Effect of composition and method of preparation of liposomes on their stability and interaction with murine monocytes infected with Brucella abortus.

The success of the use of liposomes as drug carriers depends on both their formulation and the method of preparation. We have carried out a series of in vitro studies using different formulations and preparation methods, with the aim of obtaining a type of liposome which is efficient in the treatment of brucellosis. On the basis of results obtained in studies of stability at 37 degrees C in the presence of serum lipoproteins and of the activation of phagocytic cells and antibiotic transport to the interior of monocytes infected with Brucella abortus, we conclude that the most suitable vesicles are positively charged, stable plurilamellar vesicles (phosphatidylcholine, 30% cholesterol, and 10% stearylamine). Gentamicin incorporated into these cationic liposomes completely eliminated all of the intracellular Brucella organisms (4.6 logs), while free gentamicin was capable of reducing the number of intracellular bacteria by only 0.3 log.