Safety of Intravitreal Ketorolac and Diclofenac: An Electroretinographic and Histopathologic Study

Human Retinal Organoids Provide a Suitable Tool for Toxicological Investigations: A Comprehensive Validation Using Drugs and Compounds Affecting the Retina

Retinal drug toxicity screening is essential for the development of safe treatment strategies for a large number of diseases. To this end, retinal organoids derived from human pluripotent stem cells (hPSCs) provide a suitable screening platform due to their similarity to the human retina and the ease of generation in large-scale formats. In this study, two hPSC cell lines were differentiated to retinal organoids, which comprised all key retinal cell types in multiple nuclear and synaptic layers. Single-cell RNA-Seq of retinal organoids indicated the maintenance of retinal ganglion cells and development of bipolar cells: both cell types segregated into several subtypes. Ketorolac, digoxin, thioridazine, sildenafil, ethanol, and methanol were selected as key compounds to screen on retinal organoids because of their well-known retinal toxicity profile described in the literature. Exposure of the hPSC-derived retinal organoids to digoxin, thioridazine, and sildenafil resulted in photoreceptor cell death, while digoxin and thioridazine additionally affected all other cell types, including Müller glia cells. All drug treatments caused activation of astrocytes, indicated by dendrites sprouting into neuroepithelium. The ability to respond to light was preserved in organoids although the number of responsive retinal ganglion cells decreased after drug exposure. These data indicate similar drug effects in organoids to those reported in in vivo models and/or in humans, thus providing the first robust experimental evidence of their suitability for toxicological studies.

UNREPORTED SIDE EFFECT OF INTRAVITREAL DICLOFENAC IN CHRONIC DIABETIC MACULAR EDEMA

PURPOSE

To evaluate the safety and efficacy of intravitreal diclofenac sodium.

METHODS

A 61-year-old male with persistent diabetic macular edema was treated with 450 μg of intravitreal diclofenac sodium (systemic preparation).

RESULTS

Postinjection Day 1, the spectral domain optical coherence tomography showed irregular vitreoretinal interface with wrinkling and separation of the internal limiting membrane from the nerve fiber layer with homogeneity of the inner layers. At 1 month, the compactness of the retinal layers was restored. Complete resolution of the cystoid macular edema was seen. At 1 year, there was mild flattening of the foveal depression with epiretinal membrane.

CONCLUSION

Various studies have shown the safety and efficacy of intravitreal diclofenac without any reported side effect. We report the inner retinal toxicity in the form of cystic spaces and splitting of internal limiting membrane from nerve fiber layer on the first follow-up day, postinjection, which resolved over a period of 1 month. Further studies are needed to assess the safety of intravitreal diclofenac sodium.

Intravitreal Diclofenac in the Treatment of Macular Edema Due to Branch Retinal Vein Occlusion

BACKGROUND AND OBJECTIVE

To evaluate the effect of a single dose of intravitreal diclofenac on macular edema (ME) due to branch retinal vein occlusion (BRVO).

PATIENTS AND METHODS

In this prospective, interventional case series, 15 eyes with BRVO and ME with central macular thickness (CMT) greater than 250 µm on spectral-domain optical coherence tomography (SD-OCT) were enrolled. All patients were given 0.05 mg/0.1 mL of intravitreal diclofenac under aseptic conditions and followed up for 3 months with respect to best-corrected visual acuity (BCVA), intraocular pressure (IOP), fundus fluorescein angiography, and CMT measured on OCT.

RESULTS

The mean visual acuity improved from 0.115 ± 0.03 preoperatively to 0.356 ± 0.29 at 3 months (P = .002). Mean line improvement was 2.2 ± 1.6. Mean preoperative CMT decreased from 453.2 µm ± 55.3 µm to 340.47 µm ± 101 µm at 3 months postoperatively (P = .001). The mean preoperative IOP was 16.4 mm Hg ± 1.59 mm Hg, whereas the mean postoperative IOP was 16.6 mm Hg ± 1.58 mm Hg (P = .08). None of the 12 phakic eyes showed evidence of cataract progression.

CONCLUSION

Intravitreal diclofenac is safe and effective in improving BCVA and decreasing CMT in patients with BRVO and ME.

Solid Lipid Nanoparticles Improve the Diclofenac Availability in Vitreous after Intraocular Injection

Purpose. In order to improve the drug availability after intravitreal administration, solid lipid nanoparticles (SLNs) containing diclofenac were prepared. Methods. In this experimental study, 18 albino rabbits were included. In right and left eyes of all rabbits, SLNs containing diclofenac and commercial form of diclofenac (0.3 mg drug) were intravitreally injected, respectively. One, four, twelve, twenty-four, and forty-eight hours after injection, vitreous and aqueous humor samples were obtained in all cases. Then, the concentration of diclofenac sodium was evaluated in all samples. Results. Size of nanoparticles was around 170 nm after preparation. Drug concentration in eyes injected with SLNs was significantly higher than left eyes injected with commercial formulation up to 4 hours after intravitreal injection (p < 0.05). Diclofenac was quantified in samples up to 48 hours after intraocular injection. Four hours after intravitreal injection, the concentration of diclofenac in vitreous and aqueous humor of eyes receiving SLNs was, respectively, 2.5 and 6.5 times higher than eyes injected with commercial form of drug. Conclusions. Here, we demonstrate the potential of SLNs as a carrier of diclofenac for intraocular injection in order to prevent the systemic effects of the drug, increase the injection intervals, and improve the patient compliance.

Intravitreal ketorolac for the treatment of chronic cystoid macular edema after cataract surgery

Purpose

To report two cases of chronic postoperative cystoid macular edema, resistant to topical therapy, treated with consecutive intravitreal injections of ketorolac tromethamine.

Methods

Four daily intravitreal injections of 500 μg/0.05 mL of ketorolac were given to each patient. Complete clinical examination and OCT were performed before every injection, 1, 2, 3 weeks, and 1, 3, and 6 months after the last injection. Fluorescein angiography was performed at baseline examination, 1, 3, and 6 months after the last injection.

Results

In both cases, the edema regressed and visual acuity increased. At 6 months after the last injection, the leakage was significantly reduced at the fluorescein angiography.

Discussion

Both cases responded favorably to the consecutive intravitreal administration of ketorolac tromethamine. The long-lasting remission of the macular edema in these chronic cases underlines the therapeutic potential of these agents when delivered intravitreally.

A comprehensive review and update on the non-biologic treatment of adult noninfectious uveitis: part I

INTRODUCTION

Treatment of adult, noninfectious uveitis remains a challenge for ophthalmologists around the world. The disease accounts for almost 10% of preventable blindness in the US and can be idiopathic or associated with infectious and systemic disorders. Strong evidence is still emerging to indicate that pharmacologic strategies presently used in rheumatologic or autoimmune disease may be translated to the treatment of intraocular inflammation. Corticosteroid monotherapy is widely regarded as wholly inappropriate, due to the unfavorable risk/benefit profile and poor long-term outcomes. Treatment plans have shifted away from low-dose, chronic corticosteroid therapy for maintenance, towards medium- to high-dose therapy for acute inflammation, followed immediately by initiation of immunomodulatory therapy. These therapies follow the 'stepladder approach', whereby least to more aggressive therapies are trialed to induce remission of inflammation, eventually without corticosteroids of any form (topical, local and systemic).

AREAS COVERED

This two-part review gives a comprehensive overview of the existing medical treatment options for patients with adult, noninfectious uveitis, as well as important advances for the treatment of ocular inflammation. Part I covers classic immunomodulation and latest information on corticosteroid therapy.

EXPERT OPINION

The hazard of chronic corticosteroid use for the treatment of adult, noninfectious uveitis is well-documented. Corticosteroid-sparing therapies, which offer a very favorable risk-benefit profile when administered properly, should be substituted.

Novel Approaches for Retinal Drug and Gene Delivery

The ARVO 2014 minisymposium on "Novel Approaches for Retinal Drug and Gene Delivery" was held on May 6, 2014 in Orlando, FL. The main intent of the symposium was to review recent advances in retinal drug and gene delivery with specific emphasis on novel approaches that address current limitations and have the potential to translate into clinical practice. The symposium was sponsored by Translational Vision Science and Technology.

The safety, pharmacokinetics, and efficacy of intraocular celecoxib

PURPOSE

To determine safety, pharmacokinetics, and anti-inflammatory effects of intraocular celecoxib.

METHODS

The right eye of animals was injected with 1.5, 3, or 6 mg celecoxib prepared in dimethyl sulfoxide (DMSO). Left eyes served as controls and received 0.1 mL DMSO. Electroretinograms (ERG) were obtained at baseline and at 1, 4, and 12 weeks, and eyes were enucleated afterward for histopathologic analysis. For pharmacokinetics, 3 mg celecoxib was injected, and vitreous and retina/choroid drug levels were then analyzed at specific time points. For efficacy, 1 μg lipopolysaccharide was injected to induce inflammation; the right eye was then injected with 3 mg celecoxib (six eyes) or 2 mg triamcinolone acetonide (six eyes) and the left eye with saline. Twenty-four hours later, aqueous fluid was removed, and total leukocyte concentration and prostaglandin E2 (PGE2) concentration were determined.

RESULTS

Histologic and ERG studies demonstrated no signs of retinal or optic nerve toxicity. After a single 3-mg injection, vitreous (0.06 μg/mL) and retina/choroid (132.31 μg/g) celecoxib concentrations at 8 weeks exceeded median inhibitory concentration. Treatment with celecoxib and triamcinolone significantly reduced total leukocyte count by 40% (P = 0.02) and 31% (P = 0.01), respectively. Reduction in PGE2 levels paralleled reduction in leukocyte counts (P < 0.05). There was no increase in intraocular pressure, but cataract formation was observed at higher concentrations.

CONCLUSIONS

Intraocular injection of celecoxib appeared to be nontoxic and demonstrated excellent penetration into the retina/choroid and sustained drug levels out to 8 weeks. Celecoxib demonstrated potent anti-inflammatory effects, but there was an association with cataract formation at higher doses.

Suprachoroidal injection of ketorolac tromethamine does not cause retinal damage

Rabbit right eyes were injected with 3 or 6 mg ketorolac tromethamine into the suprachoroidal space. Electroretinography results demonstrated no abnormal changes in rod cell response, maximum rod cell or cone cell mixing reaction, oscillation potential, cone cell response, waveform, amplitude, and potential of 30 Hz scintillation response in right eyes before injection, and at 1, 2, and 4 weeks after injection. There was no difference between left (control) and right eyes. Under light microscopy, the histomorphology of cells in each retinal layer was normal at 4 weeks following 6 mg ketorolac tromethamine administration. These results indicate that a single suprachoroidal injection of 3 or 6 mg ketorolac tromethamine into rabbits was safe. Suprachoroidal space injection appears to be safe.

Update on twice-daily bromfenac sodium sesquihydrate to treat postoperative ocular inflammation following cataract extraction

Ophthalmic bromfenac sodium sesquihydrate is a topically applied selective cyclooxygenase (COX)-2 inhibitor. It is similar to amfenac, except for a bromine atom at the C(4) of the benzoyl ring position, which markedly affects its in vitro and in vivo potency, extends the duration of anti-inflammatory activity, and enhances its inhibitory effect on COX-2 absorption across the cornea and penetration into ocular tissues. The United States Food and Drug Administration approved bromfenac in 2005 for the treatment of postoperative inflammation and the reduction of ocular pain in patients who have undergone cataract surgery. Nonsteroidal anti-inflammatory drugs (NSAIDs), and among them bromfenac, could be even more effective than steroids at reestablishing the blood-aqueous barrier, as revealed by flare on slit-lamp examination and as quantitatively measured using ocular fluorophotometry. Similar to other NSAIDs, it has a role in inhibiting intraoperative miosis during cataract surgery. However, bromfenac also seems to be useful in other situations, such as refractive surgery, allergic conjunctivitis (not useful in dry eye), choroidal neovascularization, and even ocular oncology. No reports of systemic toxicity have been published and bromfenac has good topical tolerance with a low incidence of adverse effects.

Intravitreal diclofenac versus intravitreal triamcinolone acetonide in the treatment of diabetic macular edema

PURPOSE

To compare the efficacy and safety of intravitreal diclofenac versus intravitreal triamcinolone acetonide in the treatment of diabetic macular edema.

METHODS

Thirty-two eyes with diffuse diabetic macular edema were randomly allocated to intravitreal injection of 4 mg/0.1 mL of triamcinolone (Group 1: N = 16) or 500 μg/0.1 mL of diclofenac (Group 2: N = 16). Preoperative and postoperative visual acuity, intraocular pressure, and central macular thickness were recorded and compared between the 2 groups up to 12 weeks.

RESULTS

Both groups showed statistically significant reduction in central macular thickness (triamcinolone: P = 0.02 and diclofenac: P = 0.01), without statistically significant difference between the 2 groups. Visual improvement was significant only in triamcinolone group (P = 0.05). However, the 2 groups showed no statistically significant difference in mean visual acuity or mean line improvement. Transient elevation of intraocular pressure occurred in 12.5% of the triamcinolone group. Diclofenac group showed statistically significant reduced intraocular pressure (P = 0.02).

CONCLUSION

Intravitreal diclofenac is effective in the treatment of diffuse diabetic macular edema up to 12 weeks. Intravitreal triamcinolone and diclofenac appear to have comparable therapeutic effects on retinal thickness. The degree of visual improvement is higher with triamcinolone.

Intravitreal injection of commercially available ketorolac tromethamine in eyes with diabetic macular edema refractory to laser photocoagulation

PURPOSE

To evaluate the short-term effect of a single intravitreal injection of commercially available ketorolac tromethamine (KT) in eyes with diabetic macular edema refractory to laser photocoagulation.

METHODS

Prospective interventional case series. Twenty five patients with diabetic macular edema refractory to laser photocoagulation received a single intravitreal injection of commercially available KT (Toradol®), in a dose of 3000 µg. Examination included assessment of ETDRS-best corrected visual acuity (BCVA), measurement of intraocular pressure and high resolution imaging by optical coherence tomography, preoperatively and 7, 15, and 30 days postoperatively.

RESULTS

In the follow up visits at 7, 15 and 30 days, BCVA had improved five or more letters in 20% (95% confidence interval, 7.7-38.9%), 16% (95% confidence interval, 5.3-34.2%) and 28% (95% confidence interval, 13.2-47.7%) respectively. An improvement in macular thickness was also observed, although it has not been statistically significant.

CONCLUSION

This pilot study showed that a single intravitreal injection of 3000 µg of commercial KT led to a short-term improvement of visual acuity in approximately 30% of eyes with diabetic macular edema refractory to laser photocoagulation.

Nonsteroidal anti-inflammatory drugs in ophthalmology

Nonsteroidal anti-inflammatory drugs (NSAIDs) are increasingly employed in ophthalmology to reduce miosis and inflammation, manage scleritis, and prevent and treat cystoid macular edema associated with cataract surgery. In addition, they may decrease postoperative pain and photophobia associated with refractive surgery and may reduce the itching associated with allergic conjunctivitis. In recent years, the U.S. Food and Drug Administration has approved new topical NSAIDs, and previously approved NSAIDs have been reformulated. These additions and changes result in different pharmacokinetics and dosing intervals, which may offer therapeutic advantages. For example, therapeutic effects on diabetic retinopathy and age-related macular degeneration may now be achievable. We provide an updated review on NSAIDs and a summary of their current uses in ophthalmology with attention to potential future applications.

Interaction of intravitreal combination drugs and the effect on the targeted site

BACKGROUND

After evaluating experimentally the diffusion processes in the retina using peroxidase as a tracer material (previously published work), we found that junctional complexes of the retinal pigment epithelium and retinal capillaries were the major impediment to free diffusion between the retina and choroidal-retinal blood vessels. These experiments indicated that to achieve high therapeutic concentrations of medications inside the eye, it was necessary to administer them by intravitreal injection. Soon after initial experimental work the necessity of combining antibiotics or antibiotics with steroids became obvious. As the use of intravitreal injection grew over the last 2 decades, so did the concept of combination therapy.

METHODS

This review describes potential causes of drug-drug interaction and the rationale for combination therapy when injected into the vitreous cavity, encompassing publications between 1971 and 2008.

RESULTS

We describe the conditions that can cause physical-chemical interactions between the medications and the need for combination therapy for treatment of various intraocular disease processes.

CONCLUSIONS

The intravitreal injection of medication and their combinations has become a part of standard care for many diseases of the retina and choroid. This article reviews the potential interaction of nontoxic doses of medications when injected simultaneously in the vitreous cavity, and disease processes that are now treated with these combination therapies.

Influence of dosage form on the intravitreal pharmacokinetics of diclofenac

PURPOSE

To prepare a suspension form of diclofenac and compare the influence of the injected form (suspension versus solution) on the intravitreal pharmacokinetics of diclofenac in Dutch belted pigmented rabbits.

METHODS

Diclofenac acid was prepared and characterized in a suspension formulation. Rabbit eyes were injected with either diclofenac sodium solution (0.3 mg) or diclofenac acid suspension (10 mg) prepared in 0.1 mL balanced salt solution. Rabbits were killed at regular time intervals, the eyes enucleated, and drug content quantified in the vitreous humor and retina-choroid tissue by high-performance liquid chromatography. Pharmacokinetic models were developed for both the dosage forms, and simulations were performed for different doses.

RESULTS

Diclofenac acid with an approximate 5-mum particle size exhibited 3.5-fold lower solubility in vitreous humor, when compared with its sodium salt. The estimated settling velocity of the suspension in the vitreous humor was 3 cm/h. After diclofenac sodium salt solution injection, drug levels declined rapidly with no drug levels detectable after 24 hours in the vitreous humor and 4 hours in the RC. Throughout the assessed time course, drug levels were higher in the vitreous. However, sustained, high drug levels were observed in both the vitreous humor and the retina-choroid even on day 21 after diclofenac acid suspension injection, with retina-choroid drug levels being higher beginning at 0.25 hour. The elimination half-life of diclofenac suspension was 24 and 18 days in vitreous and retina-choroid, respectively, compared to 2.9 and 0.9 hours observed with diclofenac sodium. The pharmacokinetic models developed indicated a slow-release distribution or depot compartment for the diclofenac acid suspension in the posterior segment. Simulations indicated the inability of a 10-mg dose of diclofenac sodium solution to sustain drug levels in the vitreous beyond 11 days.

CONCLUSIONS

By choosing a less soluble form of a drug such as diclofenac acid, vitreous elimination half-life can be prolonged up to 24 days, potentially resulting in therapeutic levels in the posterior segment tissues for a few months. Higher detectable drug levels in the retina-choroid suggest rapid settling and persistent retention of suspension in retina-choroid tissue.

Pathophysiology of cyclooxygenase inhibition in animal models

Cyclooxygenase (COX) catalyzes the conversion of arachidonic acid into prostaglandins (PGs), which play a significant role in health and disease in the gastrointestinal tract (GI) and in the renal, skeletal, and ocular systems. COX-1 is constitutively expressed and found in most normal tissues, whereas COX-2 can be expressed at low levels in normal tissues and is highly induced by pro-inflammatory mediators. Inhibitors of COX activity include: (1) conventional nonselective, nonsteroidal anti-inflammatory drugs (ns-NSAIDs) and (2) COX-2 selective nonsteroidal anti-inflammatory drugs (COX-2 s-NSAIDs). Inhibition of COX-1 often elicits GI toxicity in animals and humans. Therefore, COX-2 s-NSAIDs were developed to provide a selective COX-2 agent, while minimizing the attendant COX-1-mediated GI toxicities. Rats and dogs overpredict COX inhibition for renal effects such as renal handling of electrolytes in humans. COX inhibitors are shown to have both beneficial and detrimental effects, such as on healing of ligament or tendon tears, on the skeletal system in animal models. Certain ophthalmic conditions such as glaucoma and keratitis are associated with increased COX-2 expression, suggesting a potential role in their pathophysiology.