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Thalitone

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Thalitone

Warnings
Precautions

WARNINGS

Thalitone® (chlorthalidone USP) 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, because 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.

PRECAUTIONS

General

Hypokalemia and other electrolyte abnormalities, including hyponatremia and hypochloremic alkalosis, are common in patients receiving chlorthalidone. These abnormalities are dose-related but may occur even at the lowest marketed doses of chlorthalidone. Serum electrolytes should be determined before initiating therapy and at periodic intervals during therapy.Serum and urine electrolyte determinations are particularly important when the patient is vomiting excessively or receiving parenteral fluids. All patients taking chlorthalidone should be observed for clinical signs of electrolyte imbalance, including dryness of mouth, thirst, weakness, lethargy, drowsiness, restlessness, muscle pains or cramps, muscular fatigue, hypotension, oliguria, tachycardia, palpitations and gastrointestinal disturbances, such as nausea and vomiting. Digitalis therapy may exaggerate metabolic effects of hypokalemia especially with reference to myocardial activity.

Any chloride deficit is generally mild and usually does not require specific treatment except under extraordinary circumstances (as in liver disease or renal disease). Dilutional hyponatremia may occur in edematous patients in hot weather; appropriate therapy is water restriction, rather than administration of salt, except in rare instances when the hyponatremia is life-threatening. In cases of actual salt depletion, appropriate replacement is the therapy of choice.

Thiazide-like diuretics have been shown to increase the urinary excretion of magnesium; this may result in hypomagnesemia.

Calcium excretion is decreased by thiazide-like drugs. Pathological changes in the parathyroid gland with hypercalcemia and hypophos-phatemia have been observed in a few patients on thiazide therapy. The common complications of hyperparathyroidism such as renal lithiasis, bone resorption and peptic ulceration have not been seen.

Uric Acid

Hyperuricemia may occur or frank gout may be precipitated in certain patients receiving chlorthalidone.

Other

Increases in serum glucose may occur and latent diabetes melli-tus may become manifest during chlorthalidone therapy (see PRECAUTIONS: DRUG INTERACTIONS). Chlorthalidone and related drugs may decrease serum PBI levels without signs of thyroid disturbance.

Laboratory Tests

Periodic determination of serum electrolytes to detect possible electrolyte imbalance should be performed at appropriate intervals.

All patients receiving chlorthalidone should be observed for clinical signs of fluid or electrolyte imbalance: namely, hyponatremia, hypochloremic alkalosis and hypokalemia. Serum and urine electrolyte determinations are particularly important when the patient is vomiting excessively or receiving parenteral fluids.

Carcinogenesis, Mutagenesis, Impairment of Fertility

No information is available.

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.

Pregnancy/Non-Teratogenic 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.

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.

Pediatric Use

Safety and effectiveness in children have not been established.

Geriatric Use

Clinical studies of Thalitone® (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 decreased hepatic, renal or cardiac function,and of concomitant disease or other drug therapy.

This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function,care should be taken in dose selection, and it may be useful to monitor renal function.

Last reviewed on RxList: 7/16/2008
This monograph has been modified to include the generic and brand name in many instances.

Warnings
Precautions
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