Chlorothiazide

Indications

Chlorothiazide is used for: Hypertension, Oedema

Adult Dose

Oral Hypertension Adult: 0.5-1 g daily as a single dose or in 2 divided doses. Max: 2 g daily in divided doses. Child: <6 mth 10-30 mg/kg/day in 2 divided doses. Max: 375 mg daily; 6 mth to 12 yr 10-20 mg/kg/day in 1-2 divided doses. Max: 375 mg/day (<2 yr), 1000 mg/day (2-12 yr). Oedema Adult: 0.5-1 g once daily or bid, may also be taken on alternate days or on 3-5 days wkly. Max: 2 g daily. Renal impairment: Severe: Contraindicated. Intravenous Oedema Adult: 0.5-1 g once daily or bid, may also be taken on alternate days or on 3-5 days wkly. Reconstitution: Add 18 mL of sterile water for inj to a 500 mg vial to provide a soln of 27.8 mg/mL. May be further diluted w/ NaCl, dextrose, or other compatible infusion fluids before admin.

Child Dose

Oral Hypertension Child: <6 mth 10-30 mg/kg/day in 2 divided doses. Max: 375 mg daily; 6 mth to 12 yr 10-20 mg/kg/day in 1-2 divided doses. Max: 375 mg/day (<2 yr), 1000 mg/day (2-12 yr).

Renal Dose

Renal Impairment CrCl <10 mL/minute: Do not use CrCl<30 mL/minute: Ineffective

Administration

Should be taken with food.

Contra Indications

Hypersensitivity to sulfonamide-derived drugs, anuria.

Precautions

Patient w/ gout, DM, hypercholesterolemia, hypercalcaemia, hypokalaemia, history of allergy or bronchial asthma. May exacerbate SLE. Renal and hepatic impairment. Pregnancy and lactation. Monitoring Parameters Monitor serum electrolytes, renal function, and BP. Assess wt, input and output reports daily to determine fluid loss.

Pregnancy-Lactation

Pregnancy Category: C; D (expert analysis). Chlorothiazide may cause fetal or neonatal jaundice, thrombocytopenia, and possibly other adverse reactions which have occurred in the adult. Use of diuretics for pregnancy-induced hypertension should be avoided due to risk of decreased placental perfusion. Lactation: enters breast milk/not recommended (AAP states "compatible with nursing")

Interactions

May increase risk of lithium toxicity. Potentiation of orthostatic hypotension w/ barbiturates and narcotics. Reduced therapeutic effect of antidiabetics. Additive effect w/ other antihypertensives. Reduced diuretic absorption from the GI tract w/ cholestyramine and colestipol. Intensified electrolyte depletion w/ corticosteroids. Reduced diuretic effect w/ NSAID.

Adverse Effects

Side effects of Chlorothiazide : <1% Scaling eczema Stevens-Johnson syndrome Toxic epidermal necrolysis Disorder of hematopoietic structure Hepatotoxicity Systemic lupus erythematosus Frequency Not Defined Hypotension Alopecia Photosensitivity Phototoxicity Rash Urticaria Hyperglycemia Hyperuricemia Constipation Diarrhea Loss of appetite Nausea and vomiting Electrolytes abnormal Spasticity Dizziness Headache Blurred vision Xanthopsia Impotence

Mechanism of Action

Chlorothiazide reduces the reabsorption of electrolytes from the renal tubules, hence increasing the excretion of Na and Cl ions and consequently of water. It also reduces the GFR.