Degradation of carmustine in mixed solvent and nonaqueous media

The degradation rate of carmustine in several solvent mixtures and in mannitol solution was investigated at 5, 22, and 37 degrees. The solvents chosen were those utilized as parenteral diluents. The apparent first-order degradation rate constants were computed using a linear regression procedure. The most nonaqueous solvent mixtures demonstrated minimum apparent degradation rates. The apparent degradation rate constant decreased with a decrease in the macroscopic dielectric constant. From the data at several temperatures, the apparent activation energies for carmustine degradation in the several solvent mixtures were calculated. There was no evidence for a relationship between the apparent activation energy and the dielectric constant.