🩺 What Are Vasodilators?

Vasodilators are drugs that open up blood vessels. Therefore, they lower blood pressure and reduce the heart’s workload. Clinicians use them in many emergency and chronic care settings. For a quick refresher on baseline values, see our guide to vital signs and red flags.

This guide covers three main vasodilator classes. First come the Calcium Channel Blockers. Next are the Nitrates. Finally, we look at Hydralazine. Each class works in a slightly different way. However, all three share the same goal: lower blood pressure and protect the heart. According to the American Heart Association, high blood pressure remains a leading cause of cardiovascular disease worldwide.

💊 Calcium Channel Blockers SUFFIX: -DIPINE, -ZEM, -MIL

Calcium Channel Blockers (CCBs) are a frontline option for high blood pressure and angina. Moreover, paramedics often reach for them during a hypertensive crisis. The drug names are easy to spot. Just look for the suffixes –dipine, –zem, or –mil.

Action

CCBs block calcium from entering cardiac cells. Consequently, the heart and vascular smooth muscle relax. However, not all CCBs act the same way:

• –PINEs only lower BP — for example, Nicardipine and Amlodipine
• –ZEMs & –MILs lower both BP and HR — for example, Cardizem (Diltiazem) and Verapamil

For full FDA prescribing details, you can check the entries on DailyMed.

Uses

• Hypertensive crisis
• Angina

Side Effects

Most patients tolerate CCBs well. Still, several adverse effects show up often enough to watch for:

• Orthostatic hypotension
• Constipation (especially with –MIL and –ZEM)
• Gingival hyperplasia (especially with –PINE)
• Headache
• Flushing
• Peripheral edema

Nursing Considerations

Before each dose, check vitals carefully. In addition, teach the patient how to avoid drug interactions and side effects.

• Check BP and HR before giving the dose. Then hold for HR < 60 bpm or SBP < 100.
• Ask the patient to change positions slowly.
• Recommend a high-fiber diet to prevent constipation.
• If the heart rate drops too low, follow our adult bradycardia algorithm.

💊 Nitrates NITROGLYCERINE & ISOSORBIDE

Nitrates have been the cornerstone of angina treatment for over a century. Furthermore, they help in heart failure and hypertensive emergencies. Nitroglycerine and Isosorbide are the two most common examples.

Action

The body converts nitrates into nitric oxide. In turn, nitric oxide forms a protein that relaxes blood vessels. As a result, three things happen at once:

• ↑ Blood flow to the heart
• ↓ Vascular resistance
• ↓ Oxygen consumption

Uses

• Hypertensive crisis
• Angina
• Heart failure

Side Effects

Most side effects are mild. However, they can still scare an unprepared patient:

• Headache
• Flushing
• Orthostatic hypotension

Routes of Administration

Onset time depends on the route. Therefore, choose the route that fits the situation. For emergencies, pick a fast-onset form. For long-term control, a slow-onset form works better.

Nursing Considerations

Nitrates can drop blood pressure fast. Therefore, you must check BP before each dose. Additionally, store the drug correctly to keep it potent.

• Check BP before giving the dose. Hold for SBP < 100 or a drop > 30 mmHg.
• Sublingual nitro: give 3 doses, 5 minutes apart. If chest pain is not relieved or worsens 5 minutes after the first dose, call 911.
• Always keep the drug in its original dark container.
• For more drug details, see MedlinePlus on nitroglycerin.

💊 Hydralazine APRESOLINE — DIRECT VASODILATOR

Hydralazine, also known by the brand name Apresoline, is a direct-acting vasodilator. Unlike CCBs and nitrates, it works directly on the muscle of the small arteries. Doctors often prescribe it for severe hypertension and heart failure.

Action

Hydralazine relaxes the smooth muscle in the arterioles. Consequently, peripheral vasodilation occurs. This leads to three key effects:

• ↓ Afterload
• ↓ Workload of the heart
• ↓ Blood pressure

Uses

• Severe hypertension
• Heart failure

Side Effects

Hydralazine has a few unique adverse effects. For example, it can trigger a lupus-like syndrome with long use:

• Hypotension
• Drug-induced lupus
• Reflex tachycardia

If reflex tachycardia develops, review our adult tachycardia algorithm.

Nursing Considerations

Hydralazine can lower BP very fast. Moreover, it interacts with several other drug classes. Because of this, monitor the patient closely.

• Monitor BP regularly.
• Contraindicated for use in angina.
• BP can drop fast and trigger reflex tachycardia. As a result, doctors often combine it with a beta blocker.
• MAOIs may boost the potency of hydralazine. Therefore, expect more hypotension.

📋 Key Takeaways

Vasodilators are powerful tools, but they need careful handling. Here are the most important points to remember:

• First, always check BP and HR before each dose.
• Second, never combine nitrates or hydralazine with PDE-5 inhibitors.
• Third, wear gloves when handling nitro patches or paste.
• Finally, teach the patient to rise slowly and avoid grapefruit with CCBs.

For more on cardiovascular emergencies, browse our medication library or read the adult cardiac arrest algorithm. You can also find current hypertension guidelines at the American College of Cardiology.

📚 References & Further Reading

• American Heart Association — High Blood Pressure
• MedlinePlus — High Blood Pressure
• DailyMed — FDA Drug Labels
• American College of Cardiology — Clinical Guidelines
• NHLBI — Heart Failure