What is the mechanism of action of thiazide diuretics?

Thiazide diuretics increase salt and water excretion primarily by inhibiting mechanisms for electroneutral sodium and chloride transport by distal convoluted tubule cells. This might be termed the ‘specific’ effect of this class of diuretics and accounts for the ‘chlorouretic’ effectiveness of the drug.

How does thiazide reduce blood pressure?

Thiazide diuretics are used to treat high blood pressure by reducing the amount of sodium and water in the body. Thiazides are the only type of diuretic that dilates (widens) the blood vessels, which also helps to lower blood pressure.

How do diuretics work to lower blood pressure?

Diuretics, sometimes called water pills, help rid your body of salt (sodium) and water. Most of these medicines help your kidneys release more sodium into your urine. The sodium helps remove water from your blood, decreasing the amount of fluid flowing through your veins and arteries. This reduces blood pressure.

Why is thiazide a diuretic?

Thiazide diuretics are a common treatment for high blood pressure (hypertension). They are also used to clear fluid from the body in conditions where your body accumulates too much fluid, such as heart failure. (However, a type of diuretic called a loop diuretic is more commonly used to treat heart failure.)

How do vasodilators work?

Vasodilators are medications that open (dilate) blood vessels. They affect the muscles in the walls of the arteries and veins, preventing the muscles from tightening and the walls from narrowing. As a result, blood flows more easily through the vessels. The heart doesn’t have to pump as hard, reducing blood pressure.

How do thiazide and thiazides diuretics lower blood pressure?

Some of the most commonly prescribed antihypertensives, thiazide and thiazide-like diuretics are thought to chronically lower blood pressure primarily by reducing total peripheral resistance.

Why do thiazide diuretics cause hyponatremia?

(1) The propensity of thiazides to promote hyponatremia is explained by the inhibition of urinary dilution due to reduced reabsorption of NaCl in the distal renal tubules. In contrast, loop diuretics do not impair urinary dilution and are not associated with reduction of sodium levels.

How do thiazide diuretics differ from loop diuretics?

Thiazides decrease the urinary excretion of calcium, while loop-diuretics have the opposite effect. The possibility of loop-diuretic induced osteopenia cannot be ruled out, which should be considered when choosing between thiazides and loop-diuretics for the treatment of mild to moderate CHF.

How do thiazide diuretics decrease potassium?

Because loop and thiazide diuretics increase sodium delivery to the distal segment of the distal tubule, this increases potassium loss (potentially causing hypokalemia) because the increase in distal tubular sodium concentration stimulates the aldosterone-sensitive sodium pump to increase sodium reabsorption in …

How does thiazide affect urine volume?

Thiazides increase urine output by inhibiting the NaCl cotransporter on the luminal membrane of the earliest portion of the distal convoluted tubule, often called the cortical diluting segment (Fig. 9-5).

How do thiazide diuretics decrease diluting capacity of the nephron?

Thiazide diuretics act by inhibiting reabsorption of Na+ and Cl– from the distal convoluted tubule by blocking the thiazide-sensitive Na+/Cl– cotransporter. Thus, they inhibit electrolyte transport in the diluting segment and may impair urinary dilution in some vulnerable groups.

What electrolyte abnormalities commonly occur with thiazide diuretics?

The main adverse effects of thiazides include hyponatremia, hypokalemia, hypomagnesemia, and hypercalcemia. Thiazide-induced hyponatremia is an often underestimated risk that requires proactive management by clinicians and patients.

How do thiazides cause vasodilation?

The direct vasodilator actions of thiazide diuretics on isolated vessels are associated with an increase in Rb+ efflux (as a marker for K+ efflux)1032 and hyperpolarization of the plasma membrane and are inhibited by selective blockers of the KCa channel.

Why do thiazide diuretics cause hyperlipidemia?

Hyperlipidemia is prevalent in hypertension, but the cause of this association is unknown. Treatment of hypertension with thiazide diuretics accentuates the hyperlipidemia, perhaps by causing potassium or sodium depletion.

Why do thiazide diuretics cause hypercalcemia?

Thiazide diuretics can increase renal tubular reabsorption of calcium, resulting in hypercalcemia. However, thiazide-associated hypercalcemia also can represent unmasking of preexisting primary hyperparathyroidism (PHPT) or incidental development of PHPT during thiazide therapy.

How do thiazide diuretics decrease peripheral resistance?

A related hypothesis is that thiazides reduce total peripheral vascular resistance (TPR) by “dehydrating” vascular walls. However, direct measurements in small arteries failed to confirm such changes.

What part of the nephron Do thiazide diuretics work?

Thiazide diuretics work by blocking sodium and chloride (Na/Cl) channels in the distal convoluted tubule of the nephron and inhibit the reabsorption of sodium and water. This also causes a loss of potassium and calcium ions.

What is the difference between thiazide and thiazide-like diuretics?

A thiazide-like diuretic is a sulfonamide diuretic that has similar physiological properties to a thiazide diuretic, but does not have the chemical properties of a thiazide, lacking the benzothiadiazine molecular structure. Examples include metolazone and chlorthalidone.

How do diuretics increase peripheral vascular resistance?

The implication is that the increase in compliance of the peripheral artery observed with diuretics is due to the decline in blood pressure rather than to a change in the intrinsic properties of the arterial wall.

Do diuretics decrease blood volume?

The differences in diuretics

Water binds to the sodium and is then removed during urination, leaving you with a lower blood volume. The reduction in blood volume slows the rate at which blood flows through your blood vessels, helping to decrease your blood pressure.

Is diuretic a vasodilator?

Diuretics are often associated with vasodilators; however, they have to be administered at a minimal chronic daily dosage, in order to avoid deleterious neurohormonal effects. Digoxin keeps a great interest, as the unique positive inotropic agent without surmortality.

Do diuretics reduce peripheral resistance?

Thiazide diuretic (TZD)-mediated chronic reduction of arterial pressure is thought to occur through decreased total peripheral vascular resistance. Further, the decreased peripheral vascular resistance is accomplished through TZD activation of an extrarenal target, resulting in inhibition of vascular constriction.