Calcium channel blockers

Symposium on :

Antihypertensive drugs..

Presented by :

AASHNA DHINGRARoll no. 03Batch 2010

INTRODUCTION

CLASSIFICATION

MECHANISM OF ACTION

PHARMACOLOGICAL ACTIONS

PHARMACOKINETICS

USES

ADVERSE EFECTS

CONTRAINDICATIONS

SUMMARY

Layout of the presentation :

INTRODUCTION..

also known as calcium antagonists.

prevent calcium from infiltrating the cells of the

heart and blood vessel walls.

relaxes and widens blood vessels of the heart

within the arterial walls, promoting lowered blood

pressure.

may also slow the heart rate, relieve chest

pressure and control an irregular heartbeat.

they are first line antihypertensive drugs.

the onset of antihypertensive action is quick.

monotherapy with CCBs is effective in about

50% of the hypertensives.

can also be used for treating angina.

PHENYLAKYLAMINES

Verapamil Very

1,4-DIHYDROPYRIDINES

Nifedipine Nice

BENZOTHIAZEPINES

Diltiazem Drugs

1,4 dihydopyrimidines are selective for the

arteriolar beds.

The phenylalkylamines and

benzothiazepines are selective

for the atrioventricular node.

Short-acting

• nifedipine, dilatiazem, verapamil

Long-acting

• amlodipine, felodipine, isradipine,

nicardipine, nisoldipine,

Mechanism of action..

oCalcium channels are of 5 subtypes- L, N, T,

P, and R.

o L-type in cardiac and smooth muscle cells.

Moa :

CCBs block voltage sensitive L- type Ca channels by binding to specific site on the α-1 subunit.

Prevent entry of Ca into cell.

No excitation-coupling reaction in heart and vascular smooth muscles.

Increase the time that Ca2+ channels

are closed.

Relaxation of the arterial smooth

muscle.

Significant reduction in afterload.

Coronary vasodilatation.

PHARMACOLOGICAL ACTIONS..

PHARMACOKINECTICS..

well absorbed through Git.

first pass metabolism.

highly bound to plasma proteins.

metabolised in liver.

excreted through urine.

USES OF CCBs..

1. angina pectoris - Due to decrease in myocardial oxygen

consumption, and dilatation of coronary arteries.

2. supraventicular arrhythmias - because of its

depressant action on S-A and A-V nodes.

3. hypertension - they control blood pressure by their

vasodilatory effect.

4. Migraine

5. raynaud’s phenomenon - due to their vasodilatory

property.

ADVERSE EFFECTS..

Postural hypotension

palpitation

reflex tachycardia

edema

dizziness

constipation

sedation

A-V block

headache

fatigue

lowered B.P.

CONTRAINDICATIONS

o Heart failure

o Bradycardia

o Atrioventricular block.

o Dihydropyridine calcium-channel blockers

should not be used in people with uncontrolled

heart failure.

SUMMARY..

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