HYDRO-D
Clinical safety rating: caution
Comprehensive clinical and safety monograph for HYDRO-D (HYDRO-D).
Thiazide diuretic that inhibits the sodium-chloride symporter (NCC) in the distal convoluted tubule, reducing sodium and water reabsorption and increasing potassium excretion.
| Metabolism | Not extensively metabolized; undergoes hepatic metabolism via CYP450 enzymes to a minor extent (primarily hydroxylation). |
| Excretion | Renal: approximately 50% as unchanged drug; biliary/fecal: approximately 50% as metabolites and minor unchanged drug. |
| Half-life | Terminal elimination half-life: 5.6 to 15 hours; prolonged in renal impairment and in patients with heart failure. |
| Protein binding | 99% bound, primarily to albumin. |
| Volume of Distribution | 3.6 to 5.5 L/kg; extensive tissue distribution including placenta and breast milk. |
| Bioavailability | Oral: 65–85% due to first-pass metabolism; may be reduced in patients with hepatic dysfunction. |
| Onset of Action | Oral: 1 hour; Intravenous: 15 minutes; onset of diuresis within 1 hour after oral dose. |
| Duration of Action | Oral: 12–24 hours; Intravenous: 2–6 hours; diuretic effect may persist for 6–12 hours after oral administration. |
25-100 mg orally once daily in the morning.
| Dosage form | TABLET |
| Renal impairment | Contraindicated if GFR < 30 mL/min. For GFR 30-50 mL/min, reduce dose by 50%. |
| Liver impairment | Contraindicated in Child-Pugh class C. For Child-Pugh class B, reduce dose by 50%. |
| Pediatric use | 2-4 mg/kg orally once daily; maximum 100 mg/day. |
| Geriatric use | Start at 12.5-25 mg orally once daily; titrate slowly due to increased risk of electrolyte disturbances. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for HYDRO-D (HYDRO-D).
| Breastfeeding | Hydrochlorothiazide (HCTZ) is excreted into breast milk in small amounts. The M/P ratio is approximately 0.5. Risk of suppressing lactation exists, especially with high doses. Caution advised; alternative diuretics preferred. |
| Teratogenic Risk | First trimester: Use of thiazide diuretics during the first trimester is generally avoided due to risk of fetal hypotension and decreased placental perfusion, though no consistent teratogenic effects have been demonstrated. Second/third trimester: May cause fetal hypovolemia, electrolyte disturbances, and possible hypoglycemia; use only if clearly needed. |
■ FDA Black Box Warning
Sulfonamide hypersensitivity: Can cause anaphylaxis, Stevens-Johnson syndrome, and other severe allergic reactions in patients with sulfonamide allergy.
| Serious Effects |
["Anuria","Hypersensitivity to hydrochlorothiazide or sulfonamides","Severe renal impairment (CrCl <30 mL/min)","Hepatic coma or precoma","Untreated hypokalemia or hypercalcemia"]
| Precautions | ["Hypokalemia (monitor potassium levels)","Hyperglycemia (may impair glucose tolerance)","Hyperuricemia (may precipitate gout)","Volume depletion (risk of hypotension)","Electrolyte disturbances (sodium, magnesium)","Sulfonamide cross-reactivity"] |
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| Fetal Monitoring | Monitor maternal blood pressure, serum electrolytes (sodium, potassium), renal function, and fetal growth/amniotic fluid volume. Assess for signs of fetal bradycardia or hypoglycemia if used near delivery. |
| Fertility Effects | No direct adverse effects on fertility reported in women. In men, isolated reports of erectile dysfunction but no consistent effect on spermatogenesis. |