<prompt> Which of the following anti hypertensives act by decreasing heart rate only?PropranololMethyl dopaPrazosinNitrate  <response>: Ans: a Propranolol Ref: Katzung, 10th ed, p. 160Beta blockers decrease heart rate, force of contraction and cardiac output, this leads to decrease in blood pressure.Drugs used in hypertension are:1 Diuretics - Low-dose thiazide diuretics are often used as first-line agents, alone or in combination with other antihypertensive drugs e.g., hydrochlorthiazide, chlorthalidone.2 ACE-inhibitors and angiotensin receptor blockers - ACE inhibitors decrease the production of angiotensin n, increase bradykinin levels, and reduce sympathetic nervous system activity. Angiotensin II receptor blockers provide selective blockade of AT1 receptors.3 Beta Blockers - a adrenergic receptor blockers lower blood pressure by decreasing cardiac output, due to a reduction of heart rate and contractility. Other actions include renin inhibition.4 Calcium Channel Blockers - Calcium channel antagonists reduce vascular resistance through L- channel blockade, which reduces intracellular calcium and blunts vasoconstriction.5 Aldosterone Antagonists - It may be a particularly effective agent in patients with low-renin essential hypertension, resistant hypertension, and primary aldosteronism.The newer agent, eplerenone, which is a selective aldosterone antagonist have lesser side effects than spironolactone.6 a adrenergic blockers - They lower blood pressure by decreasing peripheral vascular resistance.7 Sympatholytic Agents - Centrally acting a2 agonists lower blood pressure by inhibiting sympathetic outflow and thereby decreasing peripheral resistance e.g., clonidine.8 Direct vasodilators - These agents decrease peripheral resistance.Hydralazine is a potent direct vasodilator.Se: lupus-like syndrome.Minoxidil is another vasodilator and is most frequently used in patients with renal insufficiency that is refractory to all other drugs.Se: hypertrichosis and pericardial effusion.9 Adrenergic neuron-blocking agents-These drugs lower blood pressure by preventing normal physiological release of norepinephrine from postganglionic sympathetic neurons.E.g. Guanethidine, reserpine 