LOPRESSOR HCT
Clinical safety rating: caution
Comprehensive clinical and safety monograph for LOPRESSOR HCT (LOPRESSOR HCT).
LOPRESSOR HCT is a combination of metoprolol tartrate (a beta-1 selective adrenergic receptor blocker) and hydrochlorothiazide (a thiazide diuretic). Metoprolol reduces heart rate, myocardial contractility, and blood pressure by blocking beta-1 receptors in the heart. Hydrochlorothiazide increases sodium and water excretion by inhibiting the Na+/Cl- symporter in the distal convoluted tubule of the kidney, reducing plasma volume.
| Metabolism | Metoprolol: Primarily metabolized by CYP2D6; Hydrochlorothiazide: Not extensively metabolized in the liver. |
| Excretion | Metoprolol: <5% unchanged in urine; rest metabolized in liver (CYP2D6) and excreted renally as metabolites. Hydrochlorothiazide: >95% excreted unchanged in urine within 24 hours via tubular secretion. |
| Half-life | Metoprolol: 3-7 hours (terminal half-life); extensive metabolizers (CYP2D6) ~3-4 h, poor metabolizers ~7-8 h. Hydrochlorothiazide: 6-15 hours (terminal half-life). |
| Protein binding | Metoprolol: ~12% bound to albumin. Hydrochlorothiazide: ~67% bound to albumin. |
| Volume of Distribution | Metoprolol: 3.2-5.6 L/kg (extensive distribution into tissues). Hydrochlorothiazide: 0.8-1.5 L/kg (distributes into but not highly concentrated in tissues). |
| Bioavailability | Metoprolol: Oral ~50% (first-pass effect; extensive vs poor metabolizers affect AUC). Hydrochlorothiazide: Oral ~70% (range 60-80%). |
| Onset of Action | Metoprolol: Oral 1-2 hours for beta-blockade; IV 5-15 minutes. Hydrochlorothiazide: Oral 2 hours for diuresis; peak effect at 4-6 hours. |
| Duration of Action | Metoprolol: Oral 6-12 hours (dose-dependent); IV up to 4-6 hours. Hydrochlorothiazide: Oral 6-12 hours (diuretic effect); antihypertensive effect 12-24 hours with chronic dosing. |
1-2 tablets (each containing metoprolol tartrate 50 mg and hydrochlorothiazide 25 mg) orally once daily, maximum 4 tablets daily.
| Dosage form | TABLET |
| Renal impairment | For CrCl <30 mL/min, avoid hydrochlorothiazide component; use metoprolol alone. For CrCl 30-50 mL/min, use with caution; no specific dose adjustment. |
| Liver impairment | Child-Pugh Class A: no adjustment; Class B: reduce metoprolol dose by 50%; Class C: contraindicated due to hydrochlorothiazide risk of electrolyte disturbances. |
| Pediatric use | Not recommended for pediatric use; safety and efficacy not established. |
| Geriatric use | Start at lowest dose (1 tablet daily) due to increased risk of orthostatic hypotension and electrolyte imbalance; titrate slowly. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for LOPRESSOR HCT (LOPRESSOR HCT).
| Breastfeeding | Metoprolol: Excreted in breast milk in small amounts (M/P ratio approximately 3). Infant exposure is low but may cause bradycardia; caution advised. HCTZ: Excreted in breast milk in negligible amounts, but may suppress lactation or cause electrolyte disturbances. Not recommended during breastfeeding. Overall, weigh risks and benefits. |
| Teratogenic Risk | First trimester: Limited data, but studies suggest possible risk of congenital malformations (e.g., neural tube, cardiovascular) with metoprolol; HCTZ is generally avoided due to risk of fetal/neonatal complications. Second/third trimester: Fetal/neonatal adverse effects including IUGR, bradycardia, hypoglycemia with metoprolol; HCTZ can cause electrolyte disturbances, fetal/neonatal jaundice, thrombocytopenia. Both drugs cross the placenta. Use only if benefit outweighs risk. |
■ FDA Black Box Warning
No FDA black box warning
| Serious Effects |
["Hypersensitivity to metoprolol, hydrochlorothiazide, or sulfonamide-derived drugs","Sinus bradycardia","Heart block greater than first degree","Cardiogenic shock","Decompensated heart failure","Sick sinus syndrome","Severe hepatic impairment","Anuria"]
| Precautions | ["Abrupt cessation may exacerbate angina and increase risk of myocardial infarction","Beta-blockers may mask signs of hypoglycemia and hyperthyroidism","Can cause bronchospasm in patients with asthma or COPD","May precipitate heart failure or worsen cardiac function","Hydrochlorothiazide may cause electrolyte imbalances (hypokalemia, hyponatremia), hyperglycemia, hyperuricemia","Exacerbation or activation of systemic lupus erythematosus","May increase sensitivity to methotrexate","Use caution in patients with impaired renal function"] |
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| Fetal Monitoring | Maternal: Blood pressure, heart rate, serum electrolytes (especially potassium, sodium), renal function, blood glucose, uric acid, signs of bronchospasm or heart failure. Fetal/neonatal: Fetal growth (ultrasound), heart rate monitoring, and postnatal assessment for bradycardia, hypoglycemia, electrolyte imbalance. |
| Fertility Effects | Metoprolol: No known direct effect on fertility. HCTZ: No known direct effect on fertility. However, underlying hypertension may affect fertility. No specific studies on combination product. |