TRANDATE HCT
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TRANDATE HCT (TRANDATE HCT).
TRANDATE HCT is a combination of labetalol, a non-selective beta-blocker with selective alpha-1 blocking activity, and hydrochlorothiazide, a thiazide diuretic. Labetalol reduces peripheral vascular resistance via alpha-1 blockade and decreases heart rate and cardiac output via beta-blockade. Hydrochlorothiazide inhibits the sodium-chloride symporter in the distal convoluted tubule, promoting diuresis and reducing plasma volume.
| Metabolism | Labetalol is extensively metabolized primarily via glucuronidation (direct conjugation) and minor CYP2D6-mediated oxidation to an inactive metabolite. Hydrochlorothiazide is not metabolized; it is excreted unchanged in urine. |
| Excretion | Labetalol is primarily excreted in urine as unchanged drug (approximately 55-60%) and as glucuronide conjugates. About 12-27% is excreted in feces via biliary elimination. Hydrochlorothiazide is excreted unchanged in urine (≥95%) via renal tubular secretion. Total renal elimination of labetalol: ~55-60% unchanged; HCTZ: ~95% unchanged. |
| Half-life | Labetalol: terminal elimination half-life is 6-8 hours (range 3-16 hours) consistent with twice-daily dosing. Hydrochlorothiazide: terminal half-life 9-10 hours (range 6-15 hours), prolonged in renal impairment. |
| Protein binding | Labetalol: ~50% bound to albumin. Hydrochlorothiazide: ~40-68% bound to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | Labetalol: Vd 3-16 L/kg (mean 11 L/kg), indicating extensive tissue distribution. Hydrochlorothiazide: Vd 0.8-1.5 L/kg (mean 1 L/kg), limited distribution. |
| Bioavailability | Labetalol: oral bioavailability is 25-40% due to extensive first-pass metabolism. Hydrochlorothiazide: oral bioavailability is 65-75% (fasted). |
| Onset of Action | Oral: labetalol onset 0.5-2 hours, peak effect 2-4 hours. HCTZ onset 2 hours, peak 4-6 hours. IV labetalol (not in formulation): onset 2-5 minutes. |
| Duration of Action | Oral labetalol: 8-12 hours (supports twice-daily dosing). HCTZ: 6-12 hours (antihypertensive effect up to 24 hours with chronic dosing). |
Oral: 100 mg labetalol/25 mg hydrochlorothiazide twice daily, titrated based on blood pressure response; maximum 1200 mg labetalol/300 mg hydrochlorothiazide daily.
| Dosage form | TABLET |
| Renal impairment | GFR 30-90 mL/min: No adjustment. GFR <30 mL/min: Contraindicated due to hydrochlorothiazide component. |
| Liver impairment | Child-Pugh A: Use with caution; reduce labetalol dose. Child-Pugh B or C: Contraindicated due to extensive hepatic metabolism of labetalol. |
| Pediatric use | Not recommended; safety and efficacy not established for labetalol/hydrochlorothiazide combination. |
| Geriatric use | Start at lowest dose (100/25 mg daily); titrate slowly due to increased risk of hypotension and electrolyte imbalance. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for TRANDATE HCT (TRANDATE HCT).
| Breastfeeding | Labetalol is excreted into breast milk in low amounts (M/P ratio ~0.6-0.8); generally considered compatible with breastfeeding; monitor infant for bradycardia and hypotension. |
| Teratogenic Risk | First trimester: No clear association with major malformations in limited human data; labetalol crosses placenta. Second/third trimester: Potential fetal bradycardia, hypotension, hypoglycemia, and respiratory depression; intrauterine growth restriction reported with chronic use. |
| Fetal Monitoring |
■ FDA Black Box Warning
None
| Serious Effects |
Absolute: sinus bradycardia, heart block greater than first degree, cardiogenic shock, decompensated heart failure, bronchial asthma, hypersensitivity to labetalol, hydrochlorothiazide, or sulfonamide-derived drugs, anuria. Relative: diabetes mellitus, hyperthyroidism, pheochromocytoma (labetalol may paradoxically elevate blood pressure), severe renal impairment (CrCl <30 mL/min for thiazide efficacy).
| Precautions | Beta-blocker withdrawal: abrupt discontinuation may exacerbate angina or precipitate myocardial infarction in patients with coronary artery disease. Bronchospasm: avoid in patients with bronchial asthma or COPD. Heart failure: caution in patients with decompensated heart failure; may precipitate worsening. Peripheral vascular disease: may worsen symptoms. Hepatic impairment: labetalol is hepatically metabolized; use caution. Renal impairment: hydrochlorothiazide may be ineffective with CrCl <30 mL/min. Electrolyte disturbances: monitor potassium, sodium, magnesium; risk of hypokalemia, hyponatremia, hypomagnesemia. Hyperuricemia: can precipitate gout. Photosensitivity: with hydrochlorothiazide. Exacerbation of systemic lupus erythematosus: reported with thiazides. DM: beta-blockers may mask hypoglycemia. Surgery: withdrawal before elective surgery recommended. |
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| Monitor maternal blood pressure and heart rate; fetal heart rate and growth; neonatal monitoring for bradycardia, hypotension, and hypoglycemia after delivery. |
| Fertility Effects | No known significant adverse effects on fertility in humans; animal studies showed no impairment. |