title: Encapsulation of doxorubicin into liposomes by a freeze-thawing method using buffer solution.
abstract: When doxorubicin was encapsulated into liposomes by freeze-thawing, the percentage of encapsulated doxorubicin (EN%) was found to vary according to the type of buffer solution used. The reason for this was investigated in the present report. Drug-free liposomes prepared by hydration were mixed with doxorubicin dissolved in a certain type of buffer solution that shows a pH decrease on freezing, and this mixture was subjected to freeze-thawing. Doxorubicin was encapsulated by the liposomes due to the difference in pH between freezing and thawing. EN% depended on the pH of the buffer solution before freezing and increased significantly at over pH 7. About 60% of doxorubicin was encapsulated into liposomes after the Ist freeze-thawing cycle, and EN% was increased gradually with the number of freeze-thawing cycles. The addition of sugar to the experimental system was seen to affect doxorubicin encapsulation and the particle size of liposomes.
authors.affiliation: Pharmaceutical Research Laboratories, Kyowa Hakko Kogyo Co., Ltd., Shizuoka, Japan.
authors.forename: E
authors.initials: E
authors.lastname: Hayakawa
authors.forename: M
authors.initials: M
authors.lastname: Nakakura
authors.forename: Y
authors.initials: Y
authors.lastname: Kato
authors.forename: Y
authors.initials: Y
authors.lastname: Okubo
authors.forename: T
authors.initials: T
authors.lastname: Hosokawa
mesh_terms: D002021:Buffers; D004317:Doxorubicin / Q000008:administration & dosage / Q000737:chemistry*; D004337:Drug Carriers; D004339:Drug Compounding / Q000379:methods; D005615:Freezing; D007785:Lactose / Q000737:chemistry; D008081:Liposomes
chemical_list: D002021:Buffers; D004337:Drug Carriers; D008081:Liposomes; D004317:Doxorubicin; D007785:Lactose