Labetalol Hydrochloride

INDICATIONS AND USAGE Labetalol hydrochloride tablets, USP are indicated in the management of hypertension. Labetalol hydrochloride tablets, USP may be used alone or in combination with other antihypertensive agents, especially thiazide and loop diuretics.

DOSAGE AND ADMINISTRATION DOSAGE MUST BE INDIVIDUALIZED. The recommended initial dosage is 100 mg twice daily whether used alone or added to a diuretic regimen. After 2 or 3 days, using standing blood pressure as an indicator, dosage may be titrated in increments of 100 mg b.i.d. every 2 or 3 days. The usual maintenance dosage of labetalol hydrochloride tablets is between 200 mg and 400 mg twice daily. Since the full antihypertensive effect of labetalol hydrochloride tablets is usually seen within the first 1 to 3 hours of the initial dose or dose increment, the assurance of a lack of an exaggerated hypotensive response can be clinically established in the office setting. The antihypertensive effects of continued dosing can be measured at subsequent visits, approximately 12 hours after a dose, to determine whether further titration is necessary. Patients with severe hypertension may require from 1,200 mg to 2,400 mg per day, with or without thiazide diuretics. Should side effects (principally nausea or dizziness) occur with these doses administered b.i.d. (twice daily), the same total daily dose administered t.i.d. (three times daily) may improve tolerability and facilitate further titration. Titration increments should not exceed 200 mg b.i.d. (twice daily). When a diuretic is added, an additive antihypertensive effect can be expected. In some cases this may necessitate a labetalol hydrochloride tablet dosage adjustment. As with most antihypertensive drugs, optimal dosages of labetalol hydrochloride tablets are usually lower in patients also receiving a diuretic. When transferring patients from other antihypertensive drugs, labetalol hydrochloride tablets should be introduced as recommended and the dosage of the existing therapy progressively decreased. Elderly Patients As in the general patient population, labetalol therapy may be initiated at 100 mg twice daily and titrated upwards in increments of 100 mg b.i.d. as required for control of blood pressure. Since some elderly patients eliminate labetalol more slowly, however, adequate control of blood pressure may be achieved at a lower maintenance dosage compared to the general population. The majority of elderly patients will require between 100 mg and 200 mg b.i.d.

CONTRAINDICATIONS Labetalol hydrochloride 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.

ADVERSE REACTIONS Most adverse effects are mild and transient and occur early in the course of treatment. In controlled clinical trials of 3 to 4 months' duration, discontinuation of labetalol hydrochloride due to one or more adverse effects was required in 7% of all patients. In these same trials, other agents with solely beta-blocking activity used in the control groups led to discontinuation in 8% to 10% of patients, and a centrally acting alpha-agonist led to discontinuation in 30% of patients. The incidence rates of adverse reactions listed in the following table were derived from multicenter, controlled clinical trials comparing labetalol hydrochloride, placebo, metoprolol, and propranolol over treatment periods of 3 and 4 months. Where the frequency of adverse effects for labetalol hydrochloride and placebo is similar, causal relationship is uncertain. The rates are based on adverse reactions considered probably drug related by the investigator. If all reports are considered, the rates are somewhat higher (e.g., dizziness, 20%; nausea, 14%; fatigue, 11%), but the overall conclusions are unchanged. Labetalol Hydrochloride (N=227) % Placebo (N=98) % Propranolol (N=84) % Metoprolol (N=49) % Body as a whole Fatigue 5 0 12 12 Asthenia 1 1 1 0 Headache 2 1 1 2 Gastrointestinal Nausea 6 1 1 2 Vomiting <1 0 0 0 Dyspepsia 3 1 1 0 Abdominal pain 0 0 1 2 Diarrhea <1 0 2 0 Taste distortion 1 0 0 0 Central and Peripheral Nervous Systems Dizziness 11 3 4 4 Paresthesias <1 0 0 0 Drowsiness <1 2 2 2 Autonomic Nervous System Nasal stuffiness 3 0 0 0 Ejaculation failure 2 0 0 0 Impotence 1 0 1 3 Increased sweating <1 0 0 0 Cardiovascular Edema 1 0 0 0 Postural hypotension 1 0 0 0 Bradycardia 0 0 5 12 Respiratory Dyspnea 2 0 1 2 Skin Rash 1 0 0 0 Special Senses Vision abnormality 1 0 0 0 Vertigo 2 1 0 0 The adverse effects were reported spontaneously and are representative of the incidence of adverse effects that may be observed in a properly selected hypertensive patient population, i.e., a group excluding patients with bronchospastic disease, overt congestive heart failure, or other contraindications to beta-blocker therapy. Clinical trials also included studies utilizing daily doses up to 2,400 mg in more severely hypertensive patients. Certain of the side effects increased with increasing dose, as shown in the following table that depicts the entire U.S. therapeutic trials data base for adverse reactions that are clearly or possibly dose related. Labetalol Hydrochloride Daily Dose (mg) 200 300 400 600 800 Number of Patients 522 181 606 608 503 Dizziness (%) 2 3 3 3 5 Fatigue 2 1 4 4 5 Nausea <1 0 1 2 4 Vomiting 0 0 <1 <1 <1 Dyspepsia 1 0 2 1 1 Paresthesias 2 0 2 2 1 Nasal Stuffiness 1 1 2 2 2 Ejaculation Failure 0 2 1 2 3 Impotence 1 1 1 1 2 Edema 1 0 1 1 1 Labetalol Hydrochloride Daily Dose (mg) 900 1,200 1,600 2,400 Number of Patients 117 411 242 175 Dizziness (%) 1 9 13 16 Fatigue 3 7 6 10 Nausea 0 7 11 19 Vomiting 0 1 2 3 Dyspepsia 0 2 2 4 Paresthesias 1 2 5 5 Nasal Stuffiness 2 4 5 6 Ejaculation Failure 0 4 3 5 Impotence 4 3 4 3 Edema 0 1 2 2 In addition, a number of other less common adverse events have been reported: Body as a Whole: Fever. Cardiovascular: Hypotension, and rarely, syncope, bradycardia, heart block. Central and Peripheral Nervous Systems: Paresthesia, most frequently described as scalp tingling. In most cases, it was mild and transient and usually occurred at the beginning of treatment. Collagen Disorders: Systemic lupus erythematosus, positive antinuclear factor. Eyes: Dry eyes. Immunological System: Antimitochondrial antibodies. Liver and Biliary System: Hepatic necrosis, hepatitis, cholestatic jaundice, elevated liver function tests. Musculoskeletal System: Muscle cramps, toxic myopathy. Respiratory System: Bronchospasm. Skin and Appendages: Rashes of various types, such as generalized maculopapular, lichenoid, urticarial, bullous lichen planus, psoriaform, and facial erythema; Peyronie's disease, reversible …

Drug Interactions In one survey, 2.3% of patients taking labetalol hydrochloride in combination with tricyclic antidepressants experienced tremor as compared to 0.7% reported to occur with labetalol hydrochloride alone. The contribution of each of the treatments to this adverse reaction is unknown but the possibility of a drug interaction cannot be excluded. Drugs possessing beta-blocking properties can blunt the bronchodilator effect of beta-receptor agonist drugs in patients with bronchospasm; therefore, doses greater than the normal anti-asthmatic dose of beta-agonist bronchodilator drugs may be required. Cimetidine has been shown to increase the bioavailability of labetalol hydrochloride. Since this could be explained either by enhanced absorption or by an alteration of hepatic metabolism of labetalol hydrochloride, special care should be used in establishing the dose required for blood pressure control in such patients. Synergism has been shown between halothane anesthesia and intravenously administered labetalol hydrochloride. During controlled hypotensive anesthesia using labetalol hydrochloride in association with halothane, high concentrations (3% or above) of halothane should not be used because the degree of hypotension will be increased and because of the possibility of a large reduction in cardiac output and an increase in central venous pressure. The anesthesiologist should be informed when a patient is receiving labetalol hydrochloride. Labetalol hydrochloride blunts the reflex tachycardia produced by nitroglycerin without preventing its hypotensive effect. If labetalol hydrochloride is used with nitroglycerin in patients with angina pectoris, additional antihypertensive effects may occur. Care should be taken if labetalol hydrochloride is used concomitantly with calcium antagonists of the verapamil type. Both digitalis glycosides and beta-blockers slow atrioventricular conduction and decrease heart rate. Concomitant use can increase the risk of bradycardia. Risk of Anaphylactic Reaction While taking beta-blockers, patients with a history of severe anaphylactic reaction to a variety of allergens may be more reactive to repeated challenge, either accidental, diagnostic, or therapeutic. Such patients may be unresponsive to the usual doses of epinephrine used to treat allergic reaction.

DESCRIPTION Labetalol hydrochloride tablets, USP are an adrenergic receptor blocking agent that has both selective alpha 1 -adrenergic and nonselective beta-adrenergic receptor blocking actions in a single substance. Labetalol hydrochloride, USP 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: C 19 H 24 N 2 O 3 •HCl M.W. 364.87 Labetalol hydrochloride, USP has two asymmetric centers and therefore exists as a molecular complex of two diastereoisomeric pairs. Dilevalol, the R, R' stereoisomer, makes up 25% of racemic labetalol. Labetalol hydrochloride, USP is a white or off-white crystalline powder, soluble in water. Labetalol hydrochloride tablets, USP for oral administration, contains 100 mg, 200 mg, 300 mg, or 400 mg of labetalol hydrochloride, USP. In addition, each tablet contains the following inactive ingredients: corn starch, lactose monohydrate, magnesium stearate, sodium starch glycolate, hypromellose, titanium dioxide, polyethylene glycol, polysorbate 80. In addition, the 100 mg tablets contain D&C yellow #10 aluminum lake and FD&C yellow # 6 aluminum lake and the 300 mg tablets contain D&C yellow #10 aluminum lake, FD&C yellow # 6 aluminum lake and FD&C blue#1 aluminum lake. structural-formula

OVERDOSAGE Overdosage with labetalol hydrochloride 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 hydrochloride 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, eg, norepinephrine. There is pharmacological evidence that norepinephrine may be the drug of choice. Bronchospasm - administer epinephrine and/or an aerosolized beta 2 -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/hr that can be reduced as the patient improves). Neither hemodialysis nor peritoneal dialysis removes a significant amount of labetalol hydrochloride from the general circulation (<1%). The oral LD 50 value of labetalol hydrochloride in the mouse is approximately 600 mg/kg and in the rat is greater than 2 g/kg. The intravenous LD 50 in these species is 50 to 60 mg/kg.

HOW SUPPLIED Labetalol Hydrochloride Tablets, USP are available as follows: 100 mg tablets: Yellow, round, bevel-edged, film-coated tablets, debossed 723 on one side and bisect on the other side. They are available as follows: Bottles of 100: NDC 23155-723-01 Bottles of 500: NDC 23155-723-05 200 mg tablets: White, round, bevel-edged, film-coated tablets, debossed 724 on one side and bisect on the other side. They are available as follows: Bottles of 100: NDC 23155-724-01 Bottles of 500: NDC 23155-724-05 300 mg tablets: Green, round, bevel-edged, film-coated tablets, debossed 725 on one side and plain on the other side. They are available as follows: Bottles of 100: NDC 23155-725-01 Bottles of 500: NDC 23155-725-05 400 mg tablets: White, round, bevel edged film coated tablets, debossed 726 on one side and bisect on the other side. They are available as follows: Bottles of 100: NDC 23155-726-01 Bottles of 500: NDC 23155-726-05 Dispense in a tight, light-resistant container as defined in the USP, with a child-resistant closure (as required). KEEP THIS AND ALL MEDICATIONS OUT OF THE REACH OF CHILDREN. Store at 20° to 25°C (68° to 77°F) [See USP Controlled Room Temperature]. Distributed by: Avet Pharmaceuticals Inc. East Brunswick, NJ 08816 1.866.901.DRUG (3784) 51U000000554US02 Revised: 03/2026 avet-logo