meaning, beta-blockers generic names end in –lol. A typical example is atenolol and metoprolol. 

Beta-blocker warnings – the 4 Bs

When giving beta-blockers to your clients, you have to watch out for these adverse effects.

Bradycardia

This is a condition wherein the heart rate of your client drops below 60 per minute. Yes, the goal of beta-blockers is to slow down the heart rate but that doesn’t mean killing your client in the process.

In giving anti-hypertensives, it is advised to give the client the least heavy doses first. Meaning, give your volume depleters first; this will be your diuretics, ACE inhibitors, ARBs, and potassium-sparing diuretics. Don’t opt for electrical or chronological conduction drugs until you have given the volume-depleting drugs and have thoroughly assessed your client’s vitals.

This thought is going to be very useful during exams with borderline, tricky questions. Remember, the most likely answer is holding the drug if the systolic pressure drops to 100.

Blood pressure is decreased

If you’re going to administer a couple of anti-hypertensive drugs, make sure that you ask yourself how safe is it to give. Always run scenarios inside your head especially in terms of the possible out if you gave beta-blockers with other anti-hypertensive drugs. Getting the blood pressure is the best way to assess the necessity of administering the drug. If the blood pressure has significantly dropped after an hour or so, chances are, you won’t be giving the drug.

Yes, we have mentioned that beta-blockers do not decrease blood pressure and only affects Beta-1 in the heart; however, if the stroke volume is decreased, the cardiac output is decreased as well. Low blood pressure is a possible side effect.

Bronchi constriction

Yes, it was mentioned that beta-blockers are for blocking Beta-1; however, there is a probability that Beta-2 can also be blocked. Though it may be specific, it can happen.

Blood sugar masking

If your client has low blood sugar, beta-blockers can mask the signs and symptoms of bradycardia.