Isosorbide Nitrates

isosorbide nitrates (eye soe sor' bide)

isosorbide dinitrate Apo-ISDN (CAN), Cedocard SR (CAN), Dilatrate SR, Isordil, Isordil Tembids, Isordil Titradose, Sorbitrate

isosorbide mononitrate ISMO, Imdur, Isotrate ER, Monoket Pregnancy Category C Drug classes

Antianginal Nitrate Vasodilator Therapeutic actions

Relaxes vascular smooth muscle with a resultant decrease in venous return and decrease in arterial BP, which reduces left ventricular workload and decreases myocardial oxygen consumption. Indications

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Dinitrate: Treatment and prevention of angina pectoris Mononitrate: Prevention of angina pectoris

Contraindications and cautions

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Contraindicated with allergy to nitrates, severe anemia, head trauma, cerebral hemorrhage, hypertrophic cardiomyopathy, narrow-angle glaucoma, postdural hypotension Use cautiously with pregnancy, lactation, acute MI, CHF.

Available forms

Dinitrate: tablets—5, 10, 20, 30, 40 mg; SR tablets—40 mg; SR capsules—40 mg; SL tablets—2.5, 5, 10 mg; chewable tablets—5, 10 mg Mononitrate: Tablets—10, 20 mg; ER tablets —30, 60, 120 mg Dosages ADULTS

To avoid tolerance to drug, take short-acting products bid or tid with last dose no later than 7 PM and sustained-release products once daily or bid at 8 PM and 2 PM. This creates a nitrate-free period. Isosorbide dinitrate

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Angina pectoris: Starting dose, 2.5–5 mg sublingual, 5-mg chewable tablets, 5- to 20-mg oral tablets. For maintenance, 10–40 mg q 6 hr oral tablets or capsules; sustained release, initially 40 mg, then 40–80 mg PO q 8–12 hr. Acute prophylaxis: Initial dosage, 5–10 mg sublingual or chewable tablets q 2–3 hr.

Isosorbide mononitrate

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Prevention of angina: 20 mg PO bid given at least 7 hr apart; ER tablets—30– 60 mg/day PO may be increased to 120 mg/day if needed. In smaller patients, start with 5 mg (one-half of 10-mg tablet) but then increase to at least 10 mg by day 2 or 3 of therapy. Dose with first dose when waking and second dose 7 hr later. This creates a nitrate-free period and minimizes tolerance to drug.

PEDIATRIC PATIENTS

Safety and efficacy not established. Pharmacokinetics Route Oral SL

Onset 15–45 min 2–5 min

Duration 4 hr 1–2 hr

Metabolism: Hepatic; T1/2: 5 min, then 2–5 hr Distribution: May cross placenta; may enter breast milk Excretion: Urine Adverse effects

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CNS: Headache, apprehension, restlessness, weakness, vertigo, dizziness, faintness CV: Tachycardia, retrosternal discomfort, palpitations, hypotension, syncope, collapse, orthostatic hypotension, angina, rebound hypertension, atrial fibrillation, postdural hypertension Dermatologic: Rash, exfoliative dermatitis, cutaneous vasodilation with flushing GI: Nausea, vomiting, incontinence of urine and feces, abdominal pain GU: Dysuria, impotence, urinary frequency Other: Muscle twitching, pallor, perspiration, cold sweat, arthralgia, bronchitis

Interactions

Drug-drug • Increased systolic BP and decreased antianginal effect if taken concurrently with ergot alkaloids Drug-lab test • False report of decreased serum cholesterol if done by the Zlatkis-Zak color reaction Nursing considerations CLINICAL ALERT!

Name confusion has occurred between Isordil (isosorbide) and Plendil (felodipine); use caution.

Assessment

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History: Allergy to nitrates, severe anemia, GI hypermobility, head trauma, cerebral hemorrhage, hypertrophic cardiomyopathy, pregnancy, lactation Physical: Skin color, temperature, lesions; orientation, reflexes, affect; P, BP, orthostatic BP, baseline ECG, peripheral perfusion; R, adventitious sounds; liver evaluation, normal output; CBC, Hgb

Interventions

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Give sublingual preparations under the tongue or in the buccal pouch; discourage the patient from swallowing. Create a nitrate-free period to minimize tolerance. Give chewable tablets slowly, only 5 mg initially because severe hypotension can occur; ensure that patient does not chew or crush sustained-release preparations. Give oral preparations on an empty stomach, 1 hr before or 2 hr after meals; take with meals if severe, uncontrolled headache occurs. Keep life support equipment readily available if overdose occurs or cardiac condition worsens. Gradually reduce dose if anginal treatment is being terminated; rapid discontinuation can lead to problems of withdrawal.

Teaching points

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Place sublingual tablets under your tongue or in your cheek; do not chew or swallow the tablet. Take the isosorbide before chest pain begins, when activities or situation may precipitate an attack. Take oral isosorbide dinitrate on an empty stomach, 1 hr before or 2 hr after meals; do not chew or crush sustained-release preparations. These side effects may occur: Dizziness, light-headedness (may be transient; use care to change positions slowly); headache (lie down in a cool environment, rest; over-the-counter preparations may not help; take drug with meals); flushing of the neck or face (reversible). Report blurred vision, persistent or severe headache, rash, more frequent or more severe angina attacks, fainting.

Adverse effects in Italic are most common; those in Bold are life-threatening.