An Assignment on Calcium Channel Blocker (CCB)

Definition:

A calcium channel blocker (CCB) is a chemical that disrupt the movement of calcium (Ca+) through calcium channel.

Ex: Nifedipine, Verapamil etc.

Mechanism of action:

The drug block voltage-gated L-type calcium channels, the calcium channels most important in cardiac and smooth muscle. By decreasing calcium influx during action potentials in a frequency and voltage dependent manner, these agents reduce intracellular calcium concentration and muscle contractility. None of these channel blockers interfere with calcium dependent neurotransmitter or hormone release because these processes utilize different types of calcium channels that are not block by these agents.

Classification:

First generation (Conventional)

v  Dihydropyridines ( Nifedipine )

v  Phenylalkylamines ( Verapamil )

v  Benzothiazepines ( Diltiazem )

Second generation (Modified release)

v  Verapamil SR ( Sustained Release )

v  Diltiazem CD ( Controlled Delivery )

Third generation (Intresically long acting)

v  Long plasma half life ( Amlodipine )

v  Long receptor half life ( Lacidipine )

Nifedipine:

Nifedipine is a calcium channel blocker. It is available as a tablet, capsule and injection.

Mode of action:

Nifedipine as a calcium channel blocker, it blocks the transport of calcium, via holes called channels, into the smooth muscle cells lining the coronary blood vessels and other peripheral blood vessels of the body. Blocking calcium transport relaxes the muscles of the blood vessels and makes them wider.

Indication:

v  Prophylaxis and treatment of angina,

v  Hypertension,

v  Raynauds phenomenon.

Side effect:

The most common side effect is associated with vasodilator action, such as:-

v  Dizziness,

v  Flushing,

v  Headache,

v  Hypotension,

v  Peripheral oedema.

v  Gastrointestinal disturbances,

v  Increased frequency of micturition,

v  Lethargy,

v  Eye pain and mental depression may also occur.

v  A paradoxicial increase in ischemic chest pain may occur at the start of treatment and few patients excessive fall in blood pressure may lead to cerebral or myocardial ischemia or transient blindness.

v  Gum hyperplasia, erythema also reported.

Contraindication:

v  Women of child bearing age.

Brand name:

v  Nidipine Tablet (Square)

v  Nifecap Capsule (Drug International)

Verapamil:

It is a calcium channel blocker and act by interfering with the slow inward depolarizing calcium flow particularly in the S.A and A.V nodal cells.

Indication:

v  Supraventricular arrhythmias,

v  Paroxysmal ventricular tachyarrythmias,

v  Angina,

v  Hypertension.

Side effect:

v  Constipation,

v  Less commonly nausea,

v  Vomiting,

v  Flushing,

v  Headache,

v  Dizziness,

v  Fatigue,

v  Ankle oedema.

After intravenous administration

v  Hypotension,

v  Bradycardia,

v  Heart block,

v  Ventricular fibrillation and asystole.

Contraindication:

v  Hypotension,

v  Bradycardia,

v  Second and third degree heart block,

v  Sick sinus syndrome,

v  Cardiogenic shock,

v  Sino-atrial block,

v  Uncompensated heart failure,

v  Woff-Parkinson White( WPW ) syndrome.

Brand name:

v  Veracal Tablet (Incepta)

v  Angimil SR Tablet (Medimet)

Amlodipine:

It is a dihydropyridine calcium channel blocker.

Indication:

v  Essential hypertension,

v  Angina pectoris,

v  Vasopastic angina.

Contraindication:

v  In patients with known sensitivity to dihydropyridines.

v  It should not be in cardiogenic shock,

v  Clinically significant aortic stenosis,

v  Unstable angina,

v  Pregnant women.

Brand name:

v  Amdocal Tablet (Beximco)

v  Amlotab Tablet (Incepta)

References:

Ø  Approach to clinical pharmacology, by thirty three students, edited by Majdi N. Al-Jasim.

Ø  Katzung and trevor’s pharmacology, 8^th edition.

Ø  www.wikipedia.com