A synthetic, microscopic globule consisting of layers of lipids encapsulating certain substances (as enzymes or drugs): used to introduce these substances into a cell or specified tissue.

These have a good capacity to hold lipophilic as well as hydrophilic drugs, with having high molecular weight drugs. These systems are very useful in delivering various or almost all class of drugs, including antineoplastics, sedative/hypnotics, analgesics, antibiotics, anti diabetic drugs etc.

Systems are also useful in targeting of various drugs to specific site, so that drug is delivered directly to the affected area, without causing damage or side effects to non target sites.