isosorbide mononitrate
Brand: Imdur, ISMO
Prototype: nitroglycerin
Drug Class: nitrate
Drug Family: antianginal
Subclass: organic nitrate (NO donor)
Organ Systems: cardiovascular
Mechanism of Action
Active metabolite of isosorbide dinitrate; 100% bioavailability; long-acting nitrate for chronic angina and heart failure (in combination with hydralazine).
guanylyl cyclase via NO
Indications
- chronic angina prophylaxis
- heart failure in self-identified Black patients (with hydralazine — A-HeFT)
Contraindications
- PDE-5 inhibitors
- severe hypotension
- severe aortic stenosis
Adverse Effects
Common
- headache
- flushing
- hypotension
- tolerance
Serious
- severe hypotension
- methemoglobinemia
Pharmacokinetics (ADME)
| Absorption | ~100% oral bioavailability |
| Distribution | moderate |
| Metabolism | minimal hepatic — active drug |
| Excretion | renal |
| Half-life | 4-5 hours |
| Onset | 0.5-1 hour |
| Peak | 0.6-4 hours |
| Duration | 7-8 hours |
| Protein Binding | <5% |
| Vd | 0.6-0.7 L/kg |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| PDE-5 inhibitors | profound hypotension | major |
| sildenafil | contraindicated | major |
Nursing Considerations
- Eccentric dosing for extended-release (Imdur): take once daily in morning
- Standard-release: 7am and 2pm dosing (8-hour interval prevents tolerance — NOT BID traditional)
- Dose-free interval required to prevent tolerance
- A-HeFT trial: hydralazine + ISDN (not ISMN) reduced mortality in Black HFrEF patients
Clinical Pearls
- 100% bioavailability unlike other nitrates — predictable dosing
- Eccentric dosing: once-daily or BID with 8-hour nitrate-free interval is essential
Safety Profile
Pregnancy use-with-caution
Lactation avoid
Renal Adjustment Not required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.