title: Rapid determination of the encapsulation efficiency of a liposome formulation using column-switching HPLC.
abstract: The feasibility of a rapid automated method for determination of the encapsulation efficiency (EE) of a liposome formulation using a column-switching HPLC system was confirmed by employing several types of liposome formulations containing doxorubicin (DXR). A suspension of DXR liposome was injected directly into an online solid-phase extraction (SPE) system comprising a Diol SPE column and an ODS SPE column connected in series. Free (not encapsulated) DXR was trapped on the Diol SPE column, whereas encapsulated DXR was eluted without interaction. The eluted encapsulated DXR was trapped on the ODS SPE column after being extracted from the inner phase of the liposome by mixing with an organic solvent. Trapped free and encapsulated DXR were eluted sequentially and analyzed separately by gradient HPLC. The time taken by this automated method was only 25min, whereas conventional methods such as ultracentrifugation are time consuming and labor intensive. Validation results and comparison with ultracentrifugation suggested that our method was sufficiently accurate and sensitive to be used to evaluate EE of a liposome formulation without complicated pretreatment.
authors.affiliation: Pharmaceutical Science & Technology Unit, Eisai Co. Ltd., 1 Kawashimatakehaya-machi, Kakamigahara, Gifu 501-6195, Japan.
authors.forename: Naozumi
authors.initials: N
authors.lastname: Ohnishi
authors.forename: Eiichi
authors.initials: E
authors.lastname: Yamamoto
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Tomida
authors.forename: Kenji
authors.initials: K
authors.lastname: Hyodo
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ishihara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kikuchi
authors.forename: Kohei
authors.initials: K
authors.lastname: Tahara
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Takeuchi
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000008:administration & dosage*; D001331:Automation; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004317:Doxorubicin / Q000008:administration & dosage*; D005240:Feasibility Studies; D008081:Liposomes; D015203:Reproducibility of Results; D052616:Solid Phase Extraction / Q000379:methods*; D012997:Solvents / Q000737:chemistry; D013997:Time Factors; D014461:Ultracentrifugation / Q000379:methods
chemical_list: D000903:Antibiotics, Antineoplastic; D008081:Liposomes; D012997:Solvents; D004317:Doxorubicin