Nursing Field Notes / Cardiovascular Pharmacology · Antianginal Agents
Nitrates 💥
Nitroglycerin & the nitrate family
NG-216Cardiac DrugsADHD-friendly visual edition
Nitrates release nitric oxide, which relaxes the smooth muscle layer of blood vessels — widening the artery/arteriole and letting more blood (and O2) flow through. That's the whole drug in one sentence. Everything else is protocol, tolerance, and one absolute interaction that can kill.
Nitrates relax the smooth muscle layer of blood vessels, increasing the lumen of the artery or arteriole and increasing the amount of blood flowing through. Veins dilate more than arteries — so the biggest effect is less blood returning to the heart (↓preload), which means less work and less O2 demand for the heart muscle.
🧠 “NO means GO.” Nitric oxide (NO) = the vessel opens up and blood GOes through. The whole point is to make the heart's job easier, not to fix a clot.
🎯 Why we give it — “Reason”
🚨 Relieve pain of an acute anginal attack
🛡️ Prevent angina attacks — prophylaxis
💔 Treat chronic stable angina pectoris
🧠 Three jobs, one mechanism: rescue (SL, acute), prevention (long-acting forms), maintenance (chronic stable angina).
The same vasodilation that relieves chest pain also dilates cerebral vessels. Headache is a common, benign side effect — it usually eases with continued use and can be treated with a mild analgesic.
🧠 “No headache, no nitrate.” Ironically, a mild headache is often a sign the drug is working — don't let the patient stop it on their own for this alone.
❌ ABSOLUTE contraindication — PDE5 inhibitors
Sildenafil, tadalafil, and vardenafil (drugs for erectile dysfunction / pulmonary hypertension) both cause vasodilation through the same nitric-oxide pathway. Combined with a nitrate, the two vasodilating effects stack — the result can be severe, life-threatening hypotension and cardiovascular collapse. Always ask about ED medication use before giving a nitrate, and never give a nitrate to a patient who has recently taken one.
🧠 “Two vasodilators, one blood pressure to crash.” Always ask before you give — this is a hard-stop question, not a maybe.
🧍 Orthostatic hypotension
Vasodilation drops BP — teach the patient to sit or lie down before taking a nitrate and to rise slowly afterward to avoid fainting.
🚫 Other contraindications
Known hypersensitivity to the drug
Severe anemia
Closed-angle glaucoma
Head trauma / cerebral hemorrhage — vasodilation can worsen intracranial pressure
Constrictive pericarditis
Allergy to adhesive (transdermal forms)
🌙 Tolerance — why a nitrate-free interval matters
With continuous exposure (long-acting oral, ointment, or patch forms), blood vessels stop responding to the nitrate — the drug simply quits working as well. Scheduling a daily nitrate-free interval (commonly overnight) lets the vessels "reset" so the next dose works again.
🧠 “No break, no bang.” Skip the nitrate-free window and the drug quietly stops protecting against angina, even though the patch is still on.
🧑🏫
TEACH
STEP 3 · THE CHEST PAIN PROTOCOL
One protocol she should be able to say in her sleep.
🚨 Sublingual nitro for chest pain — the protocol
1
🛑 Stop what you're doing, sit or lie down
2
👅 Take 1 sublingual tablet or spray at the onset of chest pain
3
⏱️ Wait 5 minutes
4
☎️ Pain still there? Call EMS immediately — don't drive yourself, don't wait for more doses
5
🔁 May repeat every 5 minutes, up to 3 doses total while waiting for EMS to arrive
Call EMS as soon as pain persists after the first dose — don't wait to "use up" all 3 doses before getting help.
🧠 “1, 5, CALL.” One tablet, five minutes, then call — everything after that is happening on the way to the hospital, not instead of it.
🤕 Headache ≠ stop the drug
Remind the patient a headache is an expected side effect, not a reason to discontinue therapy on their own — a mild analgesic can help, and it often improves with continued use.
🧴 Handling
Don't rub ointment forms in with bare fingers — it absorbs through skin and can cause a severe headache
Sit or lie down before taking a dose — fall risk from a sudden BP drop
Avoid alcohol unless cleared by the prescriber — compounds the hypotension
📋 Report to the provider
💓 Heart rate well above the patient's normal baseline
⚖️ Rapid weight gain
🦵 New/unusual swelling of the extremities, face, or abdomen
😮💨 Dyspnea, angina, severe indigestion, or fainting
📓 Keep a log of anginal attacks — date, time, drug, dose used — bring it to every visit
🤕 Headache is expectednot a reason to stop the drug
❌ Never with PDE5 inhibitorssevere hypotension risk
🎯 Cover & check — 4 rapid-fire questions
Q1: How do nitrates relieve angina?
They release nitric oxide, relaxing vascular smooth muscle — vessels dilate (mostly veins), which drops preload and lowers the heart's oxygen demand.
Q2: A patient takes sublingual nitro for chest pain and it's still there 5 minutes later. Next step?
Call EMS immediately — do not wait to take all three doses before getting help.
Q3: A patient wants to stop their nitrate patch because of a daily headache. What do you teach?
Headache is an expected, benign side effect of the vasodilation and is not a reason to stop the drug — a mild analgesic can help and it often improves with continued use.
Q4: What question must you always ask before giving a nitrate, and why?
Ask about recent use of a PDE5 inhibitor (sildenafil, tadalafil, vardenafil) — combining them causes severe, potentially fatal hypotension. This is an absolute contraindication.