All diuretics increase the excretion of water from bodies. The thiazide diuretic hydrochlorothiazide hctz is the second most commonly prescribed antihypertensive in the usa, with approximately 47. It is also thought to directly decrease peripheral vascular resistance via another mechanism. Dec 22, 2010 it is a long 8 minute 47 second animation showing the molecular mechanism of the working of the nephron and the drugs which act on the various different regions of the nephron. Distal convoluted tubule is responsible for reabsorption of 810% nacl, and is relatively impermeable to water.
The thiazide drug class was discovered and developed at merck and co. For more detailed explanation, particularly related to ion and fluid movement across the renal. Jun 19, 2018 diuretics mechanism of action,diuretic types and adverse effects,drug specifications 1. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment. It is possible that the natriuretic action of thiazides and resulting extracellular fluid. Thiazide diuretics are a group of urine producing medicines also called as diuretics belonging to the chemical group of benzothiadiazines. They are primarily used in medicine to treat hypertension and edema often due to congestive heart failure or chronic kidney disease. Chemical structure of thiazidelike diuretics is shown. As a side effect of their chronic use, excess amounts of electrolytes can be lost in the urine leading to low levels of potassium, sodium. Thiazides inhibit the nacl cotransporter ncc in the proximal part of the convoluted tubule, the connecting segment, and maybe the cortical collecting tubule. A longacting oral diuretic that does not contain the same benzothiadiazine chemical structure as other thiazide diuretics, but shares the same mechanism of action inhibition of the nacl symporter in the renal distal convoluted tubule.
Diureticsmechanism of action,diuretic types and adverse. Diuretics mechanism of action of different classes of. Mechanisms for blood pressure lowering and metabolic. Thiazide diuretics can increase the risk of lithium eskalith. The most important and frequent problem with thiazide and loop diuretics is hypokalemia. What is the mechanism of action for thiazide diuretics.
As described above for the loop diuretics, the actions of thiazides can also be inhibited by nsaids under certain conditions. High yield usmle prep from kaplan medical helps you study nephrology, including diuretics and other important exam topics. Inhibit tubular resoption of sodium, chloride, and potassium ions result. Diuretics lower the blood pressure, at least initially, by inducing sodium and fluid loss. Thiazide diuretics act on the early distal convoluted tubules in the kidneys by blocking reabsorption of sodium, chloride and water. Diuretic dosing and adverse effects are discussed separately. Pharmacology and clinical use of diuretics katie herndon, pharm. Diuretic a diuretic is any substance that promotes diuresis, the increased production of urine.
Thiazide type diuretics have enjoyed a considerable success in the management of hypertension. Thus, they must be excreted into the tubular fluid to be active, so that a decrease in renal function makes thiazide diuretics much less effective. They have a similar mechanism of action to that of thiazides. Thiazide diuretics can also mobilize mild edema and are sometimes used for this purpose, but loop diuretics are generally used to treat edema. Hence it has been classified as both a thiazide as well as thiazidelike diuretic. Diabetes insipidus di is defined as the passage of large volumes 3 l24 hr of dilute urine oct 28, 2017 thiazides are the most widely used class of diuretics. As a result of these actions, urine output is increase and potassium is excreted. Their mechanism depends on renal prostaglandin production. The risk factors for the development of thiazideassociated hyponatremia are shown in table 1. Diuretics mechanism of action of different classes of diuretics, animation. They increase the rate of delivery of tubular fluid and electrolytes to the distal sites of hydrogen and potassium ion secretion, while plasma volume contraction increases. Oct 30, 2018 diuretics, particularly thiazide type and thiazide like diuretics, are commonly used in the treatment of hypertension. Thiazide diuretics are more effective in patients with normal kidney functions.
These are some of the most commonly prescribed diuretics and are frequently used as a first line antihypertensives. Thiazide diuretics appear to exert their effect by a combination effects, one of which is by producing a mild hypovolemia, which causes an increase in proximal sodium and water reabsorption, and decreased water delivery to the adhsensitive sites. The initial mechanism of thiazides is short lived and the. In peritoneal dialysis or hemodialysis, more solutes are lost decreasing the osmolarity and water from vascular compartment moves into intracellular spaces. Thiazides have been associated with significant side effects in some nursing infants and should be. This promotes excretion of sodium and chloride which carry water along with them.
The ability to induce negative fluid balance has made diuretics useful in the treatment of a variety of conditions, particularly edematous states and hypertension. Specifically, thiazides inhibit sodium reabsorption at the distal convoluted tubule, promoting naturesis and water loss. While thiazide diuretics are more effective in patients with normal kidney function, loop diuretics are more effective in patients with impaired kidney. Phramacology quiz 3 biology 390 with smith at william. But thiazide like diuretics has a longer duration of action compared to thiazides. Decreased na, cl, mg, decreased k as a lot of na can be exchanged for k in the late distal. The role of these drugs in the treatment of primary hypertension is discussed elsewhere. Bertram katzung, basic and clinical pharmacology, mc graw hill medical, 2007. The mechanism of action of triamterene dyrenium is to. Because this class of diuretic has relatively weak effects on overall sodium balance, they are often used in conjunction with thiazide or loop diuretics to help prevent hypokalemia. Its not just high blood pressure that thiazide diuretics can be used for, though.
This video discusses about the mechanisms of action of diuretics as antihypertensives agents. The primary site of action of thiazide diuretics in the nephron is. The clinically available thiazides and thiazidelike agents have the same mechanism of action. These drugs have assumed a standard of care position in the minds of many health care providers. Thiazides also possess some vasodilatory effects, exact mechanism is unknown. Distinguishing the nondiuretic mechanism of thiazides vs. Where indicated, the mechanistic basis and treatment of such side effects is further discussed. Correlation of the daily clinical doses of thiazide diuretics with their affinity for highaffinity 3 hmetolazone binding sites in rat kidney. Thiazide like diuretics is drugs which are structurally similar to thiazides. Thiazide refers to both a class of sulfurcontaining organic molecules and a class of diuretics based on the chemical structure of benzothiadiazine. Despite the bewildering number of diuretics available to the physician, these drugs can be divided into 4 main groups, characterised by their site of action on sodium reabsorption in the kidney. They differ only in pharmacokinetic properties such as the plasma halflife. Other side effects are similar to those of loop diuretics and include.
Loop diuretics are diuretics that act at the ascending limb of the loop of henle in the kidney. Possible mechanisms include direct endothelial or vascular smooth musclemediated vasodilation and indirect. Urine output in such patients can be reduced with a low sodium diet, nsaids and thiazide diuretics. Early disinhibition of the nacl cotransporter, resulting in decreased nacl reabsorption.
There are a few different drugs that work in a similar way, known as thiazide diuretics or thiaziderelated diuretics. If the kidney excretes more sodium, then water excretion will also increase 8. Diureticsmechanism of action,diuretic types and adverse effects,drug specifications 1. Mar 23, 2020 an important property of thiazide diuretics is their action on the luminal membrane, which means they must be present in the tubular fluid to have any effect on the nacl cotransporter. However, the mechanism by which these drugs chronically lower blood pressure is poorly understood.
The protein bound nature of the loop diuretic molecules causes it to be secreted via several transporter molecules along luminal wall of the proximal convoluted tubules to be able to exert its function. Mechanism of action of carbonic anhydrase inhibitors, osmotic diuretics, loop diuretics, thiazides, and potassiumsparing diuretics. Thiazide and thiazidelike diuretics are among the most commonly used antihypertensives and have been available for over 50 years. Thiazide and thiazide like diuretics are among the most commonly used antihypertensives and have been available for over 50 years. It shows the detailed mechanism of action of the diuretics such as the loop diuretics, the potassium sparing diuretics, and the thiazide diuretics.
Domenic sica discusses the mechanisms of action of thiazidetype diuretics, comparability to loopdiuretics, and the basis for combining them with nondiuretic antihypertensive medication classes. Doctors give trusted answers on uses, effects, sideeffects, and cautions. Side effect of thiazide diuretics answers on healthtap. Thiazide diuretics can lower potassium and magnesium blood levels since they are both eliminated in urine. It is a long 8 minute 47 second animation showing the molecular mechanism of the working of the nephron and the drugs which act on the various different regions of the nephron. Furosemide lasix, torsemide demadex, ethacrynic acid edecrin and bumetanide bumex are all examples of loop diuretics. Like cai and some loop diuretics, thiazide diuretics also has unsubstituted sulphonamide group which is the main functional group for its diuretic activity. Thiazide diuretics enhance the effectiveness of most other antihypertensive agents, especially vasodilators such as hydralazine and minoxidil, which by themselves promote volume expansion. Thiazide diuretics appeared as a result to synthesize more potent carbonic anhydrase inhibitors. See use of thiazide diuretics in patients with primary essential hypertension and mechanism of action of diuretics. Thiazide diuretics these drugs act by inhibiting nacl reabsorption in the distal convoluted tubule of the kidney. Mechanism of action of potasium sparing diuretics source.
Hydrochlorothiazide is a thiazide class diuretic that works by inhibiting the kidneys ability to retain water. Molecular mechanisms and potential clinical implications. Study 81 phramacology quiz 3 flashcards from darrian o. Thiazide diuretics initially lower blood pressure by increasing sodium and water loss as well as other electrolytes and nutrients in the kidneys and decreasing the volume of blood required for the. Diureticthiazide diuretics increase urinary excretion of sodium and water by inhibiting sodium reabsorption in the early distal tubules 04. Domenic sica discusses the mechanisms of action of thiazide type diuretics, comparability to loop diuretics, and the basis for combining them with nondiuretic antihypertensive medication classes. The nondiuretic hypotensive effects of thiazides are enhanced. Low levels of potassium and magnesium in the blood can result in abnormal heart rhythms, particularly in those who are also taking digoxin lanoxin in addition to a thiazide. Thiazide diuretics are the results of the chemical modification of sulfanilamide, an inhibitor of the carbonic anhydrase. Thiazide diuretics initially lower blood pressure by increasing sodium and water loss as well as other electrolytes and nutrients in the kidneys and decreasing the volume of blood required for the heart to circulate in the body, thereby reducing blood pressure. This action is mediated through suppression of the sodium chloride cotransporter. They are a structurally diverse group of sulfonamide derivatives that contain the sulfonamide group but not the benzothiadiazine ring.
What is the site and mechanism of action of thiazide. Thiazide diuretics are secreted into the tubular fluid by proximal tubule cells. It is possible that the natriuretic action of thiazides. In pocket companion to brenner and rectors the kidney eighth edition, 2011. Side effects include increased urination and sodium loss. 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. The action of thiazides depends in part on renal prostaglandin production. Mechanisms for blood pressure lowering and metabolic effects. Jan 14, 2020 thiazide diuretics and thiazide analogs. Data sources include ibm watson micromedex updated 10 apr 2020, cerner multum updated 6 apr. Diuretics mechanism of action of different classes of diuretics. The onset of action occurs after 2 to 3 hours for most thiazides, with little natriuretic effect occuring beyond 6 hours 2. Learn vocabulary, terms, and more with flashcards, games, and other study tools.
Loop diuretics are highly protein bound and therefore have a low volume of distribution. Video animation on renal physiology and diuretics mechanism. The main function of diuretics is to increase the output of urine, thereby helping to manage high blood pressure. The exact mechanism of thiazide diuretics for hypertension is not known, but these drugs seem to widen the artery of the heart, thereby lower the pressure that heart has to overcome to pump out blood to body. Diuretics water pills list of drugs and mechanism of. Mannitol is used with diuretics to regain the balance. Mechanisms for blood pressure lowering and metabolic effects of. Can anybody explain briefly how to perform the same using spss software. Thiazide diuretics are analogs of 1,2,4benzothiadiazine1,1dioxide. What is the site and mechanism of action of thiazide diuretics for. An important property of thiazide diuretics is their action on the luminal membrane, which means they must be present in the tubular fluid to have any effect on the nacl cotransporter. The following discussion and accompanying illustration provide a simple overview of how the kidney handles water and electrolytes.
Hydrochlorothiazide, chlorthalidone, mefruside, xipamide. Thiazide diuretics may be less effect in what population. From beaumont et al thiazide diuretic drug receptors in rat kidney. Diuretics water pills list of drugs and mechanism of action. This video explains the mechanism of action of carbonic anhydrase inhibitors, loop diuretics, thiazide diuretics and k sparing diuretics. Background carbonic anhydrase inhibitors cai are mild diuretics, hence not. They can also help if you have oedema swelling due to excess fluid or a specific type of diabetes. Reach the site of action by active tubular secretion.
Potentiation of the effect of thiazide derivatives by carbonic. Potentiation of the effect of thiazide derivatives by carbonic anhydrase inhibitors. Mechanism of action most diuretics produce diuresis by inhibiting the reabsorption of sodium at different segments of the renal tubular system this is accomplished by altering how the kidney handles sodium. They are used for urine production if the urine output decreases. Thiazide like diuretics thiazide diuretics thiazide. Use of thiazide diuretics in patients with primary. Thus, a vasodilator action of thiazides is proposed, likely via.
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