Chlorthalidone 50 MG Oral Tablet

Generic Name: CHLORTHALIDONE
Brand Name: Chlorthalidone
  • Substance Name(s):
  • CHLORTHALIDONE

WARNINGS

Chlorthalidone should be used with caution in severe renal disease.

In patients with renal disease, chlorthalidone or related drugs may precipitate azotemia.

Cumulative effects of the drug may develop in patients with impaired renal function.

Chlorthalidone should be used with caution in patients with impaired hepatic function or progressive liver disease, since minor alterations of fluid and electrolyte balance may precipitate hepatic coma.

Sensitivity reactions may occur in patients with a history of allergy or bronchial asthma.

The possibility of exacerbation or activation of systemic lupus erythematosus has been reported with thiazide diuretics, which are structurally related to chlorthalidone.

However, systemic lupus erythematosus has not been reported following chlorthalidone administration.

DRUG INTERACTIONS

Drug Interactions Chlorthalidone may add to or potentiate the action of other antihypertensive drugs.

Potentiation occurs with ganglionic peripheral adrenergic blocking drugs.

Medication such as digitalis may also influence serum electrolytes.

Warning signs, irrespective of cause, are: dryness of mouth, thirst, weakness, lethargy, drowsiness, restlessness, muscle pains or cramps, muscular fatigue, hypotension, oliguria, tachycardia, and gastrointestinal disturbances such as nausea and vomiting.

Insulin requirements in diabetic patients may be increased, decreased, or unchanged.

Higher dosage of oral hypoglycemic agents may be required.

Latent diabetes mellitus may become manifest during chlorthalidone administration.

Chlorthalidone and related drugs may increase the responsiveness to tubocurarine.

Chlorthalidone and related drugs may decrease arterial responsiveness to norepinephrine.

This diminution is not sufficient to preclude effectiveness of the pressor agent for therapeutic use.

OVERDOSAGE

Symptoms of acute overdosage include nausea, weakness, dizziness, and disturbances of 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 intravenous dextrose-saline with potassium, administered with caution.

DESCRIPTION

Chlorthalidone an oral antihypertensive/diuretic.

It is a monosulfamyl diuretic that differs chemically from thiazide diuretics in that a double-ring system is incorporated in its structure.

It is 2-Chloro-5(1-hydroxy-3-oxo-1- isoindolinyl) benzenesulfonamide with the following structural formula: Molecular Formula: C14H11ClN2O4S Molecular weight: 338.76 Chlorthalidone, USP is practically insoluble in water, in ether, and in chloroform; soluble in methanol; slightly soluble in ethanol.

Chlorthalidone tablets are available containing either 25 mg or 50 mg of chlorthalidone, USP and the following inactive ingredients: colloidal silicon dioxide, D&C Yellow No.10 Aluminum Lake, microcrystalline cellulose, pregelatinized starch (corn), sodium starch glycolate (potato), stearic acid.

The 50 mg tablets also contain FD&C Blue No.1 Aluminum Lake.

Structural Formula

HOW SUPPLIED

Chlorthalidone Tablets, USP are available containing 25 mg or 50 mg of chlorthalidone, USP.

The 25 mg tablets are light yellow, round, unscored tablets debossed with M35 on one side of the tablet and blank on the other side.

They are available as follows: NDC 0378-0222-77 bottles of 90 tablets NDC 0378-0222-01 bottles of 100 tablets NDC 0378-0222-10 bottles of 1000 tablets The 50 mg tablets are light green, round, scored tablets debossed with M to the left of the score and 75 to the right of the score on one side of the tablet and blank on the other side.

They are available as follows: NDC 0378-0213-77 bottles of 90 tablets NDC 0378-0213-01 bottles of 100 tablets NDC 0378-0213-10 bottles of 1000 tablets Store at 20° to 25°C (68° to 77°F).

[See USP for Controlled Room Temperature.] Protect from light.

Dispense in a tight, light-resistant container as defined in the USP using a child-resistant closure.

INDICATIONS AND USAGE

Diuretics such as chlorthalidone are indicated in the management of hypertension either as the sole therapeutic agent or to enhance the effect of other antihypertensive drugs in the more severe forms of hypertension.

Chlorthalidone is indicated as adjunctive therapy in edema associated with congestive heart failure, hepatic cirrhosis, and corticosteroid and estrogen therapy.

Chlorthalidone has also been found useful in edema due to various forms of renal dysfunction, such as nephrotic syndrome, acute glomerulonephritis, and chronic renal failure.

Usage in Pregnancy The routine use of diuretics in an otherwise healthy woman is inappropriate and exposes mother and fetus to unnecessary hazard.

Diuretics do not prevent development of toxemia of pregnancy, and there is no satisfactory evidence that they are useful in the treatment of developed toxemia.

Edema during pregnancy may arise from pathologic causes or from the physiologic and mechanical consequences of pregnancy.

Chlorthalidone is indicated in pregnancy when edema is due to pathologic causes, just as it is in the absence of pregnancy (however, see PRECAUTIONS, below).

Dependent edema in pregnancy, resulting from restriction of venous return by the expanded uterus, is properly treated through elevation of the lower extremities and use of support hose; use of diuretics to lower intravascular volume in this case is illogical and unnecessary.

There is hypervolemia during normal pregnancy that is harmful to neither the fetus nor the mother (in the absence of cardiovascular disease), but that is associated with edema, including generalized edema, in the majority of pregnant women.

If this edema produces discomfort, increased recumbency will often provide relief.

In rare instances, this edema may cause extreme discomfort that is not relieved by rest.

In these cases, a short course of diuretics may provide relief and be appropriate.

PEDIATRIC USE

Pediatric Use Safety and effectiveness in children have not been established.

PREGNANCY

Pregnancy Teratogenic Effects.

Pregnancy Category B Reproduction studies have been performed in the rat and the rabbit at doses up to 420 times the human dose and have revealed no evidence of harm to the fetus due to chlorthalidone.

There are, however, no adequate and well-controlled studies in pregnant women.

Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.

Nonteratogenic Effects 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.

NUSRING MOTHERS

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 to discontinue the drug, taking into account the importance of the drug to the mother.

INFORMATION FOR PATIENTS

Information for Patients Patients should inform their physician if they have: (1) had an allergic reaction to chlorthalidone or other diuretics or have asthma, (2) kidney disease, (3) liver disease, (4) gout, (5) systemic lupus erythematosus, or (6) been taking other drugs such as cortisone, digitalis, lithium carbonate, or drugs for diabetes.

Patients should be cautioned to contact their physician if they experience any of the following symptoms of potassium loss: excess thirst, tiredness, drowsiness, restlessness, muscle pains or cramps, nausea, vomiting, or increased heart rate or pulse.

Patients should also be cautioned that taking alcohol can increase the chance of dizziness occurring.

DOSAGE AND ADMINISTRATION

Therapy should be initiated with the lowest possible dose.

This dose should be titrated according to individual patient response to gain maximal therapeutic benefit while maintaining lowest dosage possible.

A single dose given in the morning with food is recommended; divided daily doses are unnecessary.

Hypertension Initiation: Therapy, in most patients, should be initiated with a single daily dose of 25 mg.

If the response is insufficient after a suitable trial, the dosage may be increased to a single daily dose of 50 mg.

If additional control is required, the dosage of chlorthalidone may be increased to 100 mg once daily or a second antihypertensive drug (step 2 therapy) may be added.

Dosage above 100 mg daily usually does not increase effectiveness.

Increases in serum uric acid and decreases in serum potassium are dose-related over the 25 to 100 mg/day range.

Maintenance: Maintenance doses may be lower than initial doses and should be adjusted according to individual patient response.

Effectiveness is well sustained during continued use.

Edema Initiation: Adults, initially 50 to 100 mg daily, or 100 mg on alternate days.

Some patients may require 150 to 200 mg at these intervals or up to 200 mg daily.

Dosages above this level, however, do not usually produce a greater response.

Maintenance: Maintenance doses may often be lower than initial doses and should be adjusted according to individual patient response.

Effectiveness is well sustained during continued use.