Antimicrobial Substances in Ophthalmic Drops

Overview

Microbial contamination of ophthalmic drops means a risk of serious injury to the eye. Ophthalmicdrops must therefore comply with sterility requirements. Protection of multiple-dose drops againstsecondary contamination is ensured by an addition of an antimicrobial agent. Selection of a suitableantimicrobial agent is conditioned by many factors, such as the spectrum of effect, properties of thepreparation, compatibility with the components of the preparation and the container, and thetechnology of manufacture. Although the added antimicrobial substance ensures the safety of thepreparation, on the other hand it can produce a number of negative effects in the eye tissue. Thepresent paper summarizes pharmacopoeial requirements for microbial quality of ophthalmic drops,outlining the properties and efficacy of antimicrobial substancescommonly used in ophthalmic drops(benzalkonium chloride BAC, cetrimide CTM, phenyl mercuric salts PHg, thiomersalTM, chlorobutanolChB, benzyl alcohol BA, phenyl ethyl alcohol PEA, chlorohexidin ChX, parabens PB), theirtypical concentrations and combinations, including the parameters of formulation and the interactionswhich affect their activity. It deals with the toxicity of these antimicrobial substances, sideeffects on the eye tissue, and alternatives to the use of antimicrobial agents.

Key words:
ophthalmic drops – antimicrobial substances – toxicity – eye tolerance