INI-CET EXAM -2026
Pharmacology
Medium
Unlike other calcium channel blockers, Cilnidipine does not cause reflex tachycardia. What is the reason for this?
Appeared in: INI-CET EXAM -2026
Explanation
- Cilnidipine is a fourth-generation calcium channel blocker (CCB) with a dual mechanism of action.
- Like other dihydropyridine CCBs, it blocks L-type calcium channels on vascular smooth muscle, causing vasodilation and lowering blood pressure.
- Uniquely, it also blocks N-type calcium channels located on presynaptic sympathetic nerve terminals.
- This N-type blockade inhibits the release of norepinephrine, which is responsible for the baroreceptor-mediated reflex tachycardia.
- By preventing this sympathetic surge, Cilnidipine effectively lowers blood pressure without causing a compensatory increase in heart rate.
Why Other Options Were Wrong
- Option B: Blocking T-type calcium channels is not the primary mechanism for preventing reflex tachycardia caused by vasodilation.
- Option C: C-type calcium channel is not a standard, recognized classification for voltage-gated calcium channels in pharmacology.
- Option D: Blocking sodium channels is the mechanism of action for other classes of drugs, not calcium channel blockers.
Related Visual
Clinical Relevance
- Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pharmacological mechanism of Cilnidipine and prevention of reflex tachycardia as background academic context rather than a clinical decision trigger.
- The absence of reflex tachycardia makes Cilnidipine a preferred antihypertensive for patients who also have conditions like angina, heart failure, or a predisposition to tachycardia, where an increased heart rate would be detrimental.
- This unique profile improves patient tolerance and adherence compared to other dihydropyridines that can cause palpitations.
- What if? If a patient with stable angina develops palpitations and tachycardia after starting amlodipine (an L-type only blocker), switching to Cilnidipine is a clinically sound strategy to achieve blood pressure control without worsening their cardiac symptoms.
How to Approach the Question
- First, identify the drug class and its general properties. Cilnidipine is a calcium channel blocker (CCB).
- Recall the common side effects of dihydropyridine CCBs. Potent vasodilation often leads to a baroreceptor-mediated reflex tachycardia.
- The question states that Cilnidipine is an exception to this rule. This implies it has a unique mechanism beyond the standard action of its class.
- Analyze the reflex tachycardia pathway: Vasodilation -> BP drop -> Sympathetic nerve activation -> Norepinephrine release -> Increased heart rate.
- Evaluate the options to see which one would interrupt this pathway. Blocking N-type calcium channels, which are crucial for neurotransmitter release from sympathetic nerves, would directly prevent the norepinephrine surge and subsequent tachycardia.
- This makes the additional blockade of N-type calcium channels the most logical explanation.
Concept Tested & Keywords
- Concept Tested: Pharmacological mechanism of Cilnidipine and prevention of reflex tachycardia.
- Stem keywords: Cilnidipine, calcium channel blockers, reflex tachycardia
- Lead-in keywords: reason
- Negative lead-in flag: false
Question ID
Q7XZ_1Neai0VM61pPfXGRB
Reference Book
E6 Pharmacology Katzung 16e p. 314-316
Practise the full INI-CET EXAM -2026
Attempt every question from this paper in a timed mock, then review the full solution for each one.
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