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cardio:diuretics:hydrochlorothiazide [2026/02/15 03:21] – andrew2393cnscardio:diuretics:hydrochlorothiazide [2026/03/15 17:02] (current) – Create Hydrochlorothiazide page wilkie
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-====== Hydrochlorothiazide (Microzide®) ====== +====== Hydrochlorothiazide (HCTZ®) ======<WRAP right 340px><WRAP infobox>| | {{ :cardio:diuretics:hydrochlorothiazide_structure.svg |}} |^ Hydrochlorothiazide || Brand Names | HCTZ® || Drug Class | [[cardio:diuretics:thiazide:start|Thiazide Diuretic]] || Primary Indications | [[cardio:hypertension:start|Hypertension]]; Mild edema || Blood Pressure Effect | ↓ BP (chronic) || Mortality Benefit | No (BP control) || Elimination | Renal || Black Box Warning | No || FDA Approval | 1959 |</WRAP></WRAP>===== Overview =====Hydrochlorothiazide is a thiazide diuretic that inhibits the Na-Cl cotransporter in the distal convoluted tubule. It lowers blood pressure chronically via reduced peripheral vascular resistance and treats mild edema.<WRAP clear></WRAP>----===== Mechanism of Action =====**Primary Molecular Target**  * Na-Cl cotransporter (NCC) in distal convoluted tubule**Segment Effects**  * ↓ NaCl reabsorption in DCT  * ↑ Ca2+ reabsorption  * Mild natriuresis**Net Physiologic Outcomes**  * ↓ blood pressure (long-term)  * Mild diuresis  * ↓ urinary calcium----===== Indications =====  * First-line hypertension (selected patients)  * Mild edema (HF, liver disease)  * Nephrolithiasis with hypercalciuria----<WRAP blackbox>===== Black Box Warning =====No black box warning.</WRAP>----<WRAP contra>===== Contraindications =====Absolute:  * AnuriaRelative / Caution:  * Gout  * Hyponatremia  * Hypokalemia  * Sulfonamide allergy (severe)</WRAP>----<WRAP details>===== Dosing =====Hypertension:  * 12.5–25 mg daily (typical)  * Max: 50 mg dailyEdema:  * 25–100 mg daily or divided</WRAP>----<WRAP details>===== Pharmacokinetics =====Absorption:  * OralBioavailability:  * ~60–70%Metabolism:  * Not significantHalf-life:  * ~6–15 hoursElimination:  * Renal</WRAP>----<WRAP details>===== Adverse Effects =====Common:  * Hypokalemia  * Hyponatremia  * Hyperuricemia  * HyperglycemiaSerious:  * Pancreatitis (rare)  * Severe hyponatremia</WRAP>----<WRAP details>===== Drug Interactions =====Increased risk:  * Lithium (↑ levels)  * NSAIDs (↓ effect)Avoid combination:  * Other QT-prolonging meds if severe hypokalemia</WRAP>----<WRAP monitoring>===== Monitoring =====Labs:  * Electrolytes (Na+, K+)  * Uric acid  * GlucoseVitals:  * Blood pressureClinical:  * Gout symptoms  * Orthostasis</WRAP>----<WRAP pearls>===== Clinical Pearls =====  * Chlorthalidone often preferred for longer duration  * Increases calcium reabsorption  * Can worsen gout and glucose control</WRAP>----===== Comparison Within Class =====Compared to other [[cardio:diuretics:thiazide:start|thiazide diuretics]]:  * Shorter half-life than chlorthalidone  * Commonly used in fixed-dose combos  * Less potent for resistant HTN----===== Related =====  * [[cardio:diuretics:thiazide:start|Thiazide Diuretics]]  * [[cardio:hypertension:start|Hypertension]]  * [[cardio:diuretics:start|Diuretics]]
- +
-<WRAP right 340px> +
-<WRAP infobox> +
-^ Hydrochlorothiazide | {{ :cardio:diuretics:hydrochlorothiazide.svg?150 |}} | +
-| Brand Names | Microzide®, HydroDIURIL® | +
-| Drug Class | [[cardio:diuretics:start|Thiazide Diuretic]] | +
-| Primary Indication | Hypertension | +
-| Site of Action | Distal Convoluted Tubule | +
-| Mechanism | Na⁺/Cl⁻ Cotransporter Inhibition | +
-| Potassium Effect | ↓ (Hypokalemia risk) | +
-| Calcium Effect | ↑ Reabsorption | +
-| Half-Life | ~6–15 hours | +
-| FDA Approval | 1959 | +
-</WRAP> +
-</WRAP> +
- +
-===== Overview ===== +
- +
-Hydrochlorothiazide (HCTZ) is a thiazide diuretic used primarily for the treatment of hypertension and mild edema. +
- +
-It lowers blood pressure by promoting natriuresis and reducing plasma volume, followed by long-term reduction in systemic vascular resistance. +
- +
-Thiazides remain first-line therapy for uncomplicated hypertension in many patients. +
- +
-<WRAP clear></WRAP> +
- +
----- +
- +
-===== Mechanism of Action ===== +
- +
-**Site of Action** +
-  * Distal convoluted tubule   +
- +
-**Transporter Blocked** +
-  * Na⁺/Cl⁻ cotransporter (NCC)   +
- +
-**Physiologic Effects** +
-  * ↑ Sodium and water excretion   +
-  * ↑ Potassium excretion   +
-  * ↑ Calcium reabsorption   +
-  * ↓ Plasma volume   +
-  * ↓ Peripheral vascular resistance (long term)   +
- +
-Net effect: +
-  * Reduction in blood pressure   +
- +
----- +
- +
-===== Indications ===== +
- +
-  * Primary hypertension   +
-  * Mild edema   +
-  * Nephrolithiasis (calcium stone prevention)   +
-  * Adjunct in heart failure (mild cases)   +
- +
-Often combined with: +
-  * [[cardio:raas:acei|ACE inhibitors]]   +
-  * [[cardio:raas:arb|ARBs]]   +
-  * [[cardio:beta_blockers:start|Beta-blockers]]   +
- +
----- +
- +
-<WRAP contra> +
-===== Contraindications ===== +
- +
-Absolute: +
-  * Anuria   +
-  * Sulfonamide allergy (relative; cross-reactivity low)   +
- +
-Relative / Caution: +
-  * Severe renal impairment (ineffective at low GFR)   +
-  * Gout   +
-  * Diabetes mellitus   +
-  * Hyponatremia   +
-  * Hypokalemia   +
- +
-</WRAP> +
- +
----- +
- +
-<WRAP details> +
-===== Dosing ===== +
- +
-Hypertension: +
-  * 12.5–25 mg once daily   +
- +
-Edema: +
-  * 25–100 mg daily   +
- +
-Higher doses increase metabolic side effects without significant additional BP benefit. +
- +
-</WRAP> +
- +
----- +
- +
-<WRAP details> +
-===== Pharmacokinetics ===== +
- +
-Absorption: +
-  * Oral   +
- +
-Bioavailability: +
-  * ~65–75%   +
- +
-Half-life: +
-  * ~6–15 hours   +
- +
-Elimination: +
-  * Renal   +
- +
-Effectiveness decreases when eGFR < 30 mL/min/1.73 m². +
- +
-</WRAP> +
- +
----- +
- +
-<WRAP details> +
-===== Adverse Effects ===== +
- +
-Electrolyte: +
-  * Hypokalemia   +
-  * Hyponatremia   +
-  * Hypomagnesemia   +
-  * Hypercalcemia   +
- +
-Metabolic: +
-  * Hyperglycemia   +
-  * Hyperuricemia (gout)   +
-  * Hyperlipidemia (mild)   +
- +
-Other: +
-  * Photosensitivity   +
- +
-</WRAP> +
- +
----- +
- +
-<WRAP details> +
-===== Drug Interactions ===== +
- +
-Increased lithium levels   +
-Additive hypokalemia with: +
-  * Loop diuretics   +
-  * Corticosteroids   +
- +
-RAAS inhibitors: +
-  * May mitigate potassium loss   +
- +
-</WRAP> +
- +
----- +
- +
-<WRAP monitoring> +
-===== Monitoring ===== +
- +
-  * Blood pressure   +
-  * Electrolytes (Na⁺, K⁺)   +
-  * Renal function   +
-  * Uric acid (if history of gout)   +
-  * Glucose (diabetics)   +
- +
-</WRAP> +
- +
----- +
- +
-<WRAP pearls> +
-===== Clinical Pearls ===== +
- +
-  * First-line therapy for uncomplicated hypertension.   +
-  * Lower doses (12.5–25 mg) preferred.   +
-  * Causes hypokalemia and metabolic alkalosis.   +
-  * Increases calcium reabsorption — useful in kidney stones.   +
-  * Less effective when eGFR < 30.   +
- +
-</WRAP> +
- +
----- +
- +
-===== Comparison Within Class ===== +
- +
-Compared to [[cardio:diuretics:chlorthalidone|Chlorthalidone]]: +
-  * Shorter half-life   +
-  * Less potent   +
-  * Less outcome data   +
- +
-Compared to [[cardio:diuretics:indapamide|Indapamide]]: +
-  * More metabolic effects   +
-  * Shorter duration   +
- +
-Compared to [[cardio:diuretics:furosemide|Furosemide]]: +
-  * Less potent diuretic   +
-  * Ineffective in severe renal failure   +
- +
----- +
- +
-===== Related ===== +
- +
-  * [[cardio:diuretics:start|Diuretics]] +
-  * [[cardio:diuretics:chlorthalidone|Chlorthalidone]] +
-  * [[cardio:raas:acei|ACE Inhibitors]] +
-  * [[cardio:hypertension:start|Hypertension]]+
cardio/diuretics/hydrochlorothiazide.1771125711.txt.gz · Last modified: by andrew2393cns