Hi to all student nurses…
This is the 3rd topic in the All about Antihypertensive series. Calcium Channel Blockers or Calcium antagonist are drugs with multiple roles, which makes it the most widely used cardiovascular medicine. This multifunction (which you can find below) property makes these drugs effective not only in hypertension but also in angina, cardiac arrhythmias, some type of a headache etc.
CCBs includes drugs in three classes
- Phenylalkylamines ( verapamil)
- Benzothiazepines ( Diltiazem)
- Dihydropyridines ( Nifedipine and other alike drugs with the suffix -dipine)
sometimes, phenylalkylamines and Benzothiazepines together is known under the class Nondihydropyridines
How CCBs act ( mechanism of action)
These drugs inhibit or block the flow of extracellular Ca2+ ions through the “L- type” Ca2+ channel, that is located on the vascular smooth muscles. This blocking results in the relaxation of smooth muscle cells, resulting in vasodilation and lowering of BP.
- L-type Ca2+ channels, located on vascular smooth muscles, cardiac myocytes, and nodal tissue (SA and AV node). It regulates Ca2+ influx into the muscle cells and stimulates smooth muscle and cardiac myocytes contraction .once these channels are blocked,
- Vascular smooth muscle relaxation – Vasodilation
- Decrease myocardial force generation – -ve inotropy
- Decrease heart rate – -ve chronotrophy
- Decrease conduction velocity within the heart – -ve dromotrophy
(If we consider the calcium channel as a mountain passage and the membrane as the mountain itself, CCBs act as a closed check post preventing the entry of ca2+ ions into the cells.)
Mainly used in the following cases
- Raynaud’s disease
- Cluster headache.
- Pregnancy and lactation
Serious side effects are rare for CCBs. Major side effects may include-
- Peripheral oedemas
Grapefruit intake is not recommended along with CCBs, as it alters the effects of the drug.
Beta blockers are not given with CCBs, as both groups depress cardiac electrical and mechanical activities
- Monitor BP and pulse before therapy, and in between the therapy
- Monitor ECG periodically for prolonged period therapy
- Administer along with meals or milk to reduce the gastric irritation
- Teach the patient self-monitoring of Pulse and BP, and ask to inform any alteration
- Advise to change position slowly to minimize the effects of Orthostatic hypotension.
- Advise to inform any signs of side effects
These are the important points in CCBs. Have a happy and enthusiastic study time.