Artificial tears preservatives

Patients may obtain symptomatic relief by using cold compresses and artificial tears.10 If artificial tear solutions sting, recommend a preservative-free formula. 

Regardless of the cause, the mainstay of treatment for dry eye is artificial tears. Artificial tears augment the tear film topically and provide relief. If a patient uses artificial tears more than four times daily, recommend a preservative-free formulation. Preservative-free formulations are also appropriate if the patient develops an allergy to ophthalmic preservatives. Artificial tears are available in gel, ointment, and emulsion forms that provide a longer duration of relief and may allow for less frequent instillation. Ointment use is appropriate at bedtime.30... 

An erodible insert developed as a potential ocular drug-delivery system is marketed as a prescription drug for the lubricant properties of the polymer base. Lacrisert is a sterile ophthalmic insert used in the treatment of moderate to severe dry eye syndrome and is usually recommended for patients unable to obtain symptomatic relief with artificial tear solutions. The insert is composed of 5 mg of hydroxypropylcellulose in a rod-shaped form about 1.27 mm diameter by about 3.5 mm long. No preservative is used, since it is essentially anhydrous. The quite rigid cellulose rod is placed in the lower conjunctival sac and first imbibes water from the tears and after several hours forms a... 

Lopez BD, Ubels JL (1991) Quantitative evaluation of the corneal epithelial barrier effect of artificial tears and preservatives. Curr Eye Res 10(7) 645-656 Rein M (2003) The ocular surface barrier function and mechanisms of injury and repair. In Salem H, Katz S (eds) Alternative Toxicological Methods. CRC Press, New York, pp 89-108... 

The preservatives methylparaben and propylparaben are used in artificial tears and nonmedicated ointments.They can cause allergic reactions and are unstable at high pH. 

The development of latanoprost-induced corneal dendritiform epitheliopathy has been reported. These lesions resemble those of herpes simplex virus epithelial keratitis, but, in contrast to herpes simplex virus disease, the pseudodendrites associated with latanoprost promptly disappear on discontinuation of drug therapy. Coincident with discontinuation of latanoprost, patients can be treated with preservative-free artificial tears with or without topical antibiotics. 

Tear supplements continue to be a rapidly evolving market.As many as 50 different over-the-counter artificial tears are available.These formulations are available either in unit-dose vials or in multidose bottle delivery systems and vary by consistency, active ingredients, and preservatives.Table 24-3 lists many of these preparations. 

Purite This preservative is a stabilized oxychloro complex and is used in brimonidine purite 0.1% and 0.15% and purite-preserved artificial tears. Purite has demonstrated antimicrobial efficacy and is reported to induce less comeal epithelial damage than BAG in a rabbit model (181,182). Glinical trials have also reported purite-containing formulations to be well tolerated (183,184). 

Kahook MY. Comparison of corneal and conjunctival changes after dosing of travoprost preserved with sofZia, latanoprost with 0.02% benzalkonium chloride, and preservative-free artificial tears. Cornea 2008 27 339-343. 

The surface chemistry of the eye is probably better understood than that of the ear. The cornea is covered with a thin, fluid film the so-called tear film, which is believed to consist of an aqueous phase, approximately 10" cm thick, with an adsorbed lipid and mucin layer at the air-water interface and an adsorbed mucin layer on the corneal side. The latter renders the cornea hydrophilic and enables the tear film to spread. In dry eye syndrome local areas of dewetting occur due to increased contact angle. Dry eye is sometimes precipitated by drug therapy, and there is a search for adequate artificial tear fluids. The surface chemistry of tear film components has been discussed by Holly [331]. Adsorption of cationic surfactants present in eye drops as preservatives can lead to the production of a hydrophobic surface due to electrostatic adsorption of the cations with the hydrocarbon chains oriented towards the tear film. Such a process can itself result in dewetting and thus cationics should be excluded from artificial tear fluids. 

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