DOSAGE AND ADMINISTRATION
Labetalol hydrochloride 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 hydrochloride injection may be used: a) repeated intravenous injections, b) slow continuous infusion.
Repeated Intravenous Injection
Initially, labetalol hydrochloride injection should be given in a dose of 20 mg labetalol HCl (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 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. In patients with excessive systolic hypertension, the decrease in systolic pressure should be used as indicator of effectiveness in addition to the response of the diastolic pressure.
Initiation of Dosing with Labetalol Hydrochloride Tablets
Subsequent oral dosing with labetalol hydrochloride tablets should begin when it has been established that the supine diastolic blood pressure has begun to rise. The recommended initial dose is 200 mg, followed in 6 to 12 hours by an additional dose of 200 or 400 mg, depending on the blood pressure response. Thereafter, inpatient titration with labetalol hydrochloride tablets may proceed as follows:
200 mg b.i.d.
400 mg b.i.d.
800 mg b.i.d.
1200 mg b.i.d.
While in the hospital, the dosage of labetalol hydrochloride tablets may be increased at 1 day intervals to achieve the desired blood pressure reduction.
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.