Calcium channel blockers are a first-line treatment for high blood pressure and are also added in to other classes of blood pressure treatment if the single drug alone does not control blood pressure.
How calcium channel blockers lower blood pressure
The flow of calcium in and out of cells is vital for the contraction of smooth muscle cells within blood vessel linings. Calcium flows in and out of cells through special protein channels. If these channels are partially inactivated, or blocked, then full contraction does not occur and blood vessels can dilate so blood pressure falls.
Calcium channel blockers (eg diltiazem, felodipine, isradipine, lacidipine, lercanidipine, nicardipine, nifedipine) therefore work by:
- blocking the transport of calcium ions through cell membranes
- relaxing muscles in arterial walls and reducing arterial spasm
- dilating peripheral veins to encourage pooling of blood
- reducing the force of contraction of the heart.
On average, a calcium-channel blocker reduces systolic blood pressure (your upper reading) by 8.4 mmHg when used alone.
Treatment must not be stopped suddenly, but tailed off slowly to prevent rebound high blood pressure and angina.
Patient information leaflets
To find out more about the most common calcium channel blockers, including their possible side effects, click on the following links. These will take you to a typical Patient Information Leaflet that is found inside a UK pack of these medicines. Always read the patient information leaflet supplied with your own medicine as different preparations vary.
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