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. |
| Molecular Weight | Total: 421.4 Da (Metoprolol tartrate: 684.8 Da, but active moiety metoprolol free base: 267.4 Da; HCTZ: 297.7 Da). Combined molecular weight: 565.1 Da (metoprolol tartrate + HCTZ). |
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 | First trimester: Risk of fetal harm based on animal data; human data limited. Use only if benefit outweighs risk. Metoprolol crosses placenta; HCTZ associated with possible teratogenicity. |
| 2nd trimester | Second trimester: Risk of fetal/neonatal adverse effects including bradycardia, hypotension, and hypoglycemia; HCTZ may cause electrolyte disturbances and reduced placental perfusion. Use with caution. |
| 3rd trimester | Third trimester: Increased risk of neonatal bradycardia, hypotension, and respiratory depression. Avoid HCTZ due to risk of neonatal thrombocytopenia, electrolyte imbalances, and potential oligohydramnios. |
Clinical note
Comprehensive clinical and safety monograph for LOPRESSOR HCT (LOPRESSOR HCT).
| Placental transfer | Both metoprolol and hydrochlorothiazide cross the placenta. Metoprolol shows moderate placental transfer; HCTZ crosses freely and may accumulate in fetus. |
| Breastfeeding |
■ FDA Black Box Warning
No FDA black box warning
| Serious Effects |
Hypersensitivity to metoprolol or hydrochlorothiazide or sulfonamide-derived drugsSinus bradycardiaHeart block greater than first degreeCardiogenic shockDecompensated heart failureSick sinus syndrome (without pacemaker)Severe hepatic impairment (for metoprolol)AnuriaSevere renal impairment (CrCl <30 mL/min) for HCTZ
| 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 |
| Food/Dietary | Avoid high-potassium foods if taking potassium-sparing diuretics concurrently; hydrochlorothiazide may cause hypokalemia, so potassium-rich foods are generally encouraged unless contraindicated by other medications. Limit sodium intake to reduce fluid retention and improve blood pressure control. Grapefruit juice may increase metoprolol levels; avoid large amounts. Reduce alcohol intake as it can exacerbate hypotension and dizziness. |
Loading safety data…
| Metoprolol is excreted into breast milk in small amounts; considered compatible with breastfeeding. HCTZ is excreted in low concentration; may suppress lactation or cause electrolyte disturbances in newborn. Monitor infant for bradycardia, hypotension, and diuretic effects. |
| Lactation Rating | L3 (Moderately Safe) - Limited data suggest risk of adverse effects in infant, but benefit may outweigh risk with caution. |
| 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. |
| 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. |
| Clinical Pearls | LOPRESSOR HCT combines metoprolol tartrate (a beta-1 selective blocker) and hydrochlorothiazide (a thiazide diuretic). Monitor heart rate and blood pressure closely; bradycardia is common. Check serum electrolytes, especially potassium, as thiazides can cause hypokalemia. Avoid abrupt discontinuation to prevent rebound hypertension. Caution in patients with asthma or COPD due to beta-blockade. |
| Patient Advice | Take exactly as prescribed; do not stop suddenly without consulting your doctor. · May cause dizziness or lightheadedness; avoid driving until you know how it affects you. · Monitor blood pressure and heart rate regularly as directed. · Report symptoms of low potassium: muscle cramps, weakness, irregular heartbeat. · Avoid alcohol as it can increase dizziness and lower blood pressure. · Limit salt intake to enhance antihypertensive effect. · May cause drowsiness; use caution with other sedatives. · Notify healthcare provider if you experience shortness of breath, swelling, or excessive fatigue. |