ISOSORBIDE MONONITRATE
| ISOSORBIDE MONONITRATe (eye-soe-sor'bide) Ismo, Imdur, Monoket Classifications: nitrate vasodilator; Therapeutic: vasodilator; nitrate Prototype: Nitroglycerin Pregnancy Category: C |
Availability
10 mg, 20 mg tablets; 30 mg, 60 mg, 120 mg sustained release tablets
Action
Isosorbide mononitrate is a long-acting metabolite of the coronary vasodilator isosorbide dinitrate. It decreases preload as measured by pulmonary capillary wedge pressure (PCWP), and left ventricular end volume and diastolic pressure (LVEDV), with a consequent reduction in myocardial oxygen consumption.
Therapeutic Effect
It is equally or more effective than isosorbide dinitrate in the treatment of chronic, stable angina. It is a potent vasodilator with antianginal and antiischemic effects.
Uses
Prevention of angina. Not indicated for acute attacks.
Contraindications
Hypersensitivity to nitrates; severe anemia; closed-angle glaucoma; recent MI; postural hypotension, head trauma, cerebral hemorrhage (increases intracranial pressure); pregnancy (category C). Extended form should not be used in patients with GI disease.
Cautious Use
Older adults, hypotension; lactation.
Route & Dosage
| Prevention of Angina Adult: PO Regular release (ISMO, Monoket) 20 mg b.i.d. 7 h apart; Sustained release (Imdur) 30–60 mg every morning, may increase up to 120 mg once daily after several days if needed (max: dose 240 mg) |
Administration
Oral- Give first dose in morning on arising and second dose 7 h later with twice daily dosing regimen. Give in morning on arising with once daily dosing.
- Store sustained release tablets in a tight container.
Adverse Effects (≥1%)
CNS: Headache, agitation, anxiety, confusion, loss of coordination, hypoesthesia, hypokinesia, insomnia or somnolence, nervousness, migraine headache, paresthesia, vertigo, ptosis, tremor. CV: Aggravation of angina, abnormal heart sounds, murmurs, MI, transient hypotension, palpitations. Hematologic: Hypochromic anemia, purpura, thrombocytopenia, methemoglobinemia (high doses). GI: Nausea, vomiting, dry mouth, abdominal pain, constipation, diarrhea, dyspepsia, flatulence, tenesmus, gastric ulcer, hemorrhoids, gastritis, glossitis. Metabolic: Hyperuricemia, hypokalemia. GU: Renal calculus, UTI, atrophic vaginitis, dysuria, polyuria, urinary frequency, decreased libido, impotence. Respiratory: Bronchitis, pneumonia, upper respiratory tract infection, nasal congestion, bronchospasm, coughing, dyspnea, rales, rhinitis. Skin: Rash, pruritus, hot flashes, acne, abnormal texture. Special Senses: Diplopia, blurred vision, photophobia, conjunctivitis.Interactions
Drug: Alcohol may cause severe hypotension and cardiovascular collapse. Aspirin may increase nitrate serum levels. calcium channel blockers may cause orthostatic hypotension.Pharmacokinetics
Absorption: Completely and rapidly absorbed from GI tract; 93% reaches systemic circulation. Onset: 1 h. Peak: Regular release 30–60 min; sustained release 3–4 h. Duration: Regular release 5–12 h; sustained release 12 h. Metabolism: In liver by denitration and conjugation to inactive metabolites. Elimination: Primarily by kidneys. Half-Life: 4–5 h.Nursing Implications
Assessment & Drug Effects
- Monitor cardiac status, frequency and severity of angina, and BP.
- Assess for and report possible S&S of toxicity, including orthostatic hypotension, syncope, dizziness, palpitations, light-headedness, severe headache, blurred vision, and difficulty breathing.
- Lab tests: Monitor serum electrolytes periodically.
Patient & Family Education
- Do not crush or chew sustained release tablets. May break tablets in two and take with adequate fluid (4–8 oz).
- Do not withdraw drug abruptly; doing so may precipitate acute angina.
- Maintain correct dosing interval with twice daily dosing.
- Note: Geriatric patients are more susceptible to the possibility of developing postural hypotension.
- Avoid alcohol ingestion and aspirin unless specifically permitted by physician.
Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; 
Canadian drug name; 
Prototype drug