Overview

Amlodipine is given to treat hypertension (high blood pressure). It is also taken to help prevent angina chest pain. You may have been prescribed it for either of these reasons.
Amlodipine works by causing some of your blood vessels to relax and widen. This lowers your blood pressure. It also reduces the force and the rate of your heartbeat, and this helps to prevent angina chest pain. It does these things by blocking the amount of calcium that goes into the 'smooth' muscle cells in the walls of your arteries and in your heart. Calcium is needed for muscles to contract, so reducing the amount of calcium causes the muscle cells to relax.

What Amlodipine tablets are and what they are used for?

Amlodipine belongs to a group of medicines called calcium antagonists. It is used to treat:
High blood pressure (hypertension).
Angina pectoris (pain in the chest caused by blockages in the arteries leading to the heart) or chest pain classed as vasospastic angina pectoris (or Prinzmetal's angina).
In patients with high blood pressure, your medicine works by relaxing blood vessels, so that blood passes through them more easily. In patients with angina, Amlodipine tablets works by improving blood supply to the heart muscle, which then receives more oxygen, and as a result chest pain is prevented.

Warnings

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking amlodipine it is important that your doctor knows:

If you are pregnant or breast-feeding.

If you have problems with the way your liver works.

If you are taking or using any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.

If you have ever had an allergic reaction to a medicine.

Contraindications

Amlodipine besylate tablets are contraindicated in patients with known sensitivity to Amlodipine.

Side Effects

Dizziness, lightheadedness, swelling ankles/feet, or flushing may occur.

Dosage

Oral:
Disclaimer:To be taken only after consulting with the doctor.

Storage

• Keep Amlodipine tablets out of the sight and reach of children.
• Do not store the tablets above 30°C.

Pharmacology

Mechanism of Action

Amlodipine is a dihydropyridine calcium antagonist (calcium ion antagonist or slow-channel blocker) that inhibits the transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle. Experimental data suggest that amlodipine binds to both dihydropyridine and nondihydropyridine binding sites. The contractile processes of cardiac muscle and vascular smooth muscle are dependent upon the movement of extracellular calcium ions into these cells through specific ion channels. Amlodipine inhibits calcium ion influx across cell membranes selectively, with a greater effect on vascular smooth muscle cells than on cardiac muscle cells. Negative inotropic effects can be detected in vitro but such effects have not been seen in intact animals at therapeutic doses. Serum calcium concentration is not affected by amlodipine. Within the physiologic pH range, amlodipine is an ionized compound (pKa=8.6), and its kinetic interaction with the calcium channel receptor is characterized by a gradual rate of association and dissociation with the receptor binding site, resulting in a gradual onset of effect.
Amlodipine is a peripheral arterial vasodilator that acts directly on vascular smooth muscle to cause a reduction in peripheral vascular resistance and reduction in blood pressure.

Pharmacodynamics

Amlodipine belongs to the dihydropyridine (DHP) class of calcium channel blockers (CCBs), the most widely used class of CCBs. There are at least five different types of calcium channels in Homo sapiens: L-, N-, P/Q-, R- and T-type. It was widely accepted that DHP CCBs target L-type calcium channels, the major channel in muscle cells that mediate contraction; however, some studies have indicated that amlodipine also binds to and inhibits N-type calcium channels (see references in Targets section). Similar to other DHP CCBs, amlodipine binds directly to inactive L-type calcium channels stabilizing their inactive conformation. Since arterial smooth muscle depolarizations are longer in duration than cardiac muscle depolarizations, inactive channels are more prevalent in smooth muscle cells. Alternative splicing of the alpha-1 subunit of the channel gives amlodipine additional arterial selectivity. At therapeutic sub-toxic concentrations, amlodipine has little effect on cardiac myocytes and conduction cells.

Interactions

Combining amlodipine with sildenafil (Viagra) and similar drugs used for treating erectile dysfunction may lead to excessive reductions in blood pressure with complications, particularly fainting upon standing (orthostatic hypotension).