Anti hypertensive drugs
Anti hypertension drugs can be classified into 8 broad categories depending upon their mode of action. In this collection of health articles, we strive hard to impart information with no commercial bias and hence you may not find any commercial name of the drugs or brand names as far as possible. Instead we may present the generic names of the drugs.
To control the high blood pressure, your doctor may use one of the following group of drugs:
Calcium Channel Blockers
Calcium channel blockers are one of the key drugs administered in cardiovascular conditions. In most cases they are used in case of hypertension and angina.They are classified depending upon their mode of action and their chemical composition. These chemicals when induced in the body block the calcium channels in the cell membrane.
They are selected for vascular sites rather than the myocardial region. These drugs facilitate good vasodilator effects with limited electro physiological effect on the cardiac conduction system pertaining to the AV and SA nodes. Thus the negative inotropic effects do not occur in these drugs.These drugs are more selective to the cerebral arteries than the systemic arteries. Eg: Nifedepine, Amlodipine, nimodipine.
These drugs cause peripheral vasodilation with a moderate inotropic effect. Subsequently they increase the coronary vasodilation. Cardiac rate may or may not increase as it causes a slight depression in the SA or AV nodal conduction route. Eg: Verapamil.
These drugs are also associated with peripheral vasodilation causing mild inotropic effect and minimum depression in the SA / AV node conduction. They increase coronary vasodilation. They also exhibit intermediate vaso-selectivity. Eg: Diltiazem.
The elimination route for most of these drugs is through the liver. In most cases the recommended dosage is twice a day for sustained release in the body. The limitation of calcium channel blockers administration for hypertension is often related to their functionality such as vasodilation. However, because of their mechanism of action and efficacy, they do not cause conditions such as reflex tachycardia.
Calcium channel blockers are given to children who have low renin levels. The drug is given with other drugs such as beta-blockers and diuretics to attain desired results of cardiac physiology. In most cases, calcium blocker administration requires investigative tests such as blood vessel abnormalities, liver and kidney function tests.
Side effects and precautions
Calcium channel blockers are known to have some side effects since they are closely associated with vascular physiology and cardiac conduction system. Syncope and presyncope episodes followed by dizziness are commonly-noticed side effects. This happens because of the decrease in blood pressure due to reduced heart rate. Arrhythmia is another potential side effect along with gastro-esophageal reflux and nausea.
Lower extremity swelling or edema is a complication of treatment with calcium channel blockers (especially with Felodipine and Amlodipine), Thioglitazones and Minoxidil. Transient Incontinence is another symptom noticed with Calcium Channel Blocker drugs.
The most common side effects of calcium channel blockers are peripheral edema, Bradycardia, headache and constipation in some cases. The dihydropyridine agents such as Nifedipine, Nicardipine, Isradipine, Felodipine, Nisoldipine and Amlodipine, can produce symptoms of vasodilation - specifically headaches, palpitations, flushing and peripheral edema or swelling in lower extremities.
Some studies indicate that juices such as grapefruit should be avoided during the administration of calcium channel blockers as they hinder with the drug absorption and breakdown in the system. Alcohol consumption must also be avoided as it may cause damage because of hepatic involvement in the respective drug.
Calcium channel blockers are taken as second line cardiac drugs with respect to anti-hypertensive drugs and beta-blockers. However careful examination of the patient drug history is performed before recommending these drugs because some studies also imply that prolonged usage of all three drugs may increase the incidence of diabetes and the risks associated with it. Drug evaluation is essential because recent studies indicate the involvement of clarithromycin along with calcium channel blockers causing kidney damage and prolonged usage of these drugs can also cause breast cancer in women.
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Bibliography / Reference
Collection of Pages - Last revised Date: August 4, 2021