Solid lipid nanoparticles (SLN) are a new pharmaceutical delivery system or pharmaceutical formulation. These are made of solid lipids which remain solid at room temperature. Solid lipid nanoparticles (SLN) are particulate systems for parenteral drug administration with mean particle diameters ranging from 50 up to 1000 nm.

Advantages of solid lipid nanoparticles (SLN) are :
  • the use of physiological lipids
  • the avoidance of organic solvents
  • a potential wide application spectrum (dermal, per os, intravenous)
  • the high pressure homogenization as an established production method
  • improved bioavailability
  • protection of sensitive drug molecules from the outer environment (water, light)
  • controlled release characteristics were claimed by incorporation of poorly water soluble drugs in the solid lipid matrix
  • allowing autoclave sterilization, a necessary step towards formulation of ocular preparations.
 SLN do not show biotoxicity as they are prepared from physiological lipids. SLNs are especially useful in ocular drug delivery as they can enhance the corneal absorption of drugs and improve the ocular bioavailability of both hydrophilic and lipophilic drugs.