title: Effect of surfactants on the physical stability of recombinant human growth hormone.
abstract: The physical stability of a human growth hormone (hGH) formulation upon exposure to air/water interfaces (with vortex mixing) and to nonisothermal stress [determined by differential scanning calorimetry (DSC)] was investigated. The effect of these stresses on the formation of soluble and insoluble aggregates was studied. The aggregates were characterized and quantified by size exclusion-HPLC and UV spectrophotometry. Vortex mixing of hGH solutions (0.5 mg/mL) in phosphate buffer, pH 7.4, for just 1 min caused 67% of the drug to precipitate as insoluble aggregates. These aggregates were noncovalent in nature. Non-ionic surfactants prevented the interfacially induced aggregation at their critical micelle concentration (cmc) for Pluronic F-68 (polyoxyethylene polyoxypropylene block polymer) and Brij 35 (polyoxyethylene alkyl ether) and above the cmc for Tween 80 (polyoxyethylene sorbitan monooleate). However, the same surfactants failed to stabilize hGH against thermal stress in DSC studies. Higher concentrations of surfactants actually destabilized hGH as evidenced by the decrease in the onset temperature for the denaturation endotherm.
authors.affiliation: Department of Pharmacal Sciences, School of Pharmacy, Auburn University, AL 36849-5503, USA.
authors.forename: M
authors.initials: M
authors.lastname: Katakam
authors.forename: L N
authors.initials: LN
authors.lastname: Bell
authors.forename: A K
authors.initials: AK
authors.lastname: Banga
mesh_terms: D002851:Chromatography, High Pressure Liquid; D004355:Drug Stability; D005612:Freeze Drying; D013006:Growth Hormone / Q000737:chemistry*; D006358:Hot Temperature; D006801:Humans; D000077423:Polidocanol; D011060:Poloxalene / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011136:Polysorbates / Q000737:chemistry; D011489:Protein Denaturation; D011994:Recombinant Proteins / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D011136:Polysorbates; D011994:Recombinant Proteins; D013501:Surface-Active Agents; D000077423:Polidocanol; D011092:Polyethylene Glycols; D013006:Growth Hormone; D011060:Poloxalene