Morphologic changes of Intralipid 20% liposomes in all-in-one solutions during prolonged storage.

Liposomes of Intralipid 20% in four solutions already mixed for total parenteral nutrition (TPN) were studied by means of a transmission electron microscope. Samples of those so-called all-in-one solutions containing all components for TPN in one bottle were taken immediately after the mixing procedure was finished, then after 24 h, 48 h, 1 week, 2 weeks, 1 month and then monthly up to 6 months afterwards. Storage was carried out for one half at 4 degrees C, for the other at 22 degrees C in darkness. The study showed that liposomes of Intralipid 20% in fresh TPN solutions decreased in their medium diameter from 0.8 to 0.6 micrometers. They carried highly osmiophilic inclusion bodies. Prolonged storage led to further alterations, as change of shape, loss of osmiophility, and lastly formation of liposome ghosts. In solutions kept at 4 degrees C those changes developed between the 1st and 2nd month of storage, whereas storage at 22 degrees C was harmful within 48 h. It is recommended, that already prepared TPN solutions should be kept at 3 degrees C and used as soon as possible, until further studies provide exact guidelines for storage time.