Table 1.

Commonly used preservatives in eye drops

Compound	Class	Antimicrobial action	Trade name	Example
BAK	Quaternary ammonium	Detergent action dissolves cell walls and membranes	N/A	Lumigan, Xalatan, etc
Polyquartenium 1	Detergent	Acts on cell membranes	Polyquad	Tears Naturale II
SOC	Oxidising	Oxidation of intracellular lipids and glutathione	Purite	Alphagan P
Sodium perborate	Oxidising	Forms hydrogen peroxide, oxidising action similar to the above	GenAqua	Genteal
Borate, sorbitol, propylene glycol and zinc	Ionic buffer	Multiple	SofZia	Travatan Z

BAK, benzalkonium chloride; SOC, Stabilised Oxychloro Complex.