Advanced Pharmacology · Topic 6 of 13

IV Antihypertensives & Antianginals

Pharmacology · IV vasoactive drugs

IV Antihypertensives & Antianginals

Short-acting titratable IV drugs lower BP in a controlled way; pick the agent by the organ at risk — and beta-block before vasodilating in aortic dissection.

Key numbers

Lower BP ≤ 25% in hour 1≤ 25% in 1st hour

Nicardipine 5 mg/h, max 15 mg/h5 → max 15 mg/h

Labetalol 20 mg IV, then 40–80 mgmax 300 mg total

Aortic dissection: beta-blocker before any vasodilatorSBP < 120, HR 60–80

Nitroprusside above 2 mcg/kg/min: cyanide toxicity> 2 mcg/kg/min

01 · The ruleLower BP ≤ 25% in hour 1

In hypertensive emergency, use a short-acting titratable IV drug in the ICU: lower BP no more than 25% in the first hour, then to about 160/100–110 over 2–6 hours.

02 · The ruleAortic dissection: beta-blocker before any vasodilator

In aortic dissection, give an IV beta-blocker (esmolol, labetalol or metoprolol) first for heart rate 60–80/min and SBP below 120 mmHg; add a vasodilator such as nitroprusside only after beta-blockade.

03 · Watch forNitroprusside above 2 mcg/kg/min: cyanide toxicity

Nitroprusside is a last resort: above 2 mcg/kg/min cyanide accumulates (agitation, seizures, cardiac instability, anion-gap metabolic acidosis), and prolonged use or renal failure causes thiocyanate toxicity.

Management

Orders

Nicardipine 5 mg/h, max 15 mg/h must knowNicardipine (dihydropyridine calcium channel blocker, arterial vasodilator): start 5 mg/h and increase 2.5 mg/h every 5–15 minutes to a maximum of 15 mg/h; reflex tachycardia and headache are common.

Labetalol 20 mg IV, then 40–80 mg must knowLabetalol (alpha-1 plus beta blocker, no reflex tachycardia): 20 mg IV over 2 minutes, then 40–80 mg every 10 minutes to a total of 300 mg, or an infusion at 2 mg/min.

Clevidipine 1–2 mg/h, doubled every 90 secondsClevidipine (ultra-short-acting dihydropyridine, cleared by blood esterases): start 1–2 mg/h and double every 90 seconds early on; most patients respond at 4–6 mg/h, rarely needing more than 16 mg/h (limited experience up to 32 mg/h).

IV nitroglycerin for ACS and pulmonary edemaIV nitroglycerin is the choice for hypertension with myocardial ischemia or pulmonary edema (with a loop diuretic): start 5 mcg/min, increase by 5 mcg/min every 3–5 minutes, then by 10–20 mcg/min above 20 mcg/min.

Nitroprusside 0.3 mcg/kg/min, light-protected, short courseNitroprusside starts at 0.3 mcg/kg/min, titrated every few minutes to a maximum of 10 mcg/kg/min for as short a time as possible; wrap bag and tubing against light and check thiocyanate daily after 3 days.

Esmolol 500 mcg/kg load, then 50 mcg/kg/minEsmolol (cardioselective beta-1 blocker, half-life about 9 minutes): 500 mcg/kg over 1 minute, then 50 mcg/kg/min titrated; up to 200 mcg/kg/min for rate control, 250–300 for hypertension.

Stroke and ICH: labetalol, nicardipine or clevidipineFor acute stroke, use IV labetalol, nicardipine or clevidipine — before thrombolysis to < 185/110 then < 180/105 for 24 hours; in ICH, to SBP 130–< 140 mmHg (avoid < 130).

Catecholamine crisis: phentolamine, no unopposed beta-blockadeFor pheochromocytoma crisis or cocaine/amphetamine toxicity, give IV phentolamine (plus benzodiazepines for stimulants) and avoid unopposed beta-blockade, which leaves alpha vasoconstriction unchecked.

Preeclampsia: IV labetalol or hydralazineFor severe-range BP (≥ 160/110) in preeclampsia or eclampsia, give IV labetalol or hydralazine titrated to about 140–155/90–105 mmHg, plus magnesium sulfate; delivery is definitive.

IV beta-blocker for ongoing ischemia without shock riskIn ACS, an IV beta-blocker may be given for ongoing ischemic pain, tachycardia or hypertension, but avoid it with hypotension, heart failure or other signs of shock risk; oral beta-blockers are the routine choice.

Red flags & don'ts

Avoid harm

No clevidipine with soy or egg allergy avoidClevidipine is a lipid emulsion: it is contraindicated with soy or egg allergy, defective lipid metabolism and severe aortic stenosis; nicardipine is likewise contraindicated in advanced aortic stenosis.

No nitrates after a PDE-5 inhibitor avoidWithhold nitroglycerin after a phosphodiesterase-5 inhibitor (sildenafil within 24 h, tadalafil within 48 h) or riociguat, with SBP under 90 mmHg or right ventricular infarction, and in tamponade, constrictive pericarditis or raised intracranial pressure.

No IV beta-blockers in asthma, block, shock avoidAvoid labetalol and esmolol in bronchial asthma, severe bradycardia, AV block greater than first degree, decompensated heart failure and cardiogenic shock.

Never give short-acting sublingual nifedipine avoidDo not give short-acting oral or sublingual nifedipine for severe hypertension: the precipitous fall in BP can cause fatal cerebral or myocardial ischemia.

The rules

Know these

No IV drugs for asymptomatic severe hypertensionSevere hypertension without acute target-organ damage needs oral therapy and follow-up, not IV or as-needed IV antihypertensives, which are linked to AKI, longer stays and higher mortality in inpatients.

Nitroglycerin or nitroprusside?

Commonly confused

Main vessel effect	Veins more than arterioles
Coronary flow	Increases it — preferred in ACS
Starting dose	5 mcg/min
Key toxicity	Headache, tolerance, methemoglobinemia
Place in therapy	ACS and pulmonary edema

More detail

Reference

Show 5 reference facts

Nicardipine is avoided in acute heart failure and used cautiously with myocardial ischemia; clevidipine is used cautiously in heart failure with reduced ejection fraction because of possible negative inotropy.

Because of lipid load, give no more than 1000 mL (an average of 21 mg/h) of clevidipine per 24 hours; change a peripheral nicardipine infusion site every 12 hours to limit phlebitis.

Continuous nitroglycerin causes tolerance within about 24 hours (nitrate-free intervals restore effect), headache in most patients and, rarely, methemoglobinemia, treated with methylene blue 1–2 mg/kg.

PVC tubing adsorbs 20–60% of nitroglycerin, so delivered doses run lower than calculated; with nonadsorptive tubing, start low at 5 mcg/min.

Enalaprilat helps acute left ventricular failure but is avoided in acute MI and pregnancy; fenoldopam, a dopamine-1 agonist, causes renal vasodilation and natriuresis but can lower potassium and raise intraocular pressure.

Pearl

Nitroglycerin opens veins and coronaries; nitroprusside opens everything and leaves cyanide behind — keep it for last.

Sources · Merck Manual Professional — Hypertensive Emergencies (updated Apr 2026, cites 2025 AHA/ACC) · Cleviprex (clevidipine) injectable emulsion prescribing information — DailyMed · Cardene IV (nicardipine) premixed injection prescribing information — DailyMed · Labetalol hydrochloride injection prescribing information (Hospira) — DailyMed · Esmolol hydrochloride in sodium chloride injection prescribing information — DailyMed · Nitroglycerin in 5% dextrose injection prescribing information (Baxter) — DailyMed · Nipride RTU (sodium nitroprusside) prescribing information — DailyMed · Merck Manual Professional — Aortic Dissection · Merck Manual Professional — Medications for Acute Coronary Syndromes · Merck Manual Professional — Ischemic Stroke (updated Jan 2026) · Blood pressure management in stroke: comparative review of the 2025 AHA/ACC, 2024 ESC, 2023 ESH and 2025 JSH guidelines. Hypertens Res 2026 · EBM Consult — Contraindications to nitroglycerin in ACS (no nitrates within 24 h of sildenafil/vardenafil or 48 h of tadalafil) · Cialis (tadalafil) prescribing information — DailyMed (≥ 48 h before nitrate administration) · UIC Drug Information Group — Overview of the 2025 Hypertension Guidelines (Dec 2025) · Merck Manual Professional — Preeclampsia and Eclampsia · The Management of Hypertensive Emergencies — Is There a "Magical" Prescription for All? J Clin Med 2022 · Kulkarni S et al. Management of hypertensive crisis: British and Irish Hypertension Society position document. J Hum Hypertens 2023 · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).