18.7: Nitrates

Learning Objectives

By the end of this section, you should be able to:

• 18.7.1 Identify the characteristics of the nitrate drugs used to treat hypertension and angina.
• 18.7.2 Explain the indications, actions, adverse reactions, and interactions of the nitrate drugs used to treat hypertension and angina.
• 18.7.3 Describe nursing implications of nitrate drugs used to treat hypertension and angina.
• 18.7.4 Explain the client education related to nitrate drugs used to treat hypertension and angina.

Introduction and Use

Nitrates are a classification of drugs that cause vasodilation of blood vessels, which relaxes smooth muscles and causes the dilation of coronary vessels. Vasodilation improves oxygen supply to the heart, decreases oxygen demand within the body, reduces cardiac workload (preload and afterload), and lowers blood pressure. Nitrates have been used to treat chest pain and angina since the early 1800s. Nitrates come in different forms including oral, sublingual, translingual spray, intravenous, topical, and transdermal and can be short-acting or long-acting. Nitrates are commonly used to treat angina, acute coronary syndrome, arterial hypertension, and heart failure (Lee & Gerriets, 2022).

Special Considerations

Nitrates

Older clients using nitrates are at a higher risk for postural hypotension and should rise from a lying or sitting position slowly to prevent falls and injuries.

(Source: Lee & Gerriets, 2023)

Table 18.13 lists common nitrates and typical routes and dosing for adult clients.

Table 18.13 Drug Emphasis Table: Nitrates (source: https://dailymed.nlm.nih.gov/dailymed/)

Drug	Routes and Dosage Ranges
Isosorbide dinitrate (Isordil)	Sublingual tablets: 2.5–10 mg by sublingual route as needed every 2–4 hours. Immediate-release tablets: 5–80 mg orally 2–3 times daily. Sustained-release capsules: 40 mg orally 1–2 times daily; maximum dose 160 mg daily.
Isosorbide mononitrate (Imdur)	Immediate-release tablets: 5–20 mg twice daily. Extended-release tablets: 30–60 mg once daily; maximum dose 240 mg daily.
Nitroglycerin (Nitrobid, Nitrostat, Nitrolingual)	Sublingual tablets: 0.15–0.6 mg administered sublingually as needed for chest pain every 5 minutes up to 3 times for continued chest pain. Sustained-release tablets: 2.5 mg orally 3–4 times daily. Spray: 1–2 metered doses (0.4 mg/dose) sprayed onto oral mucosa as needed for chest pain every 5 minutes up to 3 times for continued chest pain. Ointment: 1/2 to 2 inches applied topically every 4–8 hours daily. Patch (disk): Applied to skin once daily. Solution: 5–10 mcg/minute up to 100 mcg/minute IV.
Nitroprusside (Nipride)	Solution: 0.3 mcg/kg/min IV and titrate every few minutes until desired effect is achieved; maximum dose 10 mcg/kg/min.

Adverse Effects and Contraindications

Adverse effects for nitrates include headache, lightheadedness, flushing, syncope, reflex tachycardia, and dizziness. Serious adverse effects include hypotension.

Contraindications include allergies to nitrates, concomitant use of phosphodiesterase (PDE) inhibitors such as tadalafil and sildenafil, history of right ventricular infarction, and hypertrophic cardiomyopathy. Nitrates should be used cautiously in clients on long-term diuretic therapy, with low systolic blood pressure, with autonomic nervous system dysregulation, and who are pregnant or breastfeeding.

Safety Alert

Nitrates

Nitrates can induce hypotension. They should not be taken with PDE inhibitors because they can cause severe hypotension and cardiac decompensation.

Table 18.14 is a drug prototype table for nitrates featuring nitroglycerin. It lists drug class, mechanism of action, adult dosage, indications, therapeutic effects, drug and food interactions, adverse effects, and contraindications.

Table 18.14 Drug Prototype Table: Nitroglycerin (source: https://dailymed.nlm.nih.gov/dailymed/)

Drug Class Nitrate Mechanism of Action Relaxes the smooth muscles and blood vessels, causing vasodilation, and thereby lowering blood pressure, heart rate, and cardiac workload	Drug Dosage Sublingual tablets: 0.15–0.6 mg administered sublingually as needed for chest pain every 5 minutes up to 3 times for continued chest pain. Sustained-release tablets: 2.5 mg orally 3–4 times daily. Spray: 1–2 metered doses (0.4 mg/dose) sprayed onto oral mucosa as needed for chest pain every 5 minutes up to 3 times for continued chest pain. Ointment: 1/2 to 2 inches applied topically every 4—8 hours daily. Patch (disk): Applied to skin once daily. Solution: 5–10 mcg/minute up to 100 mcg/minute IV.
Indications To control angina In the treatment of hypertensive emergency, pulmonary edema, and heart failure Therapeutic Effects Lowers blood pressure Decreases cardiac workload	Drug Interactions Avanafil Riociguat Sildenafil Tadalafil Vardenafil Food Interactions Alcohol Tobacco
Adverse Effects Orthostatic hypotension Tachycardia Paradoxical bradycardia Flushing Peripheral edema Nausea/vomiting Headache Blurred vision Syncope Palpitations	Contraindications Hypersensitivity Increased intracranial pressure Cardiomyopathy Shock Caution: Hepatic impairment Renal impairment Myocardial infarction Hypotension Hypovolemia Head trauma Pregnancy Breastfeeding

Nursing Implications

The nurse should do the following for clients who are taking nitrates:

• Carefully assess the client for drug and herbal supplement interactions because they may cause profound hypotension.
• Assess and monitor the client’s blood pressure during initial dosing and intermittently throughout drug therapy, especially if administering nitrates intravenously, because they may cause severe hypotension.
• Do not administer nitrates if the client’s systolic blood pressure is less than 90 mm Hg and if the heart rate is greater than 100 beats/minute. Notify the health care provider.
• Adhere to health care provider instructions on how and when to administer this classification of drug or when to hold the drug.
• Assess adverse effects and therapeutic effects.
• Provide client teaching regarding the drug and when to call the health care provider. See below for client teaching guidelines.

Client Teaching Guidelines

The client taking a sublingual nitrate should:

• Take sublingual nitrates if chest pain occurs. They should take one sublingual nitrate every 5 minutes times three doses if chest pain persists. If chest pain continues, the client should call 911.
• Store sublingual nitrate bottles away from the light in a dry place and in the original amber glass bottle.

The client using nitrate patches should:

• Apply patches once daily as a maintenance medication.
• Avoid hairy areas when applying nitrate patches.
• Remove nitrate patches for 10–12 hours before placing a new one to prevent tolerance.
• Rotate sites of nitrate patches to prevent skin irritation.

The client using a nitrate should not:

• Use patches for acute chest pain.
• Take erectile dysfunction medications because this may cause profound hypotension.

Other Concerns

• Headaches may occur with the use of nitrates. Acetaminophen may help in relieving these headaches.
• If low blood pressure develops, the client should lie on their back with legs elevated and notify their health care provider.

FDA Black Box Warning

Nitroprusside

Nitroprusside can cause precipitous decreases in blood pressure which can lead to irreversible ischemic injuries or death.

Nitroprusside produces dose-related cyanide which can be lethal. Limit infusions at the maximum rate to as short as duration as possible.

Unfolding Case Study

Part C

Read the following clinical scenario to answer the questions that follow. This case study is a follow-up from Case Study Parts A and B.

Hahn Tran is following up with the health care provider 3 months after her initial diagnosis of hypertension stage 2. She reports her headaches and dizziness have improved; however, she is now reporting chest pain when she walks 1–2 miles. The chest pain is relieved by resting on a park bench. Hahn states she experiences a burning in her chest that does not radiate to other areas. She denies nausea, diaphoresis, shortness of breath, or dizziness with chest pain.

The nurse performs a 12-lead ECG on Hahn, as ordered. The health care provider notes that there are no ischemic changes and diagnoses Hahn with stable angina. The health care provider prescribes verapamil 40 mg orally three times daily and nitroglycerin 0.4 mg sublingually for chest pain. The nurse is developing a teaching care plan for Hahn.

Table 18.15

Vital Signs		Physical Examination
Temperature:	98.4°F	Cardiovascular: No jugular vein distention or pedal edema; S1, S2 noted. Respiratory: Breath sounds clear on auscultation.
Blood pressure:	144/90 mm Hg
Heart rate:	78 beats/min
Respiratory rate:	16 breaths/min
Oxygen saturation:	98% on room air
Height:	5'3"
Weight:	188 lb

Exercise \(\PageIndex{5}\)

Which instruction about verapamil will the nurse include in the teaching plan?

Limit your fluid intake when taking this medication.

Do not take this medication on an empty stomach.

Swelling of your feet is common when taking this medication.

Increase your daily fiber intake when taking this medication.

Answer

Increase your daily fiber intake when taking this medication.

Exercise \(\PageIndex{6}\)

The nurse teaches Hahn about a heart-healthy diet. Which statement by Hahn indicates a need for further teaching?

“I can eat red meat every day.”

“I need to reduce my salt intake.”

“Apples and oranges are a good snack option.”

“I can replace table salt with dried herbs.”

Answer

“I can eat red meat every day.”