Clinical beta

FMBM is currently in clinical beta. Content is for professional review/testing and must not replace local protocols, senior clinical judgment, or official prescribing references.

Drug Monograph

Hydrochlorothiazide

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USE IF: Outpatient hypertension; selected mild edema; adjunct BP therapy; some recurrent calcium stone prevention β€” with electrolyte and volume monitoring.

AVOID IF: Anuria; uncorrected severe electrolyte depletion; acute pulmonary edema / emergent decongestion (prefer loop-directed acute care).

Hydrochlorothiazide (HCTZ)

Thiazide diuretic

AdultHTNDiureticOutpatientClinicWard

Indication

HTN β€’ Mild edema (outpatient) β€’ BP adjunct β€’ Stone prevention (selected)

At a glance

INDICATIONS (CORE USE)

- Hypertension - Mild edema (selected outpatient contexts) - Adjunct with other antihypertensives - Recurrent calcium stone prevention (selected patients)

ADULT DOSE (STANDARD)

HTN: 12.5–25 mg PO daily Edema: higher doses may be used in outpatient care β€” review electrolytes and renal function before titrating

MAX DOSE

Diminishing BP benefit with more adverse effects at higher doses β€” avoid reflexive escalation without labs and renal review

Route

PO

PEDIATRIC DOSE

Specialist / weight-based use only

Do not miss

Must-not-miss safety points

Major warning

- Hyponatremia / hypokalemia risk - Volume depletion / hypotension - Gout / hyperuricemia flare risk - Thiazide less effective in significant renal impairment - Not for acute pulmonary edema / emergency decongestion

Indications

Primary

  • Hypertension
  • Mild edema states (selected outpatient contexts)

Secondary

  • Adjunct with other antihypertensives
  • Recurrent calcium stone prevention (selected patients)

Other

  • Selected combination therapy use (ACEi/ARB combination product context)

Dosing

STANDARD (ADULT PO)

HTN: 12.5–25 mg PO daily Edema: higher doses may be used β€” keep outpatient framing

ADULT DOSE

Use lowest effective dose Do not escalate reflexively without reviewing electrolytes and renal function

PEDIATRIC DOSE

Specialist / weight-based use only

MAX DOSE

Clinician-safe ceiling messaging: higher doses often add adverse effects more than BP benefit β€” titrate on BP, volume, Na⁺, K⁺, and renal function

Practical Note

- Strong outpatient BP tool β€” not an emergency decongestive like loop diuretics - If edema response is poor in advanced CKD, reassess for loop diuretic rather than blindly escalating HCTZ

Warnings

Clinical warnings

  • Hyponatremia
  • Hypokalemia
  • Hypotension / dehydration
  • Hyperuricemia / gout
  • Hyperglycemia / metabolic effects
  • Less effective at low eGFR compared with loop diuretics

Contraindications

  • Anuria
  • Severe hypersensitivity
  • Severe electrolyte depletion (uncorrected)

Drug interactions

  • ACEi / ARB β†’ hypotension / renal risk when volume depleted
  • Lithium β†’ increased lithium toxicity risk
  • Digoxin β†’ arrhythmia risk via hypokalemia
  • NSAIDs β†’ reduced antihypertensive / diuretic effect

Special populations

Pediatrics

Specialist / weight-based use only

Pregnancy

Pregnancy /

Lactation

follow current product labeling and specialist guidance (class effects and neonatal considerations per references).

Renal impairment

Reduced efficacy in advanced CKD β€” reassess if response is poor.

Hepatic impairment

Use cautiously in fluid-sensitive cirrhosis contexts.

Elderly

Higher risk of hyponatremia and orthostasis.

Administration

- PO once daily - Prefer morning dosing - Labs guide dose adjustments

Monitoring

  • Monitor: - BP - Electrolytes (Na, K) - Renal function - Volume status
  • Recheck: - 1–2 weeks after initiation or dose change - Reassess earlier if elderly, frail, volume depleted, or on RAAS blockade
  • Hold if:
    - Significant hyponatremia
    - Significant hypokalemia
    - Symptomatic hypotension
    - AKI / rising creatinine with volume depletion

Overdose / toxicity

Clinical Picture

Dehydration Hypotension Hyponatremia / hypokalemia Arrhythmia risk

Immediate Actions

Stop drug Supportive care Correct fluids / electrolytes

Antidote

None β†’ supportive care

Decontamination

Acute large ingestion: contact poison center; supportive care is mainstay.

Escalation

Refractory hypotension, severe electrolyte crisis, or arrhythmia β†’ escalate per ICU / nephrology pathways.

Clinical pearls

Common mistakes, resistance logic, and bedside traps

High-Yield

  • Strong outpatient BP drug; weak acute decongestive tool
  • Higher doses often add side effects more than BP benefit

Clinical

  • If edema / response is poor in advanced CKD, think loop diuretic rather than blindly escalating HCTZ
  • Watch sodium early, especially in older adults

Safety

  • Common silent harm = hyponatremia

Pharmacy Tool

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Hydrochlorothiazide 2 mg/mL oral suspension

suspension Β· oral

Acknowledge the statements above to unlock volume scaling and ingredient quantities.

Pharmacokinetics

- Oral only - Renal handling important - Effect and toxicity shaped by kidney function and volume status

Mechanism of action

- Distal convoluted tubule Na/Cl cotransporter inhibition

Common brand names

Saudi Arabia

Esidrex, HCTZ

Global

Microzide, HydroDIURIL, (placeholder β€” verify local formulation)

Common trade names are curated examples only β€” formulations and availability vary. Verify the exact product name with your local pharmacy and national regulator before prescribing or dispensing.

Country practice notes

Global data (no country-specific data available)

  • Follow local antimicrobial stewardship policy, hospital formulary, and national resistance guidance.
  • Confirm dosing, stock, and restrictions with institutional pharmacy and current product labeling.

References

Saudi Arabia

  • SFDA (Saudi Food & Drug Authority)
  • Saudi National Formulary / MOH (where available)

International

  • WHO Model List of Essential Medicines (verify current edition)
  • US FDA or EU EMA product information (when national SmPC is unavailable)
  • ACC / AHA hypertension guidance
  • KDIGO CKD blood pressure and diuretic use (where applicable)
  • AUA / metabolic stone prevention references (where applicable)
  • FDA / SFDA product labeling