The effect of bulking agent on the solid-state stability of freeze-dried methylprednisolone sodium succinate

• Published in: Pharmaceutical research Vol. 11; no. 10; pp. 1467 - 1473
• Main Authors: HERMAN, B. D, SINCLAIR, B. D, MILTON, N, NAIL, S. L
• Format: Journal Article
• Language: English
• Published: New York, NY Springer 01-10-1994
• Subjects: Biological and medical sciences; Calorimetry, Differential Scanning; Chromatography, High Pressure Liquid; Crystallography, X-Ray; Drug Stability; Excipients; Freeze Drying; General pharmacology; Hydrolysis; Lactose - chemistry; Mannitol - chemistry; Medical sciences; Methylprednisolone Hemisuccinate - chemistry; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Spectrophotometry, Ultraviolet; Thermodynamics; Freeze dried product; Corticosteroid; Lactose; Bulk material; Stability; Parenteral form; Vehicle(excipient); Mannitol; Methylprednisolone; Physicochemical properties; Property formulation relationship
• ISSN: 0724-8741; 1573-904X
• DOI: 10.1023/A:1018908326074

The rate of hydrolysis of methylprednisolone sodium succinate in the freeze dried solid state at 40 degrees C was determined in the presence of two common bulking agents--mannitol and lactose--at two different ratios of drug to excipient. Residual moisture levels were less than 1% in all samples tested, with no significant difference in residual moisture among different formulations. Rate of hydrolysis was significantly higher in mannitol-containing formulations versus lactose-containing formulations, and the rate of hydrolysis increases with increasing ratio of mannitol to drug. Thermal analysis and x-ray diffraction data are consistent with a composition-dependent rate of crystallization of mannitol in the formulation and its subsequent effect on distribution of water in the freeze-dried matrix. Increased water in the microenvironment of the drug decreases the glass transition temperature of the amorphous phase, resulting in an increased rate of reaction. The physical state of lactose remained constant throughout the duration of the study, and the rate of hydrolysis was not significantly different from the control formulation containing no excipient. Thermal analysis and x-ray diffraction data are consistent with formation of a liquid crystal phase in freeze-concentrated solutions of methylprednisolone sodium succinate containing no excipient.