HYDROMOX
Clinical safety rating: caution
Comprehensive clinical and safety monograph for HYDROMOX (HYDROMOX).
Inhibits the sodium-chloride symporter (NCC) in the distal convoluted tubule of the kidney, reducing sodium and chloride reabsorption and increasing water excretion.
| Metabolism | Primarily excreted unchanged in the urine; minimal hepatic metabolism. |
| Excretion | Renal: 70% unchanged via tubular secretion; biliary/fecal: <10% |
| Half-life | Terminal elimination half-life: 6-9 hours; prolonged to 24-36 hours in renal impairment (CrCl <30 mL/min) |
| Protein binding | 65% bound to albumin and erythrocytes |
| Volume of Distribution | 4 L/kg (extensive tissue distribution, including erythrocytes) |
| Bioavailability | Oral: 65% (first-pass metabolism, food may reduce absorption) |
| Onset of Action | Oral: 2 hours; IV: 15-30 minutes |
| Duration of Action | Oral: 12-24 hours; IV: 6-12 hours; antihypertensive effect peaks at 4-6 weeks |
| Molecular Weight | 332.78 |
50-100 mg orally once daily; may increase to 200 mg/day for severe edema.
| Dosage form | TABLET |
| Renal impairment | GFR 30-60 mL/min: reduce dose by 50%; GFR <30 mL/min: contraindicated. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use. |
| Pediatric use | 1-2 mg/kg orally once daily; maximum 50 mg/day. |
| Geriatric use | Initiate at 25 mg orally once daily; titrate cautiously due to risk of electrolyte imbalance and hypotension. |
| 1st trimester | Teratogenic risk unknown; avoid use unless essential. Thiazide diuretics are generally avoided in first trimester due to potential for teratogenicity (limited human data, animal studies suggest risk). |
| 2nd trimester | Use only if clearly needed. Monitor for electrolyte disturbances and fetal effects. Thiazides may cause fetal or neonatal jaundice, thrombocytopenia, and electrolyte abnormalities. |
| 3rd trimester | Contraindicated in pregnancy-induced hypertension (PIH) and preeclampsia due to decreased placental perfusion. Avoid in third trimester unless no alternative. |
Clinical note
Comprehensive clinical and safety monograph for HYDROMOX (HYDROMOX).
| Placental transfer | Thiazide diuretics cross the placenta. Hydroflumethiazide is likely transferred to fetus; specific data limited. Molecular weight < 400 Da suggests significant transfer. |
| Breastfeeding | Hydromox (hydroflumethiazide) is excreted into breast milk in low amounts. However, thiazide diuretics may suppress lactation, especially at high doses. Caution is advised; monitor infant for signs of electrolyte disturbance. Use lowest effective dose if necessary. |
■ FDA Black Box Warning
None.
| Serious Effects |
AnuriaHypersensitivity to hydroflumethiazide or sulfonamide-derived drugsSevere renal impairment (CrCl < 30 mL/min)Hepatic coma or precoma
| Precautions | Electrolyte imbalances (hypokalemia, hyponatremia, hypomagnesemia, hypochloremia), Hyperuricemia and gout, Hypercalcemia, Sulfonamide allergy cross-sensitivity, Orthostatic hypotension, Systemic lupus erythematosus exacerbation, Acute angle-closure glaucoma (rare) |
| Food/Dietary | Avoid excessive intake of potassium-rich foods (bananas, oranges, spinach) unless directed. Limit sodium intake to enhance diuretic effect. Avoid grapefruit juice as it may affect metabolism. Do not take with high-tyramine foods (aged cheese, cured meats) if also taking MAOIs. |
Loading safety data…
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | Pregnancy Category B. No evidence of teratogenicity in animal studies; limited human data. Thiazide use in pregnancy, especially during first trimester, is generally avoided due to theoretical risk of fetal electrolyte disturbances and reduced placental perfusion. During second and third trimesters, may cause fetal or neonatal jaundice, thrombocytopenia, and electrolyte imbalances. Consider alternative antihypertensives. |
| Fetal Monitoring | Monitor maternal blood pressure, serum electrolytes (particularly sodium, potassium), and renal function throughout pregnancy. Fetal monitoring for growth and well-being (ultrasound, non-stress test) if used in second/third trimester. Observe neonates for jaundice, thrombocytopenia, and electrolyte abnormalities. |
| Fertility Effects | No known adverse effects on fertility in animal studies. In humans, thiazide diuretics are not associated with impaired fertility. However, electrolyte disturbances may theoretically impact reproductive function. |
| Clinical Pearls | Hydromox is not a recognized pharmaceutical name; the intended drug is likely Hydrochlorothiazide (HCTZ). HCTZ is a thiazide diuretic. Monitor serum potassium and magnesium; may cause hypokalemia and hypomagnesemia. Use cautiously in patients with renal impairment (CrCl <30 mL/min) or anuria. May exacerbate existing lupus erythematosus. Onset of diuresis is within 2 hours, peaks at 4 hours, duration 6-12 hours. Avoid in patients with sulfonamide allergy (cross-sensitivity possible). |
| Patient Advice | Take this medication in the morning to avoid nighttime urination. · May cause dizziness or lightheadedness; avoid driving if affected. · Do not take with alcohol or medications that lower blood pressure unless approved. · Report any signs of electrolyte imbalance: muscle cramps, weakness, irregular heartbeat. · Use sun protection; this drug may increase sensitivity to sunlight. · Do not use potassium supplements or salt substitutes without consulting your doctor. |