How does Nicardipine (nicardipine) cause tachycardia?

From the Guidelines

Nicardipine causes tachycardia primarily through its vasodilatory effects as a calcium channel blocker, leading to a compensatory baroreceptor reflex and direct sympathetic nervous system activation. When nicardipine blocks L-type calcium channels in vascular smooth muscle, it causes peripheral vasodilation and reduces blood pressure 1. This drop in blood pressure triggers a compensatory baroreceptor reflex, where the body attempts to maintain adequate circulation by increasing heart rate. Additionally, nicardipine can cause direct sympathetic nervous system activation and reflex catecholamine release, further contributing to the increased heart rate. The magnitude of tachycardia depends on the dose administered and the rate of blood pressure reduction, with more rapid or significant drops in pressure typically causing more pronounced tachycardia.

Mechanism of Action

• Nicardipine is a dihydropyridine calcium channel blocker that blocks L-type calcium channels in vascular smooth muscle, leading to peripheral vasodilation and reduced blood pressure 1.
• The reduction in blood pressure triggers a compensatory baroreceptor reflex, increasing heart rate to maintain cardiac output and tissue perfusion.
• Direct sympathetic nervous system activation and reflex catecholamine release also contribute to the increased heart rate.

Clinical Implications

• The use of nicardipine can lead to reflex tachycardia, which may be a concern in certain clinical situations, such as acute aortic syndrome 1.
• In such cases, the use of beta-blockers or other rate-controlling agents may be necessary to mitigate the risk of tachycardia.
• The dose and rate of administration of nicardipine should be carefully titrated to minimize the risk of tachycardia and other adverse effects 1.

Key Considerations

• Nicardipine is a commonly used medication for the treatment of hypertensive emergencies, but its use requires careful consideration of the potential risks and benefits 1.
• The medication should be used in a controlled setting, with close monitoring of blood pressure and heart rate, to minimize the risk of adverse effects.
• Alternative medications, such as beta-blockers or other vasodilators, may be considered in certain clinical situations to minimize the risk of tachycardia and other adverse effects 1.

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. Most adverse effects were expected consequences of the vasodilator effects of nicardipine hydrochloride capsules.

Nicardipine causes tachycardia as a result of its vasodilator effects, which lead to decreases in blood pressure. This is likely a reflex response to the decreased blood pressure, as the body attempts to maintain adequate circulation 2.

• The exact mechanism is not fully explained in the label, but it is associated with the peak effect of the drug.
• Tachycardia is listed as one of the adverse effects that occurred in clinical trials, with an incidence of 1.2% in anginal patients and 3.4% in hypertensive patients.

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
• The decrease in blood pressure induced by nicardipine is related to a concurrent decrease in total peripheral vascular resistance 3
• The vasodilatory effect of nicardipine can trigger a reflex sympathetic response, which can lead to an increase in heart rate 5, 6
• Nicardipine-induced tachycardia is generally attributed to the involvement of the baroreflex, but studies suggest that it may also be caused by a direct action on central cardiovascular mechanisms 5

Effects of Nicardipine on Heart Rate

• Nicardipine can cause an increase in heart rate, particularly in the acute phase of treatment 3, 4
• However, tachycardia does not occur during long-term therapy with nicardipine 3
• In some cases, nicardipine can cause bradycardia, particularly in elderly patients with acute ischemic infarct 7
• The effects of nicardipine on heart rate can be influenced by the presence of other medications, such as beta blockers, which can prevent reflex tachycardia 3, 6

Animal Studies

• Studies in animals have shown that nicardipine can cause vasodilation and a decrease in blood pressure, leading to an increase in heart rate 5, 6
• Nicardipine has been shown to be effective in lowering blood pressure in various animal models of hypertension, including spontaneously hypertensive rats and renal hypertensive rats 6
• Long-term treatment with nicardipine has been shown to be effective in reducing cardiac hypertrophy and preventing mortality from stroke in animal models of hypertension 6