The Effect of Crystallizing and Non-crystallizing Cosolutes on Succinate Buffer Crystallization and the Consequent pH Shift in Frozen Solutions
- 371 Downloads
To effectively inhibit succinate buffer crystallization and the consequent pH changes in frozen solutions.
Using differential scanning calorimetry (DSC) and X-ray diffractometry (XRD), the crystallization behavior of succinate buffer in the presence of either (i) a crystallizing (glycine, mannitol, trehalose) or (ii) a non-crystallizing cosolute (sucrose) was evaluated. Aqueous succinate buffer solutions, 50 or 200 mM, at pH values 4.0 or 6.0 were cooled from room temperature to −25°C at 0.5°C/min. The pH of the solution was measured as a function of temperature using a probe designed to function at low temperatures. The final lyophiles prepared from these solutions were characterized using synchrotron radiation.
When the succinic acid solution buffered to pH 4.0, in the absence of a cosolute, was cooled, there was a pronounced shift in the freeze-concentrate pH. Glycine and mannitol, which have a tendency to crystallize in frozen solutions, remained amorphous when the initial pH was 6.0. Under this condition, they also inhibited buffer crystallization and prevented pH change. At pH 4.0 (50 mM initial concentration), glycine and mannitol crystallized and did not prevent pH change in frozen solutions. While sucrose, a non-crystallizing cosolute, did not completely prevent buffer crystallization, the extent of crystallization was reduced. Sucrose decomposition, based on XRD peaks attributable to β-D-glucose, was observed in frozen buffer solutions with an initial pH of 4.0. Trehalose completely inhibited crystallization of the buffer components when the initial pH was 6.0 but not at pH 4.0. At the lower pH, the crystallization of both trehalose dihydrate and buffer components was evident.
When retained amorphous, sucrose and trehalose effectively inhibited succinate buffer component crystallization and the consequent pH shift. However, when trehalose crystallized or sucrose degraded to yield a crystalline decomposition product, crystallization of buffer was observed. Similarly, glycine and mannitol, two widely used bulking agents, inhibited buffer component crystallization only when retained amorphous. In addition to stabilizing the active pharmaceutical ingredient, lyoprotectants may prevent solution pH shift by inhibiting buffer crystallization.
KEY WORDSbuffer crystallization cosolute frozen solution pH shift
The XRD studies were carried out in the College of Science and Engineering Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. The use of the Advanced Photon Source at Argonne National Laboratory through the Midwest Universities Collaborative Access Team (MUCAT sector) is gratefully acknowledged.
- 1.Akers MJ, Defelippis MR. Peptides and proteins as parenteral solutions. In: Frokjaer S, Hovgaard L, editors. Pharmaceutical Formulation Development of Peptide and Proteins. Philadelphia: Taylor and Francis Inc.; 2003. p. 145–77.Google Scholar
- 3.Akers MJ, Vasudevan V, Stickelmeyer M. Formulation development of protein dosage forms. In: Nail SL, Akers MJ, editors. Development and manufacture of protein pharmaceuticals. New York: Kluwer Academic/Plenum publishers; 2002. p. 47–127.Google Scholar
- 4.Defelippis MR, Akers MJ. Peptides and proteins as parenteral suspensions: An overview of design, development, and manufacturing considerations. In: Frokjaer S, Hovgaard L, editors. Pharmaceutical Formulation Development of Peptide and Proteins. Philadelphia: Taylor and Francis Inc; 2000. p. 113. 2003.Google Scholar
- 5.Pikal MJ. Freeze drying. In: Swarbrick J, editor. Encyclopedia of pharmaceutical technology, vol. 1. New York: Informa Healthcare; 2007. p. 1807–33.Google Scholar
- 6.Trissel LA. Handbook on injectable drugs. 14th ed. Bethesda: American Society of Health-System Pharmacists; 2007.Google Scholar
- 7.Shalaev EY. The impact of buffer on processing and stability of freeze-dried dosage forms, part 1: Solution freezing behavior. Am Pharm Rev. 2005;8:80–7.Google Scholar
- 18.Sundaramurthi P, Patapoff TW, Suryanarayanan R. Crystallization of trehalose in frozen solutions and its phase behavior during drying. Pharm. Res. 2010, doi: 10.1007/s111095-010-0243-2.
- 26.Sundaramurthi P, Suryanarayanan R. Influence of crystallizing and non-crystallizing cosolutes on trehalose crystallization during freeze-drying. Pharm. Res. 2010, doi: 10.1007/s111095-010-0221-8.
- 28.Sundaramurthi P, Suryanarayanan R. Predicting the crystallization propensity of carboxylic acid buffers in frozen systems—relevance to freeze-drying J. Pharm. Sci. 2010, in press.Google Scholar
- 33.Powder Diffraction File. Hexagonal ice, card # 00-042-1142; D- trehalose dihydrate, card # 00-029-1955; β-succinic acid, card # 00-031-1899; monosodium succinate, card # 00-030-1927; sucrose, card # 00-024-1977; β-D-Glucose 00-039-1837; β-D-mannitol, card #00-022-1797; δ-D-mannitol, card # 00-022-1794. International Centre for Diffraction Data, Newtown Square, PA; 2004.Google Scholar