TRANDATE HCT
Clinical safety rating
cautionComprehensive 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). |
| Molecular Weight | 364.87 |
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 | Avoid during first trimester due to risk of fetal bradycardia and hypotension; associated with congenital defects in animal studies. |
| 2nd trimester | Use only if benefit outweighs risk; may cause fetal growth restriction (IUGR) and oligohydramnios. |
| 3rd trimester | Avoid near term due to risk of neonatal bradycardia, hypotension, hypoglycemia, and respiratory depression. |
Clinical note
Comprehensive clinical and safety monograph for TRANDATE HCT (TRANDATE HCT).
| Placental transfer | Labetalol crosses the placenta and achieves fetal concentrations similar to maternal levels. Hydrochlorothiazide also crosses the placenta. |
| Breastfeeding | Both labetalol (molecular weight ~364.9 Da) and hydrochlorothiazide (molecular weight ~297.7 Da) are excreted into breast milk. Labetalol levels are low, but hydrochlorothiazide may suppress lactation. Monitor infant for hypotension, bradycardia, and electrolyte imbalance. |
| Lactation Rating | L3 (Moderately Safe) - Use with caution, especially with hydrochlorothiazide component. |
| 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 | 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. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to labetalol, hydrochlorothiazide, or sulfonamide derivativesBronchial asthmaOvert cardiac failureCardiogenic shockSevere bradycardia or heart block greater than first degreeAnuriaSevere renal impairment (CrCl <30 mL/min)
| 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. |
| Food/Dietary | Avoid tyramine-rich foods (aged cheese, cured meats, fermented soy products) due to potential hypertensive crises. Limit caffeine intake; may increase heart rate. Avoid excessive potassium-rich foods or supplements unless monitored due to hydrochlorothiazide's potassium-wasting effect. Take with food to reduce GI upset. |
| Clinical Pearls | Trandate HCT combines labetalol (alpha/beta blocker) and hydrochlorothiazide. Monitor heart rate, blood pressure, and electrolytes. Avoid in asthma, COPD, bradycardia, heart block, and anuria. Taper if discontinuing. May mask hypoglycemia in diabetics. Can cause orthostatic hypotension; dose at bedtime initially. |
| Patient Advice | Take exactly as prescribed, usually once daily, with or without food. · Do not stop suddenly; tapering is necessary to avoid rebound hypertension. · May cause dizziness or lightheadedness; rise slowly from sitting or lying. · Avoid alcohol; it can worsen dizziness and side effects. · Inform your doctor if you experience slow heartbeat, fainting, swelling of feet/ankles, or unusual weight gain. · May cause photosensitivity; use sunscreen and protective clothing. · Monitor blood pressure regularly at home. |
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