Treatment of cytomegalovirus retinitis with an intraocular sustained-release ganciclovir implant

Vitreoretinal Surgery in Uveitis: From Old to New Concepts - A Review

PURPOSE

The aim of this article is to do a comprehensive literature review about the current role of pars plana vitrectomy in uveitis and in its different structural complications such as cystoid macular edema, epiretinal membrane, macular hole, and retinal detachment.

METHODS

This comprehensive literature review was performed based on a search on PubMed, BioMed Central, Science Open, and CORE databases, of relevant articles abording pars plana vitrectomy in uveitis.

DISCUSSION

Uveitis is a complex disease with multiple etiologies and pathogenic mechanisms. Therapeutic pars plana vitrectomy (PPV) may aid in uveitic structural complications such as cystoid macular edema, epiretinal membranes, macular hole, and retinal detachments even though some cases may present unpredictable visual outcomes. Diagnostic PPV with appropriate ancillary testing is also a valuable tool for the assessment and diagnosis of uveitis in a large proportion of patients.

CONCLUSION

Over the years, pars plana vitrectomy has undergone significant transformations since its invention nearly 5 decades ago, however, the quality of evidence in the literature regarding its use for uveitis has not improved in the same way. Even though some structural uveitis complications (as previously mentioned) may respond well to surgery, there is still a certain unpredictability regarding its visual outcomes. On the other hand, diagnostic vitrectomy with appropriate ancillary testing is also a valuable tool for the assessment and diagnosis of uveitis in a large proportion of patients.

Ocular barriers as a double-edged sword: preventing and facilitating drug delivery to the retina

In recent decades, the growing of the aging population in the world brings increasingly heavy burden of vision-threatening retinal diseases. One of the biggest challenges in the treatment of retinal diseases is the effective drug delivery to the diseased area. Due to the existence of multiple anatomical and physiological barriers of the eye, commonly used oral drugs or topical eye drops cannot effectively reach the retinal lesions. Innovations in new drug formulations and delivery routes have been continuously applied to improve current drug delivery to the back of the eye. Unique ocular anatomical structures or physiological activities on these ocular barriers, in turn, can facilitate drug delivery to the retina if compatible formulations or delivery routes are properly designed or selected. This paper focuses on key barrier structures of the eye and summarizes advances of corresponding drug delivery means to the retina, including various local drug delivery routes by invasive approaches, as well as systemic eye drug delivery by non-invasive approaches.

Noninvasive monitoring of suprachoroidal, subretinal, and intravitreal implants using confocal scanning laser ophthalmoscope (cSLO) and optical coherence tomography (OCT)

To address the need for noninvasive monitoring of injectable preformed drug delivery implants in the eye, we developed noninvasive methods to monitor such implants in different locations within the eye. Cylindrical polymeric poly(lactide-co-glycolide) or metal implants were injected into isolated bovine eyes at suprachoroidal, subretinal, and intravitreal locations and imaged noninvasively using the cSLO and OCT modes of a Heidelberg Spectralis HRA + OCT instrument after adjusting for the corneal curvature. Length and diameter of implants were obtained using cSLO images for all three locations, and the volume was calculated. Additionally, implant volume for suprachoroidal and subretinal location was estimated by integrating the cross-sectional bleb area over the implant length in multiple OCT images or using the maximum thickness of the implant based on thickness map along with length in cSLO image. Simultaneous cSLO and OCT imaging identified implants in different regions of the eye. Image-based measurements of implant dimensions mostly correlated well with the values prior to injection using blade micrometer. The accuracy (82-112%) and precision (1-19%) for noninvasive measurement of length was better than the diameter (accuracy 69-130%; precision 3-38%) using cSLO image for both types of implants. The accuracy for the measurement of volume of both types of implants from all three intraocular locations was better with cSLO imaging (42-152%) compared to those obtained using OCT cross-sectional bleb area integration (117-556%) or cSLO and thickness map (32-279%) methods. Suprachoroidal, subretinal, and intravitreal implants can be monitored for length, diameter, and volume using cSLO and OCT imaging. Such measurements may be useful in noninvasively monitoring implant degradation and drug release in the eye.

Advanced Formulation Approaches for Ocular Drug Delivery: State-Of-The-Art and Recent Patents

The eye presents extensive perspectives and challenges for drug delivery, mainly because of the extraordinary capacity, intrinsic to this path, for drugs to permeate into the main circulatory system and also for the restrictions of the ocular barriers. Depending on the target segment of the eye, anterior or posterior, the specifications are different. The ocular route experienced in the last decades a lot of progresses related with the development of new drugs, improved formulations, specific-designed delivery and even new routes to administer a drug. Concomitantly, new categories of materials were developed and adapted to encapsulate drugs. With such advances, a multiplicity of parameters became possible to be optimized as the increase in bioavailability and decreased toxic effects of medicines. Also, the formulations were capable to easily adhere to specific tissues, increase the duration of the therapeutic effect and even target the delivery of the treatment. The ascending of new delivery systems for ocular targeting is a current focus, mainly because of the capacity to extend the normal time during which the drug exerts its therapeutic effect and, so, supplying the patients with a product which gives them fewer side effects, fewer number of applications and even more effective outcomes to their pathologies, surpassing the traditionally-used eye drops. Depending on the systems, some are capable of increasing the duration of the drug action as gels, emulsions, prodrugs, liposomes, and ocular inserts with hydrophilic properties, improving the absorption by the cornea. In parallel, other devices use as a strategy the capacity to sustain the release of the carried drugs by means of erodible and non-erodible matrices. This review discusses the different types of advanced formulations used for ocular delivery of therapeutics presenting the most recent patents according to the clinical applications.

Ganciclovir

Ganciclovir is synthetic nucleoside analog of guanine closely related to acyclovir but has greater activity against cytomegalovirus. This comprehensive profile on ganciclovir starts with a description of the drug: nomenclature, formulae, chemical structure, elemental composition, and appearance. The uses and application of the drug are explained. The methods that were used for the preparation of ganciclovir are described and their respective schemes are outlined. The methods which were used for the physical characterization of the dug are: ionization constant, solubility, X-ray powder diffraction pattern, crystal structure, melting point, and differential scanning calorimetry. The chapter contains the spectra of the drug: ultraviolet spectrum, vibrational spectrum, nuclear magnetic resonance spectra, and the mass spectrum. The compendial methods of analysis of ganciclovir include the United States Pharmacopeia methods. Other methods of analysis that were reported in the literature include: high-performance liquid chromatography alone or with mass spectrometry, electrophoresis, spectrophotometry, voltammetry, chemiluminescence, and radioimmunoassay. Biological investigation on the drug includes: pharmacokinetics, metabolism, bioavailability, and biological analysis. Reviews on the methods used for preparation or for analysis of the drug are provided. The stability of the drug in various media and storage conditions is reported. More than 240 references are listed at the end of the chapter.

Therapy and prophylaxis of opportunistic infections in HIV-infected patients: a guideline by the German and Austrian AIDS societies (DAIG/ÖAG) (AWMF 055/066)

INTRODUCTION

There was a growing need for practical guidelines for the most common OIs in Germany and Austria under consideration of the local epidemiological conditions.

MATERIALS AND METHODS

The German and Austrian AIDS societies developed these guidelines between March 2010 and November 2011. A structured Medline research was performed for 12 diseases, namely Immune reconstitution inflammatory syndrome, Pneumocystis jiroveci pneumonia, cerebral toxoplasmosis, cytomegalovirus manifestations, candidiasis, herpes simplex virus infections, varizella zoster virus infections, progressive multifocal leucencephalopathy, cryptosporidiosis, cryptococcosis, nontuberculosis mycobacteria infections and tuberculosis. Due to the lack of evidence by randomized controlled trials, part of the guidelines reflects expert opinions. The German version was accepted by the German and Austrian AIDS Societies and was previously published by the Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften (AWMF; German Association of the Scientific Medical Societies).

CONCLUSION

The review presented here is a translation of a short version of the German-Austrian Guidelines of opportunistic infections in HIV patients. These guidelines are well-accepted in a clinical setting in both Germany and Austria. They lead to a similar treatment of a heterogeneous group of patients in these countries.

Impacts of nanomedicines in ocular pharmacotherapy

INTRODUCTION

The integrity of the cells/tissues in anterior and/or posterior segments of the eye plays a crucial role in biofunctions of the vision. To maintain ocular homeostasis, selective restrictiveness of the ophthalmic membranes and barriers control must act on shuttling of biomolecules. Thus, not all attempts to apply de novo nanotechnology approaches for ocular pharmacotherapy have met with the same successes as those cited here in this review, and sometimes these novel technologies tools provoke a great deal of challenges and hurdles mainly because of functional presence of these barriers.

METHODS

Recent published articles related to applications of ocular nanomedicines were reviewed and highlighted in this review article.

RESULTS

It seems the emergence of nanomedicines have arisen great hopes for ophthalmic pharmacotherapy, in which nanostructured medicines are expected to be able to cross the restrictive barriers of the eye. Although such fast inauguration of ocular nanomedicines will literally convey new challenges in the regulatory and translational processes, it will also grant a prolific platform from which many exciting, and yet unimagined, applications of biomedical nanotechnology will emerge for pharmacotherapy of the eye.

CONCLUSION

This review provides recent advancements on ocular nanomedicines.

Economic evaluation of treatment administration strategies of ganciclovir for cytomegalovirus retinitis in HIV/AIDS patients in Thailand: a simulation study

BACKGROUND

There are many effective interventions, via various routes (intravenous [IV], oral [OR], intravitreal injection [IVT] and intraocular implantation [IMP]), for treating cytomegalovirus retinitis (CMVR) that have become available. There are large variations in treating CMVR in clinical practice in Thailand.

OBJECTIVE

To evaluate the incremental cost-effectiveness ratio (ICER) of providing (i) IVT, (ii) IV/OR and (iii) IMP ganciclovir to patients with HIV/AIDS and CMVR versus providing no treatment.

DESIGN

A simulation study for which the input parameters were derived from a systematic review of the literature, a hospital-based survey and patient interviews.

SETTING

The analysis assumed a Thai healthcare system perspective. However, the model was run using both societal and healthcare provider perspectives.

RESULTS

Our results suggest that IVT ganciclovir was cost effective and the best option for treating patients with CMVR irrespective of whether patients received antiretroviral treatment (ART). In patients receiving ART, moving from IVT to IV/OR ganciclovir was also likely to be a cost-effective option. Offering IMP ganciclovir was not likely to be cost effective. Providing treatments for patients with bilateral CMVR was more cost effective than providing treatments for those with unilateral CMVR, and offering treatments for patients receiving ART was better value for money than treating patients without ART.

CONCLUSIONS

Our models suggest that IV/OR ganciclovir should be recommended for the treatment of unilateral and bilateral CMVR for patients receiving ART in the Thai healthcare system. IVT ganciclovir may also have a role in the treatment of CMVR patients not receiving ART.

Safety of intravitreous fomivirsen for treatment of cytomegalovirus retinitis in patients with AIDS

PURPOSE

To report data regarding the safety of intravitreous fomivirsen for treatment of cytomegalovirus (CMV) retinitis in patients with acquired immunodeficiency syndrome (AIDS).

DESIGN

Critical review of safety data from three randomized controlled clinical trials with supplemental information from an expanded drug access program.

METHODS

Adverse ocular events reported by clinician investigators were listed using terms modified from the COSTART dictionary. Data for two doses (165-microg/injection [35 eyes, 30 patients] and 330-microg/injection [153 eyes, 120 patients]) and two 330-microg/injection dose schedules of different intensity were pooled to calculate incidence rates for each event. Rates were calculated as "events/patient-year" (based on total cumulative reported events and duration of treatment) for events that could recur during treatment. Rates were calculated as "patients with events/person-year" for the following events: retinal detachment, cataract, visual field disturbance, and retinal pigment epitheliopathy. To assess the ability to manage events, we reviewed treatments given for two events (anterior chamber inflammation, increased intraocular pressure) in one trial. We also report an analysis comparing the proportion of eyes that developed one or more key events to the cumulative number of injections.

RESULTS

Incidence rates were dose and schedule dependent (165 microg/injection, 4.06 events/patient-year; 330 microg/injection, 6.58 events/patient-year [less intense regimen] and 8.35 events/patient-year [more intense regimen]). The most frequently reported events were anterior chamber inflammation and increased intraocular pressure. We found no evidence that the proportion of patients with events increased as the number of injections increased.

CONCLUSIONS

Intravitreous fomivirsen is well tolerated with an acceptable safety profile. Adverse ocular events associated with doses and schedules used clinically can be managed successfully with medical therapy.