Generic Name

Chlorthalidone

Precaution

Existing fluid and electrolyte disturbances, hepatic cirrhosis, severe heart failure, hyperuricaemia, mild to moderate renal impairment. Elderly. Monitor fluid and electrolyte balance. Kidney or liver disease; diabetes; gout; hyperlipidaemia and ventricular extra systoles. Lactation: Drug enters breast milk; not recommended (American Academy of Pediatrics states that it is "compatible with nursing")

Indication

Hypertension, Oedema, Diabetes insipidus, Congestive heart failure

Contra Indication

Severe renal impairment or anuria. Severe hepatic impairment, addison's disease, preexisting hypercalcaemia, asthma; hypersensitivity; severe allergy. Pregnancy and lactation.

Dose

N/A

Side Effect

Common Cardiovascular: Hypotension, vasculitis Dermatologic: Photosensitivity, phototoxicity Endocrine/metabolic: Electrolyte abnormalities, hyperglycemia, hyperuricemia Gastrointestinal: Constipation, diarrhea, loss of appetite, nausea, vomiting Musculoskeletal: Spasticity Neurologic: Dizziness, headache, paresthesia Ophthalmologic: Blurred vision, xanthopsia Psychiatric: Restlessness Reproductive: Impotence Potentially Fatal: Rare. Severe hyponatraemia and idiosyncratic hypersensitivity.

Pregnancy Category

Mode of Action

Chlortalidone is an oral, long acting antihypertensive/diuretic. It is a monosulfamyl diuretic that acts by enhancing the excretion of sodium and chloride ions, and water by interfering with the transport of sodium ions across the renal tubular epithelium. Their primary site of action appears to be at the cortical diluting segment in the nephron of the loop of Henle.

Interaction

NSAIDs antagonise hypotensive action. Suppresses action of oral anticoagulants due to reduced prothrombin activity. Increased risk of hypokalaemia when corticosteroids are given concurrently. Potentially Fatal: Potentiates bone marrow suppression caused by anticancer drugs. Diuretic-induced vol depletion can potentiate aminoglycoside nephrotoxicity. Impairs action of oral hypoglycaemic agents. Enhances digitalis toxicity due to hypokalaemia. vol depletion enhances lithium toxicity, conversely, sudden withdrawal of diuretics may result in subtherapeutic levels of circulating lithium. Prolonged paralysis with tubocurarine due to hypokalaemia.

Pregnancy Category Note

Pregnancy Available data over decades from observational studies and reports with chlorthalidone use in pregnant women have 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 reported following maternal use of thiazide diuretics Drug not for use as first-line therapy to treat hypertension in pregnancy; advise pregnant women of potential risk to fetus Hypertension in pregnancy increases maternal risk for pre-eclampsia, gestational diabetes, premature delivery, and delivery complications (eg, need for cesarean section, and post-partum hemorrhage); hypertension increases fetal risk for intrauterine growth restriction and stillbirth Thiazides can cross placenta, and concentrations reached in umbilical vein approach those in maternal plasma; thiazides, like other diuretics, can cause placental hypoperfusion Use of thiazides during pregnancy associated with risk of fetal or neonatal jaundice, thrombocytopenia, hypoglycemia, and electrolyte abnormalities; thiazides do not prevent or alter course of EPH (Edema, Proteinuria, Hypertension) gestosis (pre-eclampsia) and should not be used as first-line therapy to treat hypertension in pregnant women Lactation Drug is present in human milk; there is no information regarding effects of on breastfed infant or on milk production; because of potential for drug accumulation which may lead to serious adverse reactions in breastfed infant (such as jaundice, thrombocytopenia, hyperglycemia, electrolyte abnormalities), advise patients that breastfeeding is not recommended during therapy Pregnancy Categories

Adult Dose

Hypertension 25-100 mg/day PO; usual range, 12.5-25 mg/day Edema 50-100 mg/day PO or 100 mg PO every other day; not to exceed 200 mg/day Heart Failure 12.5-25 mg/day PO; not to exceed 100 mg/day

Child Dose

N/A

Renal Dose

Renal impairment CrCl <10 mL/min: Ineffective; do not use CrCl >10 mL/min: Dose adjustment not necessary

Administration

Should be taken with food. Take during meals.