AQUATENSEN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for AQUATENSEN (AQUATENSEN).
AQUATENSEN (methylclothiazide) is a thiazide diuretic that inhibits the sodium-chloride cotransporter (NCC) in the distal convoluted tubule of the nephron, increasing excretion of sodium, chloride, and water, thereby reducing plasma volume and blood pressure.
| Metabolism | Methylclothiazide is primarily excreted unchanged in urine; hepatic metabolism is minimal. |
| Excretion | Renal: 50% unchanged; Fecal: 20% (via bile); remainder as inactive metabolites |
| Half-life | Terminal elimination half-life is 8-12 hours (mean 10 h); clinically, allows twice-daily dosing |
| Protein binding | 90-95% bound to albumin and alpha-1-acid glycoprotein |
| Volume of Distribution | 0.5-0.8 L/kg, indicating extensive tissue distribution |
| Bioavailability | Oral: 70-80% (first-pass metabolism 20-30%); IM: 90% |
| Onset of Action | Oral: 2 hours; IV: 15-30 minutes |
| Duration of Action | Oral: 12-24 hours (antihypertensive effect persists for 24 h with single dose); IV: 6-12 hours |
1-2 mg orally once daily, titrated to blood pressure response; maximum dose 4 mg/day.
| Dosage form | TABLET |
| Renal impairment | GFR 30-60 mL/min: dose reduction by 50%; GFR <30 mL/min: use contraindicated. |
| Liver impairment | Child-Pugh class A: no adjustment; Child-Pugh class B: 50% dose reduction; Child-Pugh class C: contraindicated. |
| Pediatric use | Weight-based: 0.01-0.02 mg/kg orally once daily; maximum 0.04 mg/kg/day or 1 mg/day. |
| Geriatric use | Start at 0.5 mg orally once daily; increase cautiously based on response and renal function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for AQUATENSEN (AQUATENSEN).
| Breastfeeding | Excreted into breast milk in low amounts; M/P ratio not established. Limited human data suggests no adverse effects in term infants. However, due to the potential for hypotension, use with caution in breastfeeding mothers of preterm or low-birth-weight infants. |
| Teratogenic Risk | First trimester: No increased risk of major malformations based on limited human data. Second and third trimesters: Risk of fetal and neonatal hypotension, oligohydramnios, and renal dysfunction due to decreased placental perfusion. Potential for skull ossification defects and anuria. |
■ FDA Black Box Warning
No FDA black box warning exists for methylclothiazide.
| Serious Effects |
["Anuria","Hypersensitivity to methylclothiazide or other sulfonamide-derived drugs","Severe renal impairment (creatinine clearance <30 mL/min)"]
| Precautions | ["Electrolyte imbalance (hypokalemia, hyponatremia, hypomagnesemia)","Hyperuricemia and gout","Hyperglycemia and diabetes mellitus","Hypercalcemia","Azotemia in renal impairment","Exacerbation of systemic lupus erythematosus","Photosensitivity","Orthostatic hypotension"] |
| Food/Dietary | Avoid high-sodium foods; limit potassium-rich foods if taking potassium supplements or ACE inhibitors. Grapefruit juice may increase absorption; avoid excessive intake. |
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| Fetal Monitoring |
| Monitor maternal blood pressure, renal function, and electrolytes. Assess fetal growth, amniotic fluid volume via ultrasound, and fetal heart rate monitoring. In neonates, monitor for hypotension, oliguria, and hyperkalemia. |
| Fertility Effects | No significant effects on fertility reported in animal studies. In humans, no evidence of impaired fertility or adverse reproductive outcomes. |
| Clinical Pearls | AQUATENSEN is a thiazide-like diuretic; monitor serum potassium, sodium, and magnesium. Avoid in anuria or sulfonamide allergy. May exacerbate gout, SLE, or diabetes. Use with caution in hepatic impairment; may precipitate hepatic coma. |
| Patient Advice | Take in the morning to avoid nighttime urination. · Avoid excessive sun exposure; use sunscreen. · Report symptoms of electrolyte imbalance: muscle cramps, weakness, irregular heartbeat. · Do not stop medication abruptly; may increase blood pressure. · Avoid alcohol or limit intake; may enhance hypotensive effects. |