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Kaji H, Nagai N, Nishizawa M, Abe T. Drug delivery devices for retinal diseases. Adv Drug Deliv Rev 2018; 128:148-157. [PMID: 28690136 DOI: 10.1016/j.addr.2017.07.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 06/29/2017] [Accepted: 07/04/2017] [Indexed: 12/16/2022]
Abstract
Retinal degenerative diseases are a leading cause of irreversible blindness and visual impairment, affecting millions of people worldwide. Although intravitreal injection can directly deliver drugs to the posterior segment of the eye, it is invasive and associated with serious side effects. The design of drug delivery systems targeting the posterior segment of the eye in a less invasive manner has still been challenging because of various anatomical and physiological barriers. In this review, we provide an overview of the current implant device-based approaches used for treating retinal degenerative diseases. We then offer our perspectives on future directions and challenges that remain for developing more effective device-based therapies for retinal diseases.
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Affiliation(s)
- Hirokazu Kaji
- Department of Finemechanics, Graduate School of Engineering, Tohoku University, 6-6-01 Aramaki, Aoba-ku, Sendai 980-8579, Japan.
| | - Nobuhiro Nagai
- Division of Clinical Cell Therapy, United Centers for Advanced Research and Translational Medicine (ART), Tohoku University Graduate School of Medicine, 2-1 Seiryo, Aoba-ku, Sendai 980-8575, Japan
| | - Matsuhiko Nishizawa
- Department of Finemechanics, Graduate School of Engineering, Tohoku University, 6-6-01 Aramaki, Aoba-ku, Sendai 980-8579, Japan
| | - Toshiaki Abe
- Division of Clinical Cell Therapy, United Centers for Advanced Research and Translational Medicine (ART), Tohoku University Graduate School of Medicine, 2-1 Seiryo, Aoba-ku, Sendai 980-8575, Japan
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2
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Chiquet C, Rouberol F. Prolifération vitréo-rétinienne : traitement préventif. J Fr Ophtalmol 2014; 37:737-43. [DOI: 10.1016/j.jfo.2014.04.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 04/22/2014] [Accepted: 04/23/2014] [Indexed: 10/25/2022]
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Perez AC, Cunha Junior ADS, Fialho SL, Silva LM, Dorgam JV, Murashima ADAB, Silva AR, Rossato M, Anselmo-Lima WT. Assessing the maxillary sinus mucosa of rabbits in the presence of biodegradable implants. Braz J Otorhinolaryngol 2013; 78:40-6. [PMID: 23306566 PMCID: PMC9446343 DOI: 10.5935/1808-8694.20120031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 08/23/2012] [Indexed: 11/25/2022] Open
Abstract
In an attempt to improve the quality of life of patients with vitreous humor disease, ophthalmologists began offering steroid-eluting biodegradable implants to their patients. These implants can be used as an alternative treatment for CRS and this is why this experimental study was carried out on rabbit maxillary sinuses. Objective This study aims to assess the histology of the mucosa of the maxillary sinuses of rabbits after the placement of a prednisolone-eluting biodegradable implant. Method Eighteen rabbits were randomly divided into two groups: group 1 - subjects had drug-eluting implants placed on their left maxillary sinuses; group 2 - subjects had non-drug-eluting implants placed on their left maxillary sinuses. The right maxillary sinuses served as the controls. After seven, 14, and 28 days three rabbits in each group were randomly picked to have their tissue inflammatory response assessed. Results Levels of mucosal inflammation were not significantly different between the groups with and without drug-eluting implants and the control group, or when the groups with drug-eluting implants and non-drug-eluting implants were compared. Conclusion Signs of toxicity or mucosal inflammation were not observed in the maxillary sinuses of rabbits given prednisolone-eluting implants or non-drug-eluting implants.
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Affiliation(s)
- André Coura Perez
- Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes no. 3900, Ribeirão Preto - SP, Brazil.
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Fialho SL, Rêgo MB, Siqueira RC, Jorge R, Haddad A, Rodrigues AL, Maia-Filho A, Silva-Cunha A. Safety and Pharmacokinetics of an Intravitreal Biodegradable Implant of Dexamethasone Acetate in Rabbit Eyes. Curr Eye Res 2009; 31:525-34. [PMID: 16769612 DOI: 10.1080/02713680600719036] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The treatment of vitreoretinal diseases is limited and, nowadays, new drug delivery approaches have been reported in order to increase drug bioavailability. The objective of the current study was to determine the pharmacokinetic profile of a biodegradable dexamethasone acetate implant inserted into the vitreous of rabbits and to evaluate its potential signs of toxicity to the rabbits' eyes. The results showed that the intravitreous drug concentration remained within the therapeutic range along the 8-week period of evaluation. The system under study was not toxic to the normal rabbit retina, and no significant increase in intraocular pressure was observed.
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Affiliation(s)
- S L Fialho
- Faculty of Pharmacy, Federal University of Minas Gerais, Belo Horizonte, Brazil
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Pradeep AR, Sagar SV, Daisy H. Clinical and microbiologic effects of subgingivally delivered 0.5% azithromycin in the treatment of chronic periodontitis. J Periodontol 2009; 79:2125-35. [PMID: 18980521 DOI: 10.1902/jop.2008.070589] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND Recent developments suggest that the local delivery of antimicrobials into periodontal pockets can improve periodontal health. The present study was undertaken to investigate the clinical and microbiologic effectiveness of azithromycin (AZM) at 0.5% concentration in an indigenously prepared bioabsorbable controlled-release gel as an adjunct to non-surgical mechanical therapy in the treatment of chronic periodontitis. METHODS Eighty patients were categorized into two treatment groups: scaling and root planing (SRP) only (group 1) and SRP plus 0.5% AZM (group 2). Clinical parameters were recorded at baseline and 1, 2, and 3 months; they included modified gingival index, modified sulcus bleeding index, probing depth (PD), and clinical attachment level (CAL). At baseline and 6 and 12 weeks, microbiologic assessment was done of the percentage of morphologically different microorganisms (coccoid cells, others [straight rods, filaments, and fusiforms], motile rods, and spirochetes) using darkfield microscopy. The mean concentration of 0.5% AZM in gingival crevicular fluid was estimated by reverse phase high performance liquid chromatography. RESULTS Both therapies resulted in significant improvements. Mean PD reduction from baseline to 3 months was 2.13 +/- 0.35 mm and 2.53 +/- 0.52 in groups 1 and 2, respectively. Mean CAL gain from baseline to 3 months was 0.60 +/- 0.63 mm and 1.07 +/- 0.70 mm in groups 1 and 2, respectively. All microbiologic categories showed significant improvement in both groups, with greater improvement in the test group. The mean concentration of AZM at all observed periods (baseline to 28 days) provided sufficient antimicrobial activity (>2 microg/ml) and fulfilled the conditions for a controlled-release device. CONCLUSION Although both treatment strategies seemed to benefit the patients, the adjunctive use of 0.5% AZM as a controlled drug-delivery system enhanced the clinical and microbiologic results as shown by the intergroup comparison.
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Affiliation(s)
- A R Pradeep
- Department of Periodontics, Government Dental College and Research Institute, Fort, Bangalore, Karnataka, India.
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Fialho SL, da Silva Cunha A. Manufacturing Techniques of Biodegradable Implants Intended for Intraocular Application. Drug Deliv 2008; 12:109-16. [PMID: 15824036 DOI: 10.1080/10717540590921432] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Polylactic acid and polylactic-co-glycolic acid are biocompatible and biodegradable polymers with wide utility for the design of controlled release systems for drugs. Regarding intraocular application, polymeric sustained-drug release systems are being studied to treat vitreoretinal diseases. Our work aimed to compare the influence of two implant manufacturing techniques, compression and hot molding, on the in vitro degradation of the polymeric matrices and on the release of dexamethasone acetate. The results showed that the manufacturing technique highly influences degradation and drug release processes. The compressed systems degraded faster and allowed one faster release of the drug.
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Affiliation(s)
- Sílvia Ligório Fialho
- Faculty of Pharmacy, Federal University of Minas Gerais, Avenida Antônio Carlos 6627, CEP 31270-010, Belo Horizonte, Minas Gerais, Brazil.
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Eperon S, Bossy-Nobs L, Petropoulos I, Gurny R, Guex-Crosier Y. A biodegradable drug delivery system for the treatment of postoperative inflammation. Int J Pharm 2008; 352:240-7. [DOI: 10.1016/j.ijpharm.2007.10.054] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2007] [Revised: 10/30/2007] [Accepted: 10/31/2007] [Indexed: 10/22/2022]
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Bourges JL, Touchard E, Kowalczuk L, Berdugo M, Thomas-Doyle A, Bochot A, Gomez A, Azan F, Gurny R, Behar-Cohen F. Dispositifs de délivrance de principes actifs pour des applications ophtalmologiques. J Fr Ophtalmol 2007; 30:1070-88. [DOI: 10.1016/s0181-5512(07)79290-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Booth BA, Vidal Denham L, Bouhanik S, Jacob JT, Hill JM. Sustained-release ophthalmic drug delivery systems for treatment of macular disorders: present and future applications. Drugs Aging 2007; 24:581-602. [PMID: 17658909 DOI: 10.2165/00002512-200724070-00006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Macular disease currently poses the greatest threat to vision in aging populations. Historically, most of this pathology could only be dealt with surgically, and then only after much damage to the macula had already occurred. Current pathophysiological insights into macular diseases have allowed the development of effective new pharmacotherapies. The field of drug delivery systems has advanced over the last several years with emphasis placed on controlled release of drug to specific areas of the eye. Its unique location and tendency toward chronic disease make the macula an important and attractive target for drug delivery systems, especially sustained-release systems. This review evaluates the current literature on the research and development of sustained-release posterior segment drug delivery systems that are primarily intended for macular disease with an emphasis on age-related macular degeneration.Current effective therapies include corticosteroids and anti-vascular endothelial growth factor compounds. Recent successes have been reported using anti-angiogenic drugs for therapy of age-related macular degeneration. This review also includes information on implantable devices (biodegradable and non-biodegradable), the use of injected particles (microspheres and liposomes) and future enhanced drug delivery systems, such as ultrasound drug delivery. The devices reviewed show significant drug release over a period of days or weeks. However, macular disorders are chronic diseases requiring years of treatment. Currently, there is no 'gold standard' for therapy and/or drug delivery. Future studies will focus on improving the efficiency and effectiveness of drug delivery to the posterior chamber. If successful, therapeutic modalities will significantly delay loss of vision and improve the quality of life for patients with chronic macular disorders.
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Affiliation(s)
- Blake A Booth
- Department of Ophthalmology, LSU Health Sciences Center, New Orleans, Louisiana, USA
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Abstract
Research into treatment modalities affecting vision is rapidly progressing due to the high incidence of diseases such as diabetic macular edema, proliferative vitreoretinopathy, wet and dry age-related macular degeneration and cytomegalovirus retinitis. The unique anatomy and physiology of eye offers many challenges to developing effective retinal drug delivery systems. Historically, drugs have been administered to the eye as liquid drops instilled in the cul-de-sac. However retinal drug delivery is a challenging area. The transport of molecules between the vitreous/retina and systemic circulation is restricted by the blood-retinal barrier, which is made up of retinal pigment epithelium and endothelial cells of the retinal blood vessels. An increase in the understanding of drug absorption mechanisms into the retina from local and systemic administration has led to the development of various drug delivery systems, such as biodegradable and non-biodegradable implants, microspheres, nanoparticles and liposomes, gels and transporter-targeted prodrugs. Such diversity in approaches is an indication that there is still a need for an optimized noninvasive or minimally invasive drug delivery system to the eye. A number of large molecular weight compounds (i.e., oligonucleotides, RNA aptamers, peptides and monoclonal antibodies) have been and continue to be introduced as new therapeutic entities. However, for high molecular weight polar compounds the mechanism of epithelial transport is primarily through the tight junctions in the retinal pigment epithelium, as these agents undergo limited transcellular diffusion. Delivery and administration of these new drugs in a safe and effective manner is still a major challenge facing pharmaceutical scientists. In this review article, the authors discuss various drug delivery strategies, devices and challenges associated with drug delivery to the retina.
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Affiliation(s)
- Kumar G Janoria
- University of Missouri-Kansas City, Department of Pharmaceutical Sciences, School of Pharmacy, 5005 Rockhill Road, Kansas City, MO 64110, USA
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Ramaiah S, Kumar TMP, Ravi V. Studies on Biopolymers for Ophthalmic Drug Delivery. JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY 2007. [DOI: 10.1080/10601320601031416] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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12
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Fialho S, Siqueira R, Jorge R, Silva-Cunha A. Biodegradable implants for ocular delivery of anti-inflammatory drug. J Drug Deliv Sci Technol 2007. [DOI: 10.1016/s1773-2247(07)50013-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Bourges JL, Bloquel C, Thomas A, Froussart F, Bochot A, Azan F, Gurny R, BenEzra D, Behar-Cohen F. Intraocular implants for extended drug delivery: therapeutic applications. Adv Drug Deliv Rev 2006; 58:1182-202. [PMID: 17107737 DOI: 10.1016/j.addr.2006.07.026] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Accepted: 07/31/2006] [Indexed: 12/16/2022]
Abstract
An overview of ocular implants with therapeutic application potentials is provided. Various types of implants can be used as slow release devices delivering locally the needed drug for an extended period of time. Thus, multiple periocular or intraocular injections of the drug can be circumvented and secondary complications minimized. The various compositions of polymers fulfilling specific delivery goals are described. Several of these implants are undergoing clinical trials while a few are already commercialized. Despite the paramount progress in design, safety and efficacy, the place of these implants in our clinical therapeutic arsenal remains limited. Miniaturization of the implants allowing for their direct injection without the need for a complicated surgery is a necessary development avenue. Particulate systems which can be engineered to target specifically certain cells or tissues are another promising alternative. For ocular diseases affecting the choroid and outer retina, transscleral or intrasscleral implants are gaining momentum.
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Affiliation(s)
- J L Bourges
- INSERM, U598, Physiopathology of Ocular Diseases, Therapeutic Innovations, 15 Rue de l'Ecole de Médecine 75006 Paris, France
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Abstract
Developing an intraocular drug delivery system (DDS) is urgently needed because most vitreoretinal diseases are refractory to conventional pharmacological approaches; eye drops and systemically administered drugs cannot deliver therapeutic drug concentrations into vitreoretinal tissue. Intraocular DDSs address this problem. Intraocular sustained-drug release via implantable devices or injectable microparticles has been investigated to treat vitreoretinal diseases. A nonbiodegradable implant was first used in 1996 for cytomegalovirus retinitis secondary to the acquired immunodeficiency syndrome. Biodegradable implants, composed of hydrophilic or hydrophobic polymers, in the shape of rods, plugs, discs or sheets have been investigated. An injectable rod is presently being assessed in a Phase III trial to treat macular oedema secondary to diabetic retinopathy or branch-retinal vein occlusion. Intraocular DDSs using a biodegradable implant may soon be successfully used to treat serious intraocular disorders.
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Affiliation(s)
- Tsutomu Yasukawa
- Department of Ophthalmology, Nagoya City University Medical School, Aichi 467-8601, Japan.
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Santoveña A, García JT, Oliva A, Llabrés M, Fariña JB. A mathematical model for interpreting in vitro rhGH release from laminar implants. Int J Pharm 2006; 309:38-43. [PMID: 16376037 DOI: 10.1016/j.ijpharm.2005.10.045] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2005] [Revised: 10/06/2005] [Accepted: 10/26/2005] [Indexed: 11/27/2022]
Abstract
Recombinant human growth hormone (rhGH), used mainly for the treatment of growth hormone deficiency in children, requires daily subcutaneous injections. The use of controlled release formulations with appropriate rhGH release kinetics reduces the frequency of medication, improving patient compliance and quality of life. Biodegradable implants are a valid alternative, offering the feasibility of a regular release rate after administering a single dose, though it exists the slight disadvantage of a very minor surgical operation. Three laminar implant formulations (F(1), F(2) and F(3)) were produced by different manufacture procedures using solvent-casting techniques with the same copoly(D,L-lactic) glycolic acid (PLGA) polymer (Mw=48 kDa). A correlation in vitro between polymer matrix degradation and drug release rate from these formulations was found and a mathematical model was developed to interpret this. This model was applied to each formulation. The obtained results where explained in terms of manufacture parameters with the aim of elucidate whether drug release only occurs by diffusion or erosion, or by a combination of both mechanisms. Controlling the manufacture method and the resultant changes in polymer structure facilitates a suitable rhGH release profile for different rhGH deficiency treatments.
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Affiliation(s)
- A Santoveña
- Departamento de Ingeniería Química y Tecnología Farmacéutica, Facultad de Farmacia, Universidad de La Laguna, 38200 La Laguna, Tenerife, Spain.
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Yasukawa T, Ogura Y, Tabata Y, Kimura H, Wiedemann P, Honda Y. Drug delivery systems for vitreoretinal diseases. Prog Retin Eye Res 2004; 23:253-81. [PMID: 15177203 DOI: 10.1016/j.preteyeres.2004.02.003] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The eye has an environment that is specific unto itself in terms of pharmacokinetics: the inner and outer blood-retinal barriers separate the retina and the vitreous from the systemic circulation and vitreous body, which physiologically has no cellular components, occupies the vitreous cavity, an inner space of the eye, and reduces practical convection of molecules. Considering this, development of a drug delivery system (DDS) is becoming increasingly important in the treatment of vitreoretinal diseases not only to facilitate drug efficacy but also to attenuate adverse effects. The DDS has three major goals: enhances drug permeation (e.g., iontophoresis and transscleral DDS), controls release of drugs (e.g., microspheres, liposomes, and intraocular implants), and targets drugs (e.g., prodrugs with high molecular weight and immunoconjugates). Comprehensive knowledge of these should lead to development of innovative treatment modalities.
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Affiliation(s)
- Tsutomu Yasukawa
- Department of Ophthalmology, Nagoya City University Medical School, Aichi 467-8601, Japan.
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Shinohara K, Tanaka M, Sakuma T, Kobayashi Y. Efficacy of Daunorubicin Encapsulated in Liposome for the Treatment of Proliferative Vitreoretinopathy. Ophthalmic Surg Lasers Imaging Retina 2003. [DOI: 10.3928/1542-8877-20030701-05] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
The main aim of pharmacotherapeutics is the attainment of an effective drug concentration at the intended site of action for a sufficient period of time to elicit the response. A major problem being faced in ocular therapeutics is the attainment of an optimal concentration at the site of action. Poor bioavailability of drugs from ocular dosage forms is mainly due to the tear production, non-productive absorption, transient residence time, and impermeability of corneal epithelium. This article reviews: (1) the barriers that decrease the bioavailability of an ophthalmic drug; (2) the objectives to be considered in producing optimal formulations; and (3) the approaches being used to improve the corneal penetration of a drug molecule and delay its elimination from the eye. The focus of this review is on the recent developments in topical ocular drug delivery systems, the rationale for their use, their drug release mechanism, and the characteristic advantages and limitations of each system. In addition, the review attempts to give various analytical procedures including the animal models and other models required for bioavailability and pharmacokinetic studies. The latter can aid in the design and predictive evaluation of newer delivery systems. The dosage forms are divided into the ones which affect the precorneal parameters, and those that provide a controlled and continuous delivery to the pre- and intraocular tissues. The systems discussed include: (a) the commonly used dosage forms such as gels, viscosity imparting agents, ointments, and aqueous suspensions; (b) the newer concept of penetration enhancers, phase transition systems, use of cyclodextrins to increase solubility of various drugs, vesicular systems, and chemical delivery systems such as the prodrugs; (c) the developed and under-development controlled/continuous drug delivery systems including ocular inserts, collagen shields, ocular films, disposable contact lenses, and other new ophthalmic drug delivery systems; and (d) the newer trends directed towards a combination of drug delivery technologies for improving the therapeutic response of a non-efficacious drug. The fruitful resolution of the above-mentioned technological suggestions can result in a superior dosage form for both topical and intraocular ophthalmic application.
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Affiliation(s)
- Indu Pal Kaur
- University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh 160 014, India
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19
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Mannerström M, Zorn-Kruppa M, Diehl H, Engelke M, Toimela T, Mäenpää H, Huhtala A, Uusitalo H, Salminen L, Pappas P, Marselos M, Mäntylä M, Mäntylä E, Tähti H. Evaluation of the cytotoxicity of selected systemic and intravitreally dosed drugs in the cultures of human retinal pigment epithelial cell line and of pig primary retinal pigment epithelial cells. Toxicol In Vitro 2002; 16:193-200. [PMID: 11869882 DOI: 10.1016/s0887-2333(01)00113-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The cytotoxicity of the selected systemic and intravitreally dosed drugs tamoxifen, toremifene, chloroquine, 5-fluorouracil, gentamicin and ganciclovir was studied in retinal pigment epithelium (RPE) in vitro. The cytotoxicity was assayed in the human RPE cell line D407 and the pig RPE cell culture using the WST-1 test, which is an assay of cell proliferation and viability. The effects of experimental conditions on the WST-1 test (cell density, serum content in the culture medium, the exposure time) were evaluated. The EC50 values in tamoxifen-treated D407 cells ranged between 6.7 and 8.9 micromol/l, and in pig RPE cells between 10.1 and 12.2 micromol/l, depending on the cell density used. The corresponding values for toremifene were 7.4 to 11.1 micromol/l in D407 cells and 10.0 to 11.6 micromol/l in pig RPE cells. In chloroquine-treated cells, the EC50 values were 110.0 micromol/l for D407 cells and 58.4 micromol/l for pig RPE cells. Gentamicin and ganciclovir did not show any toxicity in micromolar concentrations. The exposure time was a significant factor, especially when the drug did not induce cell death, but was antiproliferative (5-fluorouracil). Serum protected the cells from the toxic effects of the drugs. Both cell cultures were most sensitive to tamoxifen and toremifene, and next to chloroquine. The drug toxicities obtained in the present study were quite similar in both cell types; that is, the pig RPE cells and the human D 407 cell line, despite the differences in, for example, the growth rate and melanin contents of the cell types. Owing to the homeostatic functions important for the whole neuroretina, RPE is an interesting in vitro model for the evaluation of retinal toxicity, but, in addition to the WST-1 test, more specific tests and markers based on the homeostatic functions of the RPE are needed.
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Affiliation(s)
- M Mannerström
- Medical School, University of Tampere, Tampere, Finland
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Yasukawa T, Kimura H, Tabata Y, Ogura Y. Biodegradable scleral plugs for vitreoretinal drug delivery. Adv Drug Deliv Rev 2001; 52:25-36. [PMID: 11672873 DOI: 10.1016/s0169-409x(01)00192-2] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Intraocular controlled drug release is one way to facilitate drug efficacy and decrease side effects that occur with systemic administration. Vitreoretinal drug delivery with the biodegradable scleral plug has been investigated. The scleral plug, which is made of biodegradable polymers and drugs, can be implanted at the pars plana using a simple procedure, and it gradually releases effective doses of drugs with polymer biodegradation for several months. The release profiles of the drugs were dependent on the kind of polymers used, their molecular weights, and the amount of drug in the plug. The plugs are effective for treating vitreoretinal diseases such as proliferative vitreoretinopathy. The implantation site was replaced with connective tissue. Electroretinography and histologic studies revealed little retinal toxicity. This implantable scleral plug was supposed to be advantageous for diseases such as cytomegalovirus retinitis that respond to repeated intravitreal injections and for vitreoretinal disorders that require vitrectomy.
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Affiliation(s)
- T Yasukawa
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, 606-8507, Kyoto, Japan.
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Affiliation(s)
- Y Ogura
- Department of Ophthalmology and Visual Science, Nagoya City University Medical School, Kawasumi, Mizuho-ku, 467-8601, Nagoya, Japan.
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22
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Kawakami S, Yamamura K, Mukai T, Nishida K, Nakamura J, Sakaeda T, Nakashima M, Sasaki H. Sustained ocular delivery of tilisolol to rabbits after topical administration or intravitreal injection of lipophilic prodrug incorporated in liposomes. J Pharm Pharmacol 2001; 53:1157-61. [PMID: 11518027 DOI: 10.1211/0022357011776423] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
To improve the retention time of tilisolol in the precorneal area or vitreous body, we prepared liposomes incorporating the O-palmitoyl prodrug of tilisolol. O-Palmitoyl tilisolol was completely incorporated in the liposomes. After topical administration of O-palmitoyl tilisolol liposomes to the rabbit eye, O-palmitoyl tilisolol rapidly disappeared from the tear fluid. The inclusion of 2% carmellose sodium slightly prolonged the retention of O-palmitoyl tilisolol in the tear fluid. After intravitreal injection of O-palmitoyl tilisolol liposomes, there was a relatively prolonged retention of O-palmitoyl tilisolol in the vitreous body. At 24 and 48 h after intravitreal injection of O-palmitoyl tilisolol liposomes, the tilisolol concentration in the vitreous body was significantly higher compared with the concentration after intravitreal injection of tilisolol liposomes.
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Affiliation(s)
- S Kawakami
- School of Pharmaceutical Sciences, Nagasaki University, Japan.
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Kunou N, Ogura Y, Honda Y, Hyon SH, Ikada Y. Biodegradable scleral implant for controlled intraocular delivery of betamethasone phosphate. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 2000; 51:635-41. [PMID: 10880111 DOI: 10.1002/1097-4636(20000915)51:4<635::aid-jbm11>3.0.co;2-o] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We evaluated nail-like, biodegradable scleral implants as a controlled intraocular delivery system of betamethasone phosphate (BP) for the treatment of chronic uveitis using pigmented rabbits. The scleral implants, which contained 10% and 25% of BP (weight 8.5 mg; length 5 mm), were made of poly (D,L-lactide-co-glycolide) (PLGA). In vivo release and retinal toxicity after implantation were also studied in pigmented rabbits. The in vitro release studies demonstrated the 10% and 25% BP-loaded scleral implants released BP in a biphasic release pattern for at least 1 month. The BP concentrations in the vitreous and the retina/choroid after application of scleral implants in pigmented rabbit eyes stayed within the concentration range capable of suppressing inflammatory responses for over 1 month. The BP concentration was greater in the retina/choroid than in the vitreous throughout the study. No substantial toxic reactions in the retina were observed by electroretinography. Our findings suggest that the BP-loaded scleral implant may be a promising device for treatment of chronic uveitis.
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Affiliation(s)
- N Kunou
- Department of Ophthalmology, Nagoya City University Medical School, Mizuho-ku, Nagoya 467-0001, Japan.
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Einmahl S, Behar-Cohen F, Tabatabay C, Savoldelli M, D'Hermies F, Chauvaud D, Heller J, Gurny R. A viscous bioerodible poly(ortho ester) as a new biomaterial for intraocular application. JOURNAL OF BIOMEDICAL MATERIALS RESEARCH 2000; 50:566-73. [PMID: 10756315 DOI: 10.1002/(sici)1097-4636(20000615)50:4<566::aid-jbm12>3.0.co;2-m] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The biocompatibility of a viscous, hydrophobic, bioerodible poly(ortho ester) (POE) intended for intraocular application was investigated. POE was evaluated as a blank carrier and as containing modulators of degradation. Each formulation was injected intracamerally and intravitreally in rabbit eyes, and clinical and histological examinations were performed postoperatively for 2 weeks. In the case of intracameral injections, polymer biocompatibility appeared to depend on the amount injected in the anterior chamber. When 50 microL was administered, the polymer degraded within 2 weeks, and clinical observations showed good biocompatibility of POE with no toxicity to the ocular tissues or increase in intraocular pressure. The injection of a larger volume, 100 microL, of POE, appeared inappropriate because of direct contact of polymeric material with the corneal endothelium, and triggered reversible edema and inflammation in the anterior chamber of the eye that regressed after a few days. After intravitreal administration, POE was well tolerated and no inflammatory reaction developed during the observation period. The polymer degraded slowly, appearing as a round whitish bubble in the vitreous cavity. The presence of modulators of degradation both improved POE biocompatibility and prolonged polymer lifetime in the eye. POE appears to be a promising biomaterial for clinical intraocular application.
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Affiliation(s)
- S Einmahl
- Department of Pharmaceutical Technology and Biopharmaceutics, School of Pharmacy, University of Geneva, 1211 Geneva 4, Switzerland
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Colthurst MJ, Williams RL, Hiscott PS, Grierson I. Biomaterials used in the posterior segment of the eye. Biomaterials 2000; 21:649-65. [PMID: 10711963 DOI: 10.1016/s0142-9612(99)00220-3] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The treatment of posterior segment eye disease and related conditions has improved greatly in recent years with the advent of new therapies, materials and devices. Vitreoretinal conditions, however, remain significant causes of blindness in the developed world. Biomaterials play a major role in the treatment of many of these disorders and the success rate of vitreoretinal surgery, especially in the repair of retinal detachment and related conditions, would increase with the introduction of new and improved materials. This review, which focuses on disorders that feature retinal detachment, briefly describes the anatomy of the eye and the nature and treatment of posterior segment eye disorders. The roles, required properties and suitability of the materials used in vitreoretinal surgery as scleral buckles, tamponade agents or drug delivery devices, are reviewed. Experimental approaches are discussed, along with the methods used for their evaluation, and future directions for biomaterial research in the posterior segment of the eye are considered.
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Affiliation(s)
- M J Colthurst
- Department of Medicine, University of Liverpool, UK.
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Abstract
Proliferative vitreoretinopathy (PVR) is one of the major causes of failure in retinal detachment surgery. To prevent PVR, it is necessary to determine factors predisposing its development. In primary PVR, large retinal tears, long duration of retinal detachment, vitreous hemorrhages, aphakia and choroidal detachment were demonstrated as clinical risk factors for PVR. In postoperative PVR, it was revealed that large breaks, pre- and postoperative choroidal detachment, minor intra- or postoperative hemorrhages, signs of uveitis, extensive retinal detachment, vitrectomy, cryopexy, air injection and preoperative PVR were risk factors for PVR by multivariate analysis. Almost all risk factors for PVR are associated with intravitreal dispersion of retinal pigment epithelial (RPE) cells or breakdown of the blood-ocular barrier which are prerequisite to development of PVR.
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Affiliation(s)
- H Nagasaki
- Department of Ophthalmology, Kurume University School of Medicine, Japan
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Merkli A, Tabatabay C, Gurny R, Heller J. Biodegradable polymers for the controlled release of ocular drugs. Prog Polym Sci 1998. [DOI: 10.1016/s0079-6700(97)00048-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
This paper provides a comprehensive overview of the various approaches currently used in the development of ocular drug delivery systems for the treatment of ocular diseases in animals. It is obvious from the literature that most of the products that are currently available are derived from human medicine without consideration given to the differences which exist between the anatomy and physiology of the eye of various animal species which ultimately affect product design and performance. As a result, many of the products for animal use seem in many circumstances inappropriate for animal care. The article deals with some aspects of eye anatomy and physiology of different animals, and then provides an overview of the most commonly encountered pathologies. The paper then discusses the currently available drug products and finally reviews new delivery concepts. Several hundred references are included in the paper and provide access to further information on the subject.
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Hashizoe M, Ogura Y, Takanashi T, Kunou N, Honda Y, Ikada Y. Biodegradable polymeric device for sustained intravitreal release of ganciclovir in rabbits. Curr Eye Res 1997; 16:633-9. [PMID: 9222079 DOI: 10.1076/ceyr.16.7.633.5063] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
PURPOSE A scleral plug made of biodegradable polymer implanted at the pars plana was evaluated to determine its ability to control the intravitreal release of ganciclovir. METHODS Scleral plugs containing 25% ganciclovir were prepared with poly(lactic-glycolic acid) (molecular weight, 121 kDa). The release of ganciclovir was evaluated in vitro by spectrophotometry. In vivo intravitreal ganciclovir concentrations were measured by high performance liquid chromatography following plug implantation in pigmented rabbits. The biocompatibility of the device was determined by indirect ophthalmoscopy, electroretinography, and light and electron microscopy. RESULTS The in vitro study showed that the plug released ganciclovir throughout a 10-week period. The in vivo study demonstrated that the plugs maintained the drug concentration in the vitreous in a therapeutic range adequate to treat cytomegalovirus (CMV) retinitis for 12 weeks. No significant retinal toxicity was observed. CONCLUSIONS This study demonstrated that this drug delivery system can potentially be useful to treat CMV retinitis.
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Affiliation(s)
- M Hashizoe
- Department of Ophthalmology and Visual Science, Faculty of Medicine, Kyoto University, Japan
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Schlingemann RO, van Hinsbergh VW. Role of vascular permeability factor/vascular endothelial growth factor in eye disease. Br J Ophthalmol 1997; 81:501-12. [PMID: 9274417 PMCID: PMC1722234 DOI: 10.1136/bjo.81.6.501] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- R O Schlingemann
- Department of Clinical Ophthalmology, Moorfields Eye Hospital, London
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32
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Controlled intraocular delivery of ganciclovir with use of biodegradable scleral implant in rabbits. J Control Release 1995. [DOI: 10.1016/0168-3659(95)00074-i] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Charteris DG. Proliferative vitreoretinopathy: pathobiology, surgical management, and adjunctive treatment. Br J Ophthalmol 1995; 79:953-60. [PMID: 7488586 PMCID: PMC505299 DOI: 10.1136/bjo.79.10.953] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Hashizoe M, Ogura Y, Takanashi T, Kunou N, Honda Y, Ikada Y. Implantable biodegradable polymeric device in the treatment of experimental proliferative vitreoretinopathy. Curr Eye Res 1995; 14:473-7. [PMID: 7671629 DOI: 10.3109/02713689509003758] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We investigated the use of a scleral plug of biodegradable polymer implanted at the pars plana to create a controlled drug-delivery system in the vitreous. We evaluated the efficacy of a plug containing doxorubicin hydrochloride to treat experimental proliferative vitreoretinopathy (PVR) in pigmented rabbits. An implantable device on the sclera, which imitates a scleral plug, containing 1% doxorubicin, was prepared with poly(lactic acid) (molecular weight, 20,000). The release of doxorubicin in phosphate-buffered saline was evaluated by spectro-photometry. After pars plana vitrectomy and plug implantation, concentrations of doxorubicin in the vitreous humor of the rabbits were measured by high performance liquid chromatography. The release profiles were evaluated during 5 weeks in vitro and 4 weeks in vivo. Cultured homologous fibroblasts were injected into the vitreous space to induce experimental PVR after gas compression of the vitreous. The scleral plugs were implanted at the pars plana in treatment animals (n = 11). Control rabbits (n = 11) were followed up without implantation after PVR induction. All eyes of the control group developed tractional retinal detachment at day 28, while the incidence of retinal detachment was decreased to 64% in the treated eyes. (P = 0.002). The implantation of the scleral plug effectively inhibited intravitreous proliferation of fibroblasts. This study demonstrated that the scleral plug of biodegradable polymers may have potential as a treatment modality for PVR.
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Affiliation(s)
- M Hashizoe
- Department of Ophthalmology, Faculty of Medicine, Kyoto University, Japan
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