Chlorthalidone

Chlorthalidone is an antihypertensive agent belonging to Thiazide Diuretics.

Chlorthalidone is a thiazide diuretic used to treat high blood pressure, edema, and heart failure. Chlorthalidone may be used alone or with other medications.

The bioavailability of Chlorthalidone is about 65%. After administration of oral Chlorthalidone, the onset of action takes place at 2-6 hours. Peak plasma time was found to be around 1.5-6 hours. In blood, approximately 75 percent of the drug is bound to plasma proteins over a concentration range of 0.2 to 7.7 ug/mL. The mean plasma half-life of chlorthalidone is about 40-60 hours and is metabolized in the liver. It is eliminated primarily as an unchanged drug in the urine.

Chlorthalidone shows common side effects Hypotension, Diarrhea, loss of appetite, Nausea, dizziness, headache, etc.

Chlorthalidone is available in the form of Oral Tablets.

Chlorthalidone is available in India, the US, Europe, the UK, Canada, and Singapore.

Chlorthalidone belonging to the Thiazide Diuretics acts as an antihypertensive agent.

The diuretic effects of chlorthalidone and benzothiadiazine (thiazide) diuretics appear to arise from similar mechanisms, and the maximal effect of chlorthalidone and thiazides appear to be similar. The site of action appears to be the distal convoluted tubule of the nephron. Although the mechanism of action of chlorthalidone and related drugs is not wholly clear, sodium and water depletion appear to provide a basis for its antihypertensive effect.

The onset of action of Chlorthalidone occurs within 2-6 hours of its administration.

The Duration of Action for Chlorthalidone in the body is approximately 24-72 hours.

The Tmax was found within 1.5-6 hours and Cmax 3200 to 7900 ng/mL following the administration of Chlorthalidone.

Chlorthalidone comes as an Oral Tablet taken by mouth. It is usually taken once daily or on alternate days.

Chlorthalidone is a thiazide diuretic used for the treatment of high blood pressure, edema, and heart failure. Chlorthalidone may be used alone or with other medications. Chlorthalidone may also be used to treat patients having diabetes insipidus and electrolyte disturbances and to prevent kidney stones in patients with high calcium levels in their blood.

Chlorthalidone is an antihypertensive agent belonging to Thiazide Diuretics.

The site of the action appears to be the distal convoluted tubule of the nephron. Although the mechanism of action of chlorthalidone and related drugs is not exactly clear, sodium and water depletion appear to provide a basis for its anti-hypertensive effect. Chlorthalidone is a diuretic used to treat high blood pressure, edema, and heart failure. Chlorthalidone may be used alone or with other medications.

Chlorthalidone is approved for use in the following clinical indications

• Edema

Chlorthalidone is indicated in adults as adjunctive therapy in edema associated with heart failure, cirrhosis of the liver, and renal disease, including nephrotic syndrome.

• Hypertension

Chlorthalidone is indicated for the treatment of hypertension to lower blood pressure. Lowering blood pressure decreases the risk of fatal and nonfatal cardiovascular events like strokes and myocardial infarctions. These benefits have been seen in controlled trials of antihypertensive drugs from various pharmacologic classes, including the class to which this drug principally belongs. There are no controlled trials demonstrating the risk reduction with Chlorthalidone.

• Edema

The recommended initial dosage is 50 to 100 mg daily or 100 mg on alternate days. Depending on the response, the dosage can be decreased or increased up to a maximum of 200 mg daily.

• Hypertension

The initial recommended dose is 15 mg once daily with food. After two weeks, the dosage may be increased to a single daily dose of 25 mg if additional blood pressure reduction is needed. Doses above 25 mg are not expected to result in increased blood pressure reduction.

Chlorthalidone is available in various strengths as 15mg, 25mg, 50mg and 100mg.

Chlorthalidone is available in the form of Oral Tablets.

Avoid consumption of a high-salt or high-sodium diet while taking Chlorothiazide.

Chlorthalidone is contraindicated in patients with

• Anuria
• Hypersensitivity to chlorthalidone or other sulfonamide-derived drugs.

• Hypotension

Chlorthalidone may cause symptomatic hypotension. Patients with an impaired sympathetic response, volume depletion, or who are salt restricted may be at increased risk for developing hypotension.

If hypotension occurs, place the patient in the supine position and, if necessary, give normal intravenous saline. The transient hypotensive response is not a contraindication to further treatment, which usually can be continued without difficulty once the blood pressure has stabilized.

• Impaired Renal Function

Changes in renal function, including acute renal failure, can be caused by diuretics. Patients with chronic kidney disease, heart failure, or volume depletion may be at particular risk of developing acute renal failure on CHLORTHALIDONE. Monitor renal function periodically. Consider withholding or discontinuing therapy in patients who develop a clinically significant decrease in renal function on CHLORTHALIDONE.

• Electrolyte Abnormalities

Chlorthalidone can cause hypokalemia, hyponatremia, hypochloremic alkalosis, and hypomagnesemia. Hypomagnesemia can result in hypokalemia which appears difficult to treat despite potassium repletion. Monitor serum electrolytes periodically.

If hypokalemia is accompanied by clinical signs (e.g., muscular weakness, paresis, or ECG alterations), Chlorthalidone should be discontinued. Correction of hypokalemia and any coexisting hypomagnesemia is recommended prior to the initiation of thiazides.

• Metabolic Disturbances

Chlorthalidone may alter glucose tolerance. Chlorthalidone may raise serum levels of cholesterol and triglycerides. Chlorthalidone may raise the serum uric acid level due to reduced clearance of uric acid and may cause or exacerbate hyperuricemia and precipitate gout in susceptible patients. Chlorthalidone decreases urinary calcium excretion and may cause elevations of serum calcium. Monitor calcium levels in patients with hypercalcemia receiving Chlorthalidone.

Consumption of alcohol is not recommended during treatment with Chlorthalidone due to the increased risk of dizziness, fainting, and very low blood pressure.

Thiazides are excreted in human milk. Because of the potential for serious adverse reactions in nursing infants from chlorthalidone, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.

Chlorthalidone should not be used as first-line therapy to treat hypertension in pregnancy. Advise pregnant women of the potential risk to a fetus. Thiazides cross the placental barrier and appear in cord blood. The use of chlorthalidone and related drugs in pregnant women requires that the anticipated benefits of the drug be weighed against possible hazards to the fetus. These hazards include fetal or neonatal jaundice, thrombocytopenia, and possibly other adverse reactions that have occurred in the adult.

Avoid consumption of a high-salt or high-sodium diet while taking Chlorothiazide.

Common Adverse effects

• Hypotension, vasculitis, Photosensitivity, phototoxicity, Electrolyte abnormalities, hyperglycemia, hyperuricemia, Constipation, diarrhea, loss of appetite, nausea, vomiting, Spasticity, Dizziness, headache, paresthesia, Blurred vision, xanthopsia, Restlessness, Impotence.

Rare Adverse effects

• Cardiac dysrhythmia, Scaling eczema, Stevens-Johnson syndrome, toxic epidermal necrolysis, Pancreatitis, Disorder of hematopoietic structure, Hepatotoxicity, Systemic lupus erythematosus, Pulmonary edema.

• Antihypertensive drugs

Chlorthalidone may add to or potentiate the action of other antihypertensive drugs. Insulin requirements in diabetic patients may be increased, decreased or unchanged. A higher dosage of oral hypoglycemic agents may be required.

• Tubocurarine

Chlorthalidone and related drugs may increase the responsiveness to tubocurarine.

• Norepinephrine

Chlorthalidone and related drugs may decrease arterial responsiveness to norepinephrine. This diminution is not sufficient to preclude the effectiveness of the pressor agent for therapeutic use.

• Lithium

Lithium renal clearance is decreased by chlorthalidone, gaining the risk of lithium toxicity.

The common side of Chlorthalidone includes the following

Common

• Hypotension
• Diarrhea
• Loss of appetite
• Nausea
• Headache
• Dizziness

Rare

• Photosensitivity
• Blurred vision
• Restlessness
• Constipation
• Vomiting

• Pregnancy

Pregnancy Category B

Chlorthalidone use in pregnant women has not identified a drug-associated risk of major birth defects or miscarriage. However, adverse fetal outcomes, including fetal or neonatal jaundice, thrombocytopenia, hypoglycemia, and electrolyte abnormalities have been reported following the maternal use of thiazide diuretics. Chlorthalidone should not be used as first-line therapy to treat hypertension in pregnancy. Advise pregnant women of the potential risk to a fetus. Thiazides cross the placental barrier and appear in cord blood. The use of chlorthalidone and related drugs in pregnant women requires that the anticipated benefits of the drug be weighed against possible hazards to the fetus. These hazards include fetal or neonatal jaundice, thrombocytopenia, and possibly other adverse reactions that have occurred in the adult.

• Nursing Mothers

Thiazides are excreted in human milk. Because of the potential for serious adverse reactions in nursing infants from chlorthalidone, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.

• Pediatric Use

Safety and effectiveness in children have not been established.

• Geriatric Use

Clinical studies of Chlorthalidone did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of reduced hepatic, renal or cardiac function, and of concomitant disease or other drug therapy.

Symptoms of acute overdosage include nausea, weakness, dizziness, and disturbances of the electrolyte balance.

The oral LD₅₀ of the drug in the mouse and the rat is more than 25,000 mg/kg body weight. The minimum lethal dose (MLD) in humans has not been established. There is no specific antidote but gastric lavage is recommended, followed by supportive treatment. Where necessary, this may include IV dextrose-saline with potassium, administered with caution.

Pharmacodynamic

The diuretic action of chlorthalidone commences a mean of 2.6 hours after dosing and continues for up to 72 hours. The drug produces diuresis with increased excretion of sodium and chloride. The diuretic effects of chlorthalidone lead to decreased extracellular fluid volume, plasma volume, cardiac output, total exchangeable sodium, glomerular filtration rate, and renal plasma flow. Chlorthalidone produces dose-related reductions in serum potassium levels, elevations in serum uric acid, and blood glucose, and it can lead to decreased sodium and chloride levels.

Pharmacokinetics

• Absorption

The bioavailability of Chlorthalidone is about 65%. After administration of oral Chlorthalidone, the onset of action takes place at 2-6 hours. Peak plasma time was found to be around 1.5-6 hours.

Distribution

In the blood, approximately 75% of the drug is bound to plasma proteins over a concentration range of 0.2 to 7.7 ug/mL.

Metabolism and Excretion

The mean plasma half-life of chlorthalidone is about 40 to 60 hours and metabolized in the liver. It is eliminated primarily as unchanged drug in the urine.