Encapsulation of drugs into large unilamellar liposomes prepared by an extemporaneous method.

The method we developed for extemporaneous preparation of large unilamellar liposomes (Philippot et al. 1984) was applied to the encapsulation of 12 different antibiotic, anti-asthmatic and anti-inflammatory drugs. The behaviour of these drugs, during encapsulation, assigns them to one of the three classes: hydrophilic, hydrophobic or both. Alone, the first type of compound gave an appreciable encapsulation. However, the entrapment yield depended on the respective charges of the liposome and the drug. The amphiphile molecules tested are permeant and thus did not stay inside the liposomes. Only one of the hydrophobic drugs analysed associated with the liposome membrane lipids with a good yield.