NITROGLYCERIN

Medical Diagnosis and Drugs, Medications
NITROGLYCERIN
(nye-troe-gli'ser-in)
Minitran, Nitrocap, Nitrodisc, Nitro-Dur, Nitrogard, Nitrogard-SR, Nitrong SR, Nitrospan, Nitrostat, Nitrostat I.V.
Classifications: nitrate vasodilator;
Therapeutic: antianginal
; nitrate vasodilator
Pregnancy Category: C

Availability

5 mg/mL injection; 0.3 mg, 0.4 mg, 0.6 mg sublingual tablets; 2.5 mg, 6.5 mg, 9 mg sustained release tablets, capsules; 0.1 mg/h, 0.2 mg/h, 0.3 mg/h, 0.4 mg/h, 0.6 mg/h, 0.8 mg/h transdermal patch; 2% ointment

Action

Organic nitrate and potent vasodilator that relaxes vascular smooth muscle after conversion to nitric oxide that leads to dose-related dilation of both venous and arterial blood vessels. Promotes peripheral pooling of blood, reduction of peripheral resistance, and decreased venous return to the heart. Both left ventricular preload and afterload are reduced and myocardial oxygen consumption or demand is decreased.

Therapeutic Effect

Therapeutic doses may reduce systolic, diastolic, and mean BP; heart rate is usually slightly increased. Produces antianginal, antiischemic, and antihypertensive effects.

Uses

Prophylaxis, treatment, and management of angina pectoris. IV nitroglycerin is used to control BP in perioperative hypertension, CHF associated with acute MI; to produce controlled hypotension during surgical procedures, and to treat angina pectoris in patients who have not responded to nitrate or beta-blocker therapy.

Unlabeled Uses

Sublingual and topical to reduce cardiac workload in patients with acute MI and in CHF. Ointment for adjunctive treatment of Raynaud's disease.

Contraindications

Hypersensitivity, idiosyncrasy, or tolerance to nitrates; severe anemia; head trauma, increased ICP; glaucoma (sustained release forms). Also (IV nitroglycerin): hypotension, uncorrected hypovolemia, constrictive pericarditis, pericardial tamponade; pregnancy (category C).

Cautious Use

Severe liver or kidney disease, conditions that cause dry mouth, early MI; lactation.

Route & Dosage

Angina
Adult: Sublingual 1–2 sprays (0.4–0.8 mg) or a 0.3–0.6-mg tablet q3–5min as needed (max: 3 doses in 15 min) PO 1.3–9 mg q8–12h IV Start with 5 mcg/min and titrate q3–5min until desired response (up to 200 mcg/min) Transdermal Unit Apply once q24h or leave on for 10–12 h, then remove and have a 10–12 h nitrate free interval Topical Apply 1.5–5 cm (?–2 in) of ointment q4–6h
Child: IV 0.25–0.5 mcg/kg/min, titrate by 0.5–1 mcg/kg/min q3–5min (max 5 mg/kg/min)

Administration

Note: Drug forms appropriate for angina prophylaxis include ointment, transdermal unit, translingual spray, transmucosal tablet, and oral sustained release forms. Drug forms appropriate for acute angina include sublingual tablet, translingual spray, or transmucosal tablet.

Sublingual Tablet
  • Give 1 tablet and if pain is not relieved, give additional tablets at 5-min intervals, but not more than 3 tablets in a 15-min period.
  • Typically available for self-administration in their original container. Instruct in correct use. Request patient to report all attacks. Count tablets daily.
  • Instruct to sit or lie down upon first indication of oncoming anginal pain and to place tablet under tongue or in buccal pouch (hypotensive effect of drug is intensified in the upright position).
Sustained Release Tablet or Capsule
  • Give on an empty stomach (1 h before or 2 h after meals), with a full glass of water. Ensure it is swallowed whole.
  • Be aware that sustained release form helps to prevent anginal attacks; it is not intended for immediate relief of angina.
  • Ensure that tablet is not crushed or chewed.
Transdermal Ointment
  • Using dose-determining applicator (paper application patch) supplied with package, squeeze prescribed dose onto this applicator. Using applicator, spread ointment in a thin, uniform layer to premarked 5.5 by 9 cm (2 1/4 by 3 ? in.) square. Place patch with ointment side down onto nonhairy skin surface (areas commonly used: chest, abdomen, anterior thigh, forearm). Cover with transparent wrap and secure with tape. Avoid getting ointment on fingers.
  • Rotate application sites to prevent dermal inflammation and sensitization. Remove ointment from previously used sites before reapplication.
  • Keep ointment container tightly closed and store in cool place.
Transdermal Unit
  • Apply transdermal unit (transdermal patch) at the same time each day, preferably to skin site free of hair and not subject to excessive movement. Avoid abraded, irritated, or scarred skin. Clip hair if necessary.
  • Change application site each time to prevent skin irritation and sensitization.
Intravenous

Note: Verify correct IV concentration and rate of infusion in infants and children with physician.

  • Check to see if patient has transdermal patch or ointment in place before starting IV infusion. The patch (or ointment) is usually removed to prevent overdosage.
  • Be aware that when switching from IV to transdermal nitroglycerin, the IV infusion rate is reduced by 50% with simultaneous application of 5 or 10 mg/24 h transdermal patch.

PREPARE: IV Infusion: Nitroglycerin is available undiluted and premixed in D5W IV solutions of varying concentrations. IV Infusion from Concentrate: Use only non-PVC plastic or glass bottles and manufacturer-supplied IV tubing. Withdraw contents of one vial (25 or 50 mg) into syringe and inject immediately into 500 mL of IV solution to minimize contact with plastic; yields 50 mcg/mL or 100 mcg/mL. If less fluid is desired, add 5 mg to 100 mL to yield 50 mcg/mL. Other concentrations within the range of 25–400 mcg/mL may be used. Do not exceed 400 mcg/mL.  

ADMINISTER: IV Infusion: Give by continuous infusion regulated exactly by an infusion pump. IV dosage titration requires careful and continuous hemodynamic monitoring.  

INCOMPATIBILITIES Solution/additive: Caffeine, hydralazine, phenytoin. Y-site: Alteplase, levofloxacin.

  • Use only glass containers for storage of reconstituted IV solution. Polyvinyl chloride (PVC) plastic can absorb nitroglycerin and therefore should not be used. Non-polyvinyl-chloride (non-PVC) sets are recommended or provided by manufacturer.

Adverse Effects (≥1%)

CNS: Headache, apprehension, blurred vision, weakness, vertigo, dizziness, faintness. CV: Postural hypotension, palpitations, tachycardia (sometimes with paradoxical bradycardia), increase in angina, syncope, and circulatory collapse. GI: Nausea, vomiting, involuntary passing of urine and feces, abdominal pain, dry mouth. Hematologic: Methemoglobinemia (high doses). Skin: Cutaneous vasodilation with flushing, rash, exfoliative dermatitis, contact dermatitis with transdermal patch; topical allergic reactions with ointment: pruritic eczematous eruptions, anaphylactoid reaction characterized by oral mucosal and conjunctival edema. Body as a Whole: Muscle twitching, pallor, perspiration, cold sweat; local sensation in oral cavity at point of dissolution of sublingual forms.

Diagnostic Test Interference

Nitroglycerin may cause increases in determinations of urinary catecholamines and VMA; may interfere with the Zlatkis-Zak color reaction, causing a false report of decreased serum cholesterol.

Interactions

Drug: Alcohol, antihypertensive agents compound hypotensive effects; IV nitroglycerin may antagonize heparin anticoagulation. Vasodilating effects may be enhanced by sildenafil, vardenafil, or tadalafil, so this combination should be avoided.

Pharmacokinetics

Absorption: Significant loss to first pass metabolism after oral dosing. Onset: 2 min SL; 3 min PO; 30 min ointment. Duration: 30 min SL; 3–5 h PO; 3–6 h ointment. Distribution: Widely distributed; not known if distributes to breast milk. Metabolism: Extensively in liver. Elimination: Inactive metabolites in urine. Half-Life: 1–4 min.

Nursing Implications

Assessment & Drug Effects

  • Administer IV nitroglycerin with extreme caution to patients with hypotension or hypovolemia since the IV drug may precipitate a severe hypotensive state.
  • Monitor patient closely for change in levels of consciousness and for dysrhythmias.
  • Be aware that moisture on sublingual tissue is required for dissolution of sublingual tablet. However, because chest pain typically leads to dry mouth, a patient may be unresponsive to sublingual nitroglycerin.
  • Assess for headaches. Approximately 50% of all patients experience mild to severe headaches following nitroglycerin. Transient headache usually lasts about 5 min after sublingual administration and seldom longer than 20 min. Assess degree of severity and consult as needed with physician about analgesics and dosage adjustment.
  • Supervise ambulation as needed, especially with older adult or debilitated patients. Postural hypotension may occur even with small doses of nitroglycerin. Patients may complain of dizziness or weakness due to postural hypotension.
  • Take baseline BP and heart rate with patient in sitting position before initiation of treatment with transdermal preparations.
  • One hour after transdermal (ointment or unit) medication has been applied, check BP and pulse again with patient in sitting position. Report measurements to physician.
  • Assess for and report blurred vision or dry mouth.
  • Assess for and report the following topical reactions. Contact dermatitis from the transdermal patch; pruritus and erythema from the ointment.
  • Be aware that local burning or tingling from the sublingual form has no clinical significance.
  • Be alert for overdose symptoms: Hypotension, tachycardia; warm, flushed skin becoming cold and cyanotic; headache, palpitations, confusion, nausea, vomiting, moderate fever, and paralysis. Tissue hypoxia leads to coma, convulsions, cardiovascular collapse. Death can occur from asphyxia.

Patient & Family Education

  • Store tablet form in its original container.
  • Sit or lie down upon first indication of oncoming anginal pain.
  • Spit out the rest of your sublingual tablet as soon as pain is completely relieved, especially if you are experiencing unpleasant adverse effects such as headache. Relax for 15–20 min after taking tablet to prevent dizziness or faintness.
  • Be aware that pain not relieved by 3 sublingual tablets over a 15-min period may indicate acute MI or severe coronary insufficiency. Contact physician immediately or go directly to emergency room.
  • Note: Sublingual tablets may be taken prophylactically 5–10 min prior to exercise or other stimulus known to trigger angina (drug effect lasts 30–60 min).
  • Keep record for physician of number of angina attacks, amount of medication required for relief of each attack, and possible precipitating factors.
  • Be aware that contact with water (swimming, bathing) does not affect your transdermal unit.
  • Remove transdermal unit or ointment immediately from skin and notify physician if faintness, dizziness, or flushing occurs following application.
  • You can use a sublingual formulation while transdermal unit or ointment is in place.
  • Report blurred vision or dry mouth. Both warrant withdrawal of drug.
  • Change position slowly and avoid prolonged standing. Dizziness, light-headedness, and syncope (due to postural hypotension) occur most frequently in older adults.
  • Do not drink alcohol too soon after taking nitroglycerin. It may cause severe postural hypotension (sharp drop in BP), vertigo, flushing, or pallor if you drink alcohol too soon after taking nitroglycerin.
  • Report any increase in frequency, duration, or severity of anginal attack.
  • Withdraw gradually after prolonged use to prevent precipitating anginal attack.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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