From the Guidelines
Nicardipine causes tachycardia primarily through its vasodilatory effects as a calcium channel blocker, triggering a compensatory baroreceptor reflex that increases heart rate in response to decreased blood pressure. According to the European Heart Journal study 1, nicardipine's mechanism of action involves blocking L-type calcium channels in vascular smooth muscle, producing peripheral vasodilation and reducing blood pressure. This drop in blood pressure triggers a reflex tachycardia, as the body attempts to maintain adequate circulation by increasing heart rate.
Some key points to consider when using nicardipine include:
- The dose and rate of administration, with faster infusions or higher doses typically causing more pronounced heart rate increases
- The selective action of nicardipine on vascular calcium channels rather than cardiac calcium channels, allowing the reflex tachycardia to occur unimpeded
- The potential limitations of nicardipine's usefulness in patients with coronary artery disease or situations where increased heart rate could be detrimental, as noted in the study 1
In terms of comparison to other medications, the study 1 notes that urapidil may be a better option for avoiding reflex tachycardia, as it provides a better BP reduction and improvement of arterial oxygen content without this side effect. However, nicardipine's efficacy in lowering blood pressure makes it a valuable option in certain clinical scenarios, despite the potential for reflex tachycardia. As with any medication, careful consideration of the patient's individual needs and medical history is essential when using nicardipine.
From the FDA Drug Label
Peak responses were not observed to be associated with adverse effects during clinical trials, but physicians should be aware that adverse effects associated with decreases in blood pressure (tachycardia, hypotension, etc.) could occur around the time of the peak effect.
Nicardipine causes tachycardia as a result of its vasodilator effects, which lead to decreases in blood pressure. This is a reflex response to the drop in blood pressure, as the body tries to compensate by increasing heart rate 2.
- Key points:
- Nicardipine is a vasodilator
- Vasodilation leads to decreased blood pressure
- Decreased blood pressure can cause reflex tachycardia
- Main idea: Nicardipine-induced tachycardia is a result of its blood pressure-lowering effect.
From the Research
Mechanism of Nicardipine-Induced Tachycardia
- Nicardipine is a calcium channel antagonist that causes vasodilation, leading to a decrease in blood pressure 3, 4, 5.
- The decrease in blood pressure is accompanied by a reflex tachycardia, which is mediated by the sympathetic nervous system 4, 6.
- However, studies suggest that nicardipine-induced tachycardia cannot be explained solely by the baroreflex mechanism 6.
- Nicardipine may induce an increase in heart rate and sympathetic tone by a direct action on central cardiovascular mechanisms 6.
Effects of Nicardipine on Heart Rate and Blood Pressure
- Nicardipine causes a significant decrease in mean blood pressure and a marked increase in heart rate in conscious dogs made hypertensive by sinoaortic denervation 6.
- The increase in heart rate is accompanied by a significant rise in plasma catecholamine levels 6.
- In patients with severe hypertension, intravenous nicardipine causes a rapid decrease in blood pressure, with an onset time of 0.31 +/- 0.13 hours at a dose of 15 mg/hour 7.
- The increase in heart rate is approximately 10 beats/minute, but does not correlate with plasma nicardipine levels 7.
Clinical Implications
- Nicardipine is an effective antihypertensive agent that can be used as monotherapy or in combination with other drugs such as beta blockers or diuretics 3, 5.
- The use of nicardipine in combination with beta blockers may be beneficial in preventing reflex tachycardia and other consequences of peripheral vasodilatation 3.
- Nicardipine appears to be a safe and effective drug for intravenous use in the treatment of severe hypertension, with minimal side effects 7.