DIURIL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for DIURIL (DIURIL).
Inhibits sodium reabsorption in the distal convoluted tubule by blocking the sodium-chloride symporter, leading to increased excretion of sodium, chloride, and water.
| Metabolism | Primarily excreted unchanged in urine; minimal hepatic metabolism. |
| Excretion | Primarily renal (90-95% excreted unchanged via glomerular filtration and tubular secretion); minimal biliary/fecal (<5%). |
| Half-life | Terminal elimination half-life is 6-15 hours (mean 10 hours). In renal impairment, half-life can exceed 24 hours. |
| Protein binding | Highly protein-bound (90-95%), primarily to albumin. |
| Volume of Distribution | Vd is 3-11 L/kg (mean 7 L/kg), indicating extensive tissue distribution. |
| Bioavailability | Oral bioavailability is 65-75% due to first-pass metabolism. |
| Onset of Action | Oral: 2 hours; IV: 15-30 minutes. |
| Duration of Action | Oral: 6-12 hours; IV: 2-6 hours. Effect duration is dose-dependent. |
| Molecular Weight | 295.72 |
Adults: 500 mg to 1000 mg orally once or twice daily; maximum 2000 mg per day.
| Dosage form | SUSPENSION |
| Renal impairment | GFR 30-50 mL/min: reduce dose by 50%; GFR <30 mL/min: avoid or use with extreme caution. |
| Liver impairment | Child-Pugh Class A: no adjustment; Class B: reduce dose by 50%; Class C: avoid. |
| Pediatric use | Children 2-12 years: 10-20 mg/kg orally once daily; maximum 375 mg per day. |
| Geriatric use | Start at lowest effective dose; monitor electrolytes and renal function; typical initial dose 250 mg once daily. |
| 1st trimester | Chlorothiazide crosses the placenta. Use in first trimester is generally avoided due to risk of fetal electrolyte disturbances and potential teratogenicity, though data are limited. Use only if clearly needed. |
| 2nd trimester | May be used if benefit outweighs risk, but caution due to possible maternal hypovolemia, electrolyte imbalance, and uteroplacental hypoperfusion. |
| 3rd trimester | Avoid in third trimester due to risk of neonatal thrombocytopenia, electrolyte disturbances, and maternal volume depletion. |
Clinical note
Comprehensive clinical and safety monograph for DIURIL (DIURIL).
| Placental transfer | Chlorothiazide crosses the placenta. Degree of transfer is moderate; fetal serum levels are about 30% of maternal levels. |
| Breastfeeding | Chlorothiazide is excreted in breast milk in small amounts. It may suppress lactation and cause jaundice or electrolyte disturbances in the infant. Avoid if possible; if used, monitor infant for signs of electrolyte imbalance. |
■ FDA Black Box Warning
None.
| Serious Effects |
AnuriaHypersensitivity to chlorothiazide or sulfonamide-derived drugsHepatic coma or pre-comaSevere renal impairment (CrCl <30 mL/min)
| Precautions | Electrolyte imbalances (hypokalemia, hyponatremia, hypochloremic alkalosis), Increase in blood glucose and uric acid levels, Photosensitivity, Systemic lupus erythematosus exacerbation |
| Food/Dietary | Avoid excessive intake of potassium-rich foods (e.g., bananas, oranges, leafy greens) unless directed by your doctor, as thiazides can cause potassium loss, but potassium supplements may be needed. Maintain a balanced diet; sodium restriction may enhance antihypertensive effect. Grapefruit juice may increase drug absorption; moderate intake is not a major concern. Alcohol can enhance hypotensive effects; limit consumption. |
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| Lactation Rating | L4 (Possibly Hazardous) |
| Teratogenic Risk | First trimester: Crosses placenta; limited human data but no clear teratogenic signal; potential for electrolyte disturbances in fetus. Second/third trimester: Associated with maternal hypovolemia and decreased placental perfusion; risk of fetal jaundice, thrombocytopenia, and electrolyte imbalances. Avoid for gestational hypertension due to plasma volume reduction. |
| Fetal Monitoring | Monitor maternal blood pressure, serum electrolytes (especially potassium), uric acid, glucose, and renal function. Serial fetal growth ultrasound and amniotic fluid assessment due to potential placental hypoperfusion. Monitor for neonatal electrolyte disturbances and thrombocytopenia at delivery. |
| Fertility Effects | No significant adverse effects on human fertility reported. Theoretical impact from electrolyte disturbances or alterations in reproductive hormone levels, but clinical data lacking. |
| Clinical Pearls | DIURIL (chlorothiazide) is a thiazide diuretic used for hypertension and edema. Monitor serum electrolytes, especially potassium and sodium, as hypokalemia and hyponatremia are common. Also monitor blood glucose and uric acid levels, as thiazides can cause hyperglycemia and hyperuricemia. Administer in the morning to avoid nocturia. Use with caution in patients with renal impairment (CrCl <30 mL/min) as efficacy decreases. |
| Patient Advice | Take this medication exactly as prescribed, usually once daily in the morning to prevent nighttime urination. · Avoid excessive sun exposure as this drug can increase sensitivity to sunlight; use sunscreen and protective clothing. · Report symptoms of electrolyte imbalance such as muscle cramps, weakness, dizziness, or irregular heartbeat. · Do not stop taking this medication without consulting your doctor as sudden discontinuation may worsen blood pressure. · Limit alcohol intake as it can enhance the blood pressure-lowering effect and increase dizziness. · Inform your healthcare provider of all medications you take, especially lithium, NSAIDs, and other antihypertensives. |