How to initiate an Isoket (Isosorbide dinitrate) infusion?

How to Start an Isoket (Isosorbide Dinitrate) Infusion

For intravenous isosorbide dinitrate (Isoket) infusion, start at a dose of 10-20 mcg/min and titrate up in increments of 5-10 mcg/min every 3-5 minutes based on blood pressure response and symptom relief.

Initial Preparation and Dosing

Preparation:

• Dilute isosorbide dinitrate in normal saline or 5% dextrose solution
• Use non-absorbing tubing for administration to prevent drug loss
• Ensure continuous blood pressure monitoring is available

Starting Dose and Titration:

1. Initial dose: 10-20 mcg/min via continuous infusion 1
2. Titration: Increase by 5-10 mcg/min every 3-5 minutes 1
3. Target: Continue titration until:
   • Symptoms of ischemia/congestion are relieved, OR
   • Blood pressure response is observed (reduction in systolic BP)
   • Maximum dose typically 200 mcg/min 1

Monitoring Parameters

• Blood pressure: Monitor frequently during initiation and titration
  • Avoid reducing systolic BP below 110 mmHg in previously normotensive patients
  • Avoid reducing mean arterial pressure by more than 25% from baseline in hypertensive patients 1
• Heart rate: Monitor for reflex tachycardia
• Signs of hypoperfusion: Monitor for dizziness, lightheadedness, or confusion
• Symptom relief: Assess for improvement in dyspnea, chest pain, or other symptoms

Contraindications and Precautions

Absolute Contraindications:

• Systolic BP <90 mmHg or ≥30 mmHg below baseline 1, 2
• Severe bradycardia (<50 bpm) or tachycardia (>100 bpm) 1
• Recent use of phosphodiesterase-5 inhibitors:
  • Within 24 hours for sildenafil
  • Within 48 hours for tadalafil 1, 2
• Right ventricular infarction 2

Use with Caution:

• Patients with aortic stenosis (risk of marked hypotension) 1
• Patients with renal dysfunction 1
• Elderly patients (may require lower initial doses)

Common Side Effects and Management

• Headache: Common side effect, may require symptomatic treatment
• Hypotension: Reduce infusion rate or temporarily stop infusion
• Tachyphylaxis: Common after 24-48 hours of continuous administration 1

Special Considerations

• For patients with acute heart failure, isosorbide dinitrate can effectively decrease pulmonary capillary wedge pressure and improve cardiac output, particularly in those with high systemic vascular resistance 3
• Consider adding a diuretic if patient has significant fluid overload
• If reaching high doses without adequate response, consider adding or switching to another vasodilator

Practical Tips

• If symptoms and signs of ischemia are relieved, there is no need to continue increasing the dose to achieve a specific blood pressure target 1
• An arterial line is not routinely required but will facilitate titration in patients with borderline pressures 1
• Tolerance to nitrates is common after 24-48 hours, which may necessitate dose adjustments for prolonged therapy 1

Remember that careful titration with frequent monitoring is key to successful isosorbide dinitrate infusion management while avoiding potential adverse effects like hypotension.