caa a22 4500 477126251 CHVBK 20180405111650.0 cr unu---uuuuu 170330e19970901xx s 000 0 eng 10.1023/A:1012142520912 doi (NATIONALLICENCE)springer-10.1023/A:1012142520912 Effect of Freezing Rate on the Stability of Liposomes During Freeze-Drying and Rehydration [Elektronische Daten] [Ewoud van Winden, Wei Zhang, Daan Crommelin] Purpose. In the present study we examined the effect of the freezing protocol on carboxyfluorescein (CF) retention in liposomes after freeze-drying and rehydration. Methods. Liposomes were frozen slowly at 0.5°C/min, or quickly by submerging the samples in boiling nitrogen before freeze-drying. The thermal behaviour of the frozen dispersions was analysed by Modulated Temperature Differential Scanning Calorimetry (MTDSC). The dried cakes were analysed by SEM, MTDSC and FTIR. The % encapsulated CF of the (re)hydrated liposomes was determined by fluorimetry after GPC, their vesicle size was measured by the Dynamic Light scattering Technique and their bilayer transition was studied by DSC. Results. Slow freezing resulted in a markedly higher CF retention after freeze-drying and rehydration as compared to quick freezing. The effect of the freezing rate depended on the lipid composition and was most pronounced for rigid liposomes. The damage caused by quick freezing did not occur after a freezing/thawing cycle. The freezing protocol did not influence the interaction between the phospholipids and the lyoprotectants (sucrose, trehalose or glucose) in the freeze-dried state. However, analysis by DSC of dipalmitoylphosphatidylcholine (DPPC): dipalmitoylphosphatidylglycerol (DPPG) =10:1 and DPPC liposome dispersions showed that the freezing protocol affected the bilayer melting characteristics of these liposomes after freeze-drying and rehydration. Conclusions. A proper design of the freezing protocol is essential to achieve optimal stability of rigid liposomes during a freeze-drying and rehydration cycle. Plenum Publishing Corporation, 1997 freeze-drying nationallicence liposomes nationallicence lyoprotection nationallicence bilayer transition nationallicence modulated temperature differential scanning calorimetry (MTDSC) nationallicence van Winden Ewoud Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht Institute for Drug Exploration, Utrecht University, PO BOX 80082, 3508 TB, Utrecht, The Netherlands aut Zhang Wei Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht Institute for Drug Exploration, Utrecht University, PO BOX 80082, 3508 TB, Utrecht, The Netherlands aut Crommelin Daan Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht Institute for Drug Exploration, Utrecht University, PO BOX 80082, 3508 TB, Utrecht, The Netherlands aut Pharmaceutical Research Kluwer Academic Publishers-Plenum Publishers 14/9(1997-09-01), 1151-1160 0724-8741 14:9<1151 1997 14 11095 https://doi.org/10.1023/A:1012142520912 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1012142520912 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- van Winden Ewoud Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht Institute for Drug Exploration, Utrecht University, PO BOX 80082, 3508 TB, Utrecht, The Netherlands aut NATIONALLICENCE 700 1- Zhang Wei Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht Institute for Drug Exploration, Utrecht University, PO BOX 80082, 3508 TB, Utrecht, The Netherlands aut NATIONALLICENCE 700 1- Crommelin Daan Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht Institute for Drug Exploration, Utrecht University, PO BOX 80082, 3508 TB, Utrecht, The Netherlands aut NATIONALLICENCE 773 0- Pharmaceutical Research Kluwer Academic Publishers-Plenum Publishers 14/9(1997-09-01), 1151-1160 0724-8741 14:9<1151 1997 14 11095 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer