Table 1

Commonly used preservatives in eye drops

CompoundClassAntimicrobial actionTrade nameExample
BAKQuaternary ammoniumDetergent action dissolves cell walls and membranesN/ALumigan, Xalatan, etc
Polyquartenium 1DetergentActs on cell membranesPolyquadTears Naturale II
SOCOxidisingOxidation of intracellular lipids and glutathionePuriteAlphagan P
Sodium perborateOxidisingForms hydrogen peroxide, oxidising action similar to the aboveGenAquaGenteal
Borate, sorbitol, propylene glycol and zincIonic bufferMultipleSofZiaTravatan Z
  • BAK, benzalkonium chloride; SOC, Stabilised Oxychloro Complex.