isosorbide nitrates

isosorbide nitrates

(eye soe sor' bide)

isosorbide dinitrate

Apo-ISDN (CAN), Dilatrate SR, Isordil, Isordil Titradose

isosorbide mononitrate

Imdur, ISMO, 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

·        Dinitrate: Treatment and prevention of angina pectoris

·        Mononitrate: Prevention of angina pectoris

Contraindications and cautions

·        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 SR products once daily or bid at 8 PM and 2 PM. This creates a nitrate-free period.

Isosorbide dinitrate

·        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; SR, 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

·        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. Give 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	Onset	Duration
Oral	15–45 min	4–6 hr
Oral SR	Up to 4 hr	6–8 hr
SL	2–5 min	1–2 hr

Metabolism: Hepatic; T_1/2: 5 min, then 2–5 hr

Distribution: May cross placenta; may enter breast milk

Excretion: Urine

Adverse effects

·        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, diarrhea

·        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

·        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

·        Give sublingual preparations under the tongue or in the buccal pouch; discourage the patient from swallowing.

·        Create a nitrate-free period to minimize tolerance.

·        WARNING: Give chewable tablets slowly, only 5 mg initially, because severe hypotension can occur; ensure that patient does not chew or crush SR preparations.

·        Give oral preparations on an empty stomach, 1 hr before or 2 hr after meals; take with meals if severe, uncontrolled headache occurs.

·        WARNING: Keep life support equipment readily available if overdose occurs or cardiac condition worsens.

·        WARNING: Gradually reduce dose if anginal treatment is being terminated; rapid discontinuation can lead to problems of withdrawal.

Teaching points

·        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 hour before or 2 hours after meals; do not chew or crush sustained-release preparations; do not take isosorbide mononitrate to relieve acute anginal episodes.

·        You may experience these side effects: 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.