The phospholipid bilayer contains at least one pharmaceutically active drug and comprises cell-specific markers on the membrane which have at least 90% biological activity when measured according to Luescher & Glueck, Antiviral Research 14, 39-50. In the membrane, the cholesterol content is preferably less than 2% by weight, the detergent content preferably less than 1 ppb. The vesicle diameter preferably is about 80 nm. the phospholipid in the membrane may comprise 70 to 95% by weight of phosphatidylcholine and preferably 10 to 20% by weight of phosphatidylethanolamine; preferably 6-8% by weight of a crosslinker, preferably of a sulfosuccinimidyl derivate, and at least one cell-specific fusion peptide are linked to the membrane. The vesicles are used for the preparation of pharmaceuticals against AIDS and carcinomas.