Dexamethasone Intracanalicular Insert: A Review in Treating Post-Surgical Ocular Pain and Inflammation

Subconjunctival injection of microcrystalline prodrug of dexamethasone for long-acting anti-inflammation after phacoemulsification surgery

Long-acting injectable formulations of dexamethasone with minimal invasiveness are highly desired to manage chronic ocular inflammatory conditions. Here, we applied microcrystals (MCs) of a hydrophobic acetone-based ketal-linked prodrug of dexamethasone (SKD) to treat postoperative ocular inflammation. We compared the efficacy and safety of SKD MCs through subconjunctival (SC) injection with that of Maxidex (a topical suspension of dexamethasone MCs) through SC injection and eye drops in the phacoemulsification combined with intraocular lens implantation (Phaco-IOL) rabbit model. In Phaco-IOL rabbit eyes, a single SC injection of SKD MCs (0.4 mg dexamethasone equiv.) showed anti-inflammatory effects comparable to Maxidex eye drops and completely alleviated the inflammation within 28 days, while an SC injection of Maxidex at the same dose only provided anti-inflammatory effects for 7 days. The study on the dose-dependent anti-inflammatory effects of SKD MCs showed no significant difference in anti-inflammatory effects for the high dosage (0.8 mg dexamethasone equiv.) and the low dosage (0.4 mg dexamethasone equiv.) in 28 days. Nevertheless, systematic drug distribution of SKD MCs and Maxidex in normal rabbits after SC injection demonstrates that the drug concentration in conjunctiva was higher for the high dosage and that a considerable amount of prodrug and dexamethasone could still be detected in the cornea and iris-ciliary body at least 84 days for SKD MCs at high dosage. Furthermore, no persistent elevated intraocular pressure and abnormality in retinal structure and thickness were observed, confirming the excellent safety of long-acting SKD MCs post-SC injection. Our findings provide valuable insights into using prodrug-based MCs for treating ocular postoperative inflammation, and the detailed drug distribution analysis would promote the clinical translation of these MCs in ocular diseases.

The Efficacy and Safety of Dexamethasone Intracanalicular Insert Use in Patients with Chronic Seasonal/Perennial Allergic Conjunctivitis: A Systematic Review and Meta-Analysis

Objective

This meta-analysis evaluated the efficacy and safety of DEXTENZA, an intracanalicular dexamethasone insert, for the treatment of seasonal/perennial allergic conjunctivitis.

Methods

Multiple databases, including PubMed, the Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.gov, the Directory of Open Access Journals, and Scopus, were searched for randomized controlled trials (RCTs) comparing the efficacy of DEXTENZA with a placebo. The primary efficacy endpoint was the change in the conjunctival allergen challenge (CAC) model. The GRADE approach was used to assess the certainty of evidence, and the revised Cochrane risk of bias tool for randomized trials was employed to assess bias.

Results

Four RCTs involving 323 participants met the eligibility criteria, and all had a low risk of bias. A meta-analysis revealed a statistically significant increase in the mean CAC change for conjunctival itching, with low heterogeneity among measurements at 3 minutes (P < 0.00001, I2 = 47%), 5 minutes (P < 0.00001, I2 = 46%), and 7 minutes (P < 0.00001, I2 = 41%). Additionally, the meta-analysis found a statistically significant increase in the mean CAC change for conjunctival redness with low heterogeneity (P < 0.00001, I2 = 15%). The pooled analysis showed no significant difference (P = 0.57, I2 = 0%) between the DEXTENZA and placebo groups in the frequency of adverse events.

Conclusion

DEXTENZA has emerged as a promising and viable treatment option for patients with seasonal/perennial allergic conjunctivitis and is an effective alternative to current therapeutic modalities.

Improving corneal permeability of dexamethasone using penetration enhancing agents: First step towards achieving topical drug delivery to the retina

With an ever-increasing burden of vision loss caused by diseases of the posterior ocular segment, there is an unmet clinical need for non-invasive treatment strategies. Topical drug application using eye drops suffers from low to negligible bioavailability to the posterior segment as a result of static and dynamic defensive ocular barriers to penetration, while invasive delivery systems are expensive to administer and suffer potentially severe complications. As the cornea is the main anatomical barrier to uptake of topically applied drugs from the ocular surface, we present an approach to increase corneal permeability of a corticosteroid, dexamethasone sodium-phosphate (DSP), using a novel penetration enhancing agent (PEA). We synthesised a novel polyacetylene (pAc) polymer and compared its activity to two previously described cell penetrating peptide (CPP) based PEAs, TAT and penetratin, with respect to increasing transcorneal permeability of DSP in a rapid ex-vivo porcine corneal assay over 60 min. The transcorneal apparent permeability coefficients (Papp) for diffusion of pAc, and fluorescein isothiocyanate (FITC) conjugated TAT and penetratin were up to 5 times higher (p < 0.001), when compared to controls. When pAc was used in formulation with DSP, an almost 5-fold significant increase was observed in Papp of DSP across the cornea (p = 0.0130), a significant 6-fold increase with TAT (p = 0.0377), and almost 7-fold mean increase with penetratin (p = 0.9540). Furthermore, we investigated whether the PEAs caused any irreversible damage to the barrier integrity of the corneal epithelium by measuring transepithelial electrical resistance (TEER) and immunostaining of tight junction proteins using zonula occludens-1 (ZO-1) and occludin antibodies. There was no damage or structural toxicity, and the barrier integrity was preserved after PEA application. Finally, an in-vitro cytotoxicity assessment of all PEAs in human retinal pigment epithelium cells (ARPE-19) demonstrated that all PEAs were very well-tolerated, with IC50 values of 64.79 mM for pAc and 1335.45 µM and 87.26 µM for TAT and penetratin, respectively. Our results suggest that this drug delivery technology could potentially be used to achieve a significantly higher intraocular therapeutic bioavailability after topical eye drop administration, than currently afforded.

Metal-Drug Coordination Nanoparticles and Hydrogels for Enhanced Delivery

Drug delivery is a key component of nanomedicine, and conventional delivery relies on the adsorption or encapsulation of drug molecules to a nanomaterial. Many delivery vehicles contain metal ions, such as metal-organic frameworks, metal oxides, transition metal dichalcogenides, MXene, and noble metal nanoparticles. These materials have a high metal content and pose potential long-term toxicity concerns leading to difficulties for clinical approval. In this review, recent developments are summarized in the use of drug molecules as ligands for metal coordination forming various nanomaterials and soft materials. In these cases, the drug-to-metal ratio is much higher than conventional adsorption-based strategies. The drug molecules are divided into small-molecule drugs, nucleic acids, and proteins. The formed hybrid materials mainly include nanoparticles and hydrogels, upon which targeting ligands can be grafted to improve efficacy and further decrease toxicity. The application of these materials for addressing cancer, viral infection, bacterial infection inflammatory bowel disease, and bone diseases is reviewed. In the end, some future directions are discussed from fundamental research, materials science, and medicine.

Intracanalicular dexamethasone insert for post-corneal crosslinking inflammation and pain: the LINK study

PURPOSE

To compare the efficacy of an intracanalicular dexamethasone insert with tapered topical steroid over 28 days after corneal cross-linking (CXL).

SETTING

Single private practice, outpatient setting.

DESIGN

Prospective observational randomized study.

METHODS

This prospective randomized study investigated the efficacy of a dexamethasone intracanalicular insert on post-CXL pain and inflammation in progressive keratoconus patients. 20 patients (40 eyes) were enrolled; half were randomized to the dexamethasone intracanalicular insert group; half were prescribed a 28-day topical tapering steroid regimen. All patients were evaluated for pain scores, rate of re-epithelialization, ease of the post-CXL regimen, and need for rescue pain medication after standard bilateral epithelium-off CXL on postoperative day (POD) 1, POD3, and POD4 to 7, as well as postoperative week (POW) 1, POW2, POW3, and POW4.

RESULTS

20 patients (40 eyes) underwent standard-of-care epithelium-off bilateral CXL for progressive keratoconus. 10 patients were randomized to receive prednisolone eyedrops on a tapering schedule after CXL; 10 patients received dexamethasone intracanalicular inserts at the time of CXL. Regardless of the postoperative steroid regimen, there was no significant difference in the rate of re-epithelialization or use of rescue pain medication between groups. There was a nominal, however, statistical difference in pain scores between groups, favoring prednisolone eyedrops. Both groups stated no difficulty in following postoperative regimens. There were no adverse events noted in relation to treatment or the CXL procedure.

CONCLUSIONS

Using a dexamethasone insert to alleviate pain and inflammation can be considered as a safe and efficacious part of a post-CXL regimen.

0.2% Betamethasone Sodium Phosphate: A Multicenter, Randomized, Double-Masked Study to Compare Its Ocular Safety, Tolerability, and Efficacy to Vehicle in Cataract Surgery Subjects

Purpose

To compare the preservative-free corticosteroid 0.2% betamethasone sodium phosphate BID (SURF-201) to vehicle BID in patients undergoing routine cataract surgery.

Methods

Phase 2, multicenter, randomized (1:1 ratio), double-masked, vehicle-controlled, parallel-group study in patients scheduled for uncomplicated cataract surgery without the aid of a femtosecond laser. Subjects instilled topical medications for 16 days beginning the day before cataract surgery (Day -1), 1 dose administered at least 1 hour prior to cataract surgery (on Day 0) and 1 dose on the evening after cataract surgery, and then 2 doses administered each day through Day 15; patients were re-evaluated on Days 22 and 32 to ensure no rebound inflammation. Primary outcome was the difference in the proportion of subjects with anterior chamber cell (ACC) grade 0 between the two groups at Day 15. Secondary outcomes included pain scores and overall safety.

Results

There was a statistically significant difference (P=0.004) in the proportion of subjects in the SURF-201 treatment group with an ACC grade of 0 at Day 15 (n=22/39 [56.4%]) compared to subjects in the vehicle treatment group (n=9/43 [20.9%]). There was no statistically significant difference (P=0.528) in the proportion of subjects in the SURF-201 treatment group who had a visual analog scale pain score of 0 at Day 15 (n=35/38 [89.7%]) compared to subjects in the vehicle group (n=33/40 [82.5%]). A slightly higher incidence of adverse events occurred in subjects in the SURF-201 treatment group (n=27/40 [67.5%]) compared to the vehicle treatment group (n=23/43 [53.5%]).

Conclusion

SURF-201 is an effective topical, preservative-free corticosteroid when dosed BID for the treatment of postoperative inflammation and prevention of pain in a post-cataract population.

Regulating macrophage-MSC interaction to optimize BMP-2-induced osteogenesis in the local microenvironment

Bone morphogenetic protein (BMP-2) has been approved by the FDA to promote bone regeneration, but uncertain osteogenic effect and dose-dependent side effects may occur. Osteoimmunomodulation plays an important role in growth factor-based osteogenesis. Here, we explored how proinflammatory signals affect the dose-dependent osteogenic potential of BMP-2. We observed that the expression level of local IL-1β did not increase with the dose of BMP-2 in the mouse osteogenesis model. A low dose of BMP-2 could not promote new bone formation, but trigger the release of IL-1β from M1 macrophages. As the dose of BMP-2 increased, the IL-1β expression and M1 infiltration in local microenvironment were inhibited by IL-1Ra from MSCs under osteogenic differentiation induced by BMP-2, and new bone tissues formed, even excessively. Anti-inflammatory drugs (Dexamethasone, Dex) promoted osteogenesis via inhibiting M1 polarization and enhancing BMP-2-induced MSC osteo-differentiation. Thus, we suggest that the osteogenic effect of BMP-2 involves macrophage-MSC interaction that is dependent on BMP-2 dose and based on IL-1R1 ligands, including IL-1β and IL-1Ra. The dose of BMP-2 could be reduced by introducing immunoregulatory strategies.

Implantable sustained-release drug delivery systems: a revolution for ocular therapeutics

PURPOSE

Due to the inimitable anatomical structure of the eyeball and various physiological barriers, conventional ocular local administration is often complicated by apparent shortcomings, such as limited bioavailability and short drug retention. Thus, developing methods for sustainable, safe and efficient drug delivery to ocular target sites has long been an urgent need. This study briefly summarizes the barriers to ocular drug administration and various ocular drug delivery routes and highlights recent progress in ocular implantable sustained-release drug delivery systems (DDSs) to provide literature evidence for developing novel ocular implants for sustained drug delivery.

METHODS

We conducted a comprehensive search of studies on ocular implantable sustained-release DDSs in PubMed and Web of Science using the following keywords: ocular, implantable and drug delivery system. More than 400 papers were extracted. Publications focused on sustained and controlled drug release were primarily considered. Experimental articles involving DDSs that cannot be implanted into the eye through surgeries and cannot be inserted into ocular tissues in solid form were excluded. Approximately 143 publications were reviewed to summarize the most current information on the subject.

RESULTS

In recent years, numerous ocular sustained-release DDSs using lipids, nanoparticles and hydrogels as carriers have emerged. With unique properties and systematic design, ocular implantable sustained-release DDSs are able to continuously maintain drug release, effectively sustain the therapeutic concentration in target tissues, and substantially enhance the therapeutic efficacy. Nevertheless, few ocular implantable sustained-release DDSs have been available in clinical use.

CONCLUSIONS

Ocular implantable sustained-release DDSs have become a new focus in the field of ocular drug development through unique designs and improvements in the materials of drug carriers, administration methods and dosage forms. With more ocular implantable sustained-release DDSs being commercialized, ocular therapeutics may be revolutionized.

Comparison of postcataract surgery anti-inflammatory regimens on the incidence of cystoid macular edema, iritis, pain, and photophobia

PURPOSE

To compare postcataract surgery anti-inflammatory regimens of intracanalicular dexamethasone insert and topical bromfenac on the incidence of cystoid macular edema (CME), iritis, pain, and photophobia.

SETTING

Eyes of York Cataract & Laser Center, York, Pennsylvania.

DESIGN

Retrospective chart review.

METHODS

Case records of 647 consecutive patients (1001 eyes) who underwent cataract surgery and received dexamethasone intracanalicular insert 0.4 mg (Group 1; 482 eyes) or topical nonsteroidal anti-inflammatory drug (NSAID) (bromfenac 0.075% 2 times a day) for 4 weeks postoperatively (Group 2; 519 eyes) were included. Both groups received intracameral moxifloxacin and phenylephrine/ketorolac. Patients with prior CME, vitreomacular traction, combined cataract/glaucoma surgery, and medication protocols different from those examined in this study were excluded.

RESULTS

Compared with the dexamethasone insert group, the topical NSAID group had a significantly lower incidence of CME (0.4% [2/519] vs 3.9% [19/482], P < .001) and photophobia (1.9% [10/519] vs 4.8% [23/482], P = .012). The incidence of breakthrough iritis (3.5% [18/519] vs 5.6% [27/482], P = .104) and pain also trended lower (4.0% [21/519] vs 5.4% [26/482], P = .314) in the topical NSAID group.

CONCLUSIONS

Topical NSAIDs were found to be more effective in controlling CME, pain, iritis, and photophobia after cataract surgery compared with the intracanalicular dexamethasone insert in the presence of intracameral phenylephrine/ketorolac.

Long-acting ocular drug delivery technologies with clinical precedent

INTRODUCTION

Ocular long-acting injectables and implants (LAIIs) deliver drug at a controlled release rate over weeks to years. A reduced dose frequency eases the treatment burden on patients, minimizes the potential for treatment-related adverse effects, and improves treatment adherence and persistence.

AREAS COVERED

This review provides a comprehensive landscape of ocular LAII drug delivery technologies with clinical precedent, including eight commercial products and 27 clinical programs. Analysis of this landscape, and the specific technologies with the greatest precedent, provides instructive lessons for researchers interested in this space and insights into the direction of the field.

EXPERT OPINION

Further technological advancement is required to create biodegradable LAIIs with extended release durations and LAIIs that are compatible with a broader array of therapeutic modalities. In the future, ocular LAII innovations can be applied to diseases with limited treatment options, prophylactic treatment at earlier stages of disease, and cost-effective treatment of ocular diseases in global health settings.

Dry eye syndrome: comprehensive etiologies and recent clinical trials

Dry eye syndrome (DES) is multifactorial and likely to be a cause of concern more so than ever given the rapid pace of modernization, which is directly associated with many of the extrinsic causative factors. Additionally, recent studies have also postulated novel etiologies that may provide the basis for alternative treatment methods clinically. Such insights are especially important given that current approaches to tackle DES remains suboptimal. This review will primarily cover a comprehensive list of causes that lead to DES, summarize all the upcoming and ongoing clinical trials that focuses on treating this disease as well as discuss future potential treatments that can improve inclusivity.

Thermal Pulsation with or without Dexamethasone Intracanalicular Insert for Meibomian Gland Dysfunction: A Prospective, Masked Trial

Significance

Meibomian gland dysfunction (MGD) is among the most common causes of dry eye disease worldwide. Few studies have compared treatment options, and the basis for an evidentiary approach to MGD management is lacking. We have conducted a non-randomized trial evaluating the additive benefit of a recently developed therapy.

Purpose

To compare the efficacy of thermal pulsation therapy alone or combined with the dexamethasone intracanalicular insert (Dextenza) on the signs and symptoms of MGD.

Methods

This was a prospective, patient-masked, sham-controlled, non-randomized trial. All subjects underwent thermal pulsation therapy using the LipiFlow system. The dexamethasone intracanalicular insert was placed in the inferior canaliculus of the more symptomatic eye (DEX group), while sham punctal dilation of the fellow eye was performed to preserve patient masking (SHAM group). Key outcomes were improvement in meibum expressibility at 1, 4, and 12 weeks and patient treatment preference at week 12.

Results

Nineteen subjects underwent thermal pulsation therapy and received the DEX insert. Meibomian gland expressibility scores improved significantly in both groups at 1, 4, and 12 weeks, with significantly greater improvement in DEX eyes than SHAM eyes at 12 weeks (P=0.027). Improvement from baseline in TBUT was significant at all time points in DEX eyes and only at week 4 in SHAM eyes, with significantly greater improvement in DEX eyes over SHAM eyes at week 12 (P=0.028). Mean best-corrected visual acuity and intraocular pressure remained unchanged from baseline throughout follow-up in both groups, and no adverse events were noted. Combined therapy with DEX was preferred by 61% of subjects.

Conclusion

This study demonstrated a significant benefit of combining thermal pulsation therapy with the dexamethasone intracanalicular insert on signs of MGD including TBUT and meibomian gland expressibility score. Consequently, a majority of patients preferred combination therapy to thermal pulsation therapy alone.

Surgical Techniques and Adjuvants for the Management of Pterygium

OBJECTIVE

To provide an updated review of surgical techniques and adjuvants for the management of pterygium.

METHODS

A literature search was conducted in PubMed for studies published since January 2011. "Pterygium surgery" and the MeSH term "Pterygium/surgery" was used. The results were filtered for randomized controlled trials in English, yielding 60 citations.

RESULTS

One study compared topical anesthetic agents. One study compared methods of corneal polishing of the corneoscleral bed after pterygium excision. Numerous studies evaluated the use of conjunctival autograft versus amniotic membrane, superior versus inferior conjunctival autograft, and conjunctival versus limbal-conjunctival autograft. Many studies evaluated graft fixation methods. Several studies evaluated the adjuvant use of mitomycin C, 5-fluorouracil, and bevacizumab. A few studies evaluated the adjuvant use of steroids. Eleven studies evaluated various methods of postoperative management.

CONCLUSIONS

Current evidence supports pterygium excision with conjunctival autograft fixation using fibrin glue, followed by patching until the first postoperative visit. Surgical adjuvants and postoperative use of artificial tears and topical cyclosporine 0.05% may further reduce recurrence. Postoperative use of topical steroids is highly variable because there is no consensus regarding the optimal dose, frequency, and duration of treatment.

Topical drug delivery to the retina: obstacles and routes to success

INTRODUCTION

Retinal diseases are one of the main reasons for vision loss where all available drug treatments are based on invasive drug administration such as intravitreal injections. Despite huge efforts and some promising results in animal models, almost all delivery technologies tested have failed in human trials. There are however examples of clinically effective topical delivery systems such as fast dissolving aqueous eye drop suspensions.

AREAS COVERED

Six obstacles to topical drug delivery to the eye have been identified and discussed in some details. These obstacles consist of static membrane barriers to drug permeation into the eye, dynamic barriers such as the lacrimal drainage and physiochemical barriers such as low thermodynamic activity. It is explained how and why these obstacles hamper drug permeation and how different technologies, both those that are applied in marketed drug products and those that are under investigation, have addressed these obstacles.

EXPERT OPINION

The reason that most topical drug delivery systems have failed to deliver therapeutic drug concentrations to the retina is that they do not address physiochemical barriers such as the thermodynamic activity of the permeating drug molecules. Topical drug delivery to the retina has only been successful when the static, dynamic, and physiochemical barriers are addressed simultaneously.

Evaluation of Same-Day versus Next-Day Implantation of Intracanalicular Dexamethasone for the Control of Postoperative Inflammation and Pain Following Cataract Surgery

Purpose

To evaluate the safety and efficacy of a sustained-release intracanalicular dexamethasone insert for postoperative inflammation and pain implanted in a clinical setting preoperatively or on postoperative day 1.

Methods

Single-site, retrospective, contralateral eye study of patients undergoing cataract surgery. Included were subjects with a dexamethasone intracanalicular insert implanted in the clinic immediately prior to surgery in one eye (same-day) and on postoperative day 1 (POD1) in the contralateral eye. The primary outcome measure was the resolution of anterior chamber inflammation at 1 week postoperative. Secondary outcome measures included proportion of eyes requiring additional therapy for pain and inflammation through 1 month as well as the number of eyes with IOP spikes above baseline. Safety measures included adverse events through 1 month postoperative.

Results

Sixty-two eyes of 31 subjects were included in the case series. At 1 week postoperative, 52% of the eyes (n = 16) achieved complete resolution of inflammation in the same-day group and 58% (n = 18) met this endpoint at 1 week in the POD1 group. One subject in the same-day group required additional therapy for rebound inflammation and no eyes required additional therapy in the POD1 group. There were no reports of pain at 1 week or 1 month in either group. There were no implant-related adverse events in either group.

Conclusion

The favorable results of this study indicate that the sustained-release dexamethasone insert can be safely implanted in the clinic either preoperatively on the day of surgery or on postoperative day 1 for the control of pain and inflammation following cataract surgery.

Enhanced topical corticosteroids delivery to the eye: A trade-off in strategy choice

Topical corticosteroids are the primary treatment of ocular inflammation caused by surgery, injury, or other conditions. Drug pre-corneal residence time, drug water solubility, and drug corneal permeability coefficient are the major factors that determine the ocular drug bioavailability after topical administration. Although growing research successfully enhanced local delivery of corticosteroids utilizing various strategies, rational and dynamic approaches to strategy selection are still lacking. Within this review, an overview of the various strategies as well as their performance in retention, solubility, and permeability coefficient of corticosteroids are provided. On this basis, the tradeoff of strategy selection is discussed, which may shed light on the rational choice and application of ophthalmic delivery enhancement strategies.

Associated risk factors of postoperative pain after glaucoma surgery: a prospective study

PURPOSE

This study aimed to determine degree of postoperative pain and the incidence of serious postoperative pain after glaucoma surgery and further to identify the associated risk factors.

METHODS

A total of 194 consecutive patients who were diagnosed with glaucoma and underwent glaucoma surgery were enrolled in this study. The intensity of postoperative pain was evaluated using numerical rating scale (NRS) within 24 h after surgery; NRS ≥ 5 was considered as clinically significant postoperative pain. Risk factors associated with the development of postoperative pain were analyzed by multivariate logistic regression analysis.

RESULTS

Clinically significant postoperative pain was experienced at any time after glaucoma surgery in 41.75% of the patients, which peak at 2 h. 27.8% of the patients requested analgesic medication within 24 h after surgery. According to multivariate logistic regression analysis, preoperative anxiety (OR = 4.13 [1.29-13.2], p = 0.017), cyclophotocoagulation (OR = 30.9 [3.47-375.1], p = 0.002), and phacotrabeculectomy combined with or without intraocular lens implantation (OR = 30.0 [2.69-335.6], p = 0.006) were associated with increased clinically significant postoperative pain. Interestingly, patients with diabetes and/or hypertension were associated with less postoperative pain after glaucoma surgery (OR = 0.23 [0.08-0.64], p = 0.005).

CONCLUSION

Patients undergoing glaucoma surgery tend to experience postoperative pain in the early postoperative period. Anxiety level and surgery types of cyclophotocoagulation and phacotrabeculectomy are risk factors for postoperative pain. Patients with diabetes and/or hypertension are less likely to develop postoperative pain.

Phase 3 Randomized Study of Efficacy and Safety of a Dexamethasone Intracanalicular Insert in Patients With Allergic Conjunctivitis

PURPOSE

The purpose of this study was to evaluate the efficacy and safety of a dexamethasone intracanalicular ocular insert for the treatment of allergic conjunctivitis.

DESIGN

Multicenter, randomized, double-masked, placebo-controlled, Phase 3 clinical trial.

METHODS

Subjects with allergic conjunctivitis were randomized 1:1 to receive a dexamethasone insert or a placebo insert in both eyes and were evaluated using a modified version of the conjunctival allergen challenge (CAC) model. After inserts were placed in office, a series of 4 closely spaced post-insertion CACs were conducted at weeks 1, 2, and 4 across approximately 30 days. Primary efficacy endpoints, assessed at week-1 CAC-day 8, were reported by subjects of ocular itching at 3, 5, and 7 minutes post CAC and investigator-evaluated conjunctival redness at 7, 15, and 20 minutes post CAC.

RESULTS

For the primary endpoints, dexamethasone inserts showed statistically significantly lower mean ocular itching scores than placebo at all time points (P <.001), with differences favoring dexamethasone inserts over placebo (0.86, 0.98, and 0.96 units at 3, 5, and 7 minutes, respectively) and statistically significantly lower conjunctival redness scores at 20 minutes (P <.05) but not at 7 or 15 minutes (P ≥.05). Results also showed statistically significantly less itching and conjunctival redness at 31 and 29 of 33 other time points, respectively (P <.05). There were no serious adverse events; 1 subject had elevated intraocular pressure in both eyes.

CONCLUSIONS

Data presented in this study demonstrate the potential for a single, physician-administered dexamethasone intracanalicular insert to provide relief of ocular itching for up to 4 weeks in subjects with allergic conjunctivitis, while maintaining a favorable safety profile.

Plasma Pharmacokinetic Parameters of Dexamethasone Following Administration of a Dexamethasone Intracanalicular Insert in Healthy Adults

Purpose

Intracanalicular dexamethasone insert is a resorbable sustained-release polyethylene glycol-based hydrogel insert delivering a 0.4 mg tapered dose of dexamethasone for up to 30 days to the ocular surface. It is FDA-approved for treating inflammation and pain after ocular surgery. It has also been studied for ocular surface diseases such as allergic conjunctivitis. This study assessed the plasma pharmacokinetic (PK) parameters of dexamethasone following intracanalicular insertion.

Patients and Methods

Study subjects (N=16) were healthy adults. A dexamethasone insert was unilaterally placed into the canaliculus, and blood samples were obtained for analysis 1 hour prior to insertion and 1, 2, 4, 8, 16, 24 hours and 4, 8, 15, 22 and 29 days after insertion. Safety analyses included slit lamp and dilated fundus examinations, best corrected visual acuity, intraocular pressure (IOP) and adverse events (AEs).

Results

Plasma results were below the lower limit of quantitation (LLOQ) at all time points in five subjects (31.3%). Among subjects with quantifiable plasma concentrations, C_max was <1 ng/mL (range, 0.05 to 0.81 ng/mL), AUC_0-last ranged from 0.13 to 7.18 h∙ng/mL, and T_max ranged from 4.0 to 163.0 hours. Mean (SD) IOP increased from 16.3 (1.4) mmHg at baseline to 19.3 (3.2) at Day 22 but returned to baseline after treatment. No changes occurred in dilated fundus, punctum, or visual acuity examinations.

Conclusion

The dexamethasone 0.4 mg insert results in minimal systemic exposure following intracanalicular administration.

Review of Approaches for Increasing Ophthalmic Bioavailability for Eye Drop Formulations

Ophthalmic diseases represent a significant problem as over 2 billion people worldwide suffer from vison impairment and blindness. Eye drops account for around 90% of ophthalmic medications but are limited in success due to poor patient compliance and low bioavailability. Low bioavailability can be attributed to short retention times in the eye caused by rapid tear turnover and the difficulty of drug diffusion through the multi-layered structure of the eye that includes lipid-rich endothelial and epithelial layers as well as the stroma which is high in water content. In addition, there are barriers such as tight junctional complexes in the corneal epithelium, lacrimal turnover, nasolacrimal drainage, blinking reflexes, efflux transporters, drug metabolism by ocular enzymes, and drug binding to or repulsion from conjunctival mucins, tear proteins, and melanin. In order to maximize transport through the cornea while minimizing drug loss through other pathways, researchers have developed numerous methods to improve eye drop formulations including the addition of viscosity enhancers, permeability enhancers, mucoadhesives, and vasoconstrictors, or using formulations that include puncta occlusion, nanocarriers, or prodrugs. This review explains the mechanism behind each of these methods, examines their history, analyzes previous and current research, evaluates future applications, and discusses the pros and cons of each technique.