Dosing and uses of Dilatrate-SR, Isordil (isosorbide dinitrate)
Adult dosage forms and strengths
capsule/tablet, extended release
- 40mg
tablet, sublinguaL
- 2.5mg
- 5mg
tablet
- 5mg
- 10mg
- 20mg
- 30mg
- 40mg
Angina Pectoris
Immediate release: 5-20 mg PO q8-12hr initially; maintenance: 10-40 mg PO q8-12hr
Extended release: 40 mg PO initially; maintenance: 40-80 mg PO q8-12hr
SL (prophylaxis): 2.5-5 mg 15 minutes before performing activities likely to cause angina
SL (treatment): 2.5-5 mg; may be repeated q5-10min; not to exceed 3 doses in 15-30 minutes
Pediatric dosage forms and strengths
Safety and efficacy not established
Geriatric dosage forms and strengths
Angina Pectoris
Start with lowest recommended dose
Start with lowest recommended adult dose
Dilatrate-SR, Isordil (isosorbide dinitrate) adverse (side) effects
Frequency not defined
Cardiovascular: Rebound hypertension (uncommon), syncope, unstable angina flushing, hypotension/orthostatic hypotension, lightheadedness, palpitations, tachyarrhythmia
Central nervous system (CNS): Dizziness, headache, restlessness, weakness
Gastrointestinal (GI): Nausea
Hematologic: Methemoglobinemia (infrequent)
Warnings
Contraindications
Hypersensitivity
Recent use (within several days) of PDE-5 inhibitors (eg, avanafil, sildenafil, tadalafil, or vardenafil) may cause dangerously low hypotension; the time course of the interaction appears to be related to the PDE-5 inhibitor half-life
Severe anemia, shock, markedly low blood pressure (BP)
Concomitant administration with guanylate stimulator riociguat
Cautions
Allergies to nitrates, head trauma/cerebral hemorrhage (potential contraindication), hypertrophic cardiomyopathy, increased intraocular pressure, postural hypotension, acute myocardial infarction (MI), congestive heart failure, hyperthyroidism
Inability to relieve chest pain after 3 doses may signal acute MI necessitating emergency management
Tolerance to extended-release formulation may develop, rendering formulation ineffective after a few weeks
Do not change brands unintentionally; formulations are not all bioequivalent
Severe hypotension, particularly with upright posture, may occur with even small doses; use with caution in patients who may be volume depleted or who are already hypotensive; hypotension induced by isosorbide dinitrate may be accompanied by paradoxical bradycardia and increased angina pectoris
Nitrate therapy may aggravate angina caused by hypertrophic cardiomyopathy
Treat drug-induced headache with aspirin or acetaminophen
Provide nitrate-free interval (10-12 hours or overnight) to prevent development of tolerance
Use supportive treatment in overdose
Avoid use of extended release formulation in acute MI or acute heart failure; adverse events are not easily reversible if they develop
Avoid use in patients with hypertrophic cardiomyopathy with outflow tract obstruction; nitrates may reduce preload, which may cause exacerbation of obstruction and cause hypotension or syncope and/or worsening of heart failure
Pregnancy and lactation
Pregnancy category: C
Lactation: Unknown whether drug is distributed into breast milk
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Dilatrate-SR, Isordil (isosorbide dinitrate)
Mechanism of action
Vasodilating agent (nitric oxide donor); relaxes smooth muscle via dose-dependent dilation of arterial and venous beds to reduce both preload and afterload, as well as myocardial oxygen demand; also improves coronary collateral circulation, lowering blood pressure, increasing heart rate, and causing occasional paradoxical bradycardia
Absorption
~100% absorbed from GI tract or oral mucosa
Bioavailability: Immediate release, 40-50%
Duration: 1-2 hr
Distribution
Vd: 2-4 L/kg
Metabolism
Extensively metabolized in liver to conjugated metabolites
Elimination
Half-life: 1 hr
Excretion: Urine (80-100%), feces
