Hydrochlorothiazide


Generic Medicine Info
Indications and Dosage
Oral
Oedema
Adult: 25-100 mg daily in 1-2 divided dose. Max: 200 mg daily. Dose may be administered on alternate days or on 3-5 days each week.
Elderly: >65 years Initially, 12.5 mg daily, titrate as necessary in increments of 12.5 mg.
Child: <6 months 3 mg/kg daily in 2 divided doses; 6 months to <2 years 1-2 mg/kg daily as single or in 2 divided doses. Max: 37.5 mg daily; 2-12 years 1-2 mg/kg daily as single or in 2 divided doses. Max: 100 mg daily.

Oral
Hypertension
Adult: As monotherapy or in combination with other antihypertensives: Initially, 12.5 mg daily, may be increased up to 50 mg daily as necessary. Max: 100 mg daily. Dosage is individualised according to patient response.
Elderly: >65 years Initially, 12.5 mg daily, titrate as necessary in increments of 12.5 mg.
Child: <6 months 3 mg/kg daily in 2 divided doses; 6 months to <2 years 1-2 mg/kg daily as single or in 2 divided doses. Max: 37.5 mg daily; 2-12 years 1-2 mg/kg daily as single or in 2 divided doses. Max: 100 mg daily.
Administration
Should be taken with food.
Contraindications
Hypersensitivity to sulfonamide-derived drugs. Anuria.
Special Precautions
Patient with fluid or electrolyte imbalance, Addison’s disease, ascites due to cirrhosis, prediabetes or diabetes mellitus, hypercholesterolaemia, bronchial asthma, SLE, gout. Postoperative period after bariatric surgery. Hepatic and severe renal impairment. Children and elderly. Pregnancy and lactation.
Adverse Reactions
Significant: Skin photosensitivity; increased risk of non-melanoma skin cancer, basal cell carcinoma, squamous cell carcinoma; electrolyte imbalance (e.g. hyponatraemia, hypochloraemic alkalosis, hypokalaemia, hypomagnesaemia, hypercalcaemia), hyperuricaemia, hyperglycaemia, SLE exacerbation or activation, hypersensitivity reactions. Rarely, acute transient myopia, acute angle-closure glaucoma.
Blood and lymphatic system disorders: Leucopenia, agranulocytosis, thrombocytopenia, aplastic anaemia, haemolytic anaemia.
Eye disorders: Blurred vision (transient), xanthopsia.
Gastrointestinal disorders: Gastric irritation, nausea, vomiting, abdominal cramps, diarrhoea, constipation, pancreatitis, sialoadenitis.
General disorders and administration site conditions: Weakness.
Hepatobiliary disorders: Jaundice.
Metabolism and nutrition disorders: Anorexia.
Musculoskeletal and connective tissue disorders: Muscle spasm.
Nervous system disorders: Dizziness, vertigo, paraesthesia, headache.
Renal and urinary disorders: Renal dysfunction, interstitial nephritis, glycosuria.
Skin and subcutaneous tissue disorders: Alopecia, skin rash, toxic epidermal necrolysis, urticaria.
Vascular disorders: Hypotension, orthostatic, hypotension.
Patient Counseling Information
This medicine may cause photosensitivity reactions, avoid exposure to direct sunlight and UV light and apply sunscreen when going outdoors.
Monitoring Parameters
Monitor serum electrolytes (e.g. Na, K), blood pressure, BUN, creatinine. Assess skin for photosensitivity and skin cancer; visual acuity and ocular pain.
Overdosage
Symptoms: Electrolyte depletion (e.g. hypokalaemia, hypochloraemia, hyponatraemia), and dehydration. Management: Symptomatic and supportive treatment. May induce emesis or perform gastric lavage for recent ingestion. Administration of activated charcoal may be given within 1 hour of ingestion. Correct dehydration, electrolyte imbalance, hepatic coma, and hypotension by established procedures. Give oxygen or artificial respiration for respiratory impairment as needed.
Drug Interactions
May reduce renal clearance and enhance the toxic effect of lithium. Potentiation of orthostatic hypotension with alcohol, barbiturates, or narcotics. May reduce therapeutic effect of antidiabetics. Additive effect with other antihypertensive drugs. Reduced absorption with cholestyramine and colestipol resins. Enhanced hypokalaemic effect with corticosteroids, ACTH. May decrease arterial response to pressor amines (e.g. norepinephrine). May increase response to neuromuscular blocking action of skeletal muscle relaxants (e.g. tubocurarine).
Food Interaction
May potentiate orthostatic hypotension with alcohol.
Lab Interference
May interfere with parathyroid function tests. May cause false positive result to aldosterone/renin ratio (ARR).
Action
Description:
Mechanism of Action: Hydrochlorothiazide is a thiazide diuretic which acts by inhibiting Na reabsorption in the distal tubules, thereby causing increased excretion of Na, K, hydrogen ions, and water. The hypotensive effects are initially due to volume reduction, but the persisting effect includes other undetermined mechanisms that reduce peripheral resistance.
Onset: Diuresis: Approx 2 hours. Peak effect: Approx 4 hours.
Duration: 6-12 hours.
Pharmacokinetics:
Absorption: Rapidly and fairly well absorbed from the gastrointestinal tract. Bioavailability: Approx 65-75%. Time to peak plasma concentration: Approx 1-5 hours.
Distribution: Crosses placenta, enters breast milk. Volume of distribution: 3.6-7.8 L/kg. Plasma protein binding: Approx 40-68%.
Excretion: Mainly via urine (≥61% as unchanged drug). Elimination half-life: Approx 5-15 hours.
Chemical Structure

Chemical Structure Image
Hydrochlorothiazide

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 3639, Hydrochlorothiazide. https://pubchem.ncbi.nlm.nih.gov/compound/Hydrochlorothiazide. Accessed Oct. 24, 2023.

Storage
Store between 20-25°C. Protect from light and moisture.
MIMS Class
Diuretics
ATC Classification
C03AA03 - hydrochlorothiazide ; Belongs to the class of low-ceiling thiazide diuretics.
References
Anon. Hydrochlorothiazide. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 01/09/2022.

Anon. Hydrochlorothiazide. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 01/09/2022.

Apo-Hydrochlorothiazide 25 mg and 50 mg Tablets (Apotex Inc.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 01/09/2022.

Buckingham R (ed). Hydrochlorothiazide. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 01/09/2022.

Hydrochlorothiazide Capsules (Aurobindo Pharma Limited). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 01/09/2022.

Hydrochlorothiazide Tablets (Teva Pharmaceuticals). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 01/09/2022.

Joint Formulary Committee. Hydrochlorothiazide. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 01/09/2022.

Disclaimer: This information is independently developed by MIMS based on Hydrochlorothiazide from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2024 MIMS. All rights reserved. Powered by MIMS.com
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