Hydrochlorothiazide

Indications

Hydrochlorothiazide is used for: Hypertension, Congestive heart failure, Oedema, Diabetes insipidus, Renal tubular acidosis

Adult Dose

Oral Hypertension Adult: Initially, 12.5 mg, may increase to 25-50 mg once daily as necessary either alone or w/ other antihypertensives. Elderly: 12.5-25 mg once daily, titrate as necessary in increments of 12.5 mg. Oedema Adult: 25-100 mg daily in 1-2 divided doses or intermittently on alternate days or on 3-5 days a wk. Elderly: 12.5-25 mg once daily, titrate as necessary in increments of 12.5 mg.

Child Dose

Oral Hypertension Child: <6 mth 1-3 mg/kg/day in 1-2 divided doses. Max: 37.5 mg daily; 6 mth to 2 yr 1-2 mg/kg/day in 1-2 divided doses. Max: 37.5 mg daily; >2-12 yr 1-2 mg/kg/day in 1-2 divided doses Max: 100 mg daily. Oedema Child: <6 mth 1-3 mg/kg/day in 1-2 divided doses. Max: 37.5 mg daily; 6 mth to 2 yr 1-2 mg/kg/day in 1-2 divided doses. Max: 37.5 mg daily; >2-12 yr 1-2 mg/kg/day in 1-2 divided doses Max: 100 mg daily.

Renal Dose

Renal impairment CrCl <10 mL/min: Avoid use CrCl >10 mL/min: Dose adjustment not necessary; not effective with CrCl <30 mL/min unless used in combination with loop diuretic

Administration

Should be taken with food.

Contra Indications

Hypersensitivity to sulfonamide-derived drugs, anuria, severe renal impairment.

Precautions

Patients w/ electrolyte disturbances, history of gout, allergy or bronchial asthma, DM, parathyroid disease, hypercholesterolaemia. May exacerbate SLE. Hepatic and mild to moderate renal impairment. Pregnancy and lactation. Monitoring Parameters Assess wt, input and output reports daily to determine fluid loss, BP, serum electrolytes, BUN, creatinine. Lactation: Drug excreted in breast milk; use with caution (American Academy of Pediatrics states that it is "compatible with nursing")

Pregnancy-Lactation

Pregnancy category: B Lactation: Drug excreted in breast milk; use with caution (American Academy of Pediatrics states that it is "compatible with nursing")

Interactions

Increases toxicity of lithium. May potentiate orthostatic hypotension w/ barbiturates and narcotics. Enhanced neuromuscular blocking action of competitive neuromuscular blockers (e.g. atracurium). Increased hypokalaemic effect w/ corticosteroids, corticotropin, beta2 agonists (e.g. salbutamol). Additive effect w/ other antihypertensives. Potentiation of orthostatic hypotension w/ barbiturates or opioids. Reduced antihypertensive effect by drugs that cause fluid retention (e.g. corticosteroids, NSAIDs, carbenoxolone). Enhanced nephrotoxicity of NSAIDs. Reduced therapeutic effect of antidiabetics.

Adverse Effects

Side effects of Hydrochlorothiazide : Electrolyte disturbances, weakness, hypotension, pancreatitis, jaundice, diarrhoea, vomiting, sialadenitis, cramping, constipation, gastric irritation, nausea, anorexia, aplastic anaemia, agranulocytosis, leukopenia, haemolytic anaemia, thrombocytopenia, anaphylactic reactions, necrotising angiitis, resp distress, photosensitivity, fever, urticaria, rash, purpura, hyperglycaemia, glycosuria, hyperuricaemia., muscle spasm, vertigo, paraesthesias, dizziness, headache, restlessness, renal failure, renal dysfunction, interstitial nephritis, erythema multiforme, exfoliative dermatitis, alopecia, transient blurred vision, xanthopsia, impotence. Potentially Fatal: Hypersensitivity reactions.

Mechanism of Action

Hydrochlorothiazide inhibits the reabsorption of Na and chloride in the distal tubules causing increased excretion of Na and water K and hydrogen ions.