HYDROCHLOROTHIAZIDE

Hydrochlorothiazide

Created by Brenda Hughes, Tess Camfield, Robyn Wilkinson, and Dr Carl Kuschel
November 2001
Administration Newborn Drug Protocol Index Newborn Services Home Page

Note:   This is NOT Chlorothiazide.  Please check the preparation carefully, particularly if obtained after hours from other paediatric wards or units.  Chlorothiazide is not used in NICU.

Dose and Administration 4,5,7

1 –2 mg/kg/dose orally every 12 hours.

Indications 4

  1. Diuretic for long term control of mild to moderate oedema associated with congestive heart failure.
  2. Diuretic for control of pulmonary oedema in preterm infants with chronic ventilator-dependent-induced lung disease.

Contraindications 6

  1. Severe renal or hepatic dysfunction
  2. Anuria.

Precautions 6

  1. Decreased renal or hepatic function.
  2. Electrolyte imbalance.

Drug Interactions

  1. Captopril or Enalapril: possible decrease in renal function or renal failure in patients with renal arterial stenosis.
  2. Digoxin: possible digoxin toxicity if hypokalaemia exists.
  3. Indomethacin: decrease in diuretic-induced antihypertensive effect.
  4. Sotalol: prolongation of QT interval and development of torsades de pointes, especially if hypokalaemia exists.

Clinical Pharmacology 6

Hydrochlorothiazide is a thiazide diuretic. The thiazides are moderately potent diuretics which act at the proximal end of the distal tubule causing a decrease in reabsorption of electrolytes and an increase in excretion of sodium and chloride ions with accompanying water loss. The hypotensive effect is possibly due to a decrease in peripheral resistance. They are generally not effective in adults with a creatinine clearance of < 30ml/min.

Hydrochlorothiazide is fairly rapidly absorbed from the gastrointestinal tract with a bioavailability of 65 – 70 % (adults), a half life = 5 to 15 hours (adults) and is predominantly bound to red blood cells. Elimination half life is dependent on glomerular filtration rate (creatinine clearance) and is longer than for chlorothiazide. It is excreted mainly unchanged in the urine.

Possible Adverse Effects 5, 6

  1. Hypokalaemia, hypochloraemic alkalosis, hypomagnesaemia, hypercalcaemia, hypophosphotaemia, hyponatraemia, hyperglycaemia, hyperuricaemia.
  2. Small increase in excretion of bicarbonate due to decrease in carbonic-anhydrase activity.
  3. Zinc deficiency.
  4. Possibly kernicterus in very jaundiced babies, as the thiazides compete with bilirubin for plasma albumin binding sites.

Special Considerations

  1. The use of spironolactone in combination with chlorothiazide is common. There is, however, little evidence to support that this results in any clinical benefit in preterm infants with neonatal Chronic Lung Disease. 8
  2. Distal diuretics (eg. hydrochlorothiazide) improve pulmonary mechanics in preterm infants, aged greater than 3 weeks, with chronic lung disease. 8  The use of distal diuretics reduces the need for furosemide.