Midazolamdrug info

Midazolam is a benzodiazepine available as midazolam HCl syrup for oral administration. Midazolam, a white to light yellow crystalline compound, is insoluble in water, but can be solubilized in aqueous solutions by formation of the hydrochloride salt in situ under acidic conditions. 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 molecular formula C 18 H 13 ClFN 3 ·HCl, a calculated molecular weight of 362.25 and the following structural formula: Each mL of the syrup contains midazolam hydrochloride equivalent to 2 mg midazolam compounded with artificial bitterness modifier, citric acid anhydrous, D&C Red #33, edetate disodium, glycerin, mixed fruit flavor, sodium benzoate, sodium citrate, sorbitol, and water; the pH is adjusted to 2.8 to 3.6 with hydrochloric acid. Under the acidic conditions required to solubilize midazolam in the syrup, 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 syrup, the solution may contain up to about 40% 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 below 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: 2.8 to 3.6. Above pH 5, at least 99% of the mixture is present in the closed-ring form. chemical-structure-1.jpg chemical-structure-2.jpg midazolam-chart.jpg