Management of Isosorbide Dinitrate (Isoket) Infusion for Hypertensive Emergency
For hypertensive emergencies, isosorbide dinitrate (Isoket) infusion should be started at 5 mcg/min and increased in increments of 5 mcg/min every 3-5 minutes to a maximum of 20 mcg/min. 1
Initial Assessment and Monitoring
- Admit patient to intensive care unit for continuous BP monitoring and parenteral administration of antihypertensive agents
- Establish intra-arterial BP monitoring to prevent "overshoot" hypotension
- Ensure continuous ECG monitoring
- Determine if patient has a "compelling condition" requiring more aggressive BP lowering:
- Aortic dissection
- Severe preeclampsia/eclampsia
- Pheochromocytoma crisis
BP Reduction Targets
- For patients with compelling conditions: Reduce SBP to <140 mmHg during first hour and <120 mmHg in aortic dissection 1
- For patients without compelling conditions: Reduce SBP by no more than 25% within first hour, then if stable, to 160/100 mmHg within next 2-6 hours, and cautiously to normal during following 24-48 hours 1
Isosorbide Dinitrate (Isoket) Administration Protocol
- Starting dose: 5 mcg/min intravenous infusion 1
- Titration: Increase in increments of 5 mcg/min every 3-5 minutes
- Maximum dose: 20 mcg/min 1
- Important restrictions: Use only in patients with acute coronary syndrome and/or acute pulmonary edema 1
- Contraindication: Do not use in volume-depleted patients 1
Monitoring During Administration
- Check BP every 2-5 minutes during initial titration
- Monitor for common side effects:
- Headache
- Hypotension
- Reflex tachycardia
- Methemoglobinemia (with prolonged use)
- Be aware that tolerance may develop with extended use
Alternative Agents Based on Specific Conditions
If isosorbide dinitrate is not appropriate, consider these alternatives based on comorbidities:
- Acute pulmonary edema: Clevidipine, nitroglycerin, nitroprusside 1
- Acute coronary syndromes: Esmolol, labetalol, nicardipine, nitroglycerin 1
- Acute renal failure: Clevidipine, fenoldopam, nicardipine 1
- Eclampsia/preeclampsia: Hydralazine, labetalol, nicardipine 1
Clinical Pearls and Pitfalls
- Isosorbide dinitrate is primarily indicated for patients with hypertensive emergency complicated by acute coronary syndrome or pulmonary edema
- Avoid using nitrates in patients taking PDE-5 inhibitors (sildenafil, tadalafil) due to risk of profound hypotension
- Aerosol formulations of isosorbide dinitrate have been shown to be effective for hypertensive emergencies with faster onset than tablet forms (10 min vs 45 min) 2, 3
- Monitor for development of tolerance with prolonged use
- Transition to oral antihypertensive therapy once BP is stabilized
Remember that the primary goal in hypertensive emergency is to prevent further target organ damage through controlled BP reduction, not necessarily immediate normalization of BP.