The droplet size changes of 1% propofol before and after the storage procedure for 6 and 24 hours periods

Abstract

Propofol (2,6-diisopropylphenol) is a popular anesthetic agent for induction and anesthetic
maintenance. Propofol preparation is formulated as a lipid macroemulsion that is thermodynamically
unstable and degraded over time, causing the enlargement of droplet size. The degradation is faster
when propofol emulsion preparation package has been opened. This droplet enlargement results in
decreasing propofol releasing-rate and its concentration. The risk of embolism occurs whenever the
mean droplet size (MDS) exceeds Food and Drug Administration (FDA) limit (<0.45) and fat globule
population percentage >5 m (PFAT5) is <0.05%. In the daily practice, some propofol emulsion
preparation are often used although they are already opened and saved more than 24 hours. The aim
of this study was to evaluate the droplet size changes of propofol emulsion preparation during
storage. This was an observational study using cohort prospective design. The droplet size changes
of sixteen propofol preparation samples were evaluated before and after storage procedure for 6 and
24 hours in the refrigerator at the temperature of 4ºC. The droplet diameter was determined under a
light microscope. Mean droplet size before and after storage were calculated and analyzed by one
way analysis of variance (ANOVA), followed by Tukey’s post hoc test with 95% confidence interval
(p<0.05). The droplet diameter of propofol emulsion preparation increased significantly (p<0.05)
after storage procedure for 6 h (MDS value were: 247 ± 22 nm) and 24 h (278 ± 29 nm) compared
to before storage (225 ± 24 nm). The PFAT5 at each interval time was 0%. There was no color and
homogeneity changing at each interval time (n=16/100% each time interval). In conclusion, there is
a change of propofol emulsion preparation droplet size after storage procedure for 6 to 24 hours at
temperature of 4ºC compared to before storage.