In article
<538437cd-d7db-4e82-bf5a-afb1dbb45fbd@i18g2000pro.googlegroups.com>,
> It's preserved with Benzalkonium Chloride ("BAK").
>
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> Do some research on BAK. It's BAD for eyes ... particularly dry eyes
> or eyes with any tear film deficiency or instability.
I really believe that BAK has irritated and possibly harming my eyes. Is
there something special about BAK that seems to make it the preferred
preservative in use for ophthalmological eye medications? Would all
preservatives have siilar problm\ems?
Bill

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Mike Tyner - 08 Jul 2009 02:03 GMT
> I really believe that BAK has irritated and possibly harming my eyes. Is
> there something special about BAK that seems to make it the preferred
> preservative in use for ophthalmological eye medications? Would all
> preservatives have siilar problm\ems?
Not all "preservatives" kill germs. Vitamin A and EDTA are antioxidants
("preservative") but have no antimicrobial action. Bad as BAK is, most
everything else is worse.
What are the alternatives - chlorhexidine, phenol, peroxide, iodine,
chlorine, ethanol?
Thimerosal is better, except for the 20% who eventually develop a dramatic
hypersensitivity.
We've known that BAK was cytotoxic to the cornea since the 1940s. But there
are several trade-offs. BAK is cheap, stable, and functions as a detergent.
The corneal cell damage is of the type that is quickly repaired, and it
serves to increase penetration of water-soluble drugs, making them more
effective.
-MT