Stability of methylprednisolone sodium succinate in 5% dextrose and 0.9% sodium chloride injections

The stability of methylprednisolone sodium succinate (MPSS) in two intravenous solutions was studied. Using a factorial design, solutions consisting of 1% or 5% (w/w) free methylprednisolone in 5% dextrose injection or 0.9% sodium chloride injection adjusted to a pH of 7.2 or 8.0 were tested for turbidity. Turbidity was assessed using a nephelometer and by visual observation. In a second set of experiments that simulated the worst conditions expected in practice, MPSS solutions of various concentrations having a pH of 7.8 and an initial free methylprednisolone percentage of 6% were examined periodically for 24 hours for turbidity. A turbidity level of 2 nephelometric turbidity units (NTU) was selected as the maximum tolerable turbidity level for defining stability. Turbidity was affected to the greatest extent by i.v. diluent, followed by initial free methylprednisolone percentage and pH. Consistently higher turbidity values at most methylprednisolone concentrations were recorded in 5% dextrose injection. In both diluents, turbidity readings were higher at intermediate (2.5-15 mg/ml) concentrations of methylprednisolone than at low (0.3 mg/ml) or high (20 mg/ml) concentrations. There was no substantial difference in the hydrolysis rate of MPSS attributable to the type of diluent. Methylprednisolone sodium succinate in 0.9% sodium chloride injection at 25 degrees C over a broad concentration range results in acceptable solutions up to 24 hours. In 5% dextrose injection, the recommended storage times at 25 degrees C range from 8 to 24 hours, depending on the drug concentration.