How to prepare an Isosorbide Dinitrate (ISDN) drip?

How to Prepare an Isosorbide Dinitrate (ISDN) Drip

ISDN is not available for intravenous use in the United States—only nitroglycerin is FDA-approved for IV administration. 1

Critical Point: ISDN Cannot Be Given as an IV Drip

• Nitroglycerin is the only nitrate formulation available for intravenous use in the United States, as stated by the ACC/AHA guidelines 1
• ISDN is available only in oral formulations (immediate-release tablets, sustained-release tablets, and sublingual forms) 1
• The half-life of ISDN ranges from 40 to 90 minutes, and it undergoes extensive hepatic metabolism to active metabolites 1

Alternative: Nitroglycerin IV Infusion

If you need intravenous nitrate therapy, you must use nitroglycerin instead of ISDN:

Nitroglycerin IV Preparation

• Nitroglycerin has a very short half-life of only several minutes, making it suitable for IV titration 1
• Standard preparation involves diluting nitroglycerin in D5W or normal saline using non-PVC tubing (as nitroglycerin absorbs into PVC)
• Typical starting dose: 5-10 mcg/min, titrated upward by 5-10 mcg/min every 3-5 minutes based on blood pressure and symptom response 1

Critical Monitoring Requirements

• Carefully monitor blood pressure to avoid inadvertent systemic hypotension, which can cause reflex tachycardia and worsen myocardial ischemia 1
• Exercise extreme caution in patients with inferior wall MI due to frequent association with right ventricular infarction—these patients depend on adequate RV preload and can experience profound hypotension 1, 2
• If hypotension occurs, manage with leg elevation, rapid fluid administration, and atropine if severe 1

Oral ISDN Dosing (If Appropriate)

If oral therapy is acceptable for your clinical scenario:

Standard Oral ISDN Regimen

• Starting dose: 20 mg three times daily 1
• Target dose: 40 mg three times daily after 2-4 weeks if tolerated 1
• When combined with hydralazine for heart failure (particularly in African American patients): start with hydralazine 37.5 mg + ISDN 20 mg three times daily, titrating to hydralazine 75 mg + ISDN 40 mg three times daily 1, 2

Essential Tolerance Prevention

• Provide a nitrate-free interval of at least 10-14 hours daily to prevent tolerance development 1, 3, 2
• Tolerance typically develops after 24 hours of continuous therapy 2, 4
• The nitrate-free interval can be achieved by timing doses appropriately (e.g., 8 AM, 1 PM, 6 PM, with overnight nitrate-free period) 1

Common Pitfalls to Avoid

• Never use ISDN within 24 hours of sildenafil or 48 hours of tadalafil due to risk of profound hypotension 2
• Do not increase dose if symptomatic hypotension occurs 1
• Watch for drug-induced lupus-like syndrome (arthralgia, joint swelling, pericarditis, rash, fever)—if suspected, check ANA and discontinue 1
• Headaches are the most common side effect but often improve with continued use 3