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Indapamide
Indapamide
from Wikipedia
Indapamide
Above: molecular structure of indapamide Below: 3D representation of an indapamide molecule
Clinical data
Trade namesLozol, Natrilix
AHFS/Drugs.comMonograph
MedlinePlusa684062
Pregnancy
category
  • AU: C
Routes of
administration
By mouth
ATC code
Legal status
Legal status
  • UK: POM (Prescription only)
  • EU: Rx-only[1]
Pharmacokinetic data
Protein binding71–79%
MetabolismLiver
Elimination half-lifestandard release: 14–18 hours,[2] slow release: 14–24 hours (mean 18)[3]
Identifiers
CAS Number
PubChem CID
IUPHAR/BPS
DrugBank
ChemSpider
UNII
KEGG
ChEMBL
CompTox Dashboard (EPA)
ECHA InfoCard100.043.633 Edit this at Wikidata
Chemical and physical data
FormulaC16H16ClN3O3S
Molar mass365.83 g·mol−1
3D model (JSmol)
  • O=S(=O)(N)c1c(Cl)ccc(c1)C(=O)NN3c2ccccc2CC3C
  • InChI=1S/C16H16ClN3O3S/c1-10-8-11-4-2-3-5-14(11)20(10)19-16(21)12-6-7-13(17)15(9-12)24(18,22)23/h2-7,9-10H,8H2,1H3,(H,19,21)(H2,18,22,23) checkY
  • Key:NDDAHWYSQHTHNT-UHFFFAOYSA-N checkY
  (verify)

Indapamide is a thiazide-like diuretic[4] drug used in the treatment of hypertension, as well as decompensated heart failure. Combination preparations with perindopril (an ACE inhibitor antihypertensive) are available. The thiazide-like diuretics (indapamide and chlorthalidone) reduce risk of major cardiovascular events and heart failure in hypertensive patients compared with hydrochlorothiazide with a comparable incidence of adverse events.[5] Both thiazide diuretics and thiazide-like diuretics are effective in reducing risk of stroke.[5][6][7] Both drug classes appear to have comparable rates of adverse effects as other antihypertensives such as angiotensin II receptor blockers and dihydropyridine calcium channel blockers and lesser prevalence of side-effects when compared to ACE-inhibitors and non-dihydropyridine calcium channel blockers.[5][8]

It was patented in 1968 and approved for medical use in 1977.[9] It is on the World Health Organization's List of Essential Medicines.[10]

Medical uses

[edit]

Its indications include hypertension and edema due to congestive heart failure. Indapamide has been shown to reduce stroke rates in people with high blood pressure.[7][11][12] Studies have shown that the blood pressure lowering effects of indapamide in combination with perindopril reduce the rate of stroke in high risk patients (those with a history of high blood pressure, stroke or type two diabetes).[7][12][13] HYVET study showed that indapamide (sustained release), with or without perindopril as antihypertensive treatment in persons 80 years of age or older with sustained systolic blood pressure of 160 mmHg or higher, demonstrated significant reduction in all-cause mortality when treated to a target of 150/80 mmHg, but there was found to be no significant reduction in risk of death from cardiac causes.[7] Two systematic reviews identified that indapamide with or without perindopril significantly reduced all cause mortality in young-elderly patients with a history of stroke, cardiovascular disease and type 2 diabetes mellitus, when greater reductions in mean office blood pressure are achieved, significant cardiovascular benefit was only observed when trials including the >75 years old cohort was included.[7][14][15]

Contraindications

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Indapamide is contraindicated in known hypersensitivity to sulfonamides, severe kidney failure, hepatic encephalopathy or severe liver failure, and a low blood potassium level.[citation needed]

There is insufficient safety data to recommend indapamide use in pregnancy or breastfeeding.[citation needed]

Adverse effects

[edit]

Commonly reported adverse events are low potassium levels, fatigue, orthostatic hypotension (an exaggerated decrease in blood pressure upon standing, often associated with syncope), and allergic manifestations.

Monitoring the serum levels of potassium and uric acid is recommended, especially in subjects with a predisposition to low levels of potassium in the blood and gout.

Interactions

[edit]

Caution is advised in the combination of indapamide with lithium and drugs causing prolonged QT interval (on EKG) or wave-burst arrhythmia (i.e.: astemizole, bepridil, IV erythromycin, halofantrine, pentamidine, sultopride, terfenadine, and vincamine).

Overdose

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Symptoms of over dosage would be those associated with a diuretic effect (i.e. electrolyte disturbances), low blood pressure, and muscular weakness. Treatment should be symptomatic, directed at correcting electrolyte abnormalities.

See also

[edit]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia
from Grokipedia
Indapamide is a primarily used to treat (high ) and (fluid retention) associated with congestive . It acts on the kidneys to increase the of sodium and , thereby reducing and peripheral while having a minimal impact on , , or rhythm. Chemically, indapamide is described as 4-chloro-N-(2-methyl-1-indolinyl)-3-sulfamoylbenzamide, a white to off-white crystalline powder with a molecular weight of 365.83 and the C16H16ClN3O3S, featuring a polar sulfamoyl chlorobenzamide moiety and a lipid-soluble indoline ring that distinguishes it from traditional diuretics. Approved by the U.S. in 1983 and formerly marketed under the brand name Lozol, indapamide is available in oral tablet form, typically in 1.25 mg and 2.5 mg strengths, and is often prescribed as monotherapy or in combination with other antihypertensives for better control. It is included on the World Health Organization's List of . Its antihypertensive effects are dose-related, with activity occurring at higher doses, and it is noted for its longer duration of action compared to some thiazide-type diuretics, making it suitable for once-daily dosing. Common side effects include , , , and muscle cramps, while serious risks involve imbalances like , particularly with prolonged use. Precautions include monitoring for to sulfonamides, use with caution in patients with severe renal impairment, as the drug may be ineffective and requires close monitoring of renal function, and caution in patients with or due to potential effects on glucose and levels.

Overview and Medical Uses

Therapeutic Indications

Indapamide, a thiazide-like , is primarily indicated for the treatment of , either as monotherapy or in combination with other antihypertensive agents. In monotherapy, it typically reduces systolic by 10-15 mmHg, contributing to effective control in patients with mild to moderate . It is also approved for managing associated with congestive , where it facilitates while exhibiting minimal impact on levels at low doses (e.g., 1.25-2.5 mg daily). Clinical evidence supports indapamide's efficacy in reducing cardiovascular risks, particularly in older adults. The Hypertension in the Very Elderly Trial (HYVET, 2008) demonstrated that indapamide-based therapy (1.5 mg sustained-release, with optional ), targeting below 150/80 mmHg, resulted in a 30% reduction in fatal or nonfatal (hazard ratio 0.70, 95% CI 0.49-1.01), a 64% reduction in events (hazard ratio 0.36, 95% CI 0.22-0.58), and a 21% reduction in all-cause mortality (hazard ratio 0.79, 95% CI 0.65-0.95) among patients aged 80 years and older. In , indapamide enhances outcomes in high-risk populations. The ADVANCE trial (2008) showed that fixed-dose perindopril-indapamide reduced cardiovascular mortality by 18% ( 0.82, 95% CI 0.68-0.98) compared to placebo in patients with , alongside benefits in total mortality and major macrovascular events.61303-8/fulltext) In 2025, the FDA approved the triple combination telmisartan/amlodipine/indapamide (Widaplik) for initial treatment of in adults, offering a convenient option for achieving goals.

Dosage and Administration

Indapamide is administered orally as a single daily dose, typically in the morning to minimize the risk of nocturia. It may be taken with or without food. For hypertension, the recommended starting dose is 1.25 mg once daily; if blood pressure control is inadequate after 4 weeks, the dose may be increased to 2.5 mg once daily, with a maximum of 5 mg once daily. For edema associated with congestive heart failure, the initial dose is 2.5 mg once daily, which may be increased to 5 mg once daily after 1 week if needed. Sustained-release formulations are dosed at 1.5 mg once daily for hypertension. In elderly patients, dosing should start at the lower end of the range, such as 1.25 mg once daily, due to potential age-related declines in renal function. For patients with renal impairment, indapamide should be used cautiously; in those with clearance less than 30 mL/min, the dose should be reduced or the drug avoided due to increased risk of disturbances and reduced efficacy. Monitoring is essential for safe use, including baseline and periodic assessments of serum electrolytes (particularly potassium and sodium), renal function (serum creatinine and electrolytes), and . supplementation is recommended if serum levels fall below 3.5 mEq/L. Pediatric use is not recommended due to insufficient safety and efficacy data, with guidelines from both the FDA and EMA restricting approval to adults.

Pharmacology

Mechanism of Action

Indapamide is classified as an indoline sulfonamide derivative, structurally related to thiazide diuretics but distinguished by its indoline ring, which replaces the benzothiadiazine moiety and confers greater lipid solubility. This enhanced lipophilicity allows better penetration into vascular tissues, contributing to its pharmacological profile. As a thiazide-like diuretic, indapamide primarily exerts its effects in the proximal segment of the distal convoluted tubule of the nephron, where it inhibits the Na⁺/Cl⁻ cotransporter. This inhibition blocks the reabsorption of sodium and chloride ions, promoting their excretion along with water, which reduces extracellular fluid volume, venous return, and cardiac output, thereby lowering blood pressure. Compared to traditional thiazides, indapamide demonstrates a milder impact on potassium excretion at antihypertensive doses, resulting in less pronounced hypokalemia due to its lower diuretic potency and structural differences that limit distal tubular effects on potassium handling. Beyond its diuretic action, indapamide exhibits antihypertensive effects through direct vascular mechanisms, particularly at low doses such as 1.5 mg daily, where the reduction occurs independently of significant . These effects involve and a decrease in total peripheral resistance by approximately 15%, achieved via reduced calcium influx in vascular cells and enhanced synthesis of vasodilatory prostaglandins like PGE₁. This dual mechanism—diuretic and antivasoconstrictor—underlies its efficacy in reducing vascular reactivity to pressor agents such as norepinephrine and angiotensin II. Through lowering and potential direct vascular protection, indapamide contributes to reduced risks of and cardiovascular events, with evidence suggesting benefits beyond alone, such as attenuation of hypertensive target-organ damage.

Indapamide exhibits rapid oral absorption, achieving peak plasma concentrations within 1 to 2 hours post-administration, with approaching 100% that remains unaffected by food intake or antacids. Following absorption, indapamide is approximately 71% to 79% bound to plasma proteins, primarily alpha-1-acid , and demonstrates a of approximately 60 L, indicating moderate tissue penetration. The drug preferentially accumulates in erythrocytes and vascular tissues due to its , with a whole blood-to-plasma ratio of about 6:1 at peak levels, declining to 3.5:1 after 8 hours. Indapamide crosses the placental barrier, as is typical for thiazide-like diuretics, though specific placental transfer data are limited; its excretion into is not well-characterized, with no reliable quantitative information available on milk concentrations. Metabolism occurs extensively in the liver, primarily through enzymes including CYP2C8, , , and , yielding conjugates and other hydroxylated or dehydrogenated metabolites, none of which are pharmacologically active. Approximately 93% of the dose undergoes hepatic transformation, with only 5% to 7% excreted unchanged. Elimination is biphasic, with a terminal of 14 to 24 hours in , facilitating once-daily dosing. About 70% of the administered dose is recovered in (primarily as metabolites) and 23% in via biliary , with renal clearance of unchanged drug being low at approximately 5 mL/min. The may be prolonged in renal or hepatic impairment, though no significant accumulation occurs in renal insufficiency, and no dose adjustment is required for mild hepatic disease, albeit with cautious use to avoid precipitating . Steady-state concentrations are typically attained within 3 to 4 days of repeated dosing.

Safety Profile

Adverse Effects

Indapamide, like other thiazide-like s, is associated with a range of adverse effects, primarily related to its diuretic action and disturbances. Common side effects, occurring in more than 1% of patients, include , which manifests in a dose-dependent manner, with clinical signs or symptoms occurring in 2% of patients at 1.25 mg, 3% at 2.5 mg, and 7% at 5 mg daily. Other frequent effects encompass fatigue, dizziness, headache, muscle cramps, and , often linked to volume depletion and shifts. These symptoms typically resolve with dose adjustment or supportive measures, such as potassium supplementation. Serious adverse effects are less common, affecting fewer than 1% of patients, but require prompt monitoring. can occur, particularly in elderly females, and may lead to confusion or seizures if severe. may elevate serum levels, potentially triggering flares in susceptible individuals. Allergic reactions, including rash and rare , are more likely in patients with sulfonamide sensitivity due to indapamide's . Additionally, prolongation has been reported, often secondary to or hyponatremia. Long-term use of indapamide may contribute to increased glucose intolerance and , with small but significant elevations in HbA1c and lipid profiles observed in some studies; patients with should undergo regular monitoring. Post-marketing surveillance indicates , predominantly among the elderly, which is generally reversible upon discontinuation or fluid repletion. Regarding use in special populations, limited human data exist for ; animal reproduction studies show no adverse effects, but use only if clearly needed due to potential risks such as rare reports of in newborns. It is recommended to avoid during due to potential reduction in milk production. monitoring is essential to mitigate these risks, particularly in vulnerable patients.

Contraindications

Indapamide is contraindicated in patients with known to the drug or other sulfonamide-derived medications, as this can lead to severe allergic reactions such as or . It is also absolutely prohibited in cases of , where the absence of production prevents the drug's elimination and increases toxicity risk. Similarly, severe hepatic impairment accompanied by is contraindicated, as indapamide may precipitate hepatic coma through alterations in fluid and electrolyte balance. Relative contraindications include a history of , where indapamide can elevate serum levels and trigger acute flares. In patients with , the drug may impair glucose tolerance or unmask latent , necessitating careful monitoring of blood sugar. Use in severe renal impairment ( clearance below 30 mL/min) requires caution due to risks of and disturbances, with close monitoring recommended; it is contraindicated in some jurisdictions. Existing requires correction prior to use and ongoing monitoring, as the drug may further deplete levels and exacerbate cardiac arrhythmias. Breastfeeding is relatively contraindicated, as indapamide may be excreted in human and could pose risks to the or reduce production. Special precautions apply to elderly patients, who face a higher risk of and , particularly women, requiring lower starting doses and frequent monitoring. Concurrent use with is cautioned, as indapamide can reduce lithium renal clearance, thereby increasing the risk of . Indapamide carries no specific black-box warnings from the FDA, though the agency emphasizes the potential for serious imbalances, including , which can lead to life-threatening arrhythmias in at-risk patients.

Clinical Considerations

Drug Interactions

Indapamide, a thiazide-like , can interact with various medications, potentially altering its efficacy, increasing toxicity risks, or exacerbating electrolyte imbalances such as or . These interactions are primarily due to indapamide's effects on renal sodium , levels, and regulation. Clinicians should monitor patients closely when indapamide is co-administered with other agents, adjusting doses as needed based on individual response and laboratory parameters.

Major Interactions

Concurrent use of indapamide with increases the risk of , as indapamide reduces lithium's renal clearance through and enhanced excretion. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and naproxen, may attenuate indapamide's and antihypertensive effects by inhibiting synthesis and renal blood flow. Corticosteroids and glycosides (e.g., ) can worsen induced by indapamide, potentially leading to cardiac arrhythmias; supplementation or monitoring is recommended.

Moderate Interactions

Indapamide combined with other antihypertensives, such as ACE inhibitors (e.g., ) or (e.g., amlodipine), may cause additive , necessitating surveillance. Antidiabetic agents, including insulin and oral hypoglycemics, may experience impaired glucose control due to indapamide's potential to elevate blood glucose levels. Cholestyramine and similar bile acid sequestrants can decrease indapamide absorption by binding in the , so indapamide should be taken at least one hour before or four hours after these agents. QT-prolonging drugs like increase the risk of when used with indapamide, which itself can prolong the ; electrocardiographic monitoring is advised. Alcohol consumption may enhance indapamide-induced , leading to or fainting. Indapamide has no significant interactions with foods, though high-salt diets can antagonize its antihypertensive effects by counteracting natriuresis. Regarding cytochrome P450 enzymes, indapamide undergoes minimal metabolism via CYP3A4, but strong inducers like rifampin may slightly reduce its plasma levels, potentially diminishing efficacy.

Overdose Management

Overdose of indapamide, a thiazide-like diuretic, primarily results in exaggerated pharmacological effects due to its natriuretic, kaliuretic, and vasodilatory actions, leading to symptoms such as nausea, vomiting, weakness, gastrointestinal disturbances, and electrolyte imbalances including hypokalemia and hyponatremia. Additional manifestations may include hypotension, drowsiness, dizziness, muscle cramps, dry mouth, and excessive thirst, with severe cases potentially involving confusion, fainting, heart rhythm abnormalities, or seizures secondary to profound electrolyte derangements. Acute overdose can induce excessive , resulting in and volume depletion, though no specific exists for indapamide . is typically clinical, based on of and presenting symptoms, supported by of serum electrolytes, renal function, and to detect arrhythmias from . Management is entirely supportive, focusing on gastrointestinal decontamination if occurred within 1-2 hours (e.g., activated charcoal), followed by intravenous fluid resuscitation with normal saline to correct and . imbalances require prompt correction, such as intravenous potassium supplementation if serum levels fall below 3.0 mEq/L, alongside monitoring for cardiac arrhythmias via continuous ECG. For refractory , vasopressors like or norepinephrine may be administered, while respiratory support (e.g., oxygen or ) is provided if needed for severe drowsiness or seizures. In cases exacerbated by drug interactions, such as those potentiating , additional monitoring for arrhythmogenic risks is essential. Hemodialysis is ineffective for indapamide removal due to its high protein binding (approximately 75-80%) and is not recommended in overdose . With timely supportive care, is generally favorable, as serious complications and fatalities are rare, though effects such as and disturbances may persist up to 3 days; poorer outcomes are more likely in patients with comorbidities like renal impairment or heart disease.

History and Development

Discovery and Synthesis

Indapamide was synthesized in 1969 by Servier Laboratories in as part of a sulfonamide research program focused on developing antihypertensive agents with reduced diuretic side effects compared to existing diuretics. The compound, a non-thiazide derivative featuring an indoline ring, was patented in 1968 and designed to enhance lipid solubility—5 to 80 times greater than thiazides—while promoting vascular effects beyond simple . Early studies in the highlighted the dissociation of indapamide's and antihypertensive actions, allowing effective reduction at low doses (e.g., 2.5 mg daily) with limited disturbances. Preclinical investigations in animal models, including rats and dogs, demonstrated that indapamide primarily induced (2- to 3-fold increase in sodium at 1 mg/kg doses) with minimal kaliuresis (1.2-fold increase in ), supporting its profile for management without substantial loss. Initial human trials for commenced in 1973, involving European investigators who reported satisfactory control in over half of treated patients across multiple studies.

Regulatory Approvals and Milestones

Indapamide received its initial regulatory approval for medical use in in 1977, marketed by Servier Laboratories under the brand name Natrilix for the treatment of . This marked the drug's introduction as a thiazide-like with antihypertensive properties, establishing its early clinical role in . Subsequent approvals followed in other regions, reflecting growing recognition of its efficacy in management. In the United States, the (FDA) approved indapamide in 1983 under the brand name Lozol specifically for , either as monotherapy or in combination with other agents. The drug was later added to the World Health Organization's Model List of Essential Medicines in 2021, listed as a square box item and therapeutic equivalent to hydrochlorothiazide for , underscoring its global importance for accessible cardiovascular care. Key clinical milestones bolstered indapamide's regulatory and therapeutic standing. The Nordic Diltiazem (NORDIL) trial, published in 2000, demonstrated that antihypertensive regimens based on diuretics—compared against —effectively reduced the combined endpoint of , , and cardiovascular death, with particular emphasis on prevention in hypertensive patients. More recently, in June 2025, the FDA approved WIDAPLIK, a fixed-dose triple combination of indapamide with telmisartan and amlodipine, for treating in adults, including as initial for those with uncontrolled , addressing adherence challenges in multidrug regimens. Indapamide's integration into major clinical guidelines highlights its evolving role. The UK's National Institute for Health and Care Excellence () recommends it as a first-line thiazide-like for in adults, typically at 2.5 mg daily. The () guidelines endorse indapamide among preferred diuretics for initial and in elevated management. In the United States, the Eighth Joint National Committee (JNC 8) guidelines classify thiazide-type diuretics like indapamide as first-line options for uncomplicated , positioning them as effective alternatives to traditional thiazides such as hydrochlorothiazide due to comparable or superior outcomes in reduction and cardiovascular risk mitigation. Generic formulations became widely available in the 1990s following expirations, facilitating broader access and contributing to peak global sales in the 2000s as treatment expanded worldwide.

Chemistry and Society

Chemical Properties

Indapamide has the molecular formula C16H16ClN3O3S and a molar mass of 365.83 g/mol. Its chemical structure is described as 4-chloro-N-(2-methyl-2,3-dihydro-1H-indol-1-yl)-3-sulfamoylbenzamide, featuring a sulfonamide group attached to a benzamide core linked to an indoline ring. This compound appears as a white to off-white crystalline powder. Indapamide exhibits low aqueous , practically insoluble in (less than 0.1 mg/mL), while it is soluble in . The compound is a weak with a pKa of 8.8 for the group and possesses moderate , indicated by a logP value of 2.5. It demonstrates stability at and under thermal and photolytic conditions, though it is sensitive to acidic, basic, and oxidative environments. Common pharmaceutical formulations of indapamide include immediate-release tablets available in 1.25 mg and 2.5 mg strengths, as well as a sustained-release tablet in 1.5 mg for once-daily administration. An overview of its synthesis involves the condensation of 4-chloro-3-sulfamoylbenzoic acid with 2-methyl-2,3-dihydro-1H-indole. Indapamide is marketed under several brand names globally, including Natrilix by Servier Laboratories in many countries and Lozol in the United States. Following the expiration of its original patents in the 1990s, generic versions of indapamide have become widely available from multiple manufacturers, enhancing accessibility and reducing costs. As a prescription-only worldwide, indapamide requires a physician's authorization for purchase and use. In , it is classified under , mandating sale only with a prescription from a registered medical practitioner. In the , it holds POM (Prescription Only Medicine) status, while in the and the , it is similarly restricted to Rx-only dispensing. Indapamide is accessible in over 100 countries through both branded and generic formulations. It is included on the World Health Organization's Model List of , with prequalified generic versions recommended for low- and middle-income settings to support management. In September 2025, the WHO added triple fixed-dose combinations for , including telmisartan/amlodipine/indapamide, to the Model List of to improve treatment access. The fixed-dose combination of and indapamide, marketed as Coversyl Plus, has been approved in the for treating . Generic indapamide typically costs $0.10 to $0.50 per dose, making it an affordable option in most markets. In the United States, newer combination therapies incorporating indapamide, such as the recently approved WIDAPLIK (telmisartan/amlodipine/indapamide), are projected to range from $50 to $100 per month, though final pricing details are forthcoming. No major controversies surround indapamide's availability, though intermittent supply shortages have occurred in the 2020s due to manufacturing constraints, affecting regions including , , and the .

References

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