Hydrochlorothiazide

Registered South African indications:

• Hypertension
• Oedema due to sodium and water retention

Contraindications

South African recommendations

• Hypersensitivity to hydrochlorothiazide, other sulphonamide-derived medicines or to any of the excipients
• Anuria
• Severe renal impairment (creatinine clearance <30ml/min)
• Severe hepatic impairment
• Addison’s disease
• Pre-existing hypercalcaemia
• Second and third trimesters of pregnancy
• Lactation

Cautions

• First trimester of pregnancy
• Mild to moderate renal impairment
• Mild to moderate hepatic impairment
• Elderly
• Renal artery stenosis
• Gout
• Hyperglycaemia
• Systemic lupus erythematosus

Forms avail. in SA and covered in this monograph: tab

Dosages below include:

• South African registered indications and dosages

South African registered indications and dosages

Essential hypertension (Additional agent(s) is required)
- In combination (preferably) with reduced doses of specific antihypertensive medicines

25mg

• Oral (tab): 25-100mg, dly

Hypertension - mild to moderate (Additional agent(s) may be required)
- As monotherapy

12.5mg

• Oral (tab): 12.5mg, dly

- As an adjunct in hypertension therapy

12.5mg

• Oral (tab): 12.5-25mg, dly in conjunction with an antihypertensive medicine

---

The dosage should not be higher than necessary to achieve the desired effect. Prolonged treatment may result in potassium ion loss. Potassium supplements may be necessary

---

Preferably be taken in the morning in order to minimise the effect of increased frequency of urination during sleep. Hydrochlorothiazide should be taken with or after meals to minimise stomach upset

---

Oedema due to sodium and water retention

25mg

• Oral (tab): Initial: 25-100mg, dly; Initial dose of up to 200mg may be necessary; Later reduced to a smaller maintenance dose often given on alternative days

---

An initial dose of up to 200mg may be necessary in some patients, but larger doses have no additional effect

---

Paradoxically, hydrochlorothiazide appears to have an antidiuretic effect on patients with diabetes insipidus and may be of value in the management of the disease

Paed. forms avail. in SA and covered in this monograph: tab

Paed. dosages below include:

• South African registered indications and dosages

South African registered indications and dosages

Essential hypertension (Additional agent(s) required)
- In combination (preferably) with reduced doses of specific antihypertensive medicines)
Oedema due to sodium and water retention

25mg

• Oral (tab): 2.5mg/kg body mass, in two divided doses

---

12.5mg tablet: No data available

Pregnancy

• Second and third trimester: Contraindicated
• First trimester: Caution
• The safety of hydrochlorothiazide in pregnancy has not been established
• There is limited experience with hydrochlorothiazide during pregnancy, especially during the first trimester
• Hydrochlorothiazide crosses the placenta barrier and appears in cord blood. There have been reports of neonatal jaundice, icterus, thrombocytopenia and electrolyte imbalances following maternal treatment
• Reductions in maternal blood volume could also adversely affect placental perfusion. Hydrochlorothiazide should not be used for gestational oedema, gestational hypertension or preeclampsia due to the risk of decreased plasma volume and placental hypoperfusion, without a beneficial effect on the course of the disease
• Hydrochlorothiazide should not be used for essential hypertension in pregnant women

Breastfeeding

• Contraindicated
• The safety of hydrochlorothiazide in lactation has not been established
• Hydrochlorothiazide is distributed into breast milk and is not recommended for use in lactation. Hydrochlorothiazide in high doses causing intense diuresis can inhibit the milk production
• Because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or to discontinue hydrochlorothiazide, considering the importance of the medicine to the mother

Fertility

• There is no data available

Renal Impairment

• Mild to moderate: Caution; no dose adjustment recommended 
• Severe: Contraindicated 

CrCl (ml/min)	Dose
>30	No adjustment necessary
<30	Contraindicated

Hepatic Impairment

• Mild to moderate: Caution; no dose adjustment recommended 
• Severe: Contraindicated

Elderly

• Caution; no dose adjustments recommended 

Porphyria Information

• Probably not porphyrinogenic (PNP) 

Drugs in Sport

• Prohibited - At all times

Central Nervous System Disorders

• Weakness
• Lethargy
• Drowsiness
• Restlessness
• Seizures
• Headache
• Paraesthesia
• Dizziness

Cardiovascular Disorders

• Postural hypotension

Gastrointestinal Disorders

• Nausea and vomiting
• Constipation
• Diarrhoea
• Intestinal ulceration

Hepatobiliary Disorders

• Cholestatic jaundice
• Pancreatitis

Genitourinary Disorders

• Oliguria
• Impotence

Endocrine and Metabolic Disorders

• Hypochloraemic alkalosis
• Hyponatremia
• Hypokalaemia
• Hyperglycaemia
• Hyperuricaemia
• Gout
• Hypomagnesaemia
• Anorexia

Musculoskeletal Disorders

• Muscle pain
• Cramps

Skin and Subcutaneous Tissue Disorders

• Hypersensitivity reactions

Immune, Blood and Lymphatic System Disorders

• Thrombocytopaenia
• Granulocytopaenia
• Leucopenia
• Aplastic anaemia
• Haemolytic anaemia

Sensory Disorders

• Dry mouth
• Thirst
• Yellow vision

• Digoxin
• Neuromuscular blocking agents
• Central nervous system depressants
• Corticosteroids
• Corticotrophin
• Beta-2 agonists
• Adrenaline
• Lithium

None routine. Specific cases may require 

• Serum potassium
• Renal function

Hydrochlorothiazide acts primarily in the distal convoluted tubule where it inhibits sodium chloride transport. It competes for the chloride site and affects the electrolyte reabsorption by increasing sodium and chloride excretion. This reduces plasma volume indirectly and increases plasma renin activity, aldosterone secretion and urinary potassium loss.

Tablet 12.5mg

• Ridaq (Pharmacare)

Tablet 25mg

• Gulf Hydrochlorothiazide 25 (Gulf)
• Hexazide (Sandoz)
• Hydrochlorot Hiazide 25 Ascendis (Dezzo Trading)
• Ridaq (Pharmacare)