Intravitreal Steroids for Macular Edema: The Past, the Present, and the Future

Slow-release drug delivery through Elvax 40W to the rat retina: implications for the treatment of chronic conditions

Diseases of the retina are difficult to treat as the retina lies deep within the eye. Invasive methods of drug delivery are often needed to treat these diseases. Chronic retinal diseases such as retinal oedema or neovascularization usually require multiple intraocular injections to effectively treat the condition. However, the risks associated with these injections increase with repeated delivery of the drug. Therefore, alternative delivery methods need to be established in order to minimize the risks of reinjection. Several other investigations have developed methods to deliver drugs over extended time, through materials capable of releasing chemicals slowly into the eye. In this investigation, we outline the use of Elvax 40W, a copolymer resin, to act as a vehicle for drug delivery to the adult rat retina. The resin is made and loaded with the drug. The drug-resin complex is then implanted into the vitreous cavity, where it will slowly release the drug over time. This method was tested using 2-amino-4-phosphonobutyrate (APB), a glutamate analogue that blocks the light response of the retina. It was demonstrated that the APB was slowly released from the resin, and was able to block the retinal response by 7 days after implantation. This indicates that slow-release drug delivery using this copolymer resin is effective for treating the retina, and could be used therapeutically with further testing.

Treatments for macular oedema following central retinal vein occlusion: systematic review

OBJECTIVES

To review systematically the randomised controlled trial (RCT) evidence for treatment of macular oedema due to central retinal vein occlusion (CRVO).

DATA SOURCES

MEDLINE, EMBASE, CDSR, DARE, HTA, NHSEED, CENTRAL and meeting abstracts (January 2005 to March 2013).

STUDY ELIGIBILITY CRITERIA, PARTICIPANTS AND INTERVENTIONS

RCTs with at least 12 months of follow-up assessing pharmacological treatments for CRVO were included with no language restrictions.

STUDY APPRAISAL AND SYNTHESIS METHODS

2 authors screened titles and abstracts and conducted data extracted and Cochrane risk of bias assessment. Meta-analysis was not possible due to lack of comparable studies.

RESULTS

8 studies (35 articles, 1714 eyes) were included, assessing aflibercept (n=2), triamcinolone (n=2), bevacizumab (n=1), pegaptanib (n=1), dexamethasone (n=1) and ranibizumab (n=1). In general, bevacizumab, ranibizumab, aflibercept and triamcinolone resulted in clinically significant increases in the proportion of participants with an improvement in visual acuity of ≥15 letters, with 40-60% gaining ≥15 letters on active drugs, compared to 12-28% with sham. Results for pegaptanib and dexamethasone were mixed. Steroids were associated with cataract formation and increased intraocular pressure. No overall increase in adverse events was found with bevacizumab, ranibizumab, aflibercept or pegaptanib compared with control. Quality of life was poorly reported. All studies had a low or unclear risk of bias.

LIMITATIONS

All studies evaluated a relatively short primary follow-up (1 year or less). Most had an unmasked extension phase. There was no head-to-head evidence. The majority of participants included had non-ischaemic CRVO.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

Bevacizumab, ranibizumab, aflibercept and triamcinolone appear to be effective in treating macular oedema secondary to CRVO. Long-term data on effectiveness and safety are needed. Head-to-head trials and research to identify 'responders' is needed to help clinicians make the right choices for their patients. Research aimed to improve sight in people with ischaemic CRVO is required.

Medical management of uveitis - current trends

Uveitis is a challenging disease to treat. Corticosteroids have been used in the treatment of uveitis for many years. Immunosuppressives are gaining momentum in recent years in the treatment of uveitis. In this article we present an overview of current treatment of uveitis and the major breakthroughs and advances in drugs and ocular drug delivery systems in the treatment of uveitis.

Inflammation and pharmacological treatment in diabetic retinopathy

Diabetic retinopathy (DR), the most common microvascular complication of diabetes mellitus, is estimated to be the leading cause of new blindness in the working population of developed countries. Primary interventions such as intensive glycemic control, strict blood pressure regulation, and lipid-modifying therapy as well as local ocular treatment (laser photocoagulation and pars plana vitrectomy) can significantly reduce the risk of retinopathy occurrence and progression. Considering the limitations of current DR treatments development of new therapeutic strategies, it becomes necessary to focus on pharmacological treatment. Currently, there is increasing evidence that inflammatory processes have a considerable role in the pathogenesis of DR with multiple studies showing an association of various systemic as well as local (vitreous and aqueous fluid) inflammatory factors and the progression of DR. Since inflammation is identified as a relevant mechanism, significant effort has been directed to the development of new concepts for the prevention and treatment of DR acting on the inflammatory processes and the use of pharmacological agents with anti-inflammatory effect. Inhibiting the inflammatory pathway could be an appealing treatment option for DR in future practices, and as further prospective randomized clinical trials accumulate data, the role and guidelines of anti-inflammatory pharmacologic treatments will become clearer.

Plasma and ocular prednisolone disposition after oral treatment in cats

Objective. To evaluate the plasma and aqueous humor disposition of prednisolone after oral administration in cats. Methods. Six cats were administered with a single oral dose of prednisolone (10 mg). Blood and aqueous humor samples were serially collected after drug administration. Prednisolone concentrations in plasma and aqueous humor were measured at 0.25, 0.5, 1.0, 1.5, 2.0, 3.0, 4.0, and 5.0 h after administration by a high-performance liquid chromatographic analytical method developed and validated for this purpose. Results. Mean ± standard error (SE) of maximum plasma prednisolone concentration (300.8 ± 67.3 ng/mL) was reached at 1 h after administration. Prednisolone was distributed to the aqueous humor reaching a mean peak concentration of 100.9 ± 25.5 ng/mL at 1.25 h after administration. The mean ± SE systemic and aqueous humor exposure (AUC) was 553.3 ± 120.0 ng∗h/mL and 378.8 ± 64.9 ng∗h/mL, respectively. A high AUC_{aqueous humor}/AUC_plasma ratio was observed (0.68 ± 0.13). The mean half-life time of elimination in plasma and aqueous humor was 0.87 ± 0.16 h and 2.25 ± 0.44 h, respectively. Clinical Significance. The observed high ratio between aqueous humor and plasma prednisolone concentrations indicates that extensive penetration of prednisolone to the anterior segment of the eye may occur. This is the first step that contributes to the optimization of the pharmacological therapeutics for the clinical treatment of uveitis.

Evaluations of therapeutic efficacy of intravitreal injected polylactic-glycolic acid microspheres loaded with triamcinolone acetonide on a rabbit model of uveitis

Conventional treatments of uveitis are not ideal because of the short period of therapeutic efficacy. In the present study, biodegradable polylactic-glycolic acid microspheres loaded with triamcinolone acetonide (TA) were prepared to achieve sustained drug release and their therapeutic efficacy was investigated on a rabbit model of uveitis. TA-loaded microspheres (TA-MS) were prepared by the solvent evaporation method and characterized for encapsulation efficiency, particle size, morphology and in vitro release. The therapeutic efficacy was studied on the rabbit experimental uveitis model based on scoring of the inflammation, aqueous leukocyte counting, aqueous protein determination and histological examination. The TA-MS exhibited smooth and intact surfaces with an average diameter of 50.87 μm. The drug-loading coefficient and encapsulation efficiency were 15.2 ± 0.6 % and 91.24 ± 3.77 %, respectively. The drug release from TA-MS lasted up to 87 days, but only 46 days for TA suspension. The change in surface morphology also showed sustained drug release from TA-MS. TA-MS exhibited improved therapeutic efficacy in lipopolysaccharide -induced uveitis compared to TA suspension, especially in regard to the inhibition of inflammation. The TA-MS had a longer-term therapeutic effect on intraocular inflammation in LPS-induced uveitis in rabbits compared to TA suspension. The results suggested that TA-MS can be developed as a potential sustained-release system for the treatment of uveitis.

Interventions for the treatment of uveitic macular edema: a systematic review and meta-analysis

Background

Uveitic macular edema is the major cause of reduced vision in eyes with uveitis.

Objectives

To assess the effectiveness of interventions in the treatment of uveitic macular edema.

Search strategy

Cochrane Central Register of Controlled Trials, Medline, and Embase. There were no language or data restrictions in the search for trials. The databases were last searched on December 1, 2011. Reference lists of included trials were searched. Archives of Ophthalmology, Ophthalmology, Retina, the British Journal of Ophthalmology, and the New England Journal of Medicine were searched for clinical trials and reviews.

Selection criteria

Participants of any age and sex with any type of uveitic macular edema were included. Early, chronic, refractory, or secondary uveitic macular edema were included. We included trials that compared any interventions of any dose and duration, including comparison with another treatment, sham treatment, or no treatment.

Data collection and analysis

Best-corrected visual acuity and central macular thickness were the primary outcome measures. Secondary outcome data including adverse effects were collected.

Conclusion

More results from randomized controlled trials with long follow-up periods are needed for interventions for uveitic macular edema to assist in determining the overall long-term benefit of different treatments. The only intervention with sufficiently robust randomized controlled trials for a meta-analysis was acetazolamide, which was shown to be ineffective in improving vision in eyes with uveitic macular edema, and is clinically now rarely used. Interventions showing promise in this disease include dexamethasone implants, immunomodulatory drugs and anti-vascular endothelial growth-factor agents. When macular edema has become refractory after multiple interventions, pars plana vitrectomy could be considered. The disease pathophysiology is uncertain and the course of disease unpredictable. As there are no clear guidelines from the literature, interventions should be tailored to the individual patient.

Score Study Report 12: Development of venous collaterals in the Score Study

PURPOSE

To investigate the prevalence of venous collaterals after branch and central retinal vein occlusion, assess the association of venous collaterals with other clinical features (including visual acuity), and determine if treatment with intravitreal corticosteroids influences the development of new venous collaterals.

METHODS

Review of data from two multicenter randomized clinical trials in the Standard of Care versus COrticosteroid for REtinal Vein Occlusion (SCORE) Study.

RESULTS

Statistically significant associations of venous collaterals and visual acuity at baseline or at follow-up were not found. Treatment with intravitreal triamcinolone acetonide did not appear to influence the development of venous collaterals.

CONCLUSION

In contrast to some previous reports, development of venous collaterals did not demonstrate an independent association with visual acuity in eyes with branch retinal vein occlusion or central retinal vein occlusion in the SCORE Study. Intravitreal steroid effects do not appear to influence the development of venous collaterals.

Pathophysiology and treatment of diabetic retinopathy

In the past years, the management of diabetic retinopathy (DR) relied primarily on a good systemic control of diabetes mellitus, and as soon as the severity of the vascular lesions required further treatment, laser photocoagulation or vitreoretinal surgery was done to the patient. Currently, even if the intensive metabolic control is still mandatory, a variety of different clinical strategies could be offered to the patient. The recent advances in understanding the complex pathophysiology of DR allowed the physician to identify many cell types involved in the pathogenesis of DR and thus to develop new treatment approaches. Vasoactive and proinflammatory molecules, such as vascular endothelial growth factor (VEGF), play a key role in this multifactorial disease. Current properly designed trials, evaluating agents targeting VEGF or other mediators, showed benefits in the management of DR, especially when metabolic control is lacking. Other agents, directing to the processes of vasopermeability and angiogenesis, are under investigations, giving more hope in the future management of this still sight-threatening disease.

Novel anti(lymph)angiogenic treatment strategies for corneal and ocular surface diseases

The cornea is one of the few tissues which actively maintain an avascular state, i.e. the absence of blood and lymphatic vessels (corneal [lymph]angiogenic privilege). Nonetheless do several diseases interfere with this privilege and cause pathologic corneal hem- and lymphangiogenesis. The ingrowths of pathologic blood and lymphatic vessels into the cornea not only reduce transparency and thereby visual acuity up to blindness, but also significantly increases the rate of graft rejections after subsequent corneal transplantation. Therefore great interest exists in new strategies to target pathologic corneal (lymph)angiogenesis to promote graft survival. This review gives an overview on the vascular anatomy of the normal ocular surface, on the molecular mechanisms contributing to the corneal (lymph)angiogenic privilege and on the cellular and molecular mechanisms occurring during pathological neovascularization of the cornea. In addition we summarize the current preclinical and clinical evidence for three novel treatment strategies against ocular surface diseases based on targeting pathologic (lymph)angiogenesis: (a) modulation of the immune responses after (corneal) transplantation by targeting pathologic (lymph)angiogenesis prior to and after transplantation, (b) novel concepts against metastasis and recurrence of ocular surface tumors such as malignant melanoma of the conjunctiva by anti(lymph)angiogenic therapy and (c) new ideas on how to target ocular surface inflammatory diseases such as dry eye by targeting conjunctival and corneal lymphatic vessels. Based on compelling preclinical evidence and early data from clinical trials the novel therapeutic concepts of promoting graft survival, inhibiting tumor metastasis and dampening ocular surface inflammation and dry eye disease by targeting (lymph)angiogenesis are on their way to translation into the clinic.

A preliminary evaluation of dexamethasone palmitate emulsion: a novel intravitreal sustained delivery of corticosteroid for treatment of macular edema

PURPOSE

Dexamethasone palmitate (DXP) is a lipophilic prodrug of dexamethasone (DXM), a potent corticosteroid used to treat a variety of ophthalmic diseases. The aim of the study was to characterize the sustained release capacity (in rabbit), efficacy (in rat and rabbit), and safety (in rabbit, cat, and minipig) of intravitreal (IVT) DXP emulsions in preclinical models.

METHODS

Oil-in-water emulsions of DXP were administered by IVT injections in rats, rabbits, cats, or minipigs. Efficacy was assessed in rabbits by the inhibition of VEGF-induced vascular leakage and in rats by inhibition of laser-induced choroidal neovascularization. Concentrations of DXP and DXM in aqueous humor, vitreous, retina, choroid, and blood were determined to characterize the ocular and systemic pharmacokinetic (PK) profile. Complete ophthalmic examinations (indirect ophthalmoscopy, slit-lamp biomacroscopy, electroretinography, tonometry) were performed to assess the ocular safety of IVT DXP doses up to 2,600 μg in minipig, followed by histopathologic examinations. A validated feline model of DXM-induced elevated intraocular pressure (IOP) was used to assess the ocular hypertensive impact (i.e., the safety) of an IVT injection of DXP emulsion.

RESULTS

Rat and rabbit efficacy data demonstrated that IVT injections of DXP emulsions were effective. Rabbit PK data demonstrated that following a single 1,280 μg IVT injection resulted in sustained DXM levels in the retina and choroid (1,179.6 and 577.7 ng/g with a half-life of 189 and 103 days, respectively) sufficient to inhibit VEGF-induced vascular hyper-permeability for up to 9 months. No adverse ocular findings were observed in the rabbit at the 1,280 μg DXP dose. Plasma levels of DXP and DXM were close to the lower limit of quantification (0.5 ng/mL). In minipigs, no systemic effects were observed at a dose up to 2,600 μg DXP. In steroid responsive cats, IVT DXP emulsions increased IOP to a lesser extent than triamcinolone acetonide with a more rapid return to basal levels and no evidence of cataract formation.

CONCLUSIONS

IVT injections of DXP emulsions were well tolerated and shown to be efficacious for the sustained release of the drug, with the potential to control vascular leakage up to 9 months following a single IVT injection. These data suggest that IVT injections of DXP emulsions could be a safe and effective alternative IVT drug delivery vehicle for corticosteroid to treat back of the eye diseases complicated by macular edema.

Analysis of single nucleotide polymorphisms in the SFRS3 and FKBP4 genes in corticosteroid-induced ocular hypertension

BACKGROUND

The use of intravitreal triamcinolone acetonide (IVTA) can cause ocular hypertension. This steroid response appears to be heritable and alleles in the SFRS3 and FKBP4 genes have recently been suggested to play a role. The purpose of the present study was to perform an independent replication study to determine whether single nucleotide polymorphisms (SNPs) in SFRS3 and FKBP4 are involved in the steroid response.

MATERIALS AND METHODS

A retrospective case-control study of native Dutch patients was performed who were treated with 4.0mg IVTA. The patients were divided into an intraocular hypertension group (intraocular pressure > 21 mmHg within a year after IVTA) and a non-intraocular hypertension group. The cohort was genotyped for three SNPs: rs7759778 and rs1406945 in SFRS3, and rs2968909 in FKBP4.

RESULTS

A total of 102 patients was included: 58 steroid responders and 44 non-responders. No significant differences in demographic parameters or medical history were observed between the study groups. None of the SNPs were found to be significantly associated with the disease as no difference was revealed either in the genotype or allele frequencies between responders and non-responders.

CONCLUSIONS

This study does not confirm a role for genetic variants in the SFRS3 and FKBP4 genes in the pathogenesis of corticosteroid-induced ocular hypertension. However, our limited sample size may have restricted the power of our study, and we therefore cannot exclude the involvement of these genetic variants in steroid response.

Treatment of steroid-induced elevated intraocular pressure with anecortave acetate: a randomized clinical trial

PURPOSE

The present study is the first randomized clinical trial designed to evaluate the intraocular pressure (IOP)-lowering effect of anecortave acetate (AA) administered at 3 doses (3, 15, or 30 mg) as an anterior juxtascleral depot (AJD) in patients experiencing elevated IOP due to corticosteroid therapy.

METHODS

This was a double-masked, randomized, placebo-controlled, multicenter, parallel group trial. Eligible patients had an IOP of at least 24 mmHg and an IOP increase of at least 10 mmHg relative to their IOP before treatment with steroids. A target IOP was established for each patient at baseline. Patients were randomized to 1 of the 4 treatment groups: vehicle, 3 mg AA, 15 mg AA, or 30 mg AA. All patients then received a 0.5 mL AJD of the assigned treatment. Patients returned for scheduled examination visits at weeks 1, 2, 4, 6, months 3, 4, 5, and 6. IOP was measured at each visit as well as best corrected visual acuity (logMAR), ocular motility, eyelid responsiveness, slit lamp examination, and assessment of any adverse events. In addition, at baseline and at exit, a dilated fundus examination was carried out and the lens was examined using LOCS II criteria.

RESULTS

Seventy patients were randomized to treatment. At week 4, eyes in the vehicle group showed a 3.4 mmHg (9.1%) decrease from baseline. Reductions for the 3 mg AA (3.1 mmHg, 10.7%) and the 30 mg AA groups (5.4 mmHg, 16.6%) were not significantly different than for vehicle control. However, IOP for the 15 mg AA group at week 4 was reduced 11.5 mmHg (31.3%) from baseline, which was statistically significant (P=0.0487). The mean time to treatment failure was 32.2, 38.9, 56.3, and 32.6 days for the vehicle, 3 mg AA, 15 mg AA, and 30 mg AA groups, respectively. Adverse events were assessed at each post-treatment visit. There were no serious adverse events that were determined to be related to the test article or its administration.

CONCLUSIONS

AA can be of benefit to some patients requiring treatment with corticosteroids, but suffering from the side effect of elevated IOP.

Novel Nanomicellar Formulation Approaches for Anterior and Posterior Segment Ocular Drug Delivery

One of the most challenging areas of pharmaceutical research is ocular drug delivery. The unique anatomy and physiology of the eye impedes drug permeation to deeper ocular tissues. Nanosized carrier systems such as nanoparticles, liposomes, suspensions, dendrimers, and nanomicelles are being explored for ocular drug delivery. In this review, we have focused on application of emerging nanomicellar carrier systems in ocular drug delivery. Nanomicelles are nanosized vesicular carriers formed from amphiphilic monomer units. Surfactant and polymeric micellar nanocarriers provide an amenable means to improve drug solubilization, develop clear aqueous formulations and deliver drugs to anterior and posterior ocular tissues. Nanomicelles due to their amphiphilic nature encapsulate hydrophobic drugs and aid in drug delivery. Various methods are employed to develop nanosized micellar formulations depending upon the physicochemical properties of the drug. Nanomicellar carriers appear to be promising vehicles with potential applications in ocular drug delivery. In this review, we attempted to discuss about the progress in ocular drug delivery research using nanomicelles as carriers from the published literature and issued patents. Also, with regards to ocular static and dynamic barriers which prevent drug permeation, a brief discussion about nanomicelles, types of nanomicelles, their methods of preparation and micellar strategy to overcome ocular barriers, delivering therapeutic levels of drugs to anterior and posterior ocular tissues are discussed.

Test-retest variation in macular thickness measurements with the Heidelberg Retina Tomograph

PURPOSE

The aim was to evaluate the test-retest variation of macular thickness measurements using the Heidelberg Retina Tomograph (HRT3) Retina Module and compare it with the Stratus optical coherence tomography (OCT). As no normative data has been published for the HRT Retina Module, a secondary purpose was to obtain reference values for this technique.

METHODS

Thirty healthy subjects and nine patients with macular oedema were examined. The healthy subjects underwent five examinations by two experienced examiners at two different occasions. The patients with maculopathy were examined twice by one examiner on one occasion. All measurements were made with both the HRT3 and the Stratus OCT and the macular thickness measurements were used for calculations of the test-retest variation.

RESULTS

In healthy subjects the coefficient of variation (CV) ranged from 4.5 to 8.8 per cent with the HRT3 and from 0.6 to 1.5 per cent with the Stratus OCT. In the nine patients with macular oedema, the HRT CV ranged from 7.9 to16.6 per cent and for OCT from 1.1 to 2.5 per cent. The intra-class correlation in the central area for intra-observer/intra-visit in healthy subjects was 0.78 with the HRT3 and 0.93 with the Stratus OCT. Corresponding values for the patients with macular oedema were 0.64 with the HRT3 and 1.0 with the Stratus OCT. Mean macular thickness was significantly larger in all areas measured with the HRT3 compared with the Stratus OCT. No significant correlations were found between the thickness values from the different instruments.

CONCLUSION

In this study, macular thickness was measured with two different techniques. The HRT3 showed lower repeatability and reproducibility as well as a higher CV compared with the Stratus OCT in both healthy subjects and patients with macular oedema. This difference might be of clinical relevance, even though the nine patients with maculopathy in the current study showed abnormal results with both methods.

Neodymium: yttrium-aluminum-garnet laser anterior hyaloidotomy to treat trapped triamcinolone acetonide behind the crystalline lens after intravitreal injection

A 65-year-old male underwent intravitreal triamcinolone acetonide (IVTA) injection for treating a clinically significant macular edema (CSME) due to background diabetic retinopathy in his left eye. On the first postoperative day, visual acuity dropped from 20/80 to hand movements. Slit-lamp examination showed the drug between the posterior capsule of the lens and the anterior hyaloid face. Two weeks later, visual acuity and the milky fluid seemed unchanged. Neodymium:yttrium-aluminum-garnet (Nd:YAG) laser anterior hyaloidotomy was performed. One week later, slit-lamp examination of the retrolental space revealed the complete disappearance of triamcinolone and intraocular pressure remained stable. After a follow-up period of 2 months, visual acuity increased to 20/50 with the lens remaining clear. Nd:YAG laser anterior hyaloidotomy is an effective, simple, useful and minimally invasive outpatient procedure in patients with persistent entrapment of triamcinolone behind the crystalline lens, allowing the drug to clear without trauma to the lens.

An Update on Intravitreal Injections for Macular Diseases: Friend or Foe?

The purpose of this article is to review the role of intravitreal injections of medications in the treatment of the two common macular diseases, macular edema and age related macular degeneration (AMD). We perform literature search by search engine Pubmed till May 2011, using keywords 'intravitreal injections', 'age-related macular degeneration' and 'macular edema' to retrieve relevant review articles and original papers. To conclude, with advance in technology, intravitreal injections of medications may have become an integral part of our ability to treat a wide range of macular diseases. The use of ranibizumab, pegaptanib in the treatment of neovascular AMD and TA in the treatment of various causes of macular edema have shown promising results in a number of prospective randomized controlled trials, with low risk of complications reported.

Anti-inflammatory therapy for diabetic retinopathy

Diabetic retinopathy (DR) is one of the most common complications of diabetes. This devastating disease is a leading cause of blindness in people of working age in industrialized countries and affects the daily lives of millions of people. Despite tight glycemic control, blood pressure control and lipid-lowering therapy, the number of DR patients keeps growing and therapeutic approaches are limited. Moreover, there are significant limitations and side effects associated with the current therapies. Thus, there is a great need for development of new strategies for prevention and treatment of DR. Studies have shown that DR has prominent features of chronic, subclinical inflammation. This article focuses on the role of inflammation in DR and summarizes the progress of studies of anti-inflammatory strategies for DR.

Emerging drugs for uveitis

INTRODUCTION

Uveitis is a challenging disease covering both infectious and noninfectious conditions. The current treatment strategies are hampered by the paucity of randomized controlled trials and trials comparing the efficacy of different agents.

AREAS COVERED

This review describes the current and future treatments of uveitis. A literature search was performed in PUBMED from 1965 to 2010 on drugs treating ocular inflammation with emphasis placed on more recent, larger studies. Readers should gain a basic understanding of current treatment strategies beginning with corticosteroids and transitioning to steroid sparing agents. Steroid sparing agents include antimetabolites such as methotrexate, azathioprine and mycophenolate mofetil; calcineurin inhibitors which include cyclosporine, tacrolimus; alkylating agents which include cyclophosphamide and chlorambucil; and biologics which include the TNF-α inhibitors infliximab, adalimumab and etanercept and daclizumab, IFN-α(2a) and rituximab.

EXPERT OPINION

Newer agents are typically formulated from existing drugs or developed based on new advances in immunology. Future treatment will require a better understanding of the mechanisms involved in autoimmune diseases and better delivery systems in order to provide targeted treatment with minimal side effects.

Development and validation of a fast and sensitive bioanalytical method for the quantitative determination of glucocorticoids--quantitative measurement of dexamethasone in rabbit ocular matrices by liquid chromatography tandem mass spectrometry

A sensitive, selective, accurate and robust LC-MS/MS method was developed and validated for the quantitative determination of glucocorticoids in rabbit ocular tissues. Samples were processed by a simple liquid-liquid extraction procedure. Chromatographic separation was performed on Phenomenex reversed phase C18 gemini column (50mmx4.6mm i.d.,) with an isocratic mobile phase composed of 30% of acetonitrile in water containing 0.1% of formic acid, at a flow rate 0.2mL/min. Dexamethasone (DEX), prednisolone (PD) and hydrocortisone (HD) were detected with proton adducts at m/z 393.20-->355.30, 361.30-->147.20 and 363.20-->121.0 in multiple reaction monitoring (MRM) positive mode respectively. Finally, 50microL of 0.1% novel DEX mixed micellar formulation was topically administered to a rabbit eye and concentrations were measured. The method was validated over a linear concentration range of 2.7-617.6ng/mL. Lower limit of quantitation (LLOQ) of DEX and PD was measured in the concentration range of 2.7 and 11.0ng/mL respectively. The resulting method demonstrated intra and inter-day precision within 13.3% and 11.1% and accuracy within 19.3% and 12.5% for DEX and PD, respectively. Both analytes were found to be stable throughout freeze-thaw cycles and during bench top and postoperative stability studies (r(2)>0.999). DEX concentrations in various ocular tissue samples i.e., aqueous humor, cornea, iris ciliary body, sclera and retina choroid were found to be 344.0, 1050.07, 529.6, 103.9 and 48.5ng/mg protein respectively. Absorption of DEX after topical administration from a novel aqueous mixed micellar formulation achieved therapeutic concentration levels in posterior segment of the rabbit eye.

Intraocular sustained-release delivery systems for triamcinolone acetonide

Recently, the use of triamcinolone acetonide (TA) injection has increased dramatically in treatment for several ocular diseases. Among them, macular diseases such as macular edema due to diabetic retinopathy, venous occlusive diseases, ocular inflammation and age-related macular degeneration (AMD) are very common vision threatening disorders and are great challenges to treat. In these types of chronic retinal diseases, repeated intraocular injections of TA are often required which increases the likelihood of complications. In order to achieve sustained-release, maintain therapeutic levels of TA over longer times and reduce frequency of intravitreal injections, researchers are investigating different implantable devices or injectable systems. However, as of yet, there is no sustained-release product for TA available on the commercial market. This review discusses and compares different sustained-release devices or injectable systems that are currently being developed.