💊 Pharmacology · Lesson 3 of 6 · 7 min

Digoxin, Beta Blockers and Nitro: Hold Parameters and Hard Stops

❤️ Before every dose of digoxin, a nurse counts an apical pulse for a full minute. If it is 58, the dose is held. The exam will give you 58, a potassium of 3.1 and blurry yellow vision, and ask what you do first.

💡 Key idea

Digoxin: apical pulse one minute, hold under 60, low potassium raises toxicity. Beta blockers: never stop abruptly. Nitroglycerin: never with PDE-5 inhibitors.

🧠 Why it matters

DIGOXIN: take an APICAL pulse for one full minute and hold for a rate under 60 in adults (under 90 to 110 in infants per order); therapeutic level about 0.5 to 2.0 ng/mL, with lower targets (about 0.5 to 1.0) often used in heart failure; toxicity shows as nausea, vomiting, anorexia, bradycardia, confusion and visual changes such as yellow-green halos. HYPOKALEMIA increases toxicity, so monitor potassium, especially with loop diuretics; the antidote is digoxin immune Fab. BETA BLOCKERS (ending in -olol): hold for heart rate under 60 or systolic pressure under 90 per order; never stop abruptly (rebound tachycardia and angina); they mask hypoglycemia symptoms in clients with diabetes, and non-selective agents can worsen asthma. NITROGLYCERIN for angina: one sublingual tablet every 5 minutes up to three doses, calling emergency services if pain is not relieved after the first dose per current guidance; expect a headache; keep tablets in the dark original bottle; absolutely contraindicated within 24 to 48 hours of PDE-5 inhibitors (sildenafil, tadalafil) because of profound hypotension. ACE INHIBITORS (-pril): dry cough, angioedema, hyperkalemia; ARBs (-sartan) as the alternative. CALCIUM CHANNEL BLOCKERS: avoid grapefruit juice. AMIODARONE: pulmonary and thyroid toxicity, photosensitivity.

🏥 In the real world

🟡 A client taking digoxin and furosemide reports nausea and seeing yellow halos around lights. Apical pulse 54, potassium 3.0. The nurse holds the digoxin, reports the findings, and anticipates a digoxin level and potassium replacement. The diuretic set the trap; the nurse who knows that potassium and digoxin are linked springs it before the arrhythmia does.

📌 Takeaways

Digoxin toxicity: GI upset, bradycardia, visual halos; low potassium makes it worse
Hold beta blockers for HR under 60 or SBP under 90; never stop abruptly
Nitroglycerin: up to 3 doses 5 minutes apart; contraindicated with sildenafil

📖 Terms in this lesson

Beta blockers (-olol): Slow the heart and lower blood pressure after a heart attack and in heart failure; hold for a heart rate under 60 or systolic pressure under 90 per order, never stop them abruptly, and warn clients with diabetes that they mask hypoglycemia.

Calcium channel blockers (-dipine, verapamil, diltiazem): Relax vessels for hypertension and angina, and verapamil or diltiazem also slow the heart rate; expect ankle swelling and headache, hold for low pressure or a slow pulse per order, and avoid grapefruit juice.

Digoxin: Strengthens and slows the heart in failure and atrial fibrillation; count an apical pulse for a full minute and hold under 60, watch for nausea, vomiting and yellow-green halos, remember low potassium raises toxicity, and the antidote is digoxin immune fab.

Nitroglycerin and nitrates: Dilate vessels to relieve angina: one sublingual tablet every 5 minutes up to three, calling emergency services if the first does not help; expect a headache, store tablets in the dark bottle, and never give within 24 to 48 hours of sildenafil or tadalafil.

Amiodarone: Controls dangerous ventricular and atrial rhythms but damages the lungs, thyroid, liver and eyes; report new cough or dyspnea at once, check thyroid and liver labs, expect bradycardia and hypotension during IV loading, and teach sun protection for the blue-gray skin and photosensitivity.

Adenosine: Resets supraventricular tachycardia by briefly stopping the heart; push it fast over 1 to 2 seconds with an immediate saline flush into a large proximal vein, keep the client on a monitor, and warn that seconds of chest pressure, flushing and asystole are expected.

Nitroprusside: A fast IV vasodilator for hypertensive emergency, titrated with continuous blood pressure monitoring (ideally an arterial line); wrap the bag to protect it from light, and watch for cyanide or thiocyanate toxicity (confusion, metabolic acidosis) with high doses, long infusions or kidney failure.

Clonidine: A central alpha-2 agonist for hypertension (also ADHD and opioid withdrawal) that causes dry mouth and drowsiness; the defining danger is rebound hypertension when it is stopped suddenly, so taper it, never skip doses, and change the weekly patch on schedule.

✅ Test yourself

Before administering digoxin, the nurse counts an apical pulse of 56 beats per minute in an adult. What should the nurse do?

Hold the dose and notify the provider
Recheck the radial pulse and give the dose if it is above 60
Administer the dose and document the rate
Give half the dose

Answer: A · Hold the dose and notify the provider

Hold digoxin for an apical rate under 60 and report. The apical pulse, not radial, is the standard assessment.

A client with chest pain took one sublingual nitroglycerin tablet 5 minutes ago without relief. The client mentions taking sildenafil last night. What is the nurse's priority concern?

The client needs a higher dose
Profound hypotension
Headache from the nitroglycerin
The tablet was probably expired

Answer: B · Profound hypotension

Nitrates with PDE-5 inhibitors cause profound, potentially fatal hypotension. The combination is contraindicated.

Which teaching is essential for a client starting a beta blocker such as metoprolol?

Stop the drug immediately if you feel tired
Take it only when your blood pressure feels high
Check your pulse; do not stop the drug abruptly
Drink grapefruit juice to improve absorption

Answer: C · Check your pulse; do not stop the drug abruptly

Abrupt withdrawal causes rebound tachycardia and can precipitate angina or MI. Clients monitor pulse and pressure.

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