HYDRODIURIL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for HYDRODIURIL (HYDRODIURIL).
Inhibits sodium-chloride symporter in the distal convoluted tubule of the kidney, increasing excretion of sodium and water, reducing plasma volume and cardiac output.
| Metabolism | Primarily eliminated unchanged by renal excretion; minor hepatic metabolism |
| Excretion | Renal: approximately 95% eliminated unchanged in urine via glomerular filtration and tubular secretion; biliary/fecal: <5%. |
| Half-life | Terminal elimination half-life is approximately 5.6–14.8 hours (mean ~10 hours); clinically, duration of diuresis correlates with half-life, allowing once or twice daily dosing. |
| Protein binding | Approximately 68% bound to plasma proteins (primarily albumin). |
| Volume of Distribution | Vd is about 3–4 L/kg; indicates extensive extravascular distribution, with accumulation in erythrocytes and kidneys. |
| Bioavailability | Oral: approximately 50–80% (mean ~65%); variable due to first-pass metabolism and food effects. |
| Onset of Action | Oral: diuresis begins within 2 hours, peak effect at 4–6 hours. |
| Duration of Action | Oral: diuretic effect lasts 6–12 hours; clinical note: antihypertensive effect may persist up to 24 hours with chronic therapy. |
| Molecular Weight | 297.74 |
25-100 mg orally once daily. For hypertension: 12.5-25 mg once daily.
| Dosage form | TABLET |
| Renal impairment | eGFR 30-50 mL/min: use with caution; eGFR <30 mL/min: not recommended (thiazides ineffective). Dose reduction may be needed. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: use with caution, consider reduced initial dose; Child-Pugh C: avoid use due to risk of electrolyte imbalances and hepatic encephalopathy. |
| Pediatric use | 1-2 mg/kg orally once daily; maximum 50 mg/day for children <12 years. For hypertension: 0.5-1 mg/kg once daily. |
| Geriatric use | Initiate at 12.5 mg orally once daily, increase slowly. Monitor electrolytes and renal function. Avoid in patients with severe renal impairment. |
| 1st trimester | Avoid. Hydrochlorothiazide crosses placenta; risk of fetal or neonatal jaundice, thrombocytopenia, and electrolyte disturbances. Use only if clearly needed. |
| 2nd trimester | Use with caution. Monitor for maternal hypovolemia and electrolyte imbalances; possible fetal effects. |
| 3rd trimester | Use with caution. May cause neonatal thrombocytopenia, jaundice, electrolyte disturbances, and hypoglycemia. Consider discontinuing if used for hypertension. |
Clinical note
Comprehensive clinical and safety monograph for HYDRODIURIL (HYDRODIURIL).
| Placental transfer | Crosses placenta. Achieves cord blood concentrations similar to maternal plasma. |
| Breastfeeding | Hydrochlorothiazide is excreted into breast milk in low amounts (peak milk concentration ~0.1 mg/L after 50 mg dose). Monitor infant for diuresis, electrolyte imbalance, and growth. Use with caution, especially in premature or ill infants. |
■ FDA Black Box Warning
None
| Serious Effects |
AnuriaSulfonamide allergy (cross-sensitivity)Hypersensitivity to hydrochlorothiazide or other sulfonamide-derived drugsSevere renal impairment (CrCl <30 mL/min)
| Precautions | Electrolyte disturbances (hypokalemia, hyponatremia, hypomagnesemia), Hypersensitivity reactions (including anaphylaxis), Acute angle-closure glaucoma, Systemic lupus erythematosus exacerbation, Photosensitivity, Sulfonamide cross-reactivity |
| Food/Dietary | Avoid high-sodium foods to prevent reduced antihypertensive effect. Do not use salt substitutes containing potassium unless approved by a physician. Grapefruit juice may increase HCTZ absorption; limit consumption. Maintain adequate fluid intake unless otherwise instructed. |
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| Lactation Rating | L2 (Probably Compatible) |
| Teratogenic Risk | First trimester: Thiazides cross the placenta. Potential association with congenital anomalies (e.g., cleft lip/palate) based on some studies; however, data are conflicting. Second and third trimesters: Risk of fetal or neonatal jaundice, thrombocytopenia, electrolyte disturbances. May cause decreased placental perfusion. Avoid in pregnancy-induced hypertension due to reduced maternal blood volume. |
| Fetal Monitoring | Monitor maternal blood pressure, serum electrolytes (especially potassium, sodium), renal function, and hydration status. Monitor fetal growth and amniotic fluid volume via ultrasound. Assess for signs of placental insufficiency. |
| Fertility Effects | No direct evidence of impaired fertility in humans. In animal studies, no adverse reproductive effects at therapeutic doses. Thiazides may reduce renal function and electrolyte balance but do not typically affect ovulation or spermatogenesis. |
| Clinical Pearls | Hydrochlorothiazide (HCTZ) is a first-line thiazide diuretic for hypertension and edema. Monitor serum potassium, sodium, and magnesium; hypokalemia is common. Use cautiously in patients with gout, as it can increase uric acid levels. Can exacerbate diabetes by impairing glucose tolerance. Effective in reducing cardiovascular events in hypertensive patients. Contraindicated in anuria and severe renal impairment (CrCl <30 mL/min). |
| Patient Advice | Take this medication in the morning to avoid nighttime urination. · Avoid prolonged sun exposure; use sunscreen, as this drug can cause photosensitivity. · Do not take supplements containing potassium unless directed by your doctor. · Report symptoms of electrolyte imbalance: muscle cramps, weakness, irregular heartbeat. · Avoid alcohol, which can increase dizziness and dehydration. |