Abstract: Liposomes of a specific bilayer composition containing an entrapped modifying compound are claimed. The liposomes of the invention are suitable for the internalisation of a variety of materials, even following long-term storage. Suitable materials of the invention include radiometals, parmagnetic compounds, radioopaque compounds and prodrugs. Upon internalisation, the material reacts chemically with the entrapped modifying compound such that said material remains internalised within the liposomes of the invention. Also claimed in the present invention are the liposomes containing internalised material and kits for their preparation. Furthermore, the use of said liposomes containing internalised material for the imaging infection, inflammation or tumour in a human is claimed.

Abstract: The invention provides a process for the preparation of a pharmaceutical composition comprising an aqueous dispersion of gas-containing vesicles the membranes whereof comprise an amphiphilic membrane-forming material, said process comprising: (i) generating a liquid dispersion of gas-containing vesicles from a mixture comprising an amphiphilic membrane forming material; (ii) lyophilizing a liquid dispersion of said gas-containing vesicles; (iii) reconstituting the lyophilized product of step (ii) with a sterile aqueous liquid to produce an aqueous dispersion of gas-containing vesicles; and (iv) treating the aqueous dispersion product of step (iii) or the lyophilized product of step (ii) to produce a substantially aggregate-free sterile aqueous dispersion of gas-containing vesicles.