Name of the Nitrates drugs:
- Glyceryl trinitrate (GTN).
- Isosorbide mononitrate
Mechanism of Action:
- Metabolized to nitric oxide that activates guanylyl cyclase, increasing production of cGMP in vascular tissues.
- This secondary messenger causes smooth muscle relaxation resulting in coronary artery dilatation (increasing oxygen supply to myocardium) and systemic vasodilation (reducing preload and thereby reducing oxygen demand).
Indications:
- Prophylaxis and treatment of angina pectoris
- Acute coronary syndrome
- LVF.
- Heart failure
- Arterial hypertension
Cautions & Contraindications:
- Hypersensitivity to nitrates.
- Hypotension/Hypovolemia.
- Cardiac outflow obstruction (aortic stenosis, cardiac tamponade, hypertrophic obstructive cardiomyopathy, constrictive pericarditis)
- Closed-angle glaucoma.
- Concomitant use of phosphodiesterase (PDE) inhibitors such as tadalafil and sildenafil
- Right ventricular infarction
- Hypertrophic cardiomyopathy
| Isosorbide mononitrate |
| Availability: Mononitrate Tablets: 10 mg, 20 mg. Tablets, Extended-Release: 30 mg, 60 mg, 120 mg |
| Administration/handling: PO • Best if taken on an empty stomach. • Do not administer around the clock. • Oral tablets may be crushed. • Do not crush/break sustained-, extended release form. |
| Angina : PO: (Isosorbide Mononitrate) (Immediate-Release): Adults, elderly: 20 mg twice daily given 7 hrs apart to decrease tolerance development. In pts with small stature, may start at 5 mg twice daily and titrate to at least 10 mg twice daily in first 2–3 days of therapy. (Sustained-Release): Initially, 30–60 mg/day in morning as a single dose. May increase dose at 3-day intervals to 120 mg once daily. Maximum daily single dose: 240 mg. |
| Glyceryl trinitrate/ Nitro-glycerine |
| Availability: Infusion, Premix: 25 mg/250 mL, 50 mg/250 mL, 100 mg/250 mL. Injection Solution: 5 mg/mL. Ointment: (NitroBid): 2%. Ointment, Rectal (Rectiv): 0.4%. Translingual Spray: 0.4 mg/ spray. Transdermal Patch: 0.1 mg/hr, 0.2 mg/hr, 0.4 mg/hr, 0.6 mg/hr. Capsules, Extended-Release: 2.5 mg, 6.5 mg, 9 mg. Tablets, Sublingual: 0.3 mg, 0.4 mg, 0.6 mg |
| Administration/handling: Cardioverter/defibrillator must not be discharged through paddle electrode overlying nitroglycerin (transdermal, ointment) application. May cause burns to pt or damage to paddle via arcing |
| IV Reconstitution • Available in ready to-use injectable containers. • Dilute vials in D5W or 0.9% NaCl. Maximum concentration: 400 mcg/mL. • Use glass bottles. Rate of administration: 3 mL/hr (10 mcg/min) • Use micro drop or infusion pump. Storage: • Store at room temperature. • Reconstituted solutions stable for 48 hrs at room temperature or 7 days if refrigerated. |
| PO: • Do not break, crush, or open extended-release capsules. • Do not shake oral aerosol canister before lingual spraying sublingual • Instruct pt to not swallow. • Dissolve under tongue. • Administer while seated. • Slight burning sensation under tongue may be lessened by placing tablet in buccal pouch. • Keep sublingual tablets in original container. |
| Topical: • Spread thin layer on clean, dry, hairless skin of upper arm or body (not below knee or elbow), using applicator or dose-measuring papers. Do not use fingers; do not rub/massage into skin. |
| Transdermal: • Apply patch on clean, dry, hairless skin of upper arm or body (not below knee or elbow). • May keep patch on when bathing/showering. • Do not cut/ trim to adjust dose. |
| Angina, CAD Translingual spray: Adults, elderly: 1 spray (0.4 mg) q5min up to 3 doses in response to chest pain. If chest pain fails to improve or worsens in 3-5min after 1 dose, call 911. Sublingual: Adults, elderly: One tablet (0.3–0.4 mg) under tongue. If chest pain fails to improve or worsens in 3–5 min, call 911. After the call, may take additional tablet. A third tablet may be taken 5 min after second dose (maximum of 3 tablets). PO: (Extended-Release): Adults, elderly: 2.5–6.5 mg 3–4 times/day. Maximum: 26 mg 4 times/day. Topical: Adults, elderly: Initially, 1/2 inch upon waking and 1/2 inch 6 hrs later. May double dose to 1 inch and double again to 2 inches. Maximum: 2 doses/day including nitrate-free interval of 10–12 hrs. Transdermal patch: Adults, elderly: Initially, 0.2–0.4 mg/hr. Maintenance: 0.4–0.8 mg/hr. Consider patch on for 12–14 hrs, patch off for 10–12 hrs (prevents tolerance). |
| HF, Acute MI : IV: Adults, elderly: Initially, 5 mcg/ min via infusion pump. Increase in 5-mcg/min increments at 3- to 5-min intervals until B/P response is noted or until dosage reaches 20 mcg/min, then increase by 10–20 mcg/min q3–5min. Dosage may be further titrated according to clinical, therapeutic response up to 400 mcg/min. |
| Anal Fissure Rectal: Adults, elderly: One- inch (1.5 mg) q12h for up to 3 wks. |
Side-Effects:
- Headaches (greater than 10%)
- Hypotension (0.1 to 10%)
- Cutaneous flushing (0.1 to 10%)
- Syncope (0.1 to 10%)
- Reflex tachycardia (0.1 to 10%)
- Methemoglobinemia (rare)
- Monday disease (tachycardia, headache, and dizziness during re-exposure)
Metabolism And Half-Life:
- Metabolized by the liver and other cells including red blood cells.
- T ½ is variable- for intravenous GTN t ½ is 4-6min and for oral ISMN t ½ is 6h.
Drug Interactions:
- Reduce the anticoagulant effect of low molecular weight heparin.
- Risk of severe hypotension with phosphodiesterase type 5 inhibitors (e.g. sildenafil)
Important points:
Tolerance to nitrates may develop, hence patients should have at least 8h nitrate-free every 24h (except when administered intravenously in the acute setting).
NURSING CONSIDERATIONS
Baseline assessment
- Record onset, type (sharp, dull, squeezing), radiation, location, intensity duration of anginal pain; precipitating factors (exertion, emotional stress).
- Assess B/P, apical pulse before administration and periodically following dose.
- Pt must have continuous ECG monitoring for IV administration.
- Rule out right sided MI, if applicable (may precipitate life-threatening hypotension).
- Receive full medication history, and screen for interactions, esp. use of PDE5 inhibitors.
- Question medical history and screen for contraindications.
Intervention/evaluation
- Monitor number of anginal episodes, orthostatic B/P.
- Monitor B/P, heart rate. Assess for facial, neck flushing.
- Assist with ambulation if light-headedness, dizziness occurs.
- Cardioverter/defibrillator must not be discharged through paddle electrode overlying nitroglycerin (transdermal, ointment) system (may cause burns to pt or damage to paddle via electrical arcing).
- Consider NS boluses for hypotension.
Patient/family teaching
- Report signs/symptoms of hypotension, angina.
- Do not chew, crush, dissolve, or divide sublingual, extended-release, sustained release forms.
- Go from lying to standing slowly.
- Take oral form on empty stomach (however, if headache occurs during therapy, take medication with meals).
- Use spray only when lying down.
- Take sublingual tablets while sitting down. Dissolve sublingual tablet under tongue; do not swallow.
- Take at first sign of angina. May take additional dose q5min if needed up to a total of 3 doses. If not relieved within 5 min, contact physician or immediately go to emergency room.
- Do not change brands. • Keep container away from heat, moisture.
- Do not inhale lingual aerosol but spray onto or under tongue (avoid swallowing after spray is administered).
- Expel from mouth any remaining lingual, sublingual, intrabuccal tablet after pain is completely relieved.
- Place transmucosal tablets under upper lip or buccal pouch (between cheek and gum); do not chew/ swallow tablet.
- Avoid alcohol (intensifies hypotensive effect). If alcohol is ingested soon after taking nitrates, possible acute hypotensive episode (marked drop in B/P, vertigo, diaphoresis, pallor) may occur. Do not use within 48 hrs of sildenafil, tadalafil, vardenafil (PDE5 inhibitors); may cause acute hypotensive episode
REFERENCES
- Robert Kizior, Keith Hodgson, Saunders Nursing Drug handbook,1st edition 2024, Elsevier Publications. ISBN-9780443116070
- McGraw Hill- Drug Handbook, Seventh Edition, 2013, McGraw Hill Education Publications,9780071799430.
- April Hazard, Cynthia Sanoski, Davi’s Drug Guide for Nurses -Sixteenth Edition 2019, FA Davis Company Publications,9780803669451.
- Jones and Bartlet, Pharmacology for Nurses, Second Edition, 2020, Jones and Bartlet Learning Publications, ISBN 9781284141986.
- Nursebro.com, Search – Nursebro
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