Labetalol

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 hydrochloride injection may be used: a) repeated intravenous injections, b) slow continuous infusion.

Additional injections of 40 mg or 80 mg can be given at 10 minute intervals until a desired supine blood pressure is achieved or a total of 300 mg labetalol HCl has been injected. The maximum effect usually occurs within 5 minutes of each injection. Slow Continuous Infusion Labetalol hydrochloride injection is prepared for continuous intravenous infusion by diluting the contents with commonly used intravenous fluids (see below).

Examples of 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 hydrochloride, 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 hydrochloride injection are added to 250 mL of a commonly used intravenous fluid. The resultant solution will contain 200 mg of labetalol hydrochloride, 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 hydrochloride started.

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 Pressure Monitoring The blood pressure should be monitored during and after completion of the infusion or intravenous injections. Rapid or excessive falls in either systolic or diastolic blood pressure during intravenous treatment should be avoided.

For subsequent outpatient titration or maintenance dosing see Labetalol Hydrochloride Tablets Product Information DOSAGE AND ADMINISTRATION for additional recommendations. Compatibility with commonly used intravenous fluids Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.

Labetalol hydrochloride injection was tested for compatibility with commonly used intravenous fluids at final concentrations of 1.25 mg to 3.75 mg labetalol hydrochloride per mL of the mixture. Labetalol hydrochloride injection was found to be compatible with and stable (for 24 hours refrigerated or at room temperature) in mixtures with the following solutions: Ringers Injection, USP Lactated Ringers Injection, USP 5% Dextrose and Ringers Injection 5% Lactated Ringers and 5% Dextrose Injection 5% Dextrose Injection, USP 0.9% Sodium Chloride Injection, USP 5% Dextrose and 0.2% Sodium Chloride Injection, USP 2.5% Dextrose and 0.45% Sodium Chloride Injection, USP 5% Dextrose and 0.9% Sodium Chloride Injection, USP 5% Dextrose and 0.33% Sodium Chloride Injection, USP Labetalol hydrochloride injection was NOT compatible with 5% Sodium Bicarbonate Injection, USP.

Care should be taken when administering alkaline drugs, including furosemide, in combination with labetalol. Compatibility should be assured prior to administering these drugs together.