Quiz 26: Anticoagulants and Coagulants
Diuretics are the class of drugs used to increase the amount of salt and water expelled from the body as urine. Some of the drugs like Thiazide diuretics, thiazide-like diuretics are used to treat hypertension (increased blood pressure - 140/90 ). The class of drugs is also called water piles. Diuretics used to treat hypertension include thiazide diuretics (Hydrochlorothiazide, chlorthalidone), High ceiling diuretics (furosemide), Potassium-sparing diuretics (spironolactone and amiloride), etc. Diuretics primarily reduce blood pressure by depleting body sodium stores. Initially, these drugs help in reducing the blood pressure by reducing the blood volume and cardiac output (the amount of blood that the heart pumps in a minute). The peripheral vascular resistance (the resistance in the circulatory system that creates blood pressure) may increase. After a few weeks, the cardiac output return toward normal while peripheral vascular resistance declines. The contribution of the sodium to vascular resistance is that by increasing the vessel stiffness as well as neuronal reactivity. This can lead to an increase in the intercellular calcium level and altered sodium-calcium exchange. So, the diuretics or sodium restriction helps in reversing these effects. In mild hypertension, diuretics are used alone. But in moderate to severe hypertension, diuretics are combined with other antihypertensive drugs. Thiazide and thiazide-like diuretics (Hydrochlorothiazide, Chlorthalidone) act in the distal tubule decrease reabsorption of sodium and potassium by acting on Na+/Cl- co-transporter. Thiazides lower the blood pressure by increasing sodium and water excretion. And this decreases extracellular volume resulting in lower cardiac output and renal blood flow. With long term use peripheral resistance decreases. Thiazides are the drug of choice for uncomplicated hypertension. Loop diuretics (furosemide) exerts a natriuretic effect by inhibiting the sodium (Na+) Potassium (K+) chlorine (2Cl-) symporters in the ascending limb of the loop of Henle, preventing passive water reabsorption from the descending limb of the loop. Thus, loop diuretics increase the excretion of sodium, potassium, and chloride ions. Magnesium and calcium ions are excreted as well. Comparing with other diuretics loop diuretics can inhibit a greater percentage of filtered sodium. Potassium-sparing diuretics(spironolactone) decrease sodium absorption in the distal convoluted tubule and thus results in potassium (K+) absorption and excretion of sodium. They help in reducing excessive potassium depletion and in enhancing the natriuretic effects of other diuretics. Thus, Diuretics reduce blood volume, venous return (preload), cardiac output, and thus the blood pressure (BP).
There are many factors that are related to life style which if controlled can produce modest decrease in blood pressure Such factors are sodium restriction is diet so that sodium intake is decreased, weight loss, eliminating smoking and regular exercise. The increase in sodium level in the blood can cause elevated blood pressure. A regular exercise can improve the blood circulation in the body and relieve the vasoconstriction to decrease the blood pressure. The blood pressure above 140/90 (mm Hg) is referred to as hyper tension and it has two stages. Stage 1 hypertension has a range of 140-159/90-99 (mm Hg) and stage 2 hypertension has a range of above 160/100 (mm Hg). Hence the patient Mr. Johnson has stage 1 hypertension and this hypertension can be controlled by improving life style. Hence Mr. Johnson must be advised to quit smoking and lose weight by regular exercising and reducing sodium intake in the daily diet. Also he can be given diuretics as these are most effective drugs in treating mold hypertension and long term use may permanently treat the hypertension.
Adrenergic beta-blockers act by decreasing heart rate, cardiac output, and release of renin in the patient. These drugs block beta-1 receptors in the heart to decrease cardiac output and blood pressure. The blockers also block beta-1 receptors in the kidneys that further decrease the release of renin from the Renin-angiotensinogen aldosterone system (RAAS). This activates the RAA mechanism. Examples of beta-blockers are atenolol, metoprolol, nadolol, and propranolol. Hence the incorrect options are a, b, c, and d. The beta-blockers act by blocking the effects of the hormone epinephrine. The administration of cold medicines, anti-histamines, or antacids is contraindicated among patients taking beta-blockers. Hence the correct option is .