10 Cardiac Drugs to Know for the Pharmacology Test

Cardiology Drugs

This article covers 10 cardiology drugs that are included on the pharmacology test. The article will introduce each drug, including its class, the indications, and a brief mechanism of action. 

The discussion includes antidotes for the drugs and if there is a need to draw serum levels. Finally, the pertinent nursing assessments are discussed.

The drugs in this article are:

• Spironolactone (Aldactone^®)
• Hydrochlorothiazide
• Furosemide (Lasix^®)
• Digoxin
• Nitroglycerin
• Lidocaine
• Amiodarone (Cordarone^®)
• Diltiazem (Cardizem^®)
• Metoprolol
• Lisinopril

Spironolactone

The following section explores the drug spironolactone.

Class and Indications

Spironolactone (brand name Aldactone^®) belongs to a class of drugs called potassium-sparing diuretics. It is an oral pill. As a diuretic, it lowers the blood pressure through diuresis. 

Spironolactone is used for many indications, including hypertension, congestive heart failure, cirrhosis of the liver, nephrotic syndrome, and edema, to name a few.

Spironolactone is often given to patients who have liver failure with fluid build-up, as it is an effective diuretic. It is also administered in combination with furosemide for patients with congestive heart failure. Taking both furosemide and spironolactone together can help offset potassium loss from the furosemide. It also helps to prevent diuretic resistance.

Mechanism of Action

There is an easy way to remember the mechanism of action for spironolactone. Look at its brand name “Aldactone^®” and remember “aldosterone.” Spironolactone blocks the effects of aldosterone. 

Aldosterone is the salt-water hormone that tells the body to hold onto salt unless spironolactone blocks that from happening. In effect, when a patient takes spironolactone, they are going to lose sodium and water and retain potassium. That is why spironolactone belongs to the potassium-sparing diuretic class.

Potassium-sparing diuretics act on the nephrons in the kidneys.

Antidote or Serum Level?

There is no antidote for spironolactone, and serum levels are not typically drawn.

Related Video – Introduction to ACLS Medications

Nursing Assessment

The nursing assessments for spironolactone and any diuretic include:

• Blood pressure. Blood pressure needs to be monitored because diuretics cause blood pressure to drop.
• Potassium. The patient’s potassium level should be checked prior to administering spironolactone as the potassium level will increase when spironolactone is given.

Hydrochlorothiazide

Below is a review of the drug hydrochlorothiazide.

Class and Indications

Hydrochlorothiazide (HCTZ) belongs to the thiazide diuretics class of drugs. Some common indications include hypertension, heart failure, and edema. 

Hydrochlorothiazide is a first-line treatment option for hypertension. When someone is initially diagnosed with hypertension, the doctor may put the patient on hydrochlorothiazide to see if that will lower the blood pressure.

Sites of action for classes of diuretics

Mechanism of Action

HCTZ works on the distal convoluted tubule in the nephron and blocks reabsorption of sodium. Therefore, HCTZ blocks the system from reabsorbing sodium back into the blood, meaning the patient is going to lose sodium into the urine. Where sodium goes, so do fluids. That is how HCTZ causes diuresis.

Antidote or Serum Level?

There is no antidote for HCTZ and serum levels are not typically drawn.

Nursing Assessment

The nursing assessment for HCTZ includes:

• Potassium level. The patient will lose a little potassium with HCTZ, so the potassium level needs to be monitored.
• Effectiveness of the diuretic. Evaluate the effectiveness of the diuretic based on why it is being administered. Did the blood pressure lower 30 min to 1 hour after giving the medication? The provider needs to evaluate how the medication is working.

Related Video – Adenosine – ACLS Drugs

Furosemide

The following is a detailed look at the drug furosemide.

Class and Indications

Furosemide (Lasix^®) belongs to the loop diuretics class of drugs. It is used to treat many conditions, including congestive heart failure (CHF), edema, and resistant hypertension. There are multiple dosage forms for furosemide, and it can be given by mouth or intravenously (IV).

IV furosemide in the hospital setting is used for acute CHF. To confirm if a patient is in CHF, the provider should review their B-type natriuretic peptide (BNP) level. The BNP level indicates the severity of the patient’s heart failure.

Mechanism of Action

Furosemide is a loop diuretic that works in the thick ascending loop of Henle. Loop diuretics block the sodium-potassium-chloride cotransporter. When someone is taking furosemide, they will lose sodium, potassium, and chloride into the urine.

Loop diuretics block the reabsorption of sodium, potassium, and chloride at the Loop of Henle.

Importantly, loop diuretics cause the body to lose sodium. Since sodium brings water with it, it creates the diuresis effect. This is how loop diuretics work to cause diuresis.

Antidote or Serum Level?

There is no antidote for furosemide, and serum levels are not typically drawn.

Nursing Assessment

When someone is taking furosemide or a loop diuretic, the provider needs to assess:

• Fluid status. Loop diuretics cause diuresis, so it is important to record daily weight, intake and output, location of edema, and lung sounds.
• Potassium level. The patient’s potassium level needs to be assessed because furosemide will drop the patient’s potassium.
• Blood pressure. Blood pressure needs to be assessed prior to administering furosemide because it will drop, especially with IV furosemide. 
• Tinnitus and hearing loss. Furosemide can be ototoxic and may need to be administered at a slower rate. Furosemide can cause ringing in the ears (tinnitus) and even hearing loss. Hearing loss is more common with prolonged IV therapy and high-dose IV administration.
• Urine output. Monitor if the patient is urinating. If the patient has not urinated within two hours of furosemide administration, something is not right and further assessment and intervention are needed.

Read: 5 Common Dysrhythmias and Treatments

Digoxin

The following explains the drug digoxin.

Class and Indications

Digoxin is a cardiac glycoside. It was originally discovered from the foxglove plant (Digitalis purpurea). 

The indications for digoxin are different in the pediatric population versus the adult population. 

In pediatrics, it is used in CHF to improve the contractility of the heart. For adults, it is given mostly in CHF, atrial fibrillation, and atrial flutter to slow the heart rate.

Mechanism of Action

Digoxin blocks the sodium potassium pumps in the cardiomyocytes. The inhibition causes an increase in sodium levels inside the cell, which ultimately causes calcium to build up in the cardiomyocytes. When calcium builds up within the cell, it strengthens the force of contraction of the heart. 

It also has some parasympathetic effects, particularly on the AV node, by potentiating the effect of the vagus nerve. This is why a decreased heart rate is observed with digoxin.

Digoxin interacts with the cardiac muscle and has parasympathetic effects.

Antidote or Serum levels?

The antidote for digoxin is digoxin immune fab (Digi bind^®).

Digoxin toxicity can cause neurological symptoms, nausea or vomiting, yellow halos when looking at lights, and potentially dysrhythmias. Serum digoxin levels need to be monitored regularly in patients taking digoxin.

Nursing Assessments

In patients receiving digoxin, the nursing assessments include:

• Apical heart rate. Count the apical heart rate for a full minute before administering digoxin. Do not give digoxin if the apical heart rate is less than 60 beats per minute (bpm) for an adult (some textbooks may say 50 bpm).
• Potassium level. Hypokalemia can cause digoxin toxicity.
• Serum digoxin level. The goal range for digoxin is 0.5–2 ng/mL. If the serum digoxin level is too high, then the digoxin needs to be held. Patients with a high serum digoxin level will have a very slow heart rate or present with signs of digoxin toxicity or peaked T-waves due to hyperkalemia.
• Effectiveness. The effectiveness of the medication will depend on why the patient is receiving digoxin. If the patient is receiving digoxin for rapid atrial fibrillation, the heart rate should slow down.

Digoxin is a chemical found in the foxglove plant. Digoxin increases the force of contractions of the heart.

Related Video – Morphine – ACLS Drugs

Nitroglycerin

In this section, nitroglycerin is explained.

Class and Indications

Nitroglycerin belongs to the nitrates class. It is a vasodilatory drug primarily used to relieve chest pain, but it is also used to treat hypertension and help control the heart failure during a heart attack. There are different dosage forms available, including a patch, a drip (liquid form), a spray, and a sublingual tablet.

Nitroglycerin sublingual tablets are used to help relieve chest pain.

The sublingual nitroglycerin is used for chest pain. When someone is having chest pain, they place one sublingual tablet under the tongue every five minutes up to three times. If there is still chest pain after three tablets, then the person should call 9-1-1 for emergency help.

The nitroglycerin patch (transdermal) and nitroglycerin drip are used to lower the blood pressure. Blood pressure is monitored to assess for treatment effectiveness. A nitroglycerin drip can be titrated to the target blood pressure. The nitroglycerin patch is commonly used in emergency departments during acute chest pain attacks. It comes as an ointment that is rubbed into the patient’s skin using paper. The transdermal form of nitroglycerin is typically used if a patient cannot tolerate the sublingual tablet.

When the provider is preparing a nitroglycerin topical cream, they need to wear gloves because this peripheral vasodilator can cause an extreme headache.

Mechanism of Action

The mechanism of action is simple. As a nitrate, nitroglycerin is a direct-acting peripheral vasodilator, which relaxes the smooth muscles of blood vessels.

Antidote or Serum Level?

There is no antidote for nitroglycerin, and serum levels are not typically drawn.

Nursing Assessment

Nursing assessments for patients on nitroglycerin include:

• Monitor the blood pressure. The blood pressure should not drop too low. Observe the blood pressure before administering nitroglycerin. If the blood pressure is too low (e.g., if the patient has a systolic pressure of 60 mm Hg), the team should look at alternatives.
• Headache. The nitroglycerin patch can cause a headache. If a patient is complaining of headache, it is possible to move the patch lower in the body, like to their leg, to help reduce the headache. Of note, if a patient has peripheral vascular disease, they do not have sufficient circulation in the legs, and the patch will not be effective if placed on the leg.
• Chest pain. Monitor chest pain if someone is taking nitroglycerin for chest pain. Is the patient’s chest pain relieved? If the chest pain is not relieved, that could indicate a heart attack.

Lidocaine

In this section, lidocaine is discussed.

Class and Indications

Lidocaine (Xylocaine^®) belongs to a class of drugs called sodium channel blockers. Some other drugs in this class are procainamide and flecainide.

Lidocaine is indicated for ventricular dysrhythmias. It is usually used if the patient has not responded to other treatments or cannot tolerate or is allergic to amiodarone.

Mechanism of Action

Lidocaine works on the sodium channel as a sodium channel blocker. It prolongs the action potential and slows conduction through the AV node. Lidocaine causes the heart rate to slow and decreases the ventricles’ response to stimulation.

People often think of lidocaine being used to numb the gums prior to oral surgery. In the same way, lidocaine “numbs” the ventricles during dysrhythmias and makes them less responsive. The goal of lidocaine is to calm the ventricles and get them out of ventricular dysrhythmia.

Antidote or Serum Level?

There is no antidote for lidocaine. 

However, serum levels for lidocaine are measured because it can have some serious side effects. Lidocaine can cause central nervous system (CNS) depression, confusion, hallucinations, psychosis, and delusions, among other symptoms. Therefore, it is important to draw serum levels of lidocaine. The therapeutic range for lidocaine is 1.5–5 mcg/mL. Lidocaine toxicity is usually seen at over 5 mcg/mL.

Nursing Assessment

Nursing assessments for lidocaine include:

• Serum level. Serum levels are measured to ensure the patient’s levels are at a therapeutic and safe level.
• Heart rate and blood pressure. Lidocaine can cause the heart rate and blood pressure to drop. Heart rate and blood pressure need to be monitored throughout therapy.
• Effectiveness. The effectiveness of lidocaine is determined by assessing whether the dysrhythmia has resolved.

Amiodarone

The following section explains the drug amiodarone.

Class and Indications

Amiodarone (Cordarone^®) is in the antiarrhythmic drug class, specifically a Class III antiarrhythmic. Amiodarone is indicated for ventricular dysrhythmias and is also used off-label for symptomatic atrial dysrhythmias, such as when a patient is in rapid atrial fibrillation.

Mechanism of Action

The mechanism of action of amiodarone is interesting. Like other Class III antiarrhythmics, amiodarone blocks the potassium channel, which prolongs the refractory period in cardiomyocytes. But, it also has some features of beta-blockers and calcium channel blockers. 

Overall, amiodarone prolongs the refractory period of the sinoatrial (SA) and AV nodes in the heart. It works directly on the SA and AV nodes to slow the heart rate and hopefully convert the patient out of the dysrhythmia.

Antidote or Serum Level?

There is no antidote for amiodarone, and serum levels are not drawn. However, it is important to know that amiodarone has a very long half-life with the mean half-life being about 58 days.

Nursing Assessment

When a patient is on amiodarone, the nursing assessments include:

• Heart rate and blood pressure. Amiodarone will drop both of these.
• Thyroid issues. Amiodarone tablets contain iodine, which is needed to produce T3 and T4 in the thyroid. The increase in iodine delivery and uptake can interfere with normal thyroid function. Patients can develop either hypo- or hyperthyroidism. Patients who start on amiodarone need a baseline thyroid-stimulating hormone (TSH) lab done and repeated every 6–12 months.
• Pulmonary effects. Amiodarone can cause pulmonary toxicity. That includes interstitial respiratory issues, so patients who have been on amiodarone for a long time will need chest X-rays performed at baseline and yearly thereafter. The provider must be wary of giving amiodarone to patients with chronic obstructive pulmonary disease (COPD) or other chronic respiratory issues.
• Drug interactions. Amiodarone interacts with many other drugs. A key interaction is amiodarone and warfarin. Amiodarone can increase the warfarin levels in the body and cause the international normalized ratio (INR) to rise. In a patient taking both amiodarone and warfarin, the provider should monitor the INR levels and watch for any bleeding and bruising.

Related Video – Amiodarone – ACLS Drugs

Diltiazem

The following section examines the drug diltiazem.

Class and Indications

Diltiazem (Cardizem^®) belongs to a class called calcium channel blockers. Diltiazem and verapamil (Calan^®) are the two calcium channel blockers that slow conduction through the AV node. These two calcium channel blockers work primarily at the heart while the rest of the calcium channel blockers, such as amlodipine, work peripherally on the blood vessels.

Diltiazem is given for a variety of cardiac conditions, including angina, atrial flutter, atrial fibrillation, and hypertension.

Mechanism of Action

Diltiazem is a calcium channel blocker that primarily slows conduction through the AV node. It also decreases blood pressure via peripheral vasodilation. 

Antidote or Serum Level?

There is no antidote for diltiazem, and serum levels are not typically drawn.

Nursing Assessment

Nursing assessments with diltiazem include:

• Heart rate and blood pressure. Diltiazem will drop both the heart rate and the blood pressure. Diltiazem should not be administered during acute CHF to avoid slowing the patient’s heart rate and further decreasing the force of contractility.
• Effectiveness. The effectiveness of diltiazem is determined by assessing why the patient is receiving it. Is the patient receiving it to slow down the heart rate during atrial fibrillation? Did it slow the patient’s heart down?

Metoprolol

The following section explores the drug metoprolol.

Class and Indications

Metoprolol belongs to a drug class called the beta-blockers. Indications for metoprolol include CHF, hypertension, premature ventricular complex (PVC), and other dysrhythmias. Metoprolol is not just for treating hypertension. While metoprolol can be used for hypertension, it is currently not one of the first-line options.

Lisinopril and metoprolol are used for a variety of cardiac conditions, such as hypertension and CHF.

Mechanism of Action

Metoprolol is a beta-blocker, but more specifically, it is a beta-1 selective blocker. There are two types of beta-adrenergic receptors, beta-1 and beta-2:

• Beta-1 adrenergic receptors are located in the heart.
• Beta-2 adrenergic receptors are located in the lungs. (Hint: think “1 heart, 2 lungs”)

Beta-blockers are divided into two major categories: selective or non-selective. The older beta-blockers are generally non-selective, while some of the newer ones are selective. That means:

• A non-selective beta blocker acts on both the beta-1 adrenergic receptors and beta-2 adrenergic receptors. They do not select which beta-adrenergic receptors to act on.
• A selective beta blocker acts selectively on the beta-1 adrenergic receptors.

The mechanism of action for beta-blockers is blocking the beta receptors from being stimulated by the sympathetic nervous system, causing the heart rate to slow. They decrease preload and afterload. The decreased heart rate allows the ventricles more time to fill, which is important in patients with CHF.

Nursing Assessments

Nursing assessments for metoprolol include:

• Heart rate and blood pressure. Metoprolol causes the heart rate to slow and blood pressure to decrease.
• Potassium level. The provider needs to know the patient’s potassium levels before administering beta-blockers because beta-blockers can increase serum potassium.
• Respiratory issues. Consider if the patient has respiratory issues, especially with the non-selective beta-blockers, which act on both the beta-adrenergic receptors of the heart and the lungs. Blocking the beta receptors in the lung causes bronchoconstriction. Therefore, care must be taken when administering beta-blockers to patients with respiratory issues, especially asthma.

Related Video – Understanding the 5 Common Dysrhythmias and Treatments

Lisinopril

The following section explains the drug lisinopril.

Class and Indications

Lisinopril is an angiotensin-converting enzyme- (ACE-) inhibitor. It is used for many indications, including hypertension and CHF.

Mechanism of Action

Lisinopril blocks the conversion of angiotensin I to angiotensin II. Angiotensin II is a very potent vasoconstrictor. In effect, lisinopril causes vasodilation and lowers the blood pressure. It also greatly decreases preload and afterload in patients with heart failure.

Antidote or Serum Levels?

There is no antidote for lisinopril, and serum levels are not typically drawn.

Nursing Assessment

The nursing assessments for lisinopril include:

• Blood pressure. Did the blood pressure go down? Is the patient’s blood pressure at goal? Lisinopril is an anti-hypertensive, so it is important to monitoring the blood pressure.
• Potassium. ACE-inhibitors can raise the potassium levels.
• Serum creatinine. ACE-inhibitors can raise the serum creatinine.
• Cough. ACE-inhibitors can cause a dry cough in some patients. If a patient develops a dry cough from lisinopril, the provider will usually switch the lisinopril to an angiotensin receptor blocker (ARB). The ARB has the same therapeutic effects as an ACE-inhibitor, but it does not cause the cough.

Many cardiology drugs are used to treat a variety of conditions, such as hypertension, heart failure, atrial fibrillation, and others. This article introduced 10 cardiology drugs, their class and indications, mechanisms of action, antidotes and serum monitoring, and nursing assessments.