The effects of four potential supercritical carbon dioxide (ScCO2) sterilization conditions on the chemical stability
of 9 phospholipids and on the physicochemical characteristics of liposomes consisting of stable phospholipids,
as well as their sterilization efficiency were evaluated. These conditions were : C1 (ScCO2/70 ◦C/150
bar/240 min), C2 (ScCO2/0.25 % water/ 0.15% H2O2/ 0.5% acetic anhydride/38◦ C/85 bar/45 min), C3
(ScCO2/0.08 % peracetic acid/35◦ C/104 bar/180 min) and C4 (ScCO2/200 ppm H2O2/40 ◦C/270 bar/90 min).
The results showed for phospholipids, a significant increase in hydrolysis products of 3.77 to 14.50 % and an
increase in oxidation index of 6.10 to 430.50 % with unsaturated phospholipids for all tested conditions while
with saturated phospholipids, no significant degradation was observed. Concerning the liposome formulation, no
change in dispersion color and no phospholipid degradation were observed. However, a decrease in liposome size
from 126.90 nm to 111.80 nm, 96.27 nm, 99.60 nm and 109.13 nm and an increase in the PdI from 0.208 to
0.271, 0.233, 0.285, and 0.298 were found with conditions C1, C2, C3 and C4 respectively. For the sterilization
efficiency, conditions C1, C2 and C3 achieved the required sterility assurance level (SAL) of 10-6 for liposomes.

Phospholipids, Liposomes, Supercritical carbon dioxide, Sterilization, Stability, Sterilizing efficacy