Updated July 2026 · 8 min read
Part of the ICU Pharmacology Hub — browse every related guide in one place.
Nitroglycerin and nitroprusside (Nipride) are the two titratable vasodilator infusions you'll run for hypertensive emergencies and acute heart failure. They sound interchangeable — both are nitric-oxide donors, both drop blood pressure minute-to-minute — but they dilate different parts of the circulation and carry very different toxicities. Nitroglycerin mostly unloads the veins; nitroprusside opens veins and arteries and hides a cyanide problem. Getting the distinction clear keeps your titration safe.
Nitroglycerin at typical infusion rates works mainly on the venous side. By dilating veins it reduces preload — the volume returning to the heart — which lowers wall stress, relieves pulmonary congestion in acute heart failure/flash pulmonary edema, and dilates coronary arteries to relieve myocardial ischemia. That's why nitroglycerin is the vasodilator of choice when the problem is cardiac: ACS with hypertension, heart failure, or ischemic chest pain. Only at higher doses does it add meaningful arterial dilation.
Nitroprusside is a balanced dilator: it opens arteries and veins at once, cutting both afterload and preload. That gives it fast, powerful, finely titratable control of blood pressure, which is why it shines in true hypertensive emergencies and settings like aortic dissection (paired with a beta-blocker for rate control) where you need to bring pressure down smoothly and predictably. Its onset and offset are almost immediate — turn the drip and the pressure follows within a minute or two.
Nitroprusside is also light-sensitive — the bag and often the tubing are protected from light per pharmacy protocol — and a change in the solution's color can indicate degradation. These aren't optional niceties; they're part of safe administration.
| Nitroglycerin | Nitroprusside (Nipride) | |
|---|---|---|
| Main effect | Venodilation (preload ↓) | Balanced arterial + venous |
| Best for | Cardiac ischemia, HF/pulmonary edema | Hypertensive emergency, dissection* |
| Onset/offset | Fast | Near-instant, very titratable |
| Signature problem | Tolerance in 24–48 h; headache | Cyanide/thiocyanate toxicity |
| Special handling | Avoid with PDE-5 inhibitors | Light-protected; caution in renal/hepatic dz |
| Monitoring | BP, HR, headache, tolerance | BP, acid-base, lactate, mental status |
*In aortic dissection, a beta-blocker is given first/with it to control heart rate and shear stress.
If the driving problem is the heart — ischemia, chest pain, heart failure with congestion — nitroglycerin's preload reduction and coronary dilation make it the natural pick. If the driving problem is severe, refractory hypertension needing precise second-to-second control — a hypertensive emergency, controlled reduction in dissection — nitroprusside's balanced, instantly titratable effect is hard to beat, with the cyanide caveat keeping infusions short and doses conservative. Many units now favor nicardipine or clevidipine over nitroprusside for routine hypertensive emergencies precisely to avoid the cyanide risk, reserving nitroprusside for when its rapid titratability is truly needed.
Related: Nitroglycerin drip guide · Nitroprusside (Nipride) guide · Labetalol vs nicardipine · Norepinephrine (Levophed) guide
Educational content for licensed clinicians. Always follow your facility's pharmacy dosing protocol and provider orders. Not medical advice.
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