Formulation and evaluation of timolol maleate ophthalmic solution using various preservatives
Author:Garvendra Singh Rathore, Shailesh Sharma, Sunaina Kumari
Abstract:
Preservatives provide important and necessary antimicrobial activity and plays very important role in
maintaining the sterility and shelf-life of multi-dose formulations of topical ophthalmic medications. Any
drop delivered in a multi-dose format must have some mechanism for maintaining the sterility of the
contents throughout its intended length of use. In topical preparations, antimicrobial activity is most often
achieved through the addition of preservatives. The most commonly used preservative in topical drops
of any form is benzalkonium chloride (BAK). Whilst it is known to be an effective antimicrobial agent,
demonstrating efficacy against a wide variety of common pathogens, considerable evidence, often from
its use in glaucoma medications, also exists detailing the deleterious effects it has on the ocular surface,
particularly when used over an extended period of time. It can be argued that the undesirable effects of
BAK have contributed to a movement into preservative-free topical preparations. BAK is quaternary
ammonium compound and this compound has been shown to cause tear film instability, loss of goblet
cells, conjunctival squamous metaplasia and apoptosis, disruption of the corneal epithelium barrier, and
damage to deeper ocular tissues.
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