Metoprolol Tartrate and Hydrochlorothiazide (Page 5 of 6)

Potential Adverse Reactions

A variety of adverse reactions not listed above have been reported with other beta-adrenergic blocking agents and should be considered potential adverse reactions to metoprolol tartrate.

Central Nervous System: Reversible mental depression progressing to catatonia; visual disturbances; hallucinations; an acute reversible syndrome characterized by disorientation for time and place, short-term memory loss, emotional lability, slightly clouded sensorium, and decreased performance on neuropsychometrics.

Cardiovascular: Intensification of AV block (see CONTRAINDICATIONS).

Hematologic: Agranulocytosis, nonthrombocytopenic purpura, thrombocytopenic purpura.

Hypersensitive Reactions: Fever combined with aching and sore throat, laryngospasm, and respiratory distress.

Postmarketing Experience

The following adverse reactions have been reported during postapproval use of metoprolol tartrate: confusional state, an increase in blood triglycerides and a decrease in High Density Lipoprotein (HDL). Because these reports are from a population of uncertain size and are subject to confounding factors, it is not possible to reliably estimate their frequency.

Non-melanoma Skin Cancer

Hydrochlorothiazide is associated with an increased risk of non-melanoma skin cancer. In a study conducted in the Sentinel System, increased risk was predominantly for squamous cell carcinoma (SCC) and in white patients taking large cumulative doses. The increased risk for SCC in the overall population was approximately 1 additional case per 16,000 patients per year, and for white patients taking a cumulative dose of ≥ 50,000 mg the risk increase was approximately 1 additional SCC case for every 6,700 patients per year.

Hydrochlorothiazide

The following adverse reactions have been observed, but there has not been enough systematic collection of data to support an estimate of their frequency. Consequently, the reactions are categorized by organ systems and are listed in decreasing order of severity and not frequency.

Digestive: Pancreatitis, jaundice (intrahepatic cholestatic), sialadenitis, vomiting, diarrhea, cramping, nausea, gastric irritation, constipation, anorexia.

Cardiovascular: Orthostatic hypotension (may be potentiated by alcohol, barbiturates, or narcotics).

Neurologic: Vertigo, dizziness, transient blurred vision, headache, paresthesia, xanthopsia, weakness, restlessness.

Musculoskeletal: Muscle spasm.

Hematologic: Aplastic anemia, agranulocytosis, leukopenia, thrombocytopenia.

Metabolic: Hyperglycemia, glycosuria, hyperuricemia.

Hypersensitive Reactions: Necrotizing angiitis, Stevens-Johnson syndrome, respiratory distress including pneumonitis and pulmonary edema, purpura, urticaria, rash, photosensitivity.

To report SUSPECTED ADVERSE REACTIONS, contact Mylan at 1-877-446-3679 (1-877-4-INFO-RX) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

OVERDOSAGE

Acute Toxicity

Several cases of overdosage with metoprolol tartrate have been reported, some leading to death. No deaths have been reported with hydrochlorothiazide.

Oral LD50 ‘s (mg/kg): mice, 1158 (metoprolol tartrate); rats, 3090 (metoprolol tartrate), 2750 (hydrochlorothiazide).

Signs and Symptoms

Metoprolol Tartrate

Potential signs and symptoms associated with overdosage with metoprolol tartrate are bradycardia, hypotension, bronchospasm, and cardiac failure.

Hydrochlorothiazide

The most prominent feature of poisoning is acute loss of fluid and electrolytes.

Cardiovascular: Tachycardia, hypotension, shock.

Neuromuscular: Weakness, confusion, dizziness, cramps of the calf muscles, paresthesia, fatigue, impairment of consciousness.

Digestive: Nausea, vomiting, thirst.

Renal: Polyuria, oliguria, or anuria (due to hemoconcentration).

Laboratory Findings: Hypokalemia, hyponatremia, hypochloremia, alkalosis; increased BUN (especially in patients with renal insufficiency).

Combined Poisoning: Signs and symptoms may be aggravated or modified by concomitant intake of antihypertensive medication, barbiturates, curare, digitalis (hypokalemia), corticosteroids, narcotics, or alcohol.

Treatment

There is no specific antidote.

On the basis of the pharmacologic actions of metoprolol tartrate and hydrochlorothiazide, the following general measures should be employed:

Elimination of the Drug

Inducement of vomiting, gastric lavage, and activated charcoal.

Bradycardia

Atropine should be administered. If there is no response to vagal blockade, isoproterenol should be administered cautiously.

Hypotension

The patient’s legs should be elevated and lost fluid and electrolytes (potassium, sodium) should be replaced. A vasopressor should be administered, e.g., levarterenol or dopamine.

Bronchospasm

A beta2 -stimulating agent and/or a theophylline derivative should be administered.

Cardiac Failure

A digitalis glycoside and diuretic should be administered. In shock resulting from inadequate cardiac contractility, administration of dobutamine, isoproterenol, or glucagon may be considered.

Surveillance

Fluid and electrolyte balance (especially serum potassium) and renal function should be monitored until conditions become normal.

DOSAGE AND ADMINISTRATION

Dosage should be determined by individual titration (see INDICATIONS AND USAGE).

Hydrochlorothiazide is usually given at a dosage of 12.5 to 50 mg per day. The usual initial dosage of metoprolol tartrate is 100 mg daily in single or divided doses. Dosage may be increased gradually until optimum blood pressure control is achieved. The effective dosage range is 100 to 450 mg per day. While once-daily dosing is effective and can maintain a reduction in blood pressure throughout the day, lower doses (especially 100 mg) may not maintain a full effect at the end of the 24-hour period, and larger or more frequent daily doses may be required. This can be evaluated by measuring blood pressure near the end of the dosing interval to determine whether satisfactory control is being maintained throughout the day. Beta1 selectivity diminishes as dosage of metoprolol tartrate is increased.

The following dosage schedule may be used to administer from 100 to 200 mg of metoprolol tartrate per day and from 25 to 50 mg of hydrochlorothiazide per day:

Metoprolol Tartrate and Hydrochlorothiazide Dosage:

Tablets of 50/25

2 tablets per day in single or divided doses

Tablets of 100/25

1 to 2 tablets per day in single or divided doses

Tablets of 100/50

1 tablet per day in single or divided doses

Dosing regimens that exceed 50 mg of hydrochlorothiazide per day are not recommended. When necessary, another antihypertensive agent may be added gradually, beginning with 50% of the usual recommended starting dose to avoid an excessive fall in blood pressure.

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