Veterinary Medicine - August 2007 - (Page 542)

Ophthalmic medications O P E E R - R E V I E W E D try some of the newer lacrimomimetic tear substitutes. Lacrimomimetic agents are preferred; they have an aqueous base more similar to natural tears than do petroleum-based agents, allowing for improved corneal health and animal comfort. However, owners Lubrithal Lubrithal (Aventix Animal Health), a veterinary product, is a carbomer gel with sodium hydroxide and benzalkonium chloride as preservatives. The drop is well-tolerated and provides excellent corneal coverage. Lubrithal also bases in which it is formulated by a compounding pharmacy, consider using tacrolimus. Tacrolimus Tacrolimus is available through compounding pharmacies and should be compounded in a 0.02% ointment or solution. Tacrolimus is similar to cyclosporine in structure and mechanism of action, but few efficacy and safety studies have been performed. In one study, 0.02% tacrolimus administered topically twice daily was effective in increasing tear production in dogs that had never received tear stimulation therapy and in some patients that had responded insufficiently to cyclosporine.3 Since only limited information concerning the efficacy and safety of tacrolimus is available, its use should be reserved for dogs with KCS that are sensitive to or insufficiently respond to cyclosporine. Topical fluoroquinolones can be effective in treating infected corneal ulcers or stromal abscesses. must be able to apply these agents multiple times a day. Also note that if a lacrimomimetic agent is applied more than six times daily, use preservativefree preparations to avoid corneal epithelial damage. If owners cannot apply medications frequently, the petroleumbased artificial tear ointments remain the best choice, as they coat the cornea and slow tear evaporation. Many tear substitutes are available over the counter. These products are typically polyvinyl alcohol, cellulose, dextran, or viscoelastic-substance (sodium hyaluronate or chondroitin sulfate) based. Because of the large number of choices, try to recommend specific products to owners. The following three products work well for dogs and cats. comes in a multidose container and is slightly more viscous than GenTeal. I-Drop Vet I-Drop Vet and I-Drop Vet Plus (I-MED Pharma) differ from GenTeal and Lubrithal because they contain sodium hyaluronate (hyaluronic acid), which has excellent mucinomimetic properties and is an excellent ocular protectant. I-Drop Vet and I-Drop Vet Plus also contain glycerin to help retain the lubricant and better disperse it after each blink, thus they require less frequent application—twice-daily application may be sufficient. Pimecrolimus and sirolimus Two other drugs, pimecrolimus and sirolimus, are under investigation for use as lacrimostimulants.4,5 However, little is known about their clinical efficacy or safety. TOPICAL ANTIBIOTICS Although they are not new, you may be unfamiliar with topical fluoroquinolones available for use in people, such as 0.3% ofloxacin, 0.3% norfloxacin, 0.3% gatifloxacin, and 0.3% ciprofloxacin. None of these medications should be used for routine antimicrobial prophylaxis; however, these topical fluoroquinolones can be effective in treating infected corneal ulcers or stromal abscesses, particularly infections involving gram-negative organisms. To treat these infections, topical fluoroquinolones should be applied six times daily until the infection resolves. Fluoroquinolones are effective against Pseudomonas species and Escherichia coli; Staphylococci species are also often susceptible. Fluoroquinolones are usually not recommended to treat Streptococci species infections because those TEAR STIMULANTS (LACRIMOSTIMULANTS) Many practitioners are familiar with using cyclosporine (Optimmune— Schering-Plough Animal Health) in dogs to stimulate tear production. The benefit of cyclosporine in patients with KCS stems from its selective T-helper lymphocyte suppression1 and direct lacrimostimulatory properties.2 Because of its selective immunosuppressive properties, cyclosporine is often also beneficial in treating pannus and other immune-mediated corneal disorders.1 If cyclosporine therapy fails in a patient with KCS or the patient is sensitive to cyclosporine or the lipid GenTeal GenTeal (Novartis Ophthalmics) is a cost-effective over-the-counter preparation that contains a small amount of hydrogen peroxide as a preservative. When placed on the eye, the hydrogen peroxide is converted into oxygen and water. GenTeal is sold in multidose vials and is available in gel and liquid formulations. The severe and PF formulations of GenTeal are preferred since they contain the highest concentration of hydroxypropyl methylcellulose (0.3%) and, thus, will remain on the cornea longer. 542 August 2007 VETERINARY MEDICINE

Table of Contents Feed for the Digital Edition of Veterinary Medicine - August 2007

Contents A Veterinary Medicine Interview Veterinary Voices Idea Exchange Diagnosis and Treatment of Solar Dermatitis in Dogs Diagnostic Imaging for Linear Foreign Bodies in Cats Overcoming the Diagnostic and Therapeutic Challenges of Canine Immune-Mediated Thrombocytopenia Ophthalmic drugs: What’s new? CE Form Product Preview Advertiser Index Marketplace/Classifieds Mind Over Miller

Veterinary Medicine - August 2007

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