SPL Set ID: 09daf48f-1d44-4b7b-bb53-bd5635b93ca6

Midazolam hydrochloride is a water-soluble benzodiazepine available as a sterile, nonpyrogenic parenteral dosage form for intravenous or intramuscular injection. Each mL contains midazolam hydrochloride equivalent to 5 mg midazolam compounded with 0.8% sodium chloride and 0.01% edetate disodium, with 1% benzyl alcohol as preservative; the pH is adjusted to 3 to 3.6 with hydrochloric acid and, if necessary, sodium hydroxide. Midazolam is a white to light yellow crystalline compound, insoluble in water. The hydrochloride salt of midazolam, which is formed in situ , is soluble in aqueous solutions. Chemically, midazolam HCl is 8-chloro-6-(2-fluorophenyl)-1-methyl-4 H -imidazo[1,5-a][1,4]benzodiazepine hydrochloride. Midazolam hydrochloride has the following structural formula: C 18 H 13 ClFN 3 • HCl M.W. 362.25 Under the acidic conditions required to solubilize midazolam in the product, midazolam is present as an equilibrium mixture (shown below) of the closed ring form shown above and an open-ring structure formed by the acid-catalyzed ring opening of the 4,5-double bond of the diazepine ring. The amount of open-ring form is dependent upon the pH of the solution. At the specified pH of the product, the solution may contain up to about 25% of the open-ring compound. At the physiologic conditions under which the product is absorbed (pH of 5 to 8) into the systemic circulation, any open-ring form present reverts to the physiologically active, lipophilic, closed-ring form (midazolam) and is absorbed as such. The following chart plots the percentage of midazolam present as the open-ring form as a function of pH in aqueous solutions. As indicated in the graph, the amount of open-ring compound present in solution is sensitive to changes in pH over the pH range specified for the product: 3.0 to 3.6 for the 5 mg/mL concentration. Above pH 5, at least 99% of the mixture is present in the closed-ring form. Midazolam Injection, USP pharmacy bulk package is a sterile solution dosage form for preparing intravenous (IV) or intramuscular (IM) injections. Each pharmacy bulk package contains 500 mg midazolam in a 100 mL vial. The contents are intended for use in a pharmacy admixture program and are restricted to the preparation of IV or IM injection, or preparation of admixture for IV infusion. structure open ring ph fig