Thiazide Diuretics/thiazide-like diuretics
Examples
Thiazide diuretics
- Bendroflumethiazide
- Chlortalidone
- Indapamide
Indications
- Hypertension
- Oedema
- Nephrogenic diabetes insipidus
Contraindications
Contraindications
- Severe electrolyte disturbance (hyponatraemia, hypokalaemia, hypercalcaemia)
- Acute gout
- Addison's disease
- Gout
- Diabetes mellitus - may cause impaired glucose tolerance
- Renal impairment
- Systemic Lupus Erythematosus
- Hepatic impairment
- Pregnancy and breast feeding
- Elderly
Mechanism
The mechanism by which thiazide diuretics cause a diuresis is well known, however it is still unclear by what mechanism they reduce blood pressure. Thiazides act on the distal tubule, inhibiting NaCl reabsorption and therefore increasing its excretion accompanied by water. Hypokalaemia is caused by the increased presence of sodium in the tubule which leads to exchange of sodium for potassium ions.
Administration
Orally. Low doses work as well as high doses, but with fewer side effects.
Adverse Reactions
- Hypokalaemia
- Hyponatraemia
- Hypomagnesaemia
- Hypercalcaemia
- Hyperuricacidaemia
- Hyperlipidaemia
- Impotence
- Blood disorders (including thrombocytopenia which can also occur in neonates if used in pregnancy)
Interactions
NSAIDs reduce the anti-hypertensive effects of thiazide diuretics and increase the risk of acute renal failure.
Lithium excretion is reduced and may lead to toxicity.
Digoxin toxicity risk is increased with bendroflumethiazide.
Other drugs which can cause hypokalaemia may worsen the hypokalaemia seen with thiazides - hypokalaemia may lead to increased toxicity from digoxin and anti-arrhythmics.
Lithium excretion is reduced and may lead to toxicity.
Digoxin toxicity risk is increased with bendroflumethiazide.
Other drugs which can cause hypokalaemia may worsen the hypokalaemia seen with thiazides - hypokalaemia may lead to increased toxicity from digoxin and anti-arrhythmics.
Education
No specific issues
Pharmacokinetics
No specific issues
