Vasoconstrictor drugs Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels. α1 adrenergic agonists and drugs that release noradrenaline from the sympathetic nerve terminals or inhibit its reuptake cause vasoconstriction. Some eicosanoids like thromboxane A and several peptides like endothelin, angiotensin and vasopressin are also predominantly vasoconstrictors. Clinical […]

Vasodilator drugs Vasodilators are drugs that dilate blood vessels. They affect the muscles in the walls of arteries and veins, preventing the muscles from tightening and the walls from narrowing. Vasodilators drugs divided into direct and indirect acting vasodilators- 1. Directly acting vasodilators Directly acting vasodilators produce their action mainly by interfering with the availability

Antihypertensive Drugs Antihypertensive drugs are agents used to reduce the elevated blood pressure. They can be classified based on the mechanism of action as under: Agents interfering with sympathetic activity Alpha adrenergic receptor blockers: Phentolamine, tolazoline, prazosin, Beta adrenergic blockers: Propranolol, Atenolol, Metoprolol Alpha and Beta adrenergic blocker: Labetalol Agents interfering with central sympathetic activity:

Clinical uses and adverse effects of antiarrhythmic drugs will be discussed here: Clinical uses of antiarrhythmic drugs Adverse effects of antiarrhythmic drugs One of the most common and serious adverse cardiac effects is proarrhythmia (arrhythmia ironically precipitated by antiarrhythmic therapy) which can occur in 5-20% of patients treated with Class I and Class III drugs. Extra-cardiac Adverse

Class IV: Calcium channel blocker Most clinical ventricular arrhythmias are neither prevented nor suppressed by calcium-channel blockers. Calcium-channel blockers are useful in treating arrhythmias involving re-entry within the AV node and in the rare forms of monomorphic ventricular tachycardia seen in patients with structurally normal myocardium. Many of the calcium-channel blockers also have the ability

Class III: Potassium channel blocker Potassium currents, predominantly the current known as the delayed rectifier, are responsible for repolarizing the membrane during the action potential. Block of potassium currents during the plateau phase of the action potential is thought to be the mechanism of action of many drugs that prolong the refractory period. Drugs that

Class II: Beta adrenergic blockers The drugs in this class suppress adrenergic mediated ectopic activity. The members of the group like propranolol block the beta receptors of the cardiac tissue. It decreases slope of Phase IV depolarization and automaticity in SA node. Propranolol is useful in treating sinus tachycardia, extrasystoles provoked by exercise or emotion.

Sodium channel blockers are divided into various classes. Class I : Sodium channel blockers Class I : Sodium channel blockers are the membrane stabilizers and functions are- Contra-indication of sodium channel blockers: Complete heart block The enhancement of sodium channel block seen in rapidly depolarizing tissue has been termed “use-dependent blockade” and is thought to

Antiarrhythmic drugs are agents used to control ectopic foci or reverse disorganised conduction of electrical impulses through the heart.

Arrhythmia Arrhythmia is any abnormal pattern of electrical activity in the heart. Normally the waves of depolarization follow a specific sequence, starting in the S-A node and ending with the contraction of the ventricles. Sometimes another area of the myocardium or conducting system begins to depolarize out of sequence or more rapidly than the S-A node, disrupting