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Indications & Uses
Clortha is indicated for:
Pharmacology
Chlorthalidone is a thiazide-type diuretic and antihypertensive used to treat high blood pressure. It may be used alone or together with other antihypertensive agents. Chlorthalidone is also used as an add-on treatment for fluid retention (edema) associated with kidney disease; mild to moderate congestive heart failure (functional class II or III), when the glomerular filtration rate is greater than 30 ml/min; ascites due to liver cirrhosis in stable patients; estrogen therapy; and corticosteroid therapy.
Chlorthalidone works by inhibiting the reabsorption of sodium and chloride in the distal renal tubule, which promotes water loss. The higher urine volume also increases potassium loss. Little information is available on the drug's absorption. Its long elimination half-life and clinical experience place it among the long-acting thiazide derivatives, and longer-acting agents of this kind tend to cause greater potassium loss.
Although it is a mild diuretic on its own, combining it with loop diuretics produces a particularly potent effect, since loop diuretics deliver much more sodium chloride to the distal tubule. The blood-pressure-lowering effect is initially due to a reduction in fluid volume, but the effect that persists afterward involves other, not fully understood, mechanisms that reduce peripheral resistance. A high salt intake reverses the antihypertensive effect.
Most of an absorbed dose of chlorthalidone is excreted by the kidneys, with an elimination half-life averaging 50 hours. Metabolism and excretion into the bile by the liver account for only a minor part of its elimination. Within 120 hours, about 70% of the dose is excreted, mainly unchanged, in the urine and feces.
Dosage Reference
Reference Information Only
Dosages shown are general references from official sources. Always consult your doctor or pharmacist for personalized dosing.
Adults:
Therapy should begin with the lowest possible dose, then be adjusted gradually to gain the greatest therapeutic benefit while keeping side effects to a minimum (for example, finding the minimum effective maintenance dose for each patient). A single dose taken once daily or every other day, in the morning with food, is recommended.
Hypertension: The usual adult dose is 25 to 50 mg daily, with a clinically useful range of 12.5 to 50 mg daily. Doses above 50 mg per day increase the risk of metabolic complications and rarely offer added therapeutic benefit. For any given dose, the full effect is reached after 3 to 4 weeks. If the blood pressure reduction achieved with 25 or 50 mg per day proves inadequate, combining treatment with other antihypertensive drugs, such as beta blockers and ACE inhibitors, is recommended. When an ACE inhibitor is added, the Chlorthalidone dose should be reduced or stopped.
Edema of Specific Origin: The lowest effective dose should be found by gradual adjustment. Maintenance doses should not exceed 50 mg per day and should be given only for limited periods. The dose should be tailored to each patient's clinical picture and response to treatment. For long-term therapy, the lowest dose that maintains an optimal effect should be used, and this is especially important for elderly patients.
The therapeutic effect of Chlorthalidone occurs even without restricting salt intake and is well maintained with continued use.
The elderly: This drug is suitable for treating hypertension in older adults, particularly systolic hypertension. A dose of 50 mg daily or less should be used to avoid hypovolemia and hypokalemia.
Side Effects
Electrolyte and Metabolic Disorders: Frequently seen, mainly at higher doses, are low potassium levels, raised uric acid, and increased blood lipids. Low sodium, low magnesium, and high blood sugar occur occasionally. Rarely, high calcium levels, sugar in the urine, worsening of diabetic control, and gout may be seen. In isolated cases, hypochloremic alkalosis has been reported. Dermatology: Hives and other skin rashes occur occasionally, while increased sensitivity to sunlight is rare. Liver: Rarely, this medicine may cause intrahepatic cholestasis or jaundice. Cardiovascular: A drop in blood pressure on standing may occur occasionally and can be made worse by alcohol, anesthetics, or sedatives. Irregular heartbeat is a rare effect. CNS: Dizziness, sluggish thinking, and slower reaction time occur occasionally.
Cautions & Contraindications
Warnings & Precautions
Renal impairment: In moderate renal failure, Thalin dosage should be reduced and given every 24 or 48 hours; it should not be used in advanced renal failure. Liver disease: In patients with liver cirrhosis and ascites, there is a risk of precipitating hepatic encephalopathy. Use in pregnancy: It is better to avoid Thalin, as it crosses the placenta. Use in lactation: In lactating mothers, a significant amount of Thalin enters breast milk; like other long-acting thiazides, it can suppress lactation. Thalin should not be prescribed for lactating mothers.
Contraindications
Chlorthalidone should not be used in anuria, severe renal failure (creatinine clearance lower than 30 mL/min), severe hepatic failure, refractory hypokalemia or conditions involving enhanced potassium loss, hyponatremia, hypercalcemia, or symptomatic hyperuricemia (a history of gout or uric acid calculi). It is also not for anyone with hypersensitivity or suspected hypersensitivity to Chlorthalidone, other sulfonamide derivatives, or their excipients. Use it with caution in patients with renal disease or impaired hepatic function. Because renal damage may progress, BUN and serum creatinine should be checked periodically. If either one rises, stop the treatment. Like the thiazides, Chlorthalidone may lose its diuretic effect when the glomerular filtration rate drops below 30 mL/min, and at that point a loop diuretic may be more appropriate. Electrolytes: As with thiazide diuretics, the potassium loss (kaluresis) caused by Chlorthalidone depends on the dose, and the size of the effect varies from person to person. At 25 mg/day, serum potassium falls by 0.5 mmol/L on average. If long-term treatment is planned, serum potassium should be measured at the start and again 3 to 4 weeks later. If potassium balance is not disturbed further after that, concentrations should be checked every 4 to 6 months. Conditions that can alter potassium balance include vomiting, diarrhea, malnutrition, a change in renal function (for example nephrosis), liver cirrhosis, hyperaldosteronism, and the concomitant use of corticosteroids or ACTH. A titrated oral potassium salt (for example KCl) may be given alongside Chlorthalidone in these patients: those receiving digitalis, those showing signs of coronary heart disease (unless they are also on an ACE inhibitor), those on high doses of a beta-adrenergic agonist, and those whose plasma potassium is below 3.0 mmol/L.
Pregnancy & Breastfeeding
Pregnancy: Like other diuretics, Chlorthalidone can reduce blood flow to the placenta. Because it does not prevent or change the course of EPH (edema, proteinuria, hypertension) preeclampsia, it must not be used to treat high blood pressure in pregnant women. For other indications (e.g. heart disease), Chlorthalidone should be avoided during pregnancy, especially in the first trimester, unless the potential benefits outweigh the possible risks, such as when no safer alternative is available.
Lactation: Chlorthalidone passes into breast milk, reaching levels of about 4% of those in the mother's blood. Because of this, it should be avoided in mothers who are breastfeeding.
⚠️ Talk to your doctor before taking any medicine during pregnancy or while breastfeeding.
Overdose
An acute overdose of chlorthalidone can cause nausea, weakness and dizziness, along with disturbances of electrolyte balance. In mice and rats, the oral LD 50 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. Gastric lavage is recommended, and supportive treatment follows. Where necessary, this can include intravenous dextrose-saline with potassium, given with caution.
⚠️ In an emergency call 999 or go to the nearest hospital emergency department.
Storage
Store Chlorthalidone below 30°C, and keep it away from light and moisture. Keep it out of the reach of children.
Drug Interactions
Common questions about Clortha 15 mg
What is Clortha 15 mg Tablet?
Clortha 15 mg Tablet is a medicine that contains Chlorthalidone. It is made by Advanced Chemical Industries PLC. It belongs to the Thiazide diuretics & related drugs group of medicines.
What is Clortha used for?
Clortha is used for: Hypertension, Heart Failure, Edema.
What are the side effects of Clortha?
Electrolyte and Metabolic Disorders: Frequently seen, mainly at higher doses, are low potassium levels, raised uric acid, and increased blood lipids. Low sodium, low magnesium, and high blood sugar occur occasionally.
Can I take Clortha during pregnancy or while breastfeeding?
Pregnancy: Like other diuretics, Chlorthalidone can reduce blood flow to the placenta. Because it does not prevent or change the course of EPH (edema, proteinuria, hypertension) preeclampsia, it must not be used to treat high blood pressure in pregnant women. Talk to your doctor before taking any medicine during pregnancy or while breastfeeding.
What happens if I take too much Clortha?
An acute overdose of chlorthalidone can cause nausea, weakness and dizziness, along with disturbances of electrolyte balance. In mice and rats, the oral LD 50 is more than 25,000 mg/kg body weight. In an emergency call 999 or go to the nearest hospital emergency department.
How should I store Clortha?
Store Chlorthalidone below 30°C, and keep it away from light and moisture. Keep it out of the reach of children.
Can I take other medicines with Clortha?
Some medicines can interact with Chlorthalidone, for example: Methyldopa, Cyclophosphamide, Indomethacin, Methotrexate, Cholestyramine, Allopurinol. Tell your doctor or pharmacist about every medicine you take.
Is there a cheaper medicine with the same ingredient?
Clortha is already among the lowest-priced brands of Chlorthalidone at this strength.
Do I need a prescription for Clortha?
Clortha is a prescription (Rx) medicine. Take it as your doctor advises.