Topic: Antihypertensive, Antidiuretics
Question: Enumerate various classes of antihypertensive drugs. Briefly discuss the role of calcium channel blockers in the treatment of hypertension.
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overview of the major classes of antihypertensive drugs and a more detailed discussion on calcium channel blockers:
Classes of Antihypertensives:
- Diuretics – increase sodium and water excretion to lower blood volume. E.g. thiazides, loop diuretics.
- Beta blockers – block beta-adrenergic receptors to reduce cardiac output. E.g. metoprolol, atenolol.
- ACE inhibitors – prevent conversion of angiotensin I to angiotensin II to induce vasodilation. E.g. lisinopril, enalapril.
- Angiotensin receptor blockers (ARBs) – block binding of angiotensin II to receptors. E.g. losartan, valsartan.
- Calcium channel blockers – discussed below.
- Direct vasodilators – relax vascular smooth muscle. E.g. hydralazine.
Role of Calcium Channel Blockers:
- Inhibit calcium influx through L-type calcium channels in vascular smooth muscle cells.
- Blocking calcium entry prevents muscle contraction and vasoconstriction. This results in arterial vasodilation and lowering of blood pressure.
- Help control blood pressure while also treating angina pectoris and arrhythmias.
- Avoid reflex tachycardia side effect of other agents. Heart rate is less affected.
- Major subgroups are dihydropyridines (amlodipine, nifedipine) and non-dihydropyridines (diltiazem, verapamil).
- Main side effects are peripheral edema, headache, dizziness, and constipation.
- Often used as add-on therapy for resistant hypertension when used with a diuretic or ACE inhibitor.
So in summary, calcium channel blockers are a key antihypertensive drug class that works by relaxing vascular smooth muscle to promote vasodilation and reduce peripheral resistance and blood pressure.
