title: Physical stability of redispersible dry emulsions containing amorphous sucrose.
abstract: The objective of the present study was to estimate the stability of redispersible dry emulsions containing amorphous sucrose. Dry emulsions were prepared by spray drying liquid o/w-emulsions in a laboratory spray dryer. The effect of hydroxypropyl methylcellulose (HPMC) on the glass transition temperature T(g) of spray dried sucrose-HPMC mixtures, relative to the T(g) of amorphous sucrose, was investigated. For the sucrose-HPMC mixtures the values of T(g) followed the ideal Gordon-Taylor equation up to 30% HPMC. For dry emulsions containing 40% HPMC, 30% lipid and 30% sucrose, the T(g) was increased by 12 degrees C relative to the T(g) of amorphous sucrose. The stability of the dry emulsions was investigated by a conventional stability study and by an enthalpy relaxation study. The measured enthalpy recovery of amorphous sucrose below T(g) was used to calculate molecular relaxation time parameters based on the Williams-Watts equation. The molecular mobility of amorphous sucrose at temperatures 50 degrees C below T(g) was low and negligible with respect to the shelf life stability. It was concluded that the dry emulsions are physically stable with respect to the lifetime of a pharmaceutical product when stored in dry condition and at temperatures up to 28 degrees C.
authors.affiliation: Department of Pharmaceutics, The Royal Danish School of Pharmacy, Copenhagen, Denmark.
authors.forename: K L
authors.initials: KL
authors.lastname: Christensen
authors.forename: G P
authors.initials: GP
authors.lastname: Pedersen
authors.forename: H G
authors.initials: HG
authors.lastname: Kristensen
mesh_terms: D002626:Chemistry, Pharmaceutical; D003890:Desiccation / Q000379:methods; D004355:Drug Stability; D004655:Emulsions / Q000737:chemistry*; D007785:Lactose / Q000031:analogs & derivatives* / Q000737:chemistry; D008747:Methylcellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D010078:Oxazines; D011208:Powders; D013395:Sucrose / Q000737:chemistry*
chemical_list: D004655:Emulsions; D010078:Oxazines; D011208:Powders; D013395:Sucrose; D008747:Methylcellulose; C071191:MK 458; D007785:Lactose