Hypersensitivity reactions: 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 dose of epinephrine used to treat allergic reaction.
Hepatic effect: Severe hepatocellular injury, confirmed by rechallenge in at least one case, occurs rarely with labetalol hydrochloride 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 hydrochloride, including two deaths. Dilevalol hydrochloride is one of the four isomers of labetalol hydrochloride. Thus, for patients taking labetalol hydrochloride, 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 jaundice or laboratory evidence of liver injury, labetalol hydrochloride should be stopped and not restarted.
Cardiac failure/Ischemic Heart Disease: 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 hydrochloride can be used with caution in patients with a history of heart failure who are well compensated (e.g., those controlled with cardiac glycosides and/or diuretics). Congestive heart failure has been observed in patients receiving labetalol hydrochloride. Labetalol hydrochloride does not abolish the inotropic action of digitalis on heart muscle. Although angina pectoris has not been reported upon labetalol hydrochloride discontinuation, exacerbation of angina pectoris and precipitation of myocardial infarction have occurred following abrupt cessation of therapy with some beta-adrenergic blocking agents in patients with coronary artery disease.
Diabetes Mellitus and Hypoglycemia: Labetalol hydrochloride should be used with caution in patients with poorly controlled diabetes mellitus. Beta-blockers can prolong or enhance hypoglycemia by interfering with glycogenolysis. Beta-adrenergic blockade can occasionally cause hyperglycemia. This is thought to be due to blockade of beta-2 receptors on pancreatic islet cells, which would inhibit insulin secretion. Thus, blood glucose levels should be monitored closely if a beta-blocker is used in a patient with diabetes mellitus; it may therefore be necessary to adjust the dose of antidiabetic drugs.
Major surgery: The necessity or desirability of withdrawing beta-blocking therapy prior to major surgery is controversial. Protracted severe hypotension and difficulty in restarting or maintaining a heartbeat have been reported with beta-blockers. Several deaths have occurred when labetalol hydrochloride injection was used during surgery (including when used in cases to control bleeding).
Rapid decreases of blood pressure: Caution must be observed when reducing severely elevated blood pressure. A number of adverse reactions, including cerebral infarction, optic nerve infarction, angina, and ischemic changes in the electrocardiogram, have been reported with other agents when severely elevated blood pressure was reduced over time courses of several hours to as long as 1 or 2 days. The desired blood pressure lowering should therefore be achieved over as long a period of time as is compatible with the patient's status.
Impaired hepatic function: May be diminished metabolism of labetalol hydrochloride injection.
Following coronary artery bypass surgery: In one uncontrolled study, patients with low cardiac indices and elevated systemic vascular resistance following intravenous labetalol hydrochloride experienced significant declines in cardiac output with little change in systemic vascular resistance. One of these patients developed hypotension following labetalol hydrochloride treatment. Therefore, use of labetalol hydrochloride should be avoided in such patients.
High dose labetalol hydrochloride: Administration of up to 3 g/d as an infusion for up to 2-3 days has been anecdotaly reported; several patients have experience hypotension or bradycardia.
Hypotension: 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 hydrochloride injection. Therefore, the patient's ability to tolerate an upright position should be established before permitting any ambulation.
Information for patients: 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. Raising the patient into the upright position within 3 h of i.v. labetalol hydrochloride injection administration should be avoided since excessive postural hypotension may occur. The patient's ability to tolerate an upright position must be established before permitting any ambulation, such as using toilet facilities.
Effects on ability to drive and use machines: There are no studies on the effect of this medicine on the ability to drive. When driving vehicles or operating machines it should be taken into account that occasionally dizziness or fatigue may occur.
Use in Children: Safety and efficacy in pediatric patients have not been established.
Use in Elderly: Because some geriatric individuals eliminate labetalol hydrochloride more slowly than younger adults, satisfactory blood pressure control may be achieved with lower maintenance doses than those required by younger patients.