Dosing and uses of Imdur, Monoket (isosorbide mononitrate)
Adult dosage forms and strengths
tablet
- 10mg
- 20mg
tablet, extended release
- 30mg
- 60mg
- 120mg
Angina Pectoris
Prevention of angina pectoris caused by coronary artery disease
Immediate release: 5-10 mg PO twice daily initially (5 mg in small patients) given each dose 7 hr apart; increased to 10 mg PO q12hr by day 2 or 3; maintenance: 20 mg PO q12hr
Extended release: 30-60 mg PO once daily in the morning initially; may be increased to 120 mg PO once daily; wait at least 3 days between increases; if warranted may increase up to 240 mg PO once daily (rare)
Dosing considerations
- Take on empty stomach, 30 minutes before meals or 1 hour after meal
- Take on empty stomach, 30 minutes before or 1 hour after meal
- Extended-release tablet should be swallowed whole; must not be chewed, crushed, or split
Pediatric dosage forms and strengths
Safety and efficacy not established
Geriatric dosage forms and strengths
Angina Pectoris
Start with lowest recommended adult dose
Imdur, Monoket (isosorbide mononitrate) adverse (side) effects
Frequency not defined
Dizziness
Flushing
Headache
Hypotension
Methemoglobinemia
Nausea
Orthostatic hypotension
Palpitations
Restlessness
Syncope
Tachycardia
Vomiting
Warnings
Contraindications
Hypersensitivity to organic nitrates
PDE-5 inhibitors (eg, avanafil, sildenafil, tadalafil, or vardenafil); concomitant use can cause severe hypotension, syncope, or myocardial ischemia
Concomitant administration with guanylate stimulator riociguat (may cause hypotension)
Cautions
Use caution in acute myocardial infarction, alcohol use, hyperthyroidism, hypertrophic cardiomyopathy, increased intracranial pressure (eg, from head trauma or cerebral hemorrhage; potential contraindication), increased intraocular pressure, postural hypotension, volume depletion, congestive heart failure, low systolic blood pressure (BP)
Do not change brands unintentionally; formulations are not all bioequivalent
Treat drug-induced headache with aspirin or acetaminophen
Provide nitrate-free interval (10-12 hr or overnight) to prevent development of tolerance
Avoid excessive, prolonged hypotension
Withdraw gradually to prevent acute angina
Discontinue if blurred vision develops
Use supportive treatment to manage overdose
Narrow-angle glaucoma (controversial: may not be clinically significant)
Pregnancy and lactation
Pregnancy category: C
Lactation: Unknown whether drug crosses into breast milk; use caution
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 Imdur, Monoket (isosorbide mononitrate)
Mechanism of action
Organic nitrate that causes systemic venodilation, decreasing preload; enters vascular smooth muscle and is converted to nitric oxide, leading to activation of cyclic guanosine monophosphate and vasodilation
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
Bioavailability: Immediate release, 93-100%; extended release, 77-80%
Onset (antianginal effects): Immediate release, 60 min; extended release, 60 min
Onset (hemodynamic effects): Immediate release, 10-30 min; extended release, ≥6 hr
Duration (antianginal effects): Immediate release, 5-7 hr; extended release, 8 hr
Duration (hemodynamic effects): Immediate release, 10-30 min; extended release, ≥6 hr
Peak plasma time: Immediate release, 30-60 min; extended release, 3-4.5 hr
Distribution
Protein bound: <5%
Vd: 0.6 L/kg
Metabolism
Metabolized in liver via conjugation
Metabolites: Isosorbide, 5-isosorbide mononitrate glucuronide, sorbitol (inactive)
Elimination
Half-life: Parent drug, 6.2-6.6 hr; glucuronide metabolite, 6 hr; sorbitol metabolite, 9 hr
Total body clearance: 115-140 mL/min
Excretion: Urine (2%); feces (1%)
