HYDROCHLOROTHIAZIDE INTENSOL
Clinical safety rating: safe
Other antihypertensive drugs can have additive effects Lithium levels may be increased Can cause hypokalemia and hyponatremia.
Inhibits sodium-chloride symporter in distal convoluted tubule, reducing sodium and chloride reabsorption and increasing water excretion.
| Metabolism | Not extensively metabolized; eliminated primarily unchanged by renal tubular secretion |
| Excretion | Primarily renal (≥95% as unchanged drug); negligible biliary/fecal elimination (<5%). |
| Half-life | Terminal half-life 6–15 hours (mean ~10 hours); prolonged in renal impairment (creatinine clearance <30 mL/min) and elderly. |
| Protein binding | ~68% bound, primarily to albumin. |
| Volume of Distribution | Vd 0.8–1.6 L/kg (mean ~1.2 L/kg); distributes into extracellular fluid and crosses placenta. |
| Bioavailability | Oral bioavailability ~65–75% (range 50–80%); food may slightly enhance absorption. |
| Onset of Action | Oral: diuresis begins within 2 hours; peak effect at 4–6 hours. |
| Duration of Action | Duration of diuretic effect ~6–12 hours; antihypertensive effect persists up to 24 hours with once-daily dosing. |
| Molecular Weight | 297.74 |
25-100 mg orally once daily or in divided doses. Titrate based on response; maximum 200 mg/day.
| Dosage form | SOLUTION |
| Renal impairment | GFR 30-50 mL/min: reduce dose by 50% or administer every 24-48 hours. GFR <30 mL/min: generally ineffective, consider alternative. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B or C: use with caution; consider dose reduction due to risk of electrolyte disturbances and hepatic encephalopathy. |
| Pediatric use | 1-2 mg/kg/day orally once daily or in divided doses. Maximum 100 mg/day. Not recommended for infants <2 years. |
| Geriatric use | Start at 12.5-25 mg orally once daily; titrate slowly. Monitor electrolyte levels and renal function. Increased risk of hyponatremia and hypokalemia. |
| 1st trimester | Crosses placenta; associated with risk of oligohydramnios and fetal/neonatal complications. Use only if clearly needed. |
| 2nd trimester | May cause fetal/neonatal complications including jaundice, electrolyte disturbances, and thrombocytopenia. Avoid if possible. |
| 3rd trimester | Can cause oligohydramnios, fetal/neonatal electrolyte disturbances, and jaundice. Avoid near term. |
Clinical note
Other antihypertensive drugs can have additive effects Lithium levels may be increased Can cause hypokalemia and hyponatremia.
| FDA category | Animal |
| Placental transfer | Crosses placenta (evidence from animal and human studies). |
| Breastfeeding |
■ FDA Black Box Warning
None
| Common Effects | edema |
| Serious Effects |
AnuriaHypersensitivity to hydrochlorothiazide or sulfonamide-derived drugsSevere renal impairment (CrCl <30 mL/min)
| Precautions | Hypokalemia, Hyponatremia, Hyperuricemia, Acute myopia/secondary angle-closure glaucoma, Sulfonamide allergy cross-reactivity |
| Food/Dietary | Avoid excessive intake of potassium-rich foods (e.g., bananas, oranges, tomatoes, leafy greens) unless directed by a physician, as HCTZ can cause hypokalemia. However, routine potassium supplementation is not recommended unless hypokalemia develops. Decrease dietary sodium intake to enhance antihypertensive effect. Grapefruit juice does not interact significantly with HCTZ. Alcohol may potentiate orthostatic hypotension. |
Loading safety data…
| Hydrochlorothiazide is excreted into breast milk. Use with caution; may suppress maternal lactation. Monitor infant for signs of dehydration and electrolyte imbalance. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | First trimester: Limited data; thiazide diuretics are generally avoided due to potential placental hypoperfusion. Second/third trimester: May cause fetal or neonatal jaundice, thrombocytopenia, and electrolyte disturbances. Avoid for treatment of gestational hypertension unless other options are contraindicated. |
| Fetal Monitoring | Monitor maternal blood pressure, serum electrolytes (Na, K, Cl), renal function, and urine output. Fetal ultrasound for growth assessment and amniotic fluid volume. Neonatal monitoring for jaundice, thrombocytopenia, and electrolyte imbalances. |
| Fertility Effects | No known direct effects on fertility in males or females. In men, thiazides have rarely been associated with erectile dysfunction. No impact on ovarian function or sperm parameters in standard studies. |
| Clinical Pearls | Hydrochlorothiazide (HCTZ) Intensol is a concentrated oral solution (100 mg/mL) used for patients who have difficulty swallowing tablets or require flexible dosing. Monitor serum electrolytes (especially potassium, sodium, magnesium) and renal function before and during therapy. HCTZ may cause acute angle-closure glaucoma; advise patients to report eye pain or blurred vision. It can precipitate gout by increasing serum uric acid. Avoid use in patients with anuria or hypersensitivity to sulfonamides. Concomitant use with lithium may increase lithium levels; monitor closely. NSAIDs can reduce the antihypertensive effect. Onset of diuresis occurs within 2 hours, peak at 4 hours, duration 6-12 hours. Use caution in hepatic impairment as electrolyte changes may precipitate hepatic encephalopathy. |
| Patient Advice | Take this medication exactly as prescribed, usually once daily in the morning to avoid nighttime urination. · Measure the dose carefully using the provided dropper; mix with water, juice, or a soft food like applesauce before taking. · Avoid prolonged sun exposure and use sunscreen as HCTZ increases risk of photosensitivity and skin cancer. · Report symptoms of electrolyte imbalance: muscle cramps, weakness, irregular heartbeat, excessive thirst, or confusion. · Do not stop taking the medication abruptly without consulting your doctor; it is used to control blood pressure or edema. · Inform your doctor of all other medications, especially lithium, NSAIDs, other blood pressure drugs, and steroids. · Limit alcohol intake as it may worsen dizziness or hypotension. · If you have diabetes, monitor blood sugar more frequently as HCTZ may increase blood glucose levels. |