What is the proper prescription and administration guidelines for sublingual nitroglycerin in a patient with a history of angina pectoris (chest pain) or coronary artery disease (CAD)?

How to Write a Prescription for Sublingual Nitroglycerin

All patients with angina pectoris or coronary artery disease should receive a prescription for sublingual nitroglycerin 0.3-0.4 mg tablets (or spray), with explicit written and verbal instructions on proper use, including the critical directive to call 9-1-1 immediately if chest pain is unimproved or worsening after 5 minutes and one dose. 1, 2, 3

Prescription Format

Write the prescription as follows:

Nitroglycerin 0.4 mg sublingual tablets

• Dispense: #100 tablets (or 200 metered doses for spray formulation) 3
• Sig: Dissolve one tablet under the tongue at the first sign of chest pain. May repeat every 5 minutes for maximum of 3 doses (total 15 minutes). If pain persists or worsens after first dose and 5 minutes, call 9-1-1 immediately. 1, 3
• Refills: 3-6 refills 3
• Additional instruction: May use prophylactically 5-10 minutes before activities that typically trigger angina 3

Critical Patient Education Points (Must Provide Written AND Verbal Instructions)

When to Take Nitroglycerin

• Take one tablet sublingually at the FIRST sign of chest discomfort—do not wait to see if pain resolves on its own 1, 2
• Patient should sit down immediately when taking nitroglycerin to prevent falls from lightheadedness or dizziness 3
• For predictable angina triggers (exercise, cold weather, sexual activity), take one tablet 5-10 minutes BEFORE the activity 3

Modified Emergency Protocol (Critical Update from Traditional Teaching)

The ACC/AHA guidelines have modified the traditional "take 3 tablets before calling 9-1-1" recommendation to encourage earlier emergency activation: 1

• Take 1 tablet sublingually at first sign of chest pain 1, 2
• If pain is unimproved or worsening after 5 minutes, call 9-1-1 IMMEDIATELY (do not wait for 3 doses) 1, 2
• While awaiting ambulance arrival, patient may take additional tablets every 5 minutes up to a maximum of 3 total doses 1, 3
• If pain is different in character or more severe than usual, call 9-1-1 immediately even after first dose 3

This modification addresses the critical problem of patient delay in seeking emergency care, which worsens outcomes in acute coronary syndrome. 1

Absolute Contraindications (Must Screen Before Prescribing)

Do NOT use nitroglycerin if: 2, 3

• Patient has used phosphodiesterase-5 inhibitors (sildenafil/Viagra, tadalafil/Cialis, vardenafil/Levitra) within 24-48 hours—this combination causes life-threatening hypotension 2, 3
• Systolic blood pressure <90 mmHg or ≥30 mmHg below baseline 2, 4
• Heart rate <50 bpm or >100 bpm (unless heart failure present) 2, 4
• Recent use of guanylate cyclase stimulators (riociguat) 3
• Very recent heart attack, severe anemia, or increased intracranial pressure 3

Storage and Shelf Life (Critical for Efficacy)

• Keep tablets in original glass container with cap tightly closed after each use—exposure to air rapidly degrades potency 3
• Shelf life is only 6 months after first opening the bottle for tablets (2 years for spray formulation) 5
• Store at room temperature 68°-77°F (20°-25°C) 3
• Write the date of first opening on the bottle and replace every 6 months even if tablets remain 5
• Studies show 35.6% of patients carry expired nitroglycerin, rendering it ineffective 5

Expected Effects and Side Effects

• Patient may feel burning or tingling sensation under the tongue—this is normal and indicates the tablet is dissolving 3
• Headache is the most common side effect and does not indicate the medication is harmful 4, 3
• Dizziness, lightheadedness, or flushing may occur due to vasodilation 3
• Effects should begin within 1-3 minutes and last 30-60 minutes 6

Special Considerations for Different Patient Populations

Patients with Chronic Stable Angina (Frequent Episodes)

For patients with predictable, frequent angina that typically responds well to nitroglycerin: 1

• May use a more tailored approach where if chest pain is significantly improved after first dose, patient may repeat every 5 minutes for maximum of 3 doses before calling 9-1-1 1
• However, if pain pattern changes (more frequent, more severe, occurs at rest, or lasts longer than usual), patient must call 9-1-1 immediately 1

Patients with New or Worsening Angina Pattern

• Any change in angina pattern (more frequent, more severe, precipitated by less effort, or occurring at rest) requires immediate contact with clinician to assess need for additional testing or treatment 1
• This represents potential acute coronary syndrome and requires urgent evaluation 1

Concomitant Medications (Must Prescribe Together)

Aspirin

• All patients receiving nitroglycerin for CAD should also receive aspirin 81-325 mg daily unless contraindicated 1, 2
• Instruct patients to chew 162-325 mg aspirin immediately if acute chest pain occurs while awaiting emergency services 2

Other Antianginal Medications

• Nitroglycerin is for acute relief only—patients require chronic antianginal therapy (beta-blockers, calcium channel blockers, long-acting nitrates) for prevention 1
• Continue all chronic medications after hospital discharge; nitroglycerin is adjunctive therapy 1

Common Prescribing Pitfalls to Avoid

Inadequate Patient Education

• Only 65.9% of patients receive proper instruction from physicians on nitroglycerin use 5
• 46% of eligible patients never receive a prescription for nitroglycerin despite guideline recommendations 5
• Provide both written and verbal instructions—this is a Class I recommendation 1

Failure to Include Family Members/Caregivers

• Include family members, friends, or caregivers in education sessions 1
• They should know when to call 9-1-1 and may need to assist with medication administration 1

Not Addressing Prophylactic Use

• Many patients only use nitroglycerin reactively after pain starts 6
• Prophylactic use 5-10 minutes before known triggers significantly reduces angina episodes and improves exercise tolerance 3, 6
• This prophylactic benefit remains under-appreciated despite strong evidence 6

Spray Formulation as Alternative

Nitroglycerin spray (400 mcg per spray) offers several advantages: 6

• Longer shelf life (2 years vs. 6 months for tablets) 5
• More reliable potency over time 6
• Faster onset of action 6
• Lower incidence of headache 6
• Better option for patients with dry mouth who cannot dissolve tablets 6

Prescription for spray: Nitroglycerin 400 mcg/spray, 1-2 sprays (400-800 mcg) under tongue at first sign of chest pain, may repeat every 5 minutes for maximum 3 doses. 4, 6

Documentation Requirements

Document in medical record: 1

• That prescription was provided
• That written AND verbal instructions were given
• That patient/caregiver demonstrated understanding of when to call 9-1-1
• That contraindications were reviewed (especially PDE-5 inhibitor use)
• That patient was instructed on storage and 6-month replacement schedule