Chlortalidone

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. …

• 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

Safety and effectiveness in children have not been established.

• Patients should inform their physician if they have: had an allergic reaction to chlorthalidone or other diuretics or have asthma, kidney disease, liver disease, gout, systemic lupus erythematosus, or 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

• Anuria
• Known hypersensitivity to chlorthalidone or other sulfonamide-derived drugs

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. …

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 following adverse reactions have been observed, but there is not enough systematic collection of data to support an estimate of their frequency. Gastrointestinal System Reactions: anorexia, gastric irritation, nausea, vomiting, cramping, diarrhea, constipation, jaundice (intrahepatic cholestatic jaundice), pancreatitis. Central Nervous System Reactions: dizziness, vertigo, paresthesias, headache, xanthopsia. Hematologic Reactions: leukopenia, agranulocytosis, thrombocytopenia, aplastic anemia. Dermatologic-Hypersensitivity Reactions: purpura, photosensitivity, rash, urticaria, necrotizing angiitis (vasculitis, cutaneous vasculitis), Lyell's syndrome (toxic epidermal necrolysis). …

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. …

Symptoms of acute overdosage include nausea, weakness, dizziness, and disturbances of electrolyte balance. The oral LD 50 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.

Take it when you remember, unless it is nearly time for the next dose. Then skip the missed one. Never take two doses at once to make up for it. Check your leaflet, as some medicines are different.