Effect of flunixin meglumine on the breakdown of the blood-aqueous barrier following paracentesis in the canine eye

Oral 5-aminolevulinic acid combined with sodium ferrous citrate prevents blood-aqueous barrier breakdown after anterior chamber paracentesis in healthy beagle dogs

This study investigated the preventive effect of 5-aminolevulinic acid combined with sodium ferrous citrate (5-ALA/SFC) on blood-aqueous barrier (BAB) breakdown induced after anterior chamber paracentesis (ACP) in beagles. 5-ALA/SFC (1/0.64 mg/kg or 3/1.92 mg/kg) or carprofen (4.0 mg/kg) was orally administered daily for 7 days prior to ACP. Then, a sample of the aqueous humor (AH) was collected from one eye via ACP (first sample) and again 60 min later (second sample). The protein and prostaglandin E2 (PGE2) concentrations in both samples were measured. Compared with the control group, high-dose 5-ALA/SFC and carprofen significantly reduced the AH protein and PGE2 concentrations in the second sample. Our findings suggest that 5-ALA/SFC suppresses BAB breakdown in dogs.

Tyrosol ameliorates lipopolysaccharide-induced ocular inflammation in rats via inhibition of nuclear factor (NF)-κB activation

We evaluated the anti-inflammatory effect of tyrosol (Tyr) on endotoxin-induced uveitis (EIU) in rats. EIU was induced in male Lewis rats by subcutaneous injection of lipopolysaccharide (LPS). Tyr (10, 50 or 100 mg/kg) was intravenously injected 2 hr before, simultaneously and 2 hr after LPS injection. The aqueous humor (AqH) was collected 24 hr after LPS injection; the infiltrating cell number, protein concentration, and tumor necrosis factor (TNF)-α, prostaglandin (PG)-E2 and nitric oxide (NO) levels were determined. Histopathologic examination and immunohistochemical studies for nuclear factor (NF)-κB, inhibitor of κB (IκB)-α, cyclooxygenase (COX)-2 and inducible NO synthase (iNOS) in the iris-ciliary body (ICB) were performed at 3 or 24 hr after LPS injection. To further clarify the anti-inflammatory effects, RAW264.7 macrophages were stimulated with LPS in the presence or absence of Tyr. Tyr reduced, in a dose-dependent manner, the infiltrating cell number, protein concentration, and TNF-α, PGE2 and NO levels in AqH and improved histopathologic scores of EIU. Tyr also inhibited LPS-induced COX-2 and iNOS expression, IκB-α degradation and nuclear translocation of activated NF-κB in ICB. Tyr significantly suppressed inflammatory mediator production in the culture medium and COX-2 and iNOS expression and activated NF-κB translocation in LPS-stimulated RAW264.7 cells. These results suggest that Tyr suppresses ocular inflammation of EIU by inhibiting NF-κB activation and subsequent proinflammatory mediator production.

Effects of oral administration of anti-inflammatory medications on inhibition of paracentesis-induced blood-aqueous barrier breakdown in clinically normal cats

OBJECTIVE

To assess inhibitory effects of orally administered anti-inflammatory medications on paracentesis-induced intraocular inflammation in clinically normal cats.

ANIMALS

30 clinically normal domestic shorthair cats.

PROCEDURES

Cats were randomly assigned to a control group and 4 treatment groups. Cats in the treatment groups received an anti-inflammatory medication orally once daily at 7 AM (acetylsalicylic acid [40.5 mg/cat], meloxicam [0.1 mg/kg], prednisone [5 mg/cat], or prednisolone [5 mg/cat]) for 5 days beginning 2 days before paracentesis-induced breakdown of the blood-aqueous barrier (BAB) and continuing until 2 days after paracentesis. Paracentesis of the anterior chamber was performed in 1 randomly selected eye of each cat. Fluorophotometry was performed in both eyes of each cat immediately before (time 0) and 6, 24, and 48 hours after paracentesis.

RESULTS

At 24 and 48 hours after paracentesis, fluorescein concentration in the eye subjected to paracentesis in the cats receiving prednisolone was decreased, compared with that in the control cats. At 48 hours, a decrease in the fluorescein concentration was also apparent in the eye subjected to paracentesis in the cats receiving meloxicam, compared with that in the control cats. There was no evidence of treatment effects for acetylsalicylic acid or prednisone. There was no evidence of treatment effects in eyes not subjected to paracentesis.

CONCLUSIONS AND CLINICAL RELEVANCE

Orally administered prednisolone and meloxicam significantly decreased intraocular inflammation in clinically normal cats with paracentesis-induced BAB breakdown. Oral administration of prednisolone or meloxicam may be an effective treatment for cats with uveitis.

Comparison of tepoxalin, carprofen, and meloxicam for reducing intraocular inflammation in dogs

OBJECTIVE

To compare effects of orally administered tepoxalin, carprofen, and meloxicam for controlling aqueocentesis-induced anterior uveitis in dogs, as determined by measurement of aqueous prostaglandin E(2) (PGE(2)) concentrations.

ANIMALS

38 mixed-breed dogs.

PROCEDURES

Dogs were allotted to a control group and 3 treatment groups. Dogs in the control group received no medication. Dogs in each of the treatment groups received an NSAID (tepoxalin, 10 mg/kg, PO, q 24 h; carprofen, 2.2 mg/kg, PO, q 12 h; or meloxicam, 0.2 mg/kg, PO, q 24 h) on days 0 and 1. On day 1, dogs were anesthetized and an initial aqueocentesis was performed on both eyes; 1 hour later, a second aqueocentesis was performed. Aqueous samples were frozen at -80 degrees C until assayed for PGE(2) concentrations via an enzyme immunoassay kit.

RESULTS

Significant differences between aqueous PGE(2) concentrations in the first and second samples from the control group indicated that aqueocentesis induced uveitis. Median change in PGE(2) concentrations for the tepoxalin group (10 dogs [16 eyes]) was significantly lower than the median change for the control group (8 dogs [16 eyes]), carprofen group (9 dogs [16 eyes]), or meloxicam group (9 dogs [16 eyes]). Median changes in PGE(2) concentrations for dogs treated with meloxicam or carprofen were lower but not significantly different from changes for control dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Tepoxalin was more effective than carprofen or meloxicam for controlling the production of PGE(2) in dogs with experimentally induced uveitis. Tepoxalin may be an appropriate choice when treating dogs with anterior uveitis.

Ocular penetration of oral doxycycline in the horse

OBJECTIVE

To investigate intraocular penetration of orally administered doxycycline in the normal equine eye and to compare intraocular and serum doxycycline concentrations. Procedures Six mares were administered doxycycline at 10 mg/kg every 12 h by nasogastric tube for 5 days. Blood, aqueous, and vitreous samples were collected on days 1 and 5. All samples were assayed for doxycycline concentrations. Aqueous and vitreous samples were also assayed for protein quantitation.

RESULTS

Doxycycline was rapidly absorbed after the first dose (T(max) value of 1.42 +/- 1.28 h); and elimination of doxycycline occurred slowly (median t(1/2) = 10.88 h). Doxycycline could not be detected in the aqueous on days 1 and 5, nor could it be detected in the vitreous on day 1. On day 5, the mean vitreous doxycycline concentration was 0.17 +/- 0.04 microg/mL at 2 h after drug administration.

CONCLUSIONS

Repeated oral administration of doxycycline in the horse resulted in steady state serum concentrations of < 1 microg/mL; however, it did not result in appreciable concentrations of drug in the aqueous and vitreous in normal eyes.

Effects of intracameral injection of preservative-free lidocaine on the anterior segment of the eyes in dogs

OBJECTIVE

To evaluate effects of intracameral injection of preservative-free 1% and 2% lidocaine hydrochloride solution on the anterior segment of the eyes in dogs.

ANIMALS

16 adult healthy dogs (8 male and 8 female) judged to be free of ocular disease.

PROCEDURE

Dogs were randomly assigned to 2 groups of 8 dogs each. Group 1 dogs received an intracameral injection of 0.10 mL of preservative-free 1% lidocaine solution in the designated eye, and group 2 dogs received 0.10 mL of preservative-free 2% lidocaine solution in the designated eye. After injection, intraocular pressure was measured every 12 hours for 48 hours and then every 24 hours until 168 hours after injection. Slit-lamp biomicroscopy was performed preceding intracameral injection, 8 hours after injection, and then every 24 hours until 168 hours after injection. Ultrasonic pachymetry and specular microscopy were performed preceding intracameral injection and 72 and 168 hours after injection. Corneal thickness and endothelial cell density and morphology were compared with baseline measurements.

RESULTS

No significant differences were found in intraocular pressure, corneal thickness, endothelial cell density, and morphologic features in either group, compared with baseline. A significant difference in aqueous flare was found for treated and control eyes 8, 24, and 48 hours after injection, compared with baseline. No significant difference in aqueous flare was found between treated and control eyes within either group.

CONCLUSIONS AND CLINICAL RELEVANCE

No adverse ocular effects were detected after intracameral injection of preservative-free 1% or 2% lidocaine solution; thus, its use would be safe for intraocular pain management in dogs.

Nonsteroidal anti-inflammatory drugs in veterinary ophthalmology

Uveitis is a common sequela to many ocular diseases. Primary treatment goals for uveitis should be to halt inflammation, prevent or control complications caused by inflammation, relieve pain, and preserve vision. Systemic and topical NSAIDs are essential components of the pharmaceutic armamentarium currently employed in the management of ocular inflammation by general practitioners and veterinary ophthalmologists worldwide. NSAIDs effectively prevent intraoperative miosis; control postoperative pain and inflammation after intraocular procedures, thus optimizing surgical outcome; control symptoms of allergic conjunctivitis;alleviate pain from various causes of uveitis; and circumvent some of the unwanted side effects that occur with corticosteroid treatment. Systemic NSAID therapy is necessary to treat posterior uveitis, because therapeutic concentrations cannot be attained in the retina and choroid with topical administration alone, and is warranted when diseases, such as diabetes mellitus or systemic infection, preclude the use of systemic corticosteroids. Risk factors have been identified with systemic and topical administration of NSAIDs. In general, ophthalmic NSAIDs may be used safely with other ophthalmic pharmaceutics; however, concurrent use of drugs known to affect the corneal epithelium adversely, such as gentamicin, may lead to increased corneal penetration of the NSAID. The concurrent use of NSAIDs with topical corticosteroids in the face of significant preexisting corneal inflammation has been identified as a risk factor in precipitating corneal erosions and melts in people and should be undertaken with caution[8]. Clinicians should remain vigilant in their screening of ophthalmic and systemic complications secondary to drug therapy and educate owners accordingly. If a sudden increase in patient ocular pain (as manifested by an increase in blepharospasm, photophobia, ocular discharge, or rubbing)is noted, owners should be instructed to contact their veterinarian promptly.

Laser flaremetric evaluation of experimentally induced blood-aqueous barrier disruption in cats

OBJECTIVES

To determine whether aqueous humor flare, measured by use of laser flaremetry, was proportional to aqueous humor protein concentration and to use laser flaremetry to evaluate disruption of the blood-aqueous barrier (BAB) in cats.

ANIMALS

30 healthy adult cats.

PROCEDURE

Laser flaremetry values for all eyes were compared with aqueous humor protein concentrations determined by use of a Coomassie blue microprotein assay. Laser flaremetry was then performed on both eyes before (0 hours) and 4, 8, and 26 hours after initiation of topical application of 2% pilocarpine (q 8 h) to 1 eye of 9 cats or paracentesis of the anterior chamber of 1 eye of 8 cats. Intraocular pressure and pupil size were also determined. Aqueous humor protein concentration was extrapolated from flare values by use of linear regression.

RESULTS

There was a linear relationship between flare values and aqueous humor protein concentrations. Topical application of 2% pilocarpine and paracentesis of the anterior chamber caused a breakdown of the BAB that was detected by use of laser flaremetry. The highest mean flare readings after application of pilocarpine or paracentesis were 24.4 and 132.8 pc/ms, respectively, which corresponded to aqueous humor protein concentrations of 85.5 and 434.9 mg/dl, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Paracentesis of the anterior chamber resulted in a more severe breakdown of the BAB in cats than topical application of 2% pilocarpine. Laser flaremetry may be a useful clinical method to detect increases in aqueous flare and, hence, disruptions of the BAB in cats.

Control of ocular inflammation

Although both topical and systemic anti-inflammatory agents have a place in veterinary ophthalmology, they play only a small role in overall patient management. They must be used appropriately to prevent ocular damage and loss of vision from inflammation and are not a replacement for a complete ophthalmic examination and specific treatment directed at the etiology of the problem. If used indiscriminately, they can result in local or systemic side effects or toxicities, many of which are worse than the initial problem for which they were selected. Just as topical corticosteroids are contraindicated with infectious keratitis, so are systemic corticosteroids contraindicated in patients with ocular inflammation resulting from a systemic infectious process. Anti-inflammatories must be used at the appropriate dosage and frequency. Use of corticosteroids that have low intraocular penetration for intraocular disease or corticosteroids with low potency is a waste of time and money. The most expensive medication is one that does not work. Avoid combination therapies when only a single medication is required. These do not save time or money and have the potential to result in the development of drug-related diseases. Diseases for which anti-inflammatory therapy has little or no indication include corneal scars, corneal edema, corneal pigmentation, corneal dystrophy, cataracts without inflammation, glaucoma, and retinal atrophy and degeneration. Last, remember that all commercially available ophthalmic medications are specifically formulated for use in the eye. Their pH, concentration, osmolality, and melting temperature all are designed to facilitate penetration. The use of dermal and otic preparations to treat ophthalmic problems is contraindicated.