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Metoprolol Tartrate / Hydrochlorothiazide

Pronunciation: MET-oh-PROE-lol TAR-trate/HYE-droe-KLOR-oh-THYE-a-zide
Class: Antihypertensive combination

Trade Names

Lopressor HCT
- Tablets 50 mg metoprolol tartrate/25 mg hydrochlorothiazide
- Tablets 100 mg metoprolol tartrate/25 mg hydrochlorothiazide
- Tablets 100 mg metoprolol tartrate/50 mg hydrochlorothiazide

Indications and Usage

Management of hypertension.

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Contraindications

Sinus bradycardia; heart block greater than first degree; cardiogenic shock; overt cardiac failure; sick-sinus syndrome; severe peripheral arterial circulatory disorder; pheochromocytoma; anuria; hypersensitivity to any component of the product, beta-blockers, or sulfonamide-derivatives.

Dosage and Administration

Determine dosage by individual titration.

Adults

PO Hydrochlorothiazide is usually given at a dose of 12.5 to 50 mg/day. Metoprolol is effective in the dose range of 100 to 450 mg/day. In general, once-daily dosing is effective and can maintain a reduction in BP throughout the day; however, lower doses of metoprolol, especially 100 mg, may not maintain full effect at end of 24-h period and larger or more frequent doses may be required.

Storage/Stability

Store at 59° to 86°F. Protect from moisture.

Drug Interactions

Barbiturates

Metoprolol bioavailability may be decreased.

Bile acid sequestrants (eg, cholestyramine)

May reduce hydrochlorothiazide absorption; give at least 2 h before the sequestrant.

Catecholamine-depleting drugs (eg, reserpine)

May have additive effect when given with metoprolol.

Clonidine

May enhance or reverse antihypertensive effect. Potentially life-threatening situations may occur, especially on abrupt withdrawal of clonidine.

Diazoxide

May increase the risk of hyperglycemia.

Digitalis glycosides

Diuretic-induced hypokalemia and hypomagnesemia may precipitate digitalis-induced arrhythmias.

General anesthetics

Metoprolol cardiodepressant effects may be increased.

Hydralazine

Serum levels of hydralazine and metoprolol may increase.

Insulin, sulfonylureas

Hypoglycemic effect may be decreased. May need higher doses of sulfonylurea or insulin.

Lidocaine

Lidocaine levels may increase, leading to toxicity.

Lithium

Renal excretion of lithium may be decreased.

Loop diuretics

Synergistic effects may result in profound diuresis and serious electrolyte abnormalities.

NSAIDs

Some agents may impair antihypertensive effect.

Potent inhibitors of CYP2D6 (eg, antiarrhythmic agents [eg, propafenone, quinidine], antifungal agents [eg, terbinafine], antihistamines [eg, diphenhydramine], antimalarial agents [eg, hydroxychloroquine], antipsychotic agents [eg, thioridazine], antiulcer agents [eg, cimetidine], antiviral agents [eg, ritonavir], bupropion, fluoxetine, paroxetine)

May elevate metoprolol plasma levels, increasing the risk of adverse reactions.

Prazosin

Orthostatic hypotension may be increased.

Rifampin

Effects of metoprolol may be decreased.

Verapamil

Effects of verapamil or metoprolol may be increased.

Laboratory Test Interactions

Antinuclear antibodies may develop but are usually reversible on discontinuation. Serum protein-bound iodine levels may be reduced without signs of thyroid disturbance. May cause diagnostic interference of serum electrolyte levels, blood and urine glucose levels, serum bilirubin levels, and serum uric acid levels.

Adverse Reactions

Cardiovascular

Bradycardia (about 6%); shortness of breath (3%); decreased exercise tolerance (about 1%); CHF, intensification of AV block.

CNS

Dizziness, drowsiness, fatigue, headache, lethargy, somnolence, tiredness, vertigo (about 10%); depression (5%); nightmares (about 1%).

Dermatologic

Purpura, sweating (1%); Stevens-Johnson syndrome.

EENT

Blurred vision, earache, tinnitus (1%).

GI

Diarrhea (5%); constipation, digestive disorder, dry mouth, flatulence, gastric pain, heartburn, nausea, vomiting (about 1%).

Genitourinary

Impotence (1%).

Hematologic-Lymphatic

Agranulocytosis, aplastic anemia, leukopenia, nonthrombocytopenic purpura, thrombocytopenia, thrombocytopenic purpura.

Hepatic

Elevated alkaline phosphatase, elevated LDH and transaminase, hepatic function impairment, hepatitis, jaundice (postmarketing).

Metabolic-Nutritional

Hypokalemia (less than 10%); anorexia, edema, gout (1%).

Musculoskeletal

Muscle pain (1%).

Respiratory

Dyspnea (about 1%).

Miscellaneous

Flu syndrome (about 10%); gangrene, hypersensitivity including fever with aching and sore throat, laryngospasm and respiratory distress, necrotizing angiitis.

Precautions

Pregnancy

Category C .

Lactation

Hydrochlorothiazide and metoprolol are excreted in breast milk.

Children

Safety and efficacy not established.

Elderly

Use with caution, usually starting at low end of dosage range because of greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant diseases or other drug therapy.

Hypersensitivity

May occur in patients with or without history of allergy or bronchial asthma; cross-sensitivity with sulfonamides may occur.

Renal Function

Use with caution in patients with severe renal disease; hydrochlorothiazide may precipitate azotemia.

Hepatic Function

Use with caution.

Bronchospastic disease

Use with caution; administer in smaller divided doses.

Cardiac failure

Use with caution in patients controlled by digitalis.

Diabetes

Metoprolol may mask tachycardia associated with hypoglycemia. Latent diabetes may become manifest with hydrochlorothiazide therapy.

Hyperuricemia

Hyperuricemia or frank gout may be precipitated.

Ischemic heart disease

May occur following abrupt discontinuation of metoprolol.

Lupus erythematosus

Exacerbation or activation may occur.

Postsympathectomy patients

Hydrochlorothiazide may enhance antihypertensive effects.

Thyrotoxicosis

Metoprolol may mask clinical signs of developing or continuing hyperthyroidism. Abrupt withdrawal of metoprolol may exacerbate symptoms of hyperthyroidism, including thyroid storm.

Overdosage

Symptoms

Alkalosis, anuria, bradycardia, bronchospasm, cardiac failure, confusion, cramps of the calf muscles, dizziness, fatigue, hypochloremia, hypokalemia, hyponatremia, hypotension, impairment of consciousness, increased BUN, nausea, oliguria, paresthesia, polyuria, shock, tachycardia, thirst, vomiting, weakness.

Patient Information

  • Instruct patients that if a dose is missed, to take only the next scheduled dose without doubling the dose.
  • Advise patient to take this medication regularly and continuously, as directed.
  • Advise patient to avoid operating machinery and driving, or engaging in other tasks requiring alertness until the response to therapy has been determined.
  • Advise patients to contact health care provider if any difficulty breathing occurs.
  • Instruct patients to inform health care provider before any type of surgery that metoprolol is being taken.

Copyright © 2009 Wolters Kluwer Health.

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