Clode 2016-BSC-Anti

OCULAR ANTI- INFLAMMATORY AGENTS

Alison Clode, DVM, DACVO

Port City Veterinary Referral Hospital Portsmouth, New Hampshire

New England Equine Medical and Surgical Center Dover, New Hampshire

Overview

• Corticosteroids

• NSAIDs Corticosteroids

• Produced in the adrenal cortex from cholesterol

• Glucocorticoids • Cortisol (endogenous) • Metabolic fxn • Immune fxn • Anti-inflammatory fxn

• Mineralocorticoids

• Electrolyte and H2O balance Glucocorticoids – MOA Glucocorticoids – Genomic MOA

1. Transactivation = activation of anti-inflammatory transcription factors

2. Transrepression = inhibition of transcription of pro- inflammatory genes (multiple mechanisms) Glucocorticoids – Genomic Effects Glucocorticoids – Transactivation

Anti-inflammatory proteins

1. GC binds cytoplasmic receptor (cGCR) à 2. GC-cGCR complex translocates to nucleus à 3. Binds GRE in target gene à 4. Up-regulation of anti-inflammatory, immunomodulatory, and metabolic processes

** Numerous and cell-specific cofactors influence specific cellular response to GC

Glucocorticoids – Transrepression

Pro-inflammatory proteins

1. GC binds cytoplasmic receptor (cGCR) à 2. GC-cGCR complex translocates to nucleus à 3. Binds negative GRE à 4. Down-regulation of pro-inflammatory protein production Glucocorticoids – Transrepression

Pro-inflammatory proteins

1. GC binds cytoplasmic receptor (cGCR) à 2. GC-cGCR complex interacts with specific transcription factors (TF) à 3. No binding of GC-cGCR complex or TFs to pro-inflammatory GREs à 4. Down-regulation of pro-inflammatory and immune stimulation factors Glucocorticoids – Transrepression

Pro-inflammatory proteins

1. GC binds cytoplasmic receptor (cGCR) à 2. GC-cGCR complex translocates to nucleus à 3. GC-cGCR binds nuclear coactivators à 4. Inhibition of pro-inflammatory protein production GC – Transactivation and Transrepression

Vandevyver S et al., Endocrinology 2013 Glucocorticoids – MOA Glucocorticoids – Non-Genomic Effects

• Possibly explain more rapid clinical response than can be explained by genomic effects

1. Non-specific interactions between GC and cell membrane 2. Specific interactions between GC and membrane-bound GCR 3. Actions of cGCR that do not involve genome

Glucocorticoids – Non-Genomic Effects

1. Non-specific interactions between GC and cell membrane:

• High concentration of extracellular GC à intercalate with cell membrane à altered physicochemical properties of cell membrane à altered Na+ and Ca2+ transport across membranes of immune cells à rapid immunosuppression

• Mitochondrial proton leak à impaired ATP production à altered cellular function Glucocorticoids – Non-Genomic Effects

2. Specific interactions between GC and membrane-bound GCR

• mGCR is unique variant of cGCR • Upregulation with immunostimulation thought to be a protective mechanism • GC-induced mGCR-mediated apoptosis Glucocorticoids – Non-Genomic Effects

3. Actions of cGCR that do not involve genome:

• cGCR exists in cytoplasm as multi-protein complex • Binding of GC to cGCR releases protein complex so GC-cGCR can translocate to nucleus • Released proteins mediate various rapid intracellular effects • HSPs, kinases, etc.

• cGCR also inhibits release of AA from plasma membrane via a transcription-independent mechanism Glucocorticoids – ‘End’ Result

• Anti-inflammatory actions: 1. Increase lipocortin-1 synthesis à

• Suppression of phospholipase A2 à • Decreased production of pro-inflammatory prostaglandins and leukotrienes

2. Increase MAPK phosphatase 1 synthesis à • Suppression of c-Jun transcription à • Decreased transcription of pro-inflammatory genes

3. Inhibition of NF-κβ à • Decreased COX-2 synthesis à • Suppression of prostaglandin production

Rhen T, et al., New Engl J Med 2008 Glucocorticoids – ‘End’ Result

• Immunosuppressive actions: 1. Decrease B- and T-cell number and function • Via inhibition of NF-κβ

2. Inhibit cell-mediated immunity • Via inhibition of multiple interleukins

3. Inhibit humoral immunity • Via decreased synthesis of IL-2/IL-2 receptors Side Effects

• Systemic: • Hyperglycemia • Skin fragility • Muscle breakdown • Osteoporosis • Etc…

• Ocular: • Cataract • Ocular hypertension • Potentiate infection • Decrease wound healing • Corneal lipid deposition Glucocorticoid-Induced Cataract

• Central posterior subcapsular • Initially clearly delineated • Vacuolated

• Only associated with corticosteroids with GC activity

• Overall prevalence of 22% (0% - 90%)

• Dependent upon: • Dose • Duration • Route STEROID CATARACT 413

CONCLUSIONS tain, in particular because the data were gener- ated following short exposure times to glucocor- Despite the long-recognized association of glu- ticoid in vitro, and because in vivo steroid cataracts cocorticoids with PSCs, the mechanism(s) re- require many months of glucocorticoid adminis- sponsible for inducing steroid cataracts remains tration to develop. Hopefully, a clearer picture re- unknown. Glucocorticoids administered locally garding the altered expression of relevant genes (to the eye) or systemically (at a distance from in lens epithelial cells will emerge from extended the eye) are both effective in inducing steroid glucocorticoid treatment studies, preferably us- cataracts. It is possible, therefore, to present a case ing patient-derived PSC material. for steroid-induced cataracts as being the result Demonstration of an active glucocorticoid re- of the direct action of glucocorticoids on lens ep- ceptor in the lens has altered the perception of ithelial cells but also for an indirect action, as fa- what mechanism(s) may underlie the develop- vored by Jobling and Augusteyn13 through ment of steroid cataract. The data from DNA ar- changes to, for example, the levels of intraocular ray studies encourage the consideration of sev- growth factors. eral feasible hypotheses, but as yet, there are very Recent studies have demonstrated the defini- few supportive data. Defining and characterizing tive existence of a glucocorticoid receptor alpha the effects of glucocorticoid receptor activation on in lens epithelial cells, whose activation results in signal transduction mechanisms in lens epithelial changes in gene expression. Glucocorticoid re- cells will likely be one of the important next steps ceptor activation (in other cell types) is associ- in unraveling the mechanism of steroid cataract ated, in particular, with changes to gene expres- induction. Monitoring the intraocular environ- sion that are linked to alterations in: (i) cell ment of the lens following exposure to glucocor- proliferation and differentiation, (ii) apoptosis, ticoid for changes in the levels of growth factors (iii) gluconeogenesis, (iv) expression and activity also promises to yield additional useful data. The of growth factors, and (v) modifications to signal issues of ROS activity and lens cell membrane transduction pathways. Changes to the levels of permeability changes also require further resolu- transcription of genes involved in these processes tion in light of observed modifications to gene have been observed in the DNA array studies and transcription. Glucocorticoid-Inducedsupplementary investigations Cataract performed with The etiology of steroid cataract induction will, cultured lens epithelial cells.25,43 However, the in all probability, turn out to be comprised of both relevance of these individual changes is uncer- direct effects of glucocorticoids on lens epithelial 1. Intralenticular glucocorticoid receptor activation à • Altered gene transcription • GC-induced lucine zipper protein • Nexin • Aberrant posterior LEC migration • Alterations in E-cadherin? • Alterations in ocular growth factors? • Alterations in enzyme pathways?FIG. 1. Steroid cataract formation: Pathways/factors potentially contributing to the formation of steroid-induced posterior subcapsular cataracts following glucocorticoid treatment. Likely prominent pathways are shown in black, with possible secondary contributing pathways in grey. GC, glucocorticoid; GSH, glutathione; ROS, reactive oxygen species; PSC, posterior subcapsular cataract; Na, sodium). 2. Alterations in oxidation and hydration GC-Induced Ocular Hypertension

• ~30% of patients receiving dexamethasone eye drops topically for 4 weeks

• Increased incidence in patients with glaucoma (46 – 92%)

• “High responders” = 15 mmHg increase (4 – 6% of population)

• “Moderate responders” = 6 – 15 mmHg increase (30% of population) www.ohsu.edu

• All routes of administration • Generally reversible Armaly MF. Arch Ophthalmol 1963 Tripathi RC, et al., Drugs Aging 1999 McGhee CNJ, et al., Drug Safety 2002 Tawara A, et al., Graefe’s Arch Clin Exp Ophthalmol 2008 GC-Induced Ocular Hypertension

• Alteration of drainage angle ECM • Activation of GC receptors in TM • Accumulation of basement membrane-like and fibrillar material in outer TM • Increased type IV collagen • Increased heparan sulfate proteoglycan • Increase fibronectin GC-Induced Ocular Hypertension in Animals • Cattle: • 1% or 0.5% prednisolone acetate TID x 49 days • Increase IOP from 16 mmHg to 30 – 35 mmHg • Within 3 – 4 weeks of treatment • Returns to normal within 4 – 5 weeks following discontinuation • Slight increase in contralateral eye GC-Induced Ocular Hypertension in Animals • TID topical prednisolone acetate

IOVS 2011 • TM gene expression: • 258 upregulated • 187 downregulated • Cytoskeletal proteins • Enzymes • Growth factors • Transcription factors • ECM proteins • Immune response proteins GC-Induced Ocular Hypertension in Animals

• Cats: • 1% dexamethasone or 1% prednisolone acetate BID • Significant increase IOP within 2 – 3 weeks • Normal IOP within 1 week following discontinuation • (Also developed cataracts)

Zhan GL, et al., Exp Eye Res 1992 GC-Induced Ocular Hypertension in Animals

• Normal dogs • Oral hydrocortisone x 5 weeks • No increase in IOP

• Glaucomatous Beagles • Topical 0.1% dexamethasone four times daily • IOP increase 5 mmHg within 2 weeks • Continued increase during duration of instillation • Contralateral control eye IOP increase 2 mmHg • Reduction to baseline within 1 week of discontinuation

Gelatt KN, et al., J Ocular Pharm Ther 1998 Glucocorticoid-Induced Corneal Damage

• Potentiate infection • Decrease wound healing • Increase collagenolysis • Decreased fibroblast activity • Decreased collagen deposition • Dexamethasone sodium phosphate has least negative effect Avoiding Corticosteroid Side Effects

• Side effects primarily (but not entirely) mediated by transactivation • Methods to minimize transactivation and maintain transrepression may therefore decrease side effects

• Increased focus on maximizing non-genomic effects for therapeutic benefit

1. Long-circulating liposomal GC 2. Nitro-steroids 3. Selective GCR agonists (SEGRAs) Long Circulating Liposomal GC

• Lipid bilayer + hydrophilic core • Hydrophilic polymers on surface prevent breakdown by mononuclear phagocytes • Encapsulate GC within core

• Accumulate at site of inflammation à very high local concentrations • More effective than repeated injection • Lower plasma levels à lesser adverse effects Nitro-Steroids

• GC + aliphatic or aromatic linker + nitric oxide (NO)

• NO slowly released à enhanced anti-inflammatory effects

• NO-prednisolone • Anti-inflammatory effects 10X stronger than prednisolone in murine arthritis model • Decreased bone resorbing activity relative to prednisolone • NO-hydrocortisone SEGRAs

• “Dissociating GC” • Avoid undesirable effects of transactivation and preserve desirable effects of transrepression • Bind cGCR with similar affinity of synthetic steroids • Compounds in development demonstrate 60 – 300x weaker transactivation capability than prednisolone or dexamethasone

• Concerns: • Will cell-level effects translate to tissue to whole organism effects? • Will anti-inflammatory/immunomodulating properties be conserved? • Is all transactivation bad? SEGRAs SEGRAs SEGRAs – Mapracorat

• Single and multiple topical ocular dosing to rabbits and monkeys • Fluid and tissue levels

• Rapidly absorbed into ocular tissues • Retinal levels higher than AH • Low systemic exposure SEGRAs – Mapracorat

• Topical administration • Dry eye model – comparable efficacy to dexamethasone and cyclosporin • Paracentesis model – comparable efficacy to dexamethasone • No increase in IOP or alterations in body weight SEGRAs – Mapracorat

• Cultured human conjunctival epithelial cells and fibroblasts • In vitro challenge with allergy-associated inflammatory cytokines • IL-4, IL-13, TNF-α • Evaluation of subsequent expression of inflammatory cytokines and chemokines and inhibition by varying doses of mapracorat • Mapracorat significantly inhibited allergy-related cytokine/ chemokine expression relative to dexamethasone SEGRAs – Mapracorat

• Phase II clinical trials • Atopic dermatitis • Allergic conjunctivitis • Inflammation following cataract surgery

Baiula M et al., Inflamm and Allergy Drug Targets 2014 Specific Corticosteroids Relative Potency

GC Effect MC Effect Duration Hydrocortisone 1 1 8 h (cortisol) Prednisone/ 4 0.8 16 – 36 h prednisolone Triamcinolone 5 0 12 – 36 h

Fludrocortisone 20 125 24 h

Dexamethasone 25 0 36 – 54 h

Betamethasone 25 0 36 – 54 h

Actual ocular bioavailability and anti-inflammatory efficacy affected by intact versus absent epithelium, presence or absence of uveitis Corticosteroids in Ophthalmology

• Topical • Subconjunctival • Intravitreal • Oral

• Blepharitis • Ocular surface inflammation • Anterior uveitis • Posterior uveitis Ophthalmic Formulations

Derivative Solubility Formulations Relative anti-inflammatory efficacy Prednisolone Dexa- Fluoro- methasone metholone Acetate Lipid Suspension 50% 55% 50% Ointment Alcohol Intermediate Suspension 40% 40% (lipid) Ointment

Phosphate Water Solution 30 – 45% 20%

** Actual ocular bioavailability and anti-inflammatory efficacy affected by intact versus absent epithelium, presence or absence of uveitis

Adapted from Sendrowski DP, et al., Clin Ocular Pharm 2008 Prednisolone

• Gold-standard for anterior segment inflammation • Anti-inflammatory activity of acetate greater than of phosphate, with or without intact epithelium

• Acetate likely increases affinity for receptor, may alter metabolism

• No greater effect with 1.5% or 3% than with 1%

• Effect may not be clinically distinguishable from phosphate Dexamethasone

• Anti-inflammatory activity of alcohol greater than that of sodium phosphate, with or without intact epithelium

• Appears to undergo minimal metabolism within AH (detectable up to 12 hours after dosing) Triamcinolone acetonide

• Intravitreal administration (IVTA) • Posterior segment edematous diseases • Posterior inflammatory diseases • Posterior segment vascular diseases

• Highly hydrophobic nature, long duration of action (5 – 6 months, depending on dose)

Ascaso FJ, et al., Mid East Afr J Ophthalmol 2012 Triamcinolone acetonide

• Complications • Cataract (15 – 20%) • Ocular hypertension (40%) • Infectious endophthalmitis (1:1000) • Retinal toxicity

* Jonas JB. Act Ophthalmol Scand 2005 Ascaso FJ, et al., Mid East Afr J Ophthalmol 2012 ** Torriglia A, et al., Biochem Pharmacol 2010 Triamcinolone acetonide

• IVTA in normal horses: • 2 eyes each received 10 mg, 20 mg, or 40 mg • BSS contralateral control • No ERG changes • Peripheral cortisol suppression at higher doses • Transient corneal edema • Bacterial endophthalmitis (4/12) “Soft” Steroids

• Synthesized from inactive, nontoxic metabolite of desired drug

• Modifications enable “optimized deactivation and detoxification routes”

• Local pharmacologic activity following deactivation to avoid undesired pharmacological activity or toxicity

• Deactivation often relies upon hydrolytic esterase enzymes • Rapid • Widely distributed

• Metabolites are inactive and nontoxic

Bodor N, et al. AAPS 2005 Loteprednol etabonate

• Highly lipophilic • Increased binding affinity to receptor • Increased therapeutic index • Metabolically labile moiety à rapid metabolism after binding GC receptor à less opportunity to induce side effects

• Primary site of metabolism is cornea

• Label indications: • Ocular surface inflammation • Anterior uveitis • Post-operative cataract surgery • Significantly less likely to elevate IOP in people than topical pred or dex

Comstock TL, et al., Int J Inflamm 2012; Sheppard JD et al., Adv Ther 2016 Loteprednol etabonate

• Topical dexamethasone, prednisolone, fluorometholone, rimexolone, loteprednol • Normal cats • IOP elevation least pronounced with loteprednol • Highest with prednisolone and dexamethasone • Magnitude of elevation decreased over time • IOP rapidly returned to baseline after discontinuation of therapy

Bhattacherjee P, et al. Arch Ophthalmol 1999.

Non-Steroidal Anti-Inflammatory Drugs COX-1 and -2

• Arachidonic acid release à conversion via COX • Prostaglandins • Thromboxane

• COX-1 = constitutive

• COX-2 = inducible COX-1 and -2

• Located on endoplasmic reticulum and nuclear envelope

• Similar active site structures between COX-1 and COX-2 • 60% homology • Slight variability allows selective targeting • Hydrophobic channel extends to catalytic domain • Fatty acids enter channel for conversion COX-1 and -2

• COX-1 = constitutive • Production of cytoprotective PGs • Gastroprotection • Renal protection

• Production of TxA2 (hemostasis) • * No change in COX-1 mRNA or protein activity with inflammation

• COX-2 = inducible • Induced by LPS, IL-1, TNF-α • Production of pro-inflammatory PGs • Prostacyclin synthesis (hemostasis) • * Increase in COX-2 mRNA and protein activity with inflammation

www.mayoresearch.mayo.edu Prostaglandins

Prostaglandin Receptors Select functions

PGI2 (prostacyclin) IP Vasodilation Bronchodilation Inhibit platelet aggregation (antithrombotic)

PGE2 EP1, EP2, EP3, Decrease gastric acid others secretion Pyrexia Hyperalgesia

PGF2α FP Uterine contraction Bronchoconstriction

• Hormone-like lipid compounds • Autocrine or paracrine actions Thromboxane A2

Thromboxane A synthase PGH Thromboxane A Vasoconstriction 2 2 Platelet aggregation (platelets)

** Thromboxane A2 (pro-thrombotic) levels are balanced with prostacyclin (anti-thrombotic) levels J Pharm Pharmaceut Sci (www. cspsCanada.org) 11 (2): 81s-110s, 2008

NSAIDs

Figure• Analgesic 5. The ribbon diagram of the murine COX-2 enzyme with the diaryheterocyclic selective COX-2 inhibitor SC-558 (represented as space filling model) bound to the COX-2 active site (ref 81). • Anti-pyretic

5.• COXAnti-inflammatory ASSAYS, INHIBITORY POTENCY AND COX ISOZYME SELECTIVITY

Table 2. Classification of NSAIDs according to their COX-1/2 inhibitory activities. ______Class Properties Examples ______

Group 1 NSAIDs that inhibit both COX-1 and COX-2 Aspirin, ibuprofen, diclofenac, completely with little selectivity indomethacin, naproxen, piroxicam Group 2 NSAIDs that inhibit COX-2 with a 5-50 fold Celecoxib, etodolac, meloxicam, selectivity nimesulide Group 3 NSAIDs that inhibit COX-2 with a > 50 fold Rofecoxib, NS-398 selectivity Group 4 NSAIDs that are weak inhibitors of both 5-Aminosalicylic acid, sodium isoforms salicylate, nabumetone, sulfasalazine ______

Each of these assay systems have their benefits and assay system. For example, if the aim is to drawbacks. Based on the aim of the experiment, one understand the enzyme-drug interaction at the can carefully select the most appropriate in vitro molecular level, then purified or recombinant

90s

NSAIDs – MOA

• NSAID occupies COX active site: • Reversible • Rapid, low-affinity reversible à time-dependent, higher-affinity slowly reversible • Rapid, reversible à covalent modification of enzyme

• COX-2 active site has an extra ‘pocket’ • COX-2 active site has different amino acid residues COX in Tumor Development

Chronic inflammation

NF-κβ

IL-1, IFN-γ, TNF-α

Inflammatory PGs + decreased 15-PDGH

Tumor development NSAIDs in Tumor Suppression

• NSAIDs à • Decreased incidence of and mortality in colon cancer • Decreased risk of breast, esophageal, stomach, bladder, ovary, lung cancers

• Low doses à PG inhibition • High doses à tumor suppression NSAIDs in Tumor Suppression

• Mechanisms:

1. Alter arachidonic acid metabolism

2. Alter gene expression NSAIDs in Tumor Suppression

1. Make arachidonic acid available for lipoxygenase pathway à 15-LOX-1

• 15-LOX-1 is anti- tumorigenic via: • Inhibition of PPAR pathway • Activation of p53 pathway NSAIDs in Tumor Suppression

2. Alter gene expression

Decreased EP4 Increased Decreased ATF3 β-catenin

Increased Decreased ESE-1 Sp

Increased Tumor Increased EGF-1 inhibition NAG-1 NSAIDS – Systemic Side Effects NSAIDS – Systemic Side Effects

• Adverse cardiovascular events • GI ulceration • Renal toxicity • Bronchial asthmatic attacks • Hepatotoxicity • Dermatologic reactions • Allergy COX-2 Inhibition

• IL-1, LPS, TNFα à COX-2 mRNA and protein expression à pro-

inflammatory PGs + prostacyclin (PGI2)

• COX-2 inhibition à decreased expression of pro-inflammatory PGs

• COX-2 inhibition à decreased expression of prostacyclin

• COX-2 inhibition DOES NOT à decreased expression of thromboxane A2

• Thromboxane A2 à increased platelet aggregation • Prostacyclin à decreased platelet aggregation

• Normal thromboxane A2 + decreased prostacyclin à increased platelet aggregation COX-2 Inhibition

• VIGOR study = VIOXX GI Outcomes Research • Rofecoxib versus naproxen • 4X increased risk of myocardial infarction patients on rofecoxib beginning at 2 months • Patients already at risk for MI • Misrepresentation of data (Merck and New England Journal of Medicine)

• APPROVe study = Adenomatous Polyp Prevention on VIOXX • Rofecoxib versus placebo • Nearly 2x increased risk of adverse cardiovascular event with long-term (18 month) use of rofecoxib

• Voluntary withdrawal of VIOXX 2004 Alternatives to NSAIDs

1. NO-NSAIDs

2. Dual COX and LOX inhibitors

3. TNF-α inhibitors

NO-NSAIDs

• Nitric oxide = GI mucosal protectant, vasodilation, inhibition of platelet aggregation

• NO + NSAID à NO released à NSAID activity + beneficial effects of NO • NO-aspirin • NO-flurbiprofen

• May lead to nitrate tolerance and decreased beneficial cardiovascular and GI effects

• Naproxcinod (phase III clinical trials in Europe) Dual COX and LOX Inhibitors

• 5-LOX à pro-inflammatory leukotrienes à • Vasoconstriction • Chemotaxis • Degranulation • GI mucosal damage

• Inhibition of COX and LOX à • Anti-inflammatory effects • Less GI damage

• Tepoxalin, Limbrel TNF-α Inhibitors

• TNF-α = pro-inflammatory • Lymphocytes and macrophages • Prominent in autoimmune diseases

• TNF-α receptors • Cell surface and solubilized

• Anti-TNF-α drugs = monoclonal antibodies • Block TNF-α binding receptors à decrease inflammatory response

www.nature.com NSAIDs and the Eye NSAIDs – Indications

• Intraocular PGs à vasodilation + BOB disruption + wbc migration + choroidal neovascularization

• Postoperative CME • Prevent miosis (cataract surgery) • Seasonal conjunctivitis • Corneal abrasion • Post-operative • Cataract surgery • Glaucoma • Refractive surgery • Strabismus

www.mvretina.com NSAIDs – Ocular Side Effects

• Impaired corneal sensation • Persistent epithelial defects • Superficial punctate keratitis • Subepithelial infiltrates • Stromal infiltrates • Corneal stromal ulceration • Atonic mydriasis Corneal Toxicities

• ASCRS survey • 140 eyes of 129 patients

• ~1/3 mild, 1/3 moderate, 1/3 severe complications

• More generic diclofenac versus Voltaren or Acular

• Poorer outcome with systemic co-morbidity Corneal Toxicity – Mechanisms?

• Definitive causal link not present

• Varies with underlying pathology • Shunting AA to LOX à leukotrienes à neutrophil chemotaxis and migration and degranulation

• Inhibition of wound healing • Activation of MMP pathways • Induction of apoptosis à increased inflammatory cell infiltration • Epithelial toxicity via preservatives

• Altered corneal homeostasis MMP-8 • May require basal level of PGs NSAID Derivatives

Derivative Class Examples Salicyclic acid Aspirin Indole acetic acid Indomethacin Aryl acetic acid Diclofenac Ketorolac (most potent COX-1) Bromfenac (most potent COX-2) Nepafenac (most potent COX-2) Aryl propionic acid Flurbiprofen Ketoprofen Enolic acid Piroxicam Meloxicam COX-2 selective Firocoxib Nicotinic acid Flunixin meglumine (highly modified) Fenamates Meclofenamate NSAIDs – Ophthalmic Formulations

• Most NSAIDs weakly acidic: • Ionized form in tear film pH • Poor corneal penetration • Formation of insoluble complexes with preservatives

• Reduce pH of topical formulation: • Increases un-ionized fraction • Increases intraocular penetration • Increases local irritant effects Flurbiprofen 0.03%

• Good intraocular penetration within 2 hours • Undetectable in AH within 8 hours • Less effective control of post- operative inflammation than diclofenac in people post-cataract surgery • Greater inhibition of pilocarpine- induced BAB disruption in dogs than diclofenac • Reduces IOP-lowering effect of latanoprost by 20% with concurrent administration in dogs

Diestelhorst M, et al., J Cataract Refract Surg 1996; Krohne S, et al., AJVR 1998 Diclofenac 0.1%

• Good intraocular penetration within 2.5 hours • Detectable in AH for 24 hours • Minimal activity in posterior segment after topical administration • More effective at reducing ocular surface pain in people than flurbiprofen

• Greater inhibition of aqueous paracentesis-induced BAB breakdown in dogs and cats than flurbiprofen • Increased IOP in cats

Ward D, et al., Am J Vet Res 1996 Ketorolac 0.4%

• Strong COX-1 inhibitory activity • Undetectable in posterior segment after topical administration in normal eyes • May be less toxic to the corneal epithelium than other NSAIDs • More effective at reducing ocular surface pain in people than flurbiprofen Bromfenac 0.09%

• Bromine substitution to active agent amfenac increases penetration, potency, duration of activity • Detectable in rabbit retina after topical administration • Significant improvement in pain and inflammation post- cataract removal, relative to placebo • No greater reduction in

intraocular PGE2 levels relative to ketorolac

Nepafenac 0.1%

• Noncharged, highly lipophilic Peak AH Time to peak • Prodrug concentration AH (ng/ml) concentration • Distributes to vascular tissues à hydrolysis à Nepafenac 205.3 30 min (amfenac) (70.1) amfenac (most COX-2 • Detectable in rabbit retina inhibition)

after topical administration Bromfenac 57.5 240 min • Leads to 55% inhibition of retinal PG synthesis Ketorolac 25.9 60 min (most COX-1 inhibition) NSAID-Induced Analgesia

• Mechanical, thermal, acidic stimulation of feline corneal nerve fibers • Nepafenac, diclofenac, ketorolac

• Nepafenac à rapid reduction in response to acidic stimuli • Proposed due to COX-inhibition

• Diclofenac and ketorolac à slower reduction in response to acidic stimuli • Proposed due to blockade of Na+ channels on peripheral nociceptors NSAIDs and PCO

• COX-2 not expressed in normal lens

• COX-2 expressed in LC following lensectomy

• COX-2 inhibition à suppression of LEC EMT à • Decreased migration • Decreased proliferation • Increased apoptosis

• Initial high dose of IOL+COX-2 inhibitor appears more effective than prolonged, less specifically delivered exposure NSAIDs and PCO

• Canine patients • Tx groups: • Bromfenac post-op • Celecoxib-IOL + pred acetate post-op • Pred acetate post-op

• Flare: C-IOL < PA < B

• IOP: C-IOL < B at 4 and 12 weeks post-op

• PCO: • C-IOL < B at 4 weeks • B < PA at 56 weeks NSAIDs and IOP

• Canine cataract surgery patients

• Pre-operative flurbiprofen versus bromfenac

• Bromfenac à • Increased mean IOP at 2 h post-op (22 mmHg versus 19 mmHg) • Greater need for intervention for POH (42% versus 25%) Summary

• Understand genomic (transactivation, transrepression) and non-genomic effects of glucocorticoids • Understand alternative methods to minimize deleterious side effects of glucocorticoids

• Understand end result of COX-1 and COX-2 activity • Understand end result of COX-1 and COX-2 inhibition • Understand multiple beneficial effects of COX inhibition