Hydrochlorothiazide

Nursing pharmacology study reference (NCLEX-style monograph). Numeric values are standard teaching ranges for study and must be verified against current manufacturer labeling before clinical use. This is educational content, not prescribing guidance.

Hydrochlorothiazide (brand name Microzide) — Antihypertensive, diuretic; Thiazide diuretic.

Identification

• Therapeutic class: Antihypertensive, diuretic.
• Pharmacologic class: Thiazide diuretic.

Pharmacology

• Mechanism of action: Inhibits sodium and chloride reabsorption in the distal tubule, promoting diuresis and lowering blood pressure.
• Onset / peak / duration: Onset about 2 hours; peak 4 to 6 hours; duration 6 to 12 hours.
• Half-life / therapeutic level: Half-life 6 to 15 hours; no routine level.

Clinical use

• Indications: Hypertension, mild edema.
• Usual dose, route, frequency: 12.5 to 50 mg PO once daily in the morning.
• Maximum dose / adjustments: Max about 50 mg/day for hypertension; ineffective at low glomerular filtration rate.

Safety

• Contraindications: Anuria, sulfonamide hypersensitivity.
• Black box warning: None.
• Interactions: Digoxin (hypokalemia raises toxicity risk), lithium (toxicity), NSAIDs (reduced effect), corticosteroids (potassium loss).
• Pregnancy / lactation: Use only if clearly needed.
• High-alert: No.

Adverse effects

• Common side effects: Increased urination, hypokalemia, hyponatremia, dizziness, photosensitivity.
• Serious effects to report: Severe electrolyte imbalance, dehydration, gout flare, elevated glucose.
• Antidote / reversal: None; correct electrolytes and fluids.

Nursing process

• Assessment before administration: Blood pressure, weight, electrolytes (especially potassium and sodium), renal function.
• Interventions during therapy: Give in the morning to avoid nighttime urination; encourage potassium-rich foods.
• Monitor: Electrolytes, blood pressure, weight, glucose, uric acid.
• Evaluation / expected outcome: Reduced blood pressure and edema.

Patient teaching

• Patient teaching: Take in the morning; use sunscreen; report muscle cramps.
• Notify provider if: Muscle weakness or cramps, dizziness, irregular heartbeat.
• Administration tips: Morning dosing; with food if GI upset.