Labetalol Hcl
FDA Drug Information • Also known as: Labetalol Hcl
- Brand Names
- Labetalol Hcl
- Route
- INTRAVENOUS
- Dosage Form
- INJECTION
- Product Type
- HUMAN PRESCRIPTION DRUG
Description
DESCRIPTION Labetalol Hydrochloride Injection, USP is an adrenergic receptor blocking agent that has both selective alpha1-adrenergic and nonselective beta-adrenergic receptor blocking actions in a single substance. Labetalol hydrochloride (HCl) is a racemate chemically designated as 5-[1-Hydroxy-2-[(1-methyl-3-phenylpropyl)amino]ethyl]-salicylamide monohydrochloride and it has the following structural formula: Labetalol HCl has the molecular formula C19H24N2O3
What Is Labetalol Hcl Used For?
INDICATIONS & USAGE Labetalol HCl Injection, USP is indicated for control of blood pressure in severe hypertension.
Dosage and Administration
DOSAGE & ADMINISTRATION Labetalol HCl injection is intended for intravenous use in hospitalized patients. DOSAGE MUST BE INDIVIDUALIZED depending upon the severity of hypertension and the response of the patient during dosing. Patients should always be kept in a supine position during the period of intravenous drug administration. A substantial fall in blood pressure on standing should be expected in these patients. The patient’s ability to tolerate an upright position should be established before permitting any ambulation, such as using toilet facilities. Either of two methods of administration of labetalol HCl injection may be used: a) repeated intravenous injection, or b) slow continuous infusion. Repeated Intravenous Injection Initially, labetalol HCl injection should be given in a 20 mg dose (which corresponds to 0.25 mg/kg for an 80 kg patient) by slow intravenous injection over a 2 minute period. Immediately before the injection and at 5 and 10 minutes after injection, supine blood pressure should be measured to evaluate response. Additional injections of 40 or 80 mg can be given at 10 minute intervals until a desired supine blood pressure is achieved or a total of 300 mg of labetalol HCl injection has been injected. The maximum effect usually occurs within 5 minutes of each injection. Slow Continuous Infusion Labetalol HCl injection is prepared for continuous intravenous infusion by diluting the vial contents with commonly used intravenous fluids (see below). Examples of two methods of preparing the infusion solution are: The contents of either two 20 mL vials (40 mL), or one 40 mL vial, are added to 160 mL of a commonly used intravenous fluid such that the resultant 200 mL of solution contains 200 mg of labetalol HCl, 1 mg/mL. The diluted solution should be administered at a rate of 2 mL/min to deliver 2 mg/min. Alternatively, the contents of either two 20 mL vials (40 mL), or one 40 mL vial, of labetalol HCl injection are added to 250 mL of a commonly used intravenous fluid. The resultant solution will contain 200 mg of labetalol HCl, approximately 2 mg/3 mL. The diluted solution should be administered at a rate of 3 mL/min to deliver approximately 2 mg/min. The rate of infusion of the diluted solution may be adjusted according to the blood pressure response, at the discretion of the physician. To facilitate a desired rate of infusion, the diluted solution can be infused using a controlled administration mechanism, e.g., graduated burette or mechanically driven infusion pump. Since the half-life of labetalol is 5 to 8 hours, steady-state blood levels (in the face of a constant rate of infusion) would not be reached during the usual infusion time period. The infusion should be continued until a satisfactory response is obtained and should then be stopped and oral labetalol HCl started (see below). The effective intravenous dose is usually in the range of 50 to 200 mg. A total dose of up to 300 mg may be required in some patients. Blood...
Side Effects (Adverse Reactions)
ADVERSE REACTIONS Labetalol HCl injection is usually well tolerated. Most adverse effects have been mild and transient and, in controlled trials involving 92 patients, did not require labetalol withdrawal. Symptomatic postural hypotension (incidence, 58%) is likely to occur if patients are tilted or allowed to assume the upright position within 3 hours of receiving labetalol HCl. Moderate hypotension occurred in 1 of 100 patients while supine. Increased sweating was noted in 4 of 100 patients, and flushing occurred in 1 of 100 patients. The following also were reported with labetalol HCl with the incidence per 100 patients as noted: Cardiovascular System:Ventricular arrhythmia in 1. Central and Peripheral Nervous Systems: Dizziness in 9, tingling of the scalp/skin in 7, hypoesthesia (numbness) and vertigo in 1 each. Gastrointestinal System: Nausea in 13, vomiting in 4, dyspepsia and taste distortion in 1 each. Metabolic Disorders: Transient increases in blood urea nitrogen and serum creatinine levels occurred in 8 of 100 patients; these were associated with drops in blood pressure, generally in patients with prior renal insufficiency. Psychiatric Disorders: Somnolence/yawning in 3. Respiratory System: Wheezing in 1. Skin: Pruritus in 1. The incidence of adverse reactions depends upon the dose of labetalol HCl. The largest experience is with oral labetalol HCl (see Labetalol HCl Tablet Product Information for details). Certain of the side effects increased with increasing oral dose, as shown in the following table that depicts the entire US therapeutic trials data base for adverse reactions that are clearly or possibly dose related. In addition, a number of other less common adverse events have been reported: Cardiovascular: Hypotension, and rarely, syncope, bradycardia, heart block. Liver and Biliary System: Hepatic necrosis, hepatitis, cholestatic jaundice, elevated liver function tests. Hypersensitivity: Rare reports of hypersensitivity (e.g., rash, urticaria, pruritus, angioedema, dyspnea) and anaphylactoid reactions. The oculomucocutaneous syndrome associated with the beta-blocker practolol has not been reported with labetalol HCl during investigational use and extensive foreign marketing experience. Clinical Laboratory Tests Among patients dosed with labetalol tablets, there have been reversible increases of serum transaminases in 4% of patients tested and, more rarely, reversible increases in blood urea. ADVERSE
Warnings and Precautions
WARNINGS Hepatic Injury Severe hepatocellular injury, confirmed by rechallenge in at least one case, occurs rarely with labetalol therapy. The hepatic injury is usually reversible, but hepatic necrosis and death have been reported. Injury has occurred after both short- and long-term treatment and may be slowly progressive despite minimal symptomatology. Similar hepatic events have been reported with a related compound, dilevalol HCl, including two deaths. Dilevalol HCl is one of the four isomers of labetalol HCl. Thus, for patients taking labetalol, periodic determination of suitable hepatic laboratory tests would be appropriate. Laboratory testing should be done at the very first symptom or sign of liver dysfunction (e.g., pruritus, dark urine, persistent anorexia, jaundice, right upper quadrant tenderness, or unexplained “flu-like” symptoms). If the patient has laboratory evidence of liver injury or jaundice, labetalol should be stopped and not restarted. Cardiac Failure Sympathetic stimulation is a vital component supporting circulatory function in congestive heart failure. Beta-blockade carries a potential hazard of further depressing myocardial contractility and precipitating more severe failure. Although beta-blockers should be avoided in overt congestive heart failure, if necessary, labetalol can be used with caution in patients with a history of heart failure who are well compensated. Congestive heart failure has been observed in patients receiving labetalol HCl. Labetalol does not abolish the inotropic action of digitalis on heart muscle. In Patients Without a History of Cardiac Failure In patients with latent cardiac insufficiency, continued depression of the myocardium with beta-blocking agents over a period of time can, in some cases, lead to cardiac failure. At the first sign or symptom of impending cardiac failure, patients should be fully digitalized and/or be given a diuretic, and the response should be observed closely. If cardiac failure continues despite adequate digitalization and diuretic, labetalol therapy should be withdrawn (gradually, if possible). Ischemic Heart Disease Angina pectoris has not been reported upon labetalol discontinuation. However, following abrupt cessation of therapy with some beta-blocking agents in patients with coronary artery disease, exacerbations of angina pectoris and, in some cases, myocardial infarction have been reported. Therefore, such patients should be cautioned against interruption of therapy without the physician’s advice. Even in the absence of overt angina pectoris, when discontinuation of labetalol is planned, the patient should be carefully observed and should be advised to limit physical activity. If angina markedly worsens or acute coronary insufficiency develops, labetalol administration should be reinstituted promptly, at least temporarily, and other measures appropriate for the management of unstable angina should be taken. Nonallergic Bronchospasm (e.g., Chronic Bronchitis and...
Contraindications
CONTRAINDICATIONS Labetalol HCl injection is contraindicated in bronchial asthma, overt cardiac failure, greater-than-first-degree heart block, cardiogenic shock, severe bradycardia, other conditions associated with severe and prolonged hypotension, and in patients with a history of hypersensitivity to any component of the product (see WARNINGS ). Beta-blockers, even those with apparent cardioselectivity, should not be used in patients with a history of obstructive airway disease, including asthma.
Overdosage
OVERDOSAGE Overdosage with labetalol HCl causes excessive hypotension that is posture sensitive and, sometimes, excessive bradycardia. Patients should be placed supine and their legs raised if necessary to improve the blood supply to the brain. If overdosage with labetalol HCl follows oral ingestion, gastric lavage or pharmacologically induced emesis (using syrup of ipecac) may be useful for removal of the drug shortly after ingestion. The following additional measures should be employed if necessary: Excessive bradycardia—administer atropine or epinephrine. Cardiac failure—administer a digitalis glycoside and a diuretic. Dopamine or dobutamine may also be useful. Hypotension—administer vasopressors, e.g., norepinephrine. There is pharmacologic evidence that norepinephrine may be the drug of choice. Bronchospasm—administer epinephrine and/or an aerosolized beta2-agonist. Seizures—administer diazepam. In severe beta-blocker overdose resulting in hypotension and/or bradycardia, glucagon has been shown to be effective when administered in large doses (5 to 10 mg rapidly over 30 seconds, followed by continuous infusion of 5 mg per hour that can be reduced as the patient improves). Neither hemodialysis nor peritoneal dialysis removes a significant amount of labetalol from the general circulation (<1%). The oral LD50 value of labetalol HCl in the mouse is approximately 600 mg/kg and in the rat is greater than 2 g/kg. The intravenous LD50 in these species is 50 to 60 mg/kg.
How Supplied
HOW SUPPLIED Labetalol HCl Injection, USP, 5 mg/mL, is supplied in 20 mL (100 mg) multidose vials, individually-boxed (NDC 51662-1602-01) Also available as 20 mL vial (100 mg) NDC 51662-1602-9 Store at 20° to 25°C (68° to 77°F) [See USP Controlled Room Temperature]. Do not freeze. Protect from light. To report SUSPECTED ADVERSE REACTIONS CONTACT HEALTHFIRST 11629 49th Pl W. Mukilteo, WA 98275 or the FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
About This Information
This drug information is sourced from FDA-approved labeling via the openFDA database. It is intended for educational and reference purposes only. This is not medical advice. Always consult your healthcare provider before making decisions about medication. Drug information may be updated by the FDA; check with your pharmacist for the most current information.
What are side effects?
Side effects are unwanted reactions that can occur when taking a medication. They range from mild (headache, nausea) to severe (allergic reactions, organ damage). Not everyone experiences side effects, and severity varies. Report any concerning side effects to your doctor.
What are drug interactions?
Drug interactions occur when a medication is affected by another drug, food, or supplement. Interactions can make medications less effective or cause dangerous side effects. Always tell your doctor about all medications and supplements you take.