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Chlorthalidone

Pronunciation

Pronunciation

(klor THAL i done)

Index Terms

  • Hygroton

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Generic: 25 mg, 50 mg, 100 mg

Pharmacologic Category

  • Antihypertensive
  • Diuretic, Thiazide-Related

Pharmacology

Sulfonamide-derived diuretic that inhibits sodium and chloride reabsorption in the cortical-diluting segment of the ascending loop of Henle

Distribution

0.14 L/kg; sequesters in erythrocytes

Metabolism

Hepatic

Excretion

Urine (~50% to 65% as unchanged drug)

Onset of Action

Diuresis: Peak effect: 2-6 hours

Time to Peak

Serum: 13.8 hours

Duration of Action

Diuresis: 24-72 hours

Half-Life Elimination

40-60 hours; may be prolonged with renal impairment; Anuria: 81 hours

Use: Labeled Indications

Management of mild-to-moderate hypertension when used alone or in combination with other agents; treatment of edema associated with heart failure, renal dysfunction, hepatic cirrhosis, or corticosteroid and estrogen therapy.

Guideline recommendations:

Hypertension: The 2014 guideline for the management of high blood pressure in adults (Eighth Joint National Committee [JNC 8]) recommends initiation of pharmacologic treatment to lower blood pressure for the following patients:

• Patients ≥60 years of age with systolic blood pressure (SBP) ≥150 mm Hg or diastolic blood pressure (DBP) ≥90 mm Hg. Goal of therapy is SBP <150 mm Hg and DBP <90 mm Hg.

• Patients <60 years of age with SBP ≥140 mm Hg or DBP is ≥90 mm Hg. Goal of therapy is SBP <140 mm Hg and DBP <90 mm Hg.

• Patients ≥18 years of age with diabetes and SBP ≥140 mm Hg or DBP ≥90 mm Hg. Goal of therapy is SBP <140 mm Hg and DBP <90 mm Hg.

• Patients ≥18 years of age with chronic kidney disease (CKD) and SBP ≥140 mm Hg or DBP ≥90 mm Hg. Goal of therapy is SBP <140 mm Hg and DBP <90 mm Hg.

Chronic kidney disease (CKD) and hypertension: In patients with CKD, regardless of race or diabetes status, the use of an ACE inhibitor (ACEI) or angiotensin receptor blocker (ARB) as initial therapy is recommended to improve kidney outcomes. In the general nonblack population (without CKD) including those with diabetes, initial antihypertensive treatment should consist of a thiazide-type diuretic, calcium channel blocker, ACEI, or ARB. In the general black population (without CKD), including those with diabetes, initial antihypertensive treatment should consist of a thiazide-type diuretic or a calcium channel blocker instead of an ACEI or ARB.

Coronary artery disease (CAD) and hypertension: The American Heart Association, American College of Cardiology and American Society of Hypertension (AHA/ACC/ASH) 2015 scientific statement for the treatment of hypertension in patients with coronary artery disease (CAD) recommends the use of a thiazide (or thiazide-like diuretic) as part of a regimen in patients with hypertension and chronic stable angina. A BP target of <140/90 mm Hg is reasonable for the secondary prevention of cardiovascular events. A lower target BP (<130/80 mm Hg) may be appropriate in some individuals with CAD, previous MI, stroke or transient ischemic attack, or CAD risk equivalents (AHA/ACC/ASH [Rosendorff 2015]).

Use: Unlabeled

Calcium nephrolithiasis: Prevention of recurrent calcium renal stones

Contraindications

Hypersensitivity to chlorthalidone, other sulfonamide-derived drugs, or any component of the formulation; anuria

Note: Although the FDA approved product labeling states this medication is contraindicated with other sulfonamide-containing drug classes, the scientific basis of this statement has been challenged. See “Warnings/Precautions” for more detail.

Dosing: Adult

Edema: Initial: 50 to 100 mg once daily or 100 mg on alternate days; maximum dose: 200 mg daily

Heart failure-associated edema: Initial: 12.5 to 25 mg once daily; maximum daily dose: 100 mg (ACCF/AHA [Yancy 2013])

Hypertension: Oral: Initial: 25 mg once daily or 12.5 mg once daily (JNC 8 [James, 2013]); may increase after a suitable trial to 50 mg once daily; maximum: 100 mg daily; usual dosage range (ASH/ISH [Weber, 2014]): 12.5 to 25 mg daily. Target dose range (JNC 8 [James, 2013]): 12.5 to 25 mg daily.

Calcium nephrolithiasis (off-label use): 25 mg once daily (AUA Guidelines [Pearle, 2014])

Dosing: Geriatric

Oral: Initial: 12.5 to 25 mg once daily or every other day; there is little advantage to using doses >25 mg daily.

Dosing: Pediatric

Hypertension (off-label use): Children and Adolescents: Oral: Initial: 0.3 mg/kg once daily, up to 2 mg/kg/day; maximum: 50 mg daily (NHBPEP, 2004; NHLBI, 2011)

Dosing: Renal Impairment

CrCl ≥10 mL/minute: No dosage adjustment necessary (Aronoff, 2007)

CrCl <10 mL/minute: Avoid use. Ineffective with low GFR (Aronoff, 2007)

Dosing: Hepatic Impairment

There are no dosage adjustments provided in manufacturer’s labeling; use with caution.

Dietary Considerations

This product may cause a potassium loss; your healthcare provider may prescribe a potassium supplement, another medication to help prevent the potassium loss, or recommend that you eat foods high in potassium, especially citrus fruits; do not change your diet on your own while taking this medication, especially if you are taking potassium supplements or medications to reduce potassium loss; too much potassium can be as harmful as too little.

Storage

Store at 20°C to 25°C (68°F to 77°F). Protect from light.

Drug Interactions

ACE Inhibitors: Thiazide and Thiazide-Like Diuretics may enhance the hypotensive effect of ACE Inhibitors. Thiazide and Thiazide-Like Diuretics may enhance the nephrotoxic effect of ACE Inhibitors. Monitor therapy

Alcohol (Ethyl): May enhance the orthostatic hypotensive effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Alfuzosin: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Allopurinol: Thiazide and Thiazide-Like Diuretics may enhance the potential for allergic or hypersensitivity reactions to Allopurinol. Thiazide and Thiazide-Like Diuretics may increase the serum concentration of Allopurinol. Specifically, Thiazide Diuretics may increase the concentration of Oxypurinol, an active metabolite of Allopurinol. Monitor therapy

Amifostine: Blood Pressure Lowering Agents may enhance the hypotensive effect of Amifostine. Management: When amifostine is used at chemotherapy doses, blood pressure lowering medications should be withheld for 24 hours prior to amifostine administration. If blood pressure lowering therapy cannot be withheld, amifostine should not be administered. Consider therapy modification

Amphetamines: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Analgesics (Opioid): May enhance the adverse/toxic effect of Diuretics. Monitor therapy

Anticholinergic Agents: May increase the serum concentration of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Antidiabetic Agents: Thiazide and Thiazide-Like Diuretics may diminish the therapeutic effect of Antidiabetic Agents. Monitor therapy

Antidiabetic Agents: Hyperglycemia-Associated Agents may diminish the therapeutic effect of Antidiabetic Agents. Monitor therapy

Antipsychotic Agents (Second Generation [Atypical]): Blood Pressure Lowering Agents may enhance the hypotensive effect of Antipsychotic Agents (Second Generation [Atypical]). Monitor therapy

Barbiturates: May enhance the orthostatic hypotensive effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Barbiturates: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Beta2-Agonists: May enhance the hypokalemic effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Bile Acid Sequestrants: May decrease the absorption of Thiazide and Thiazide-Like Diuretics. The diuretic response is likewise decreased. Consider therapy modification

Brimonidine (Topical): May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Calcium Salts: Thiazide and Thiazide-Like Diuretics may decrease the excretion of Calcium Salts. Continued concomitant use can also result in metabolic alkalosis. Monitor therapy

CarBAMazepine: Thiazide and Thiazide-Like Diuretics may enhance the adverse/toxic effect of CarBAMazepine. Specifically, there may be an increased risk for hyponatremia. Monitor therapy

Cardiac Glycosides: Thiazide and Thiazide-Like Diuretics may enhance the adverse/toxic effect of Cardiac Glycosides. Specifically, cardiac glycoside toxicity may be enhanced by the hypokalemic and hypomagnesemic effect of thiazide diuretics. Monitor therapy

Corticosteroids (Orally Inhaled): May enhance the hypokalemic effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Corticosteroids (Systemic): May enhance the hypokalemic effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Cyclophosphamide: Thiazide and Thiazide-Like Diuretics may enhance the adverse/toxic effect of Cyclophosphamide. Specifically, granulocytopenia may be enhanced. Monitor therapy

Dexketoprofen: May enhance the adverse/toxic effect of Sulfonamides. Monitor therapy

Diazoxide: Thiazide and Thiazide-Like Diuretics may enhance the adverse/toxic effect of Diazoxide. Monitor therapy

Diazoxide: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Dofetilide: Thiazide and Thiazide-Like Diuretics may enhance the QTc-prolonging effect of Dofetilide. Thiazide and Thiazide-Like Diuretics may increase the serum concentration of Dofetilide. Avoid combination

DULoxetine: Blood Pressure Lowering Agents may enhance the hypotensive effect of DULoxetine. Monitor therapy

Herbs (Hypertensive Properties): May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Herbs (Hypotensive Properties): May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Hypotension-Associated Agents: Blood Pressure Lowering Agents may enhance the hypotensive effect of Hypotension-Associated Agents. Monitor therapy

Ivabradine: Thiazide and Thiazide-Like Diuretics may enhance the arrhythmogenic effect of Ivabradine. Monitor therapy

Levodopa: Blood Pressure Lowering Agents may enhance the hypotensive effect of Levodopa. Monitor therapy

Levosulpiride: Thiazide and Thiazide-Like Diuretics may enhance the adverse/toxic effect of Levosulpiride. Avoid combination

Licorice: May enhance the hypokalemic effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Lithium: Thiazide and Thiazide-Like Diuretics may decrease the excretion of Lithium. Consider therapy modification

Mecamylamine: Sulfonamides may enhance the adverse/toxic effect of Mecamylamine. Avoid combination

Methylphenidate: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Molsidomine: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Multivitamins/Fluoride (with ADE): May enhance the hypercalcemic effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Multivitamins/Minerals (with ADEK, Folate, Iron): Thiazide and Thiazide-Like Diuretics may enhance the hypercalcemic effect of Multivitamins/Minerals (with ADEK, Folate, Iron). Monitor therapy

Multivitamins/Minerals (with AE, No Iron): Thiazide and Thiazide-Like Diuretics may increase the serum concentration of Multivitamins/Minerals (with AE, No Iron). Specifically, thiazide diuretics may decrease the excretion of calcium, and continued concomitant use can also result in metabolic alkalosis. Monitor therapy

Nicorandil: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Nonsteroidal Anti-Inflammatory Agents: Thiazide and Thiazide-Like Diuretics may enhance the nephrotoxic effect of Nonsteroidal Anti-Inflammatory Agents. Nonsteroidal Anti-Inflammatory Agents may diminish the therapeutic effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Obinutuzumab: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Management: Consider temporarily withholding blood pressure lowering medications beginning 12 hours prior to obinutuzumab infusion and continuing until 1 hour after the end of the infusion. Consider therapy modification

OXcarbazepine: Thiazide and Thiazide-Like Diuretics may enhance the adverse/toxic effect of OXcarbazepine. Specifically, there may be an increased risk for hyponatremia. Monitor therapy

Pentoxifylline: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Phosphodiesterase 5 Inhibitors: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Porfimer: Photosensitizing Agents may enhance the photosensitizing effect of Porfimer. Monitor therapy

Prostacyclin Analogues: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Reboxetine: May enhance the hypokalemic effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Selective Serotonin Reuptake Inhibitors: May enhance the hyponatremic effect of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Sodium Phosphates: Diuretics may enhance the nephrotoxic effect of Sodium Phosphates. Specifically, the risk of acute phosphate nephropathy may be enhanced. Management: Consider avoiding this combination by temporarily suspending treatment with diuretics, or seeking alternatives to oral sodium phosphate bowel preparation. If the combination cannot be avoided, hydrate adequately and monitor fluid and renal status. Consider therapy modification

Topiramate: Thiazide and Thiazide-Like Diuretics may enhance the hypokalemic effect of Topiramate. Thiazide and Thiazide-Like Diuretics may increase the serum concentration of Topiramate. Management: Monitor for increased topiramate levels/adverse effects (e.g., hypokalemia) with initiation/dose increase of a thiazide diuretic. Closely monitor serum potassium concentrations with concomitant therapy. Topiramate dose reductions may be necessary. Consider therapy modification

Toremifene: Thiazide and Thiazide-Like Diuretics may enhance the hypercalcemic effect of Toremifene. Monitor therapy

Verteporfin: Photosensitizing Agents may enhance the photosensitizing effect of Verteporfin. Monitor therapy

Vitamin D Analogs: Thiazide and Thiazide-Like Diuretics may enhance the hypercalcemic effect of Vitamin D Analogs. Monitor therapy

Yohimbine: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Adverse Reactions

Frequency not defined.

Dermatologic: Skin photosensitivity

Endocrine & metabolic: Hypokalemia

Gastrointestinal: Anorexia, dyspepsia

<1% (Limited to important or life-threatening): Agranulocytosis, aplastic anemia, cholecystitis, diabetes mellitus, gout, hypercalcemia, hyperglycemia, hypersensitivity reaction, hypochloremic alkalosis, hyponatremia, leukopenia, necrotizing angiitis, orthostatic hypotension, pancreatitis, renal insufficiency, thrombocytopenia, toxic epidermal necrolysis, vasculitis, xanthopsia

Warnings/Precautions

Concerns related to adverse effects:

• Electrolyte disturbances: Hypokalemia, hypochloremic alkalosis, and hyponatremia can occur.

• Photosensitivity: Photosensitization may occur.

• Sulfonamide (“sulfa”) allergy: The FDA-approved product labeling for many medications containing a sulfonamide chemical group includes a broad contraindication in patients with a prior allergic reaction to sulfonamides. There is a potential for cross-reactivity between members of a specific class (eg, two antibiotic sulfonamides). However, concerns for cross-reactivity have previously extended to all compounds containing the sulfonamide structure (SO2NH2). An expanded understanding of allergic mechanisms indicates cross-reactivity between antibiotic sulfonamides and nonantibiotic sulfonamides may not occur or at the very least this potential is extremely low (Brackett 2004; Johnson 2005; Slatore 2004; Tornero 2004). In particular, mechanisms of cross-reaction due to antibody production (anaphylaxis) are unlikely to occur with nonantibiotic sulfonamides. T-cell-mediated (type IV) reactions (eg, maculopapular rash) are less well understood and it is not possible to completely exclude this potential based on current insights. In cases where prior reactions were severe (Stevens-Johnson syndrome/TEN), some clinicians choose to avoid exposure to these classes.

Disease-related concerns:

• Asthma: Use with caution in patients with a history of bronchial asthma; hypersensitivity reactions may occur more readily.

• Diabetes: Use with caution in patients with prediabetes or diabetes mellitus; may see a change in glucose control.

• Gout: In certain patients with a history of gout, a familial predisposition to gout, or chronic renal failure, gout can be precipitated.

• Hepatic impairment: Use with caution in patients with severe hepatic dysfunction; in cirrhosis, avoid electrolyte and acid/base imbalances that might lead to hepatic encephalopathy.

• Hypercalcemia: Thiazide diuretics may decrease renal calcium excretion; consider avoiding use in patients with hypercalcemia.

• Hypercholesterolemia: Use with caution in patients with moderate or high cholesterol concentrations.

• Hypokalemia: Use with caution in patients with hypokalemia; correct before initiating therapy.

• Renal impairment: Avoid in severe renal disease (ineffective).

• Systemic lupus erythematosus (SLE): Can cause SLE exacerbation or activation.

Monitoring Parameters

Assess weight, I & O records daily to determine fluid loss; blood pressure, serum electrolytes, renal function

Pregnancy Risk Factor

B

Pregnancy Considerations

Adverse events were not observed in animal reproduction studies. Chlorthalidone crosses the placenta and can be detected in cord blood. Maternal use may cause fetal or neonatal jaundice, thrombocytopenia, or other adverse events observed in adults. Use of thiazide diuretics to treat edema during normal pregnancies is not appropriate; use may be considered when edema is due to pathologic causes (as in the nonpregnant patient); monitor. Untreated chronic maternal hypertension is associated with adverse events in the fetus, infant, and mother. Women who require thiazide diuretics for the treatment of hypertension prior to pregnancy may continue their use (ACOG, 2013).

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience constipation, headache, lack of appetite, nausea, vomiting, or diarrhea. Have patient report immediately to prescriber signs of fluid and electrolyte problems (mood changes, confusion, muscle pain or weakness, abnormal heartbeat, very bad dizziness or passing out, fast heartbeat, more thirst, seizures, feeling very tired or weak, not hungry, unable to pass urine or change in the amount of urine produced, dry mouth, dry eyes, or nausea or vomiting), signs of kidney problems (urinary retention, blood in urine, change in amount of urine passed, or weight gain), signs of pancreatitis (severe abdominal pain, severe back pain, severe nausea, or vomiting), severe dizziness, passing out, sexual dysfunction, agitation, jaundice, chills, pharyngitis, bruising, bleeding, or severe loss of strength and energy (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for healthcare professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience and judgment in diagnosing, treating and advising patients.

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