What are thiazide (thiazide) diuretics?

From the Guidelines

Thiazide diuretics are a class of medications that increase urine production and reduce blood pressure by affecting how the kidneys handle salt and water, with common examples including hydrochlorothiazide, chlorthalidone, and indapamide, as noted in the 2019 study 1.

Key Characteristics of Thiazide Diuretics

• They work by blocking sodium and chloride reabsorption in the distal convoluted tubule of the kidney, leading to increased excretion of sodium, chloride, and water.
• Thiazides are typically taken once daily in the morning to prevent nighttime urination.
• They're first-line treatments for hypertension and are also used for edema in heart failure and liver disease.

Side Effects and Considerations

• Side effects may include low potassium levels, elevated blood sugar, increased uric acid, and decreased calcium excretion.
• Patients taking thiazides should monitor their electrolytes periodically and may need potassium supplements, as suggested by the 2013 guideline 1.
• These medications are particularly effective in older adults and African American patients with hypertension, and they work well when combined with other blood pressure medications like ACE inhibitors or calcium channel blockers, as discussed in the 2003 report 1.

Clinical Use

• Thiazide diuretics can be used in combination with other medications, such as ACE inhibitors, calcium channel blockers, and beta-blockers, to achieve better blood pressure control.
• The choice of thiazide diuretic and dosage should be individualized based on the patient's specific needs and medical history.
• Regular monitoring of electrolyte levels, kidney function, and blood pressure is essential to minimize the risk of adverse effects and optimize the benefits of thiazide diuretic therapy.

From the FDA Drug Label

Hyperuricemia or acute gout may be precipitated in certain patients receiving thiazide diuretics. Thiazide-like diuretics have been shown to increase the urinary excretion of magnesium; this may result in hypomagnesemia. The possibility of exacerbation or activation of systemic lupus erythematosus has been reported with thiazide diuretics, which are structurally related to chlorthalidone.

Thiazide diuretics are a class of drugs that are used to treat various conditions, including:

• Hypertension: by increasing the excretion of sodium and water in the urine, which helps to lower blood pressure
• Edema: by reducing the amount of fluid in the body
• Hyperuricemia: although they may also precipitate acute gout in some patients

They work by inhibiting the reabsorption of sodium and chloride in the distal convoluted tubule of the kidney, which leads to an increase in the excretion of sodium, chloride, and water.

Key points about thiazide diuretics include:

• They may cause hypokalemia (low potassium levels) and hypomagnesemia (low magnesium levels)
• They may precipitate hyperuricemia (high uric acid levels) or acute gout
• They should be used with caution in patients with severe renal disease, impaired hepatic function, or progressive liver disease 2, 3, 3

From the Research

Definition and Mechanism of Thiazide Diuretics

• Thiazide diuretics are a class of drugs that inhibit sodium reabsorption in the early distal convoluted tubule, primarily used to treat hypertension 4, 5.
• They work by inhibiting the electroneutral Na(+)-Cl(-) cotransporter located on the apical membrane of the early segment of the distal convoluted tubule 5.
• Thiazide diuretics reduce blood pressure, although the mechanisms by which they chronically lower BP remain unknown 5.

Types and Examples of Thiazide Diuretics

• The thiazide class is heterogeneous and can be further subdivided into compounds containing the benzothiadiazine ring structure (thiazide-type, e.g., hydrochlorothiazide) and those lacking the benzothiadiazine ring (thiazide-like, e.g., chlorthalidone and indapamide) 6.
• Examples of thiazide diuretics include hydrochlorothiazide, chlorthalidone, and indapamide 6, 7.

Efficacy and Safety of Thiazide Diuretics

• Thiazide diuretics have antihypertensive efficacy equivalent to that of other major classes of antihypertensive drugs and are at least as well tolerated 8.
• They are effective when given once daily, require no dose titration, have few contraindications, and have additive effects when combined with drugs of other classes 8.
• Low-dose thiazides should be preferred for routine first-line treatment of hypertension unless they are contraindicated or there is a compelling indication for an alternative class of drug 8.
• Thiazide diuretics remain underutilized, with only about one-third of hypertensive patients receiving them 6.