Labetalol hydrochloride is an adrenergic receptor blocking agent that has both selective alpha1- and nonselective beta-adrenergic receptor blocking actions in a single substance.
Labetalol HCl is a racemate, chemically designated as 5-[1-hydroxy-2-[(1-methyl-3-phenylpropyl) amino] ethyl]-salicylamide monohydrochloride, and has the following structural formula:
Labetalol hydrochloride has the molecular formula C19H24N2O3 • HCl and a molecular weight of 364.87. It 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 is a white or off-white crystalline powder, soluble in water.
Labetalol hydrochloride injection is a clear, colorless to light yellow aqueous sterile isotonic solution for intravenous injection. It has a pH range of 3.0 to 4.5. Each mL contains 5 mg labetalol hydrochloride, USP, 45 mg anhydrous dextrose, 0.1 mg edetate disodium; 0.8 mg methylparaben and 0.1 mg propylparaben as preservatives; citric acid monohydrate and sodium hydroxide, as necessary, to bring the solution into the pH range.