4.2.7 Nitrates
Nitrates
From Pharmacology for Nurses, OpenStax Chapter 18
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.
| 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.
| Drug Class NitrateMechanism 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 failureTherapeutic Effects Lowers blood pressure Decreases cardiac workload |
Drug Interactions Avanafil Riociguat Sildenafil Tadalafil VardenafilFood 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 ShockCaution: 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.
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