What is the recommended initial intravenous (IV) dosage of Nicardipine (calcium channel blocker) for treating hypertension?

Nicardipine Intravenous Dosage

Start nicardipine at 5 mg/hr IV infusion and titrate by increasing 2.5 mg/hr every 5-15 minutes to a maximum of 15 mg/hr until desired blood pressure is achieved. 1, 2

Initial Dosing Protocol

• Begin at 5 mg/hr as the standard starting dose for all hypertensive emergencies 1, 3, 2
• Titrate by 2.5 mg/hr increments at intervals determined by urgency 1, 3, 2:
  • Every 5 minutes for rapid blood pressure reduction 1, 3
  • Every 5-15 minutes for gradual blood pressure reduction 1, 3
• Maximum dose is 15 mg/hr - do not exceed this rate 1, 3, 2

Target Blood Pressure Goals

• For general hypertensive emergencies: Reduce blood pressure by 10-15% within the first hour, not exceeding 25% reduction in the first day 3, 4
• For acute ischemic stroke patients eligible for thrombolytics: Maintain systolic BP <185 mmHg and diastolic BP <110 mmHg before rtPA administration 1, 3
• For post-thrombolytic stroke patients: Keep systolic BP <180 mmHg and diastolic BP <105 mmHg 1, 3

Maintenance Dosing

• Once desired blood pressure is achieved, reduce to 3 mg/hr as maintenance dose 3, 2
• Sustained blood pressure control occurs at constant infusion rates during maintenance 5
• Duration of action during continuous infusion is 4-6 hours 3

Monitoring Requirements

For post-thrombolytic stroke patients, the American Heart Association mandates strict monitoring 1, 3:

• Every 15 minutes for the first 2 hours
• Every 30 minutes for the next 6 hours
• Every hour for the subsequent 16 hours

For all other patients, monitor blood pressure continuously during active titration 3, 6

Pharmacokinetics

• Onset of action: 5-15 minutes after starting infusion 3, 6, 5
• Offset of action: 30-40 minutes after discontinuation, regardless of infusion duration 3, 5
• Blood pressure reduction correlates directly with plasma nicardipine levels 5, 7

Critical Safety Considerations

Venous Access Management

• Change infusion site every 12 hours to minimize peripheral venous irritation and phlebitis 2
• Avoid small veins such as those on the dorsum of the hand or wrist 2
• Do not administer intra-arterially or allow extravasation 2

Contraindications and Cautions

• Absolutely contraindicated in advanced aortic stenosis 1, 2
• Exercise extreme caution in acute cerebral infarction or hemorrhage to avoid systemic hypotension 3
• Not a beta-blocker - provides no protection against abrupt beta-blocker withdrawal 2

Managing Adverse Effects

• If hypotension or tachycardia develops: Discontinue infusion immediately 2
• After stabilization, restart at lower doses (3-5 mg/hr) 2
• Most common adverse reactions: headache (13%), hypotension (5%), tachycardia (4%), nausea/vomiting (4%) 2
• Expect heart rate increase of approximately 10 beats/minute 5, 8

Context-Specific Applications

Nicardipine is preferred for 4:

• Acute renal failure
• Eclampsia or preeclampsia (target BP <160/105 mmHg) 6
• Perioperative hypertension
• Acute sympathetic discharge states

Choose alternative agents for 4:

• Acute coronary syndrome (use nitroglycerin instead)
• Acute cardiogenic pulmonary edema (use nitroglycerin instead)
• Aortic dissection (consider beta-blockers first) 6

Drug Interactions

• Cimetidine increases nicardipine plasma levels - use with caution 2
• Nicardipine increases cyclosporine and tacrolimus levels - monitor immunosuppressant trough levels closely when co-administering 2

Common Pitfalls to Avoid

• Do not use doses measured in mg/kg/min - nicardipine IV is dosed in mg/hr 3
• Do not continue infusion at a single site beyond 12 hours due to phlebitis risk 2, 5
• Do not reduce blood pressure too rapidly in cerebrovascular disease - maintain at higher end of acceptable ranges 3
• Do not assume same blood pressure target applies throughout treatment - reassess based on clinical status 3