Duration of Action of Nicardipine
Nicardipine has a duration of action of 4-6 hours during continuous IV infusion, but after discontinuation, the offset of action occurs within 30-40 minutes. 1, 2
Pharmacokinetic Profile
The duration of action varies depending on the route of administration and clinical context:
Intravenous Nicardipine
- During continuous infusion: The duration of action is 4-6 hours, meaning sustained blood pressure control is maintained at a constant infusion rate throughout this period. 1
- After discontinuation: The offset of action (defined as an increase in diastolic blood pressure of ≥10 mm Hg) occurs within 30-40 minutes, regardless of the duration of infusion. 2, 3
- Onset of action: IV nicardipine begins working within 1-5 minutes, with therapeutic blood pressure reduction typically achieved within 5-15 minutes. 1, 2
Oral Nicardipine
- The terminal half-life of oral nicardipine averages 8.6 hours following 30-40 mg doses at steady-state (three times daily dosing). 4
- However, elimination over the first 8 hours after dosing is much faster, with a half-life of 2-4 hours. 4
- Plasma levels are detectable within 20 minutes, with maximal levels observed within 30 minutes to 2 hours (mean Tmax = 1 hour). 4
Clinical Implications
Titration and Maintenance
- The rapid offset of action (30-40 minutes) makes IV nicardipine highly titratable, allowing for precise blood pressure control in hypertensive emergencies. 3, 5
- Blood pressure control is sustained during continuous infusion, with steady-state plasma levels achieved after 8-12 hours of infusion. 6
- The time to achieve therapeutic response is dose-dependent: at 15 mg/hour, onset occurs in approximately 0.31 hours, compared to 1.11 hours at 4 mg/hour. 3
Important Caveats
- Peripheral vein phlebitis: When using peripheral IV access, change the infusion site every 12 hours to minimize the risk of thrombophlebitis, which typically occurs after 14+ hours at a single site. 7, 3, 6
- Independent of infusion duration: The offset time after discontinuation remains consistent (30-40 minutes) whether the infusion lasted 1 hour, 6 hours, or 24 hours. 3
- Monitoring requirements: During IV infusion, blood pressure should be monitored every 15 minutes during active titration, then every 30 minutes for 6 hours once stable, then hourly. 2, 7
Transition Planning
- The relatively short offset time (30-40 minutes) necessitates having oral antihypertensive agents on board before discontinuing IV nicardipine to prevent rebound hypertension. 2
- When transitioning from IV to oral therapy, oral agents should be initiated while the nicardipine infusion is still running, allowing time for the oral medication to reach therapeutic levels. 2