1
|
Ranch K, Chawnani D, Jani H, Acharya D, Patel CA, Jacob S, Babu RJ, Tiwari AK, Al-Tabakha MM, Boddu SHS. An update on the latest strategies in retinal drug delivery. Expert Opin Drug Deliv 2024; 21:695-712. [PMID: 38787783 DOI: 10.1080/17425247.2024.2358886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 05/20/2024] [Indexed: 05/26/2024]
Abstract
INTRODUCTION Retinal drug delivery has witnessed significant advancements in recent years, mainly driven by the prevalence of retinal diseases and the need for more efficient and patient-friendly treatment strategies. AREAS COVERED Advancements in nanotechnology have introduced novel drug delivery platforms to improve bioavailability and provide controlled/targeted delivery to specific retinal layers. This review highlights various treatment options for retinal diseases. Additionally, diverse strategies aimed at enhancing delivery of small molecules and antibodies to the posterior segment such as implants, polymeric nanoparticles, liposomes, niosomes, microneedles, iontophoresis and mixed micelles were emphasized. A comprehensive overview of the special technologies currently under clinical trials or already in the clinic was provided. EXPERT OPINION Ideally, drug delivery system for treating retinal diseases should be less invasive in nature and exhibit sustained release up to several months. Though topical administration in the form of eye drops offers better patient compliance, its clinical utility is limited by nature of the drug. There is a wide range of delivery platforms available, however, it is not easy to modify any single platform to accommodate all types of drugs. Coordinated efforts between ophthalmologists and drug delivery scientists are necessary while developing therapeutic compounds, right from their inception.
Collapse
Affiliation(s)
- Ketan Ranch
- Department of Pharmaceutics, L. M. College of Pharmacy, Ahmedabad, India
| | - Disha Chawnani
- Department of Pharmaceutics, L. M. College of Pharmacy, Ahmedabad, India
| | - Harshilkumar Jani
- Department of Pharmaceutics, L. M. College of Pharmacy, Ahmedabad, India
| | - Devarshi Acharya
- Department of Pharmaceutics, L. M. College of Pharmacy, Ahmedabad, India
| | - Chirag Amrutlal Patel
- Department of Pharmacology & Pharmacy practices, L. M. College of Pharmacy, Ahmedabad, India
| | - Shery Jacob
- Department of Pharmaceutical Sciences, College of Pharmacy, Gulf Medical University, Ajman, United Arab Emirates UAE
| | - R Jayachandra Babu
- Department of Drug Discovery and Development, Harrison College of Pharmacy, Auburn University, Auburn, AL, USA
| | - Amit K Tiwari
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Moawia M Al-Tabakha
- Center of Medical and Bio-allied Health Sciences Research, Ajman University, Ajman, UAE
| | - Sai H S Boddu
- Center of Medical and Bio-allied Health Sciences Research, Ajman University, Ajman, UAE
| |
Collapse
|
2
|
Guerra MCA, Neto JT, Gomes MG, Dourado LFN, Oréfice RL, Heneine LGD, Silva-Cunha A, Fialho SL. Nanofiber-coated implants: Development and safety after intravitreal application in rabbits. Int J Pharm 2023; 636:122809. [PMID: 36894043 DOI: 10.1016/j.ijpharm.2023.122809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 02/28/2023] [Accepted: 03/04/2023] [Indexed: 03/09/2023]
Abstract
Intravitreal injections are the preferred choice for drug administration to the posterior segment of the eye. However, the required frequent injections may cause complications to the patient and low adherence to the treatment. Intravitreal implants are able to maintain therapeutic levels for a long period. Biodegradable nanofibers can modulate drug release and allow the incorporation of fragile bioactive drugs. Age-related macular degeneration is one of the world major causes of blindness and irreversible vision loss. It involves the interaction between VEGF and inflammatory cells. In this work we developed nanofiber-coated intravitreal implants containing dexamethasone and bevacizumab for simultaneously delivery of these drugs. The implant was successfully prepared and the efficiency of the coating process was confirmed by scanning electron microscopy. Around 68% of dexamethasone was released in 35 days and 88% of bevacizumab in 48hs. The formulation presented activity in the reduction of vessels and was safe to the retina. It was not observed any clinical or histopathological change, neither alteration in retina function or thickness by electroretinogram and optical coherence tomography during 28 days. The nanofiber-coated implants of dexamethasone and bevacizumab may be considered as a new delivery system that can be effective for the treatment of AMD.
Collapse
Affiliation(s)
- Maria Carolina Andrade Guerra
- Federal University of Goias, Rua 240 w/n, CEP 74605-220, Goias, Goiania, Brazil; Pharmaceutical Research and Development, Ezequiel Dias Foundation, Rua Conde Pereira Carneiro 80, Gameleira, CEP 30510-010, Belo Horizonte, Minas Gerais, Brazil.
| | - Julia Teixeira Neto
- Pharmaceutical Research and Development, Ezequiel Dias Foundation, Rua Conde Pereira Carneiro 80, Gameleira, CEP 30510-010, Belo Horizonte, Minas Gerais, Brazil; Faculty of Pharmacy, Federal University of Minas Gerais, Av. Antônio Carlos 6627, Pampulha, CEP 31270-901, Belo Horizonte, Minas Gerais, Brazil.
| | - Michele Gouvea Gomes
- Faculty of Pharmacy, Federal University of Minas Gerais, Av. Antônio Carlos 6627, Pampulha, CEP 31270-901, Belo Horizonte, Minas Gerais, Brazil.
| | - Lays Fernanda Nunes Dourado
- Pharmaceutical Research and Development, Ezequiel Dias Foundation, Rua Conde Pereira Carneiro 80, Gameleira, CEP 30510-010, Belo Horizonte, Minas Gerais, Brazil.
| | - Rodrigo Lambert Oréfice
- School of Engineering, Federal University of Minas Gerais, Av. Antônio Carlos 6627, Pampulha, CEP 31270-901, Belo Horizonte, Minas Gerais, Brazil.
| | - Luiz Guilherme Dias Heneine
- Pharmaceutical Research and Development, Ezequiel Dias Foundation, Rua Conde Pereira Carneiro 80, Gameleira, CEP 30510-010, Belo Horizonte, Minas Gerais, Brazil.
| | - Armando Silva-Cunha
- Faculty of Pharmacy, Federal University of Minas Gerais, Av. Antônio Carlos 6627, Pampulha, CEP 31270-901, Belo Horizonte, Minas Gerais, Brazil.
| | - Silvia Ligorio Fialho
- Pharmaceutical Research and Development, Ezequiel Dias Foundation, Rua Conde Pereira Carneiro 80, Gameleira, CEP 30510-010, Belo Horizonte, Minas Gerais, Brazil.
| |
Collapse
|
3
|
Shastri DH, Silva AC, Almeida H. Ocular Delivery of Therapeutic Proteins: A Review. Pharmaceutics 2023; 15:pharmaceutics15010205. [PMID: 36678834 PMCID: PMC9864358 DOI: 10.3390/pharmaceutics15010205] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 12/25/2022] [Accepted: 01/04/2023] [Indexed: 01/11/2023] Open
Abstract
Therapeutic proteins, including monoclonal antibodies, single chain variable fragment (ScFv), crystallizable fragment (Fc), and fragment antigen binding (Fab), have accounted for one-third of all drugs on the world market. In particular, these medicines have been widely used in ocular therapies in the treatment of various diseases, such as age-related macular degeneration, corneal neovascularization, diabetic retinopathy, and retinal vein occlusion. However, the formulation of these biomacromolecules is challenging due to their high molecular weight, complex structure, instability, short half-life, enzymatic degradation, and immunogenicity, which leads to the failure of therapies. Various efforts have been made to overcome the ocular barriers, providing effective delivery of therapeutic proteins, such as altering the protein structure or including it in new delivery systems. These strategies are not only cost-effective and beneficial to patients but have also been shown to allow for fewer drug side effects. In this review, we discuss several factors that affect the design of formulations and the delivery of therapeutic proteins to ocular tissues, such as the use of injectable micro/nanocarriers, hydrogels, implants, iontophoresis, cell-based therapy, and combination techniques. In addition, other approaches are briefly discussed, related to the structural modification of these proteins, improving their bioavailability in the posterior segments of the eye without affecting their stability. Future research should be conducted toward the development of more effective, stable, noninvasive, and cost-effective formulations for the ocular delivery of therapeutic proteins. In addition, more insights into preclinical to clinical translation are needed.
Collapse
Affiliation(s)
- Divyesh H. Shastri
- Department of Pharmaceutics & Pharmaceutical Technology, K.B. Institute of Pharmaceutical Education and Research, Kadi Sarva Vishwavidyalaya, Sarva Vidyalaya Kelavani Mandal, Gandhinagar 382016, India
- Correspondence:
| | - Ana Catarina Silva
- FP-I3ID (Instituto de Investigação, Inovação e Desenvolvimento), FP-BHS (Biomedical and Health Sciences Research Unit), Faculty of Health Sciences, University Fernando Pessoa, 4249-004 Porto, Portugal
- UCIBIO (Research Unit on Applied Molecular Biosciences), REQUIMTE (Rede de Química e Tecnologia), MEDTECH (Medicines and Healthcare Products), Laboratory of Pharmaceutical Technology, Department of Drug Sciences, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
- Associate Laboratory i4HB-Institute for Health and Bioeconomy, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
| | - Hugo Almeida
- UCIBIO (Research Unit on Applied Molecular Biosciences), REQUIMTE (Rede de Química e Tecnologia), MEDTECH (Medicines and Healthcare Products), Laboratory of Pharmaceutical Technology, Department of Drug Sciences, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
- Associate Laboratory i4HB-Institute for Health and Bioeconomy, Faculty of Pharmacy, University of Porto, 4050-313 Porto, Portugal
- Mesosystem Investigação & Investimentos by Spinpark, Barco, 4805-017 Guimarães, Portugal
| |
Collapse
|
4
|
Vijayakumar A, Pugazhenthan T, Sathish Babu M, Sajitha V. Ophthalmology and Otorhinolaryngology. TOXICOLOGICAL ASPECTS OF MEDICAL DEVICE IMPLANTS 2020:33-66. [DOI: 10.1016/b978-0-12-820728-4.00003-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
|
5
|
Awwad S, Mohamed Ahmed AHA, Sharma G, Heng JS, Khaw PT, Brocchini S, Lockwood A. Principles of pharmacology in the eye. Br J Pharmacol 2017; 174:4205-4223. [PMID: 28865239 PMCID: PMC5715579 DOI: 10.1111/bph.14024] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 08/14/2017] [Accepted: 08/17/2017] [Indexed: 12/18/2022] Open
Abstract
The eye is a highly specialized organ that is subject to a huge range of pathology. Both local and systemic disease may affect different anatomical regions of the eye. The least invasive routes for ocular drug administration are topical (e.g. eye drops) and systemic (e.g. tablets) formulations. Barriers that subserve as protection against pathogen entry also restrict drug permeation. Topically administered drugs often display limited bioavailability due to many physical and biochemical barriers including the pre-corneal tear film, the structure and biophysiological properties of the cornea, the limited volume that can be accommodated by the cul-de-sac, the lacrimal drainage system and reflex tearing. The tissue layers of the cornea and conjunctiva are further key factors that act to restrict drug delivery. Using carriers that enhance viscosity or bind to the ocular surface increases bioavailability. Matching the pH and polarity of drug molecules to the tissue layers allows greater penetration. Drug delivery to the posterior segment is a greater challenge and, currently, the standard route is via intravitreal injection, notwithstanding the risks of endophthalmitis and retinal detachment with frequent injections. Intraocular implants that allow sustained drug release are at different stages of development. Novel exciting therapeutic approaches include methods for promoting transscleral delivery, sustained release devices, nanotechnology and gene therapy.
Collapse
Affiliation(s)
- Sahar Awwad
- UCL School of PharmacyLondonUK
- National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of OphthalmologyLondonUK
| | - Abeer H A Mohamed Ahmed
- UCL School of PharmacyLondonUK
- National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of OphthalmologyLondonUK
| | - Garima Sharma
- UCL School of PharmacyLondonUK
- National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of OphthalmologyLondonUK
| | - Jacob S Heng
- National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of OphthalmologyLondonUK
| | - Peng T Khaw
- National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of OphthalmologyLondonUK
| | - Steve Brocchini
- UCL School of PharmacyLondonUK
- National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of OphthalmologyLondonUK
| | | |
Collapse
|
6
|
Zhang Y, Xuan S, Owoseni O, Omarova M, Li X, Saito ME, He J, McPherson GL, Raghavan SR, Zhang D, John VT. Amphiphilic Polypeptoids Serve as the Connective Glue to Transform Liposomes into Multilamellar Structures with Closely Spaced Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:2780-2789. [PMID: 28248521 DOI: 10.1021/acs.langmuir.6b04190] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report the ability of hydrophobically modified polypeptoids (HMPs), which are amphiphilic pseudopeptidic macromolecules, to connect across lipid bilayers and thus form layered structures on liposomes. The HMPs are obtained by attaching hydrophobic decyl groups at random points along the polypeptoid backbone. Although native polypeptoids (with no hydrophobes) have no effect on liposomal structure, the HMPs remodel the unilamellar liposomes into structures with comparable diameters but with multiple concentric bilayers. The transition from single-bilayer to multiple-bilayer structures is revealed by small-angle neutron scattering (SANS) and cryo-transmission electron microscopy (cryo-TEM). The spacing between bilayers is found to be relatively uniform at ∼6.7 nm. We suggest that the amphiphilic nature of the HMPs explains the formation of multibilayered liposomes; i.e., the HMPs insert their hydrophobic tails into adjacent bilayers and thereby serve as the connective glue between bilayers. At higher HMP concentrations, the liposomes are entirely disrupted into much smaller micellelike structures through extensive hydrophobe insertion. Interestingly, these small structures can reattach to fresh unilamellar liposomes and self-assemble to form new two-bilayer liposomes. The two-bilayer liposomes in our study are reminiscent of two-bilayer organelles such as the nucleus in eukaryotic cells. The observations have significance in designing new nanoscale drug delivery carriers with multiple drugs on separate lipid bilayers and extending liposome circulation times with entirely biocompatible materials.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | - Srinivasa R Raghavan
- Department of Chemical and Biomolecular Engineering, University of Maryland , College Park, Maryland 20742, United States
| | | | | |
Collapse
|
7
|
Kapanigowda UG, Nagaraja SH, Ramaiah B, Boggarapu PR. Improved intraocular bioavailability of ganciclovir by mucoadhesive polymer based ocular microspheres: development and simulation process in Wistar rats. ACTA ACUST UNITED AC 2015; 23:49. [PMID: 26497653 PMCID: PMC4620023 DOI: 10.1186/s40199-015-0132-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 10/12/2015] [Indexed: 11/10/2022]
Abstract
BACKGROUND The poor ocular bioavailability of the conventional eye drops is due to lack of corneal permeability, nasolacrimal drainage and metabolic degradation. To overcome this issue, drug encapsulated in mucoadhesive polymer based ocular microspheres have the advantages of improved drug stability, easy administration in liquid form, diffuse rapidly and better ocular tissue internalization. METHODS The ganciclovir chitosan microspheres (GCM) were prepared by modified water-in-oil emulsification method. The formulation was optimized and characterized by investigating in vitro release study, release kinetics, XRD and microspheres stability. Ocular irritancy, in vivo ocular pharmacokinetic parameters and histopathology study was evaluated in Wistar rats. The use of pharmacokinetic/pharmacodynamic indices and simulation process was carried out to further ensure clinical applicability of the formulation. RESULTS The in vitro release study showed initial burst (nearly 50 %) in first few minutes and followed Fickian (R(2) = 0.9234, n-value = 0.2329) type of diffusion release mechanism. The XRD and stability studies showed favorable results. The Wistar rat eyes treated with GCM showed significant increase in ganciclovir AUC (~4.99-fold) and Cmax (2.69-fold) in aqueous humor compared to ganciclovir solution and delay in Tmax. The Cmax/MIC90, AUC0-24/MIC90, AUC above MIC90 and T above MIC90 were significantly higher in GCM group. The aqueous humor concentration-time profile of ganciclovir in GCM and ganciclovir solution was simulated with every 28.1 and 12.8 h, respectively. The simulated concentration-time profile shows that in duration of 75 h, the ganciclovir solution require six ocular instillations compared to three ocular instillations of the GCM formulation. The photomicrograph of GCM and ganciclovir solution treated rat retina showed normal organization and cytoarchitecture. CONCLUSIONS Correlating with in vitro data, the formulation showed sustained drug release along with improved intraocular bioavailability of ganciclovir in Wistar rats.
Collapse
Affiliation(s)
- Usha Ganganahalli Kapanigowda
- Department of Pharmaceutical Technology, Karnataka College of Pharmacy, #33/2, Tirumenahalli, Hegde Nagar Main Road, Bengaluru, 560064, , Karnataka, India
| | - Sree Harsha Nagaraja
- Department of Pharmaceutical Sciences, College of Clinical Pharmacy, King Faisal University, Al-Ahsa, 31982, Saudi Arabia
| | - Balakeshwa Ramaiah
- Department of Pharmaceutics, Karnataka College of Pharmacy, #33/2, Tirumenahalli, Hegde Nagar Main Road, Bengaluru, 560064, , Karnataka, India.
| | - Prakash Rao Boggarapu
- Department of Pharmaceutical Technology, Karnataka College of Pharmacy, #33/2, Tirumenahalli, Hegde Nagar Main Road, Bengaluru, 560064, , Karnataka, India
| |
Collapse
|
8
|
Arora JS, Ponnusamy T, Zheng R, Venkataraman P, Raghavan SR, Blake D, John VT. Spatially directed vesicle capture in the ordered pores of breath-figure polymer films. SOFT MATTER 2015; 11:5188-5191. [PMID: 26021456 DOI: 10.1039/c5sm01068c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This work describes a new method to selectively capture liposomes and other vesicle entities in the patterned pores of breath-figure polymer films. The process involves the deposition of a hydrophobe containing biopolymer in the pores of the breath figure, and the tethering of vesicles to the biopolymer through hydrophobic interactions. The process is versatile, can be scaled up and extended to the deposition of other functional materials in the pores of breath figures.
Collapse
Affiliation(s)
- J S Arora
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA 70118, USA.
| | | | | | | | | | | | | |
Collapse
|
9
|
Lin J, Wu H, Wang Y, Lin J, Chen Q, Zhu X. Preparation and ocular pharmacokinetics of hyaluronan acid-modified mucoadhesive liposomes. Drug Deliv 2014; 23:1144-51. [PMID: 25533876 DOI: 10.3109/10717544.2014.991952] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The aim of this research was to formulate a liposomal preparation of DOX to be applied topically, and to investigate the in vitro and in vivo performance of the prepared liposomes. DOX liposomes were prepared by the solvent evaporation method, and then modified with bioadhesive material HA. Through MTT assay, we found that the safe concentration of liposomes delivered would hit 1 mg/mL. Cellular uptake studies showed that DOX liposomes coated with HA are much more targetable to cell nucleus. Their ocular pharmacokinetics in rabbits were investigated through the comparison with those obtained after dosing with non-modified liposomes and DOX solution. The in vitro transcorneal permeability of DOX in both kinds of liposomes was found to be slower than that of the solution because of sustained release. After in vivo instillation in rabbits, HA-modified liposomes had the longest retention time, following with naked liposomes. Significantly, the area under the curve of the aqueous humor concentration-time profiles of DOX liposomes was found to be 1.7-fold higher than that of DOX solution. The confocal experiment confirmed that HA-modified liposomes were able to maintain a higher DOX concentration and residence time than that of non-modified liposomes and free DOX. These results suggest that our liposomal preparation was of great help to improve the bioavailability of DOX.
Collapse
Affiliation(s)
- Jing Lin
- a Department of Pharmaceutics, School of Pharmaceutical Science , Xiamen University , Xiamen , Fujian , China
| | - Hongjie Wu
- a Department of Pharmaceutics, School of Pharmaceutical Science , Xiamen University , Xiamen , Fujian , China
| | - Yingjun Wang
- a Department of Pharmaceutics, School of Pharmaceutical Science , Xiamen University , Xiamen , Fujian , China
| | - Jianhong Lin
- a Department of Pharmaceutics, School of Pharmaceutical Science , Xiamen University , Xiamen , Fujian , China
| | - Qing Chen
- a Department of Pharmaceutics, School of Pharmaceutical Science , Xiamen University , Xiamen , Fujian , China
| | - Xuan Zhu
- a Department of Pharmaceutics, School of Pharmaceutical Science , Xiamen University , Xiamen , Fujian , China
| |
Collapse
|
10
|
Pinto FCH, Da Silva-Cunha Junior A, Oréfice RL, Ayres E, Andrade SP, Lima LDC, Moura SAL, Da Silva GR. Controlled release of triamcinolone acetonide from polyurethane implantable devices: application for inhibition of inflammatory-angiogenesis. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2012; 23:1431-1445. [PMID: 22466817 DOI: 10.1007/s10856-012-4615-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 03/08/2012] [Indexed: 05/31/2023]
Abstract
The purpose of this study was to develop triamcinolone acetonide-loaded polyurethane implants (TA PU implants) for the local treatment of different pathologies including arthritis, ocular and neuroinflammatory disorders. The TA PU implants were characterized by FTIR, SAXS and WAXS. The in vitro and in vivo release of TA from the PU implants was evaluated. The efficacy of TA PU implants in suppressing inflammatory-angiogenesis in a murine sponge model was demonstrated. FTIR results revealed no chemical interactions between polymer and drug. SAXS results indicated that the incorporation of the drug did not disturb the polymer morphology. WAXS showed that the crystalline nature of the TA was preserved after incorporation into the PU. The TA released from the PU implants efficiently inhibited the inflammatory-angiogenesis induced by sponge discs in an experimental animal model. Finally, TA PU implants could be used as local drug delivery systems because of their controlled delivery of TA.
Collapse
Affiliation(s)
- Flávia Carmo Horta Pinto
- School of Pharmacy, Federal University of São João Del Rei, Chanadour, Divinópolis, Minas Gerais, Brazil
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Oliveira RC, Messias A, Siqueira RC, Bonini-Filho MA, Haddad A, Damico FM, Maia-Filho A, Crispim PTB, Saliba JB, Ribeiro JAS, Scott IU, Cunha-Jr AS, Jorge R. Vitreous Pharmacokinetics and Retinal Safety of Intravitreal Preserved Versus Non-preserved Triamcinolone Acetonide in Rabbit Eyes. Curr Eye Res 2011; 37:55-61. [DOI: 10.3109/02713683.2011.593722] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
12
|
|
13
|
Herrero EP, Valle EMMD, Galán MA. Understanding the Glycoproteins Release from Alginate-Barium Capsules in Physiologic Enviroments. ACTA ACUST UNITED AC 2011. [DOI: 10.4236/aces.2011.14037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
14
|
Silva GRD, Fialho SL, Siqueira RC, Jorge R, Cunha Júnior ADS. Implants as drug delivery devices for the treatment of eye diseases. BRAZ J PHARM SCI 2010. [DOI: 10.1590/s1984-82502010000300024] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The treatment of diseases affecting the posterior segment of the eye is limited by the difficulty in transporting effective doses of drugs to the vitreous, retina, and choroid. Topically applied drugs are poorly absorbed due to the low permeability of the external ocular tissues and tearing. The blood-retina barrier limits drug diffusion from the systemic blood to the posterior segment, thus high doses of drug are needed to maintain therapeutic levels. In addition, systemic side effects are common. Intraocular injections could be an alternative, but the fast flowing blood supply in this region, associated with rapid clearance rates, causes drug concentration to quickly fall below therapeutic levels. To obtain therapeutic levels over longer time periods, polymeric sustained-drug release systems implanted within the vitreous are being studied for the treatment of vitreoretinal disorders. These systems are prepared using different kinds of biodegradable or non-biodegradable polymers. This review aims to demonstrate the main characteristics of these drug delivery implants and their potential for clinical application.
Collapse
|
15
|
Bertram JP, Rauch MF, Chang K, Lavik EB. Using polymer chemistry to modulate the delivery of neurotrophic factors from degradable microspheres: delivery of BDNF. Pharm Res 2009; 27:82-91. [PMID: 19921405 DOI: 10.1007/s11095-009-0009-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Accepted: 11/02/2009] [Indexed: 12/22/2022]
Abstract
PURPOSE Brain-derived neurotrophic factor (BDNF) plays an important role in neuroprotection and repair, but long-term delivery from polymer systems has been challenging. We investigated the role the chemistry of the polymer played in loading and delivery of BDNF via microspheres, which are suitable for minimally invasive administration. METHODS We synthesized polymers based on PLGA and PEG to determine what components augmented loading and delivery. We characterized microspheres fabricated from these polymers using a battery of tests, including sizing, in vitro release, and bioactivity of the BDNF using PC12 cells engineered to express the trkB receptor. RESULTS We found that a triblock polymer of PLGA, PLL, and PEG led to the delivery of BDNF for periods of time greater than 60 days and that the BDNF delivered was bioactive. The microsphere size was amendable to injection via a 30 gauge needle, allowing minimally invasive delivery. CONCLUSIONS PLGA-PLL-PEG leads to greater loading and longer-term delivery of BDNF than PLGA or a blend of the polymers. We hypothesize that the introduction of an amphiphilic PLGA-based polymer increases the interaction of the BDNF with the polymer and leads to release that more closely correlates with the degradation of the polymer.
Collapse
Affiliation(s)
- James P Bertram
- Department of Biomedical Engineering, Yale University, 55 Prospect Street, Malone Engineering Center, New Haven, Connecticut 06520, USA
| | | | | | | |
Collapse
|
16
|
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.
Collapse
Affiliation(s)
- S L Fialho
- Faculty of Pharmacy, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | | | | | | | | | | | | | | |
Collapse
|
17
|
Hacker MC, Haesslein A, Ueda H, Foster WJ, Garcia CA, Ammon DM, Borazjani RN, Kunzler JF, Salamone JC, Mikos AG. Biodegradable fumarate-based drug-delivery systems for ophthalmic applications. J Biomed Mater Res A 2009; 88:976-89. [DOI: 10.1002/jbm.a.31942] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
18
|
Claro C, Ruiz R, Cordero E, Pastor MT, López-Cortés LF, Jiménez-Castellanos MR, Lucero MJ. Determination and pharmacokinetic profile of liposomal foscarnet in rabbit ocular tissues after intravitreal administration. Exp Eye Res 2009; 88:528-34. [DOI: 10.1016/j.exer.2008.11.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Revised: 11/07/2008] [Accepted: 11/10/2008] [Indexed: 10/21/2022]
|
19
|
Mello-Filho PAA, Guven D, Beeley NRF, de Juan E, Erickson SR. Helical Intravitreal Triamcinolone Acetonide Implant: A 6-Month Surgical Feasibility Study in Rabbits. Ophthalmic Surg Lasers Imaging Retina 2009; 40:160-8. [DOI: 10.3928/15428877-20090301-17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
20
|
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.
Collapse
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.
| | | |
Collapse
|
21
|
Howard-Sparks M, Al-Ghananeem AM, Crooks PA, Pearson AP. A Novel Chemical Delivery System Comprising an Ocular Sustained Release Formulation of a 3α, 17α, 21-trihydroxy-5β-pregnan-20-one-BIS-5-Flourouracil Codrug. Drug Dev Ind Pharm 2008; 33:677-82. [PMID: 17613031 DOI: 10.1080/03639040601134108] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Directly compressed sustained release pellets were prepared from material consisting of a molecule of 3alpha, 17alpha, 21-trihydroxy-5beta-pregnan-20-one (trihydroxy steroid, THS) covalently linked via carbonate moieties to two molecules of 5-flourouracil (5FU) to form a novel THS-BIS-5FU codrug for the treatment of angiogenesis. Dissolution and drug release was tested in vitro in 0.1M phosphate buffer (pH 7.4), human serum, and vitreous humor. The results suggest that neat THS-BIS-5FU codrug pellets are useful for sustained release ocular delivery of the parent compounds, and that the unique physicochemical properties of the codrug allow slow dissolution and rapid release of the two parent drugs. This codrug formulation is regarded as a "chemical delivery" system that involves dissolution of the codrug as the rate-limiting step followed by rapid hydrolysis of the carbonate ester linkages to release the parent drugs via sustained delivery.
Collapse
Affiliation(s)
- Michelle Howard-Sparks
- College of Pharmacy, Chandler Medical Center, University of Kentucky, Lexington, Kentucky 40536-0082, USA
| | | | | | | |
Collapse
|
22
|
Abstract
PURPOSE The use of biopolymers in peribulbar injection for controlled drug delivery provides alternative options to eyedrops and intravitreal or surgical methods. Polymerizable biopolymers are especially likely to have a role because of their particular properties. In liquid form, they can be easily injected into the target site and, after polymerization, they provide a prolonged and controlled release of the drug. This study was undertaken to demonstrate the suitability of a thermopolymerizable biopolymer poloxamer (Lutrol F127) for peribulbar injections and controlled drug release. METHODS The toxicity of injected poloxamer compounds was evaluated by visual inspection and histological and immunohistochemical tissue evaluation. The release of marker substances such as 5(6)-carboxyfluorescein (376 Da) or fluorescein isothiocyanate-dextran (FITC-dextran) (4-40 kDa) from poloxamer was used to simulate drug release and penetration into the eye using in vivo fluorometry. RESULTS According to our clinical and pathological analyses, poloxamer was well tolerated in peribulbar injections and did not cause acute toxicity at the site of injection. The marker compounds were released from the site of injection during the first 24 hours. CONCLUSIONS Although poloxamer appears to be suitable for peribulbar injections, a more prolonged period of dissolution is desirable for clinical purposes.
Collapse
Affiliation(s)
- Katja Vehanen
- Department of Ophthalmology, University of Kuopio, Kuopio, Finland.
| | | | | | | |
Collapse
|
23
|
Ueda H, Hacker MC, Haesslein A, Jo S, Ammon DM, Borazjani RN, Kunzler JF, Salamone JC, Mikos AG. Injectable,in situ forming poly(propylene fumarate)-based ocular drug delivery systems. J Biomed Mater Res A 2007; 83:656-66. [PMID: 17514745 DOI: 10.1002/jbm.a.31226] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This study sought to develop an injectable formulation for long-term ocular delivery of fluocinolone acetonide (FA) by dissolving the anti-inflammatory drug and the biodegradable polymer poly(propylene fumarate) (PPF) in the biocompatible, water-miscible, organic solvent N-methyl-2-pyrrolidone (NMP). Upon injection of the solution into an aqueous environment, a FA-loaded PPF matrix is precipitated in situ through the diffusion/extraction of NMP into surrounding aqueous fluids. Fabrication of the matrices and in vitro release studies were performed in phosphate buffered saline at 37 degrees C. Drug loadings up to 5% were achieved. High performance liquid chromatography was employed to determine the released amount of FA. The effects of drug loading, PPF content of the injectable formulation, and additional photo-crosslinking of the matrix surface were investigated. Overall, FA release was sustained in vitro over up to 400 days. After an initial burst release of 22 to 68% of initial FA loading, controlled drug release driven by diffusion and bulk erosion was observed. Drug release rates in a therapeutic range were demonstrated. Release kinetics were found to be dependent on drug loading, formulation PPF content, and extent of surface crosslinking. The results suggest that injectable, in situ formed PPF matrices are promising candidates for the formulation of long-term, controlled delivery devices for intraocular drug delivery.
Collapse
Affiliation(s)
- H Ueda
- Department of Bioengineering, Rice University, Houston, Texas 77251-1892, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
24
|
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.
Collapse
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
| | | | | | | |
Collapse
|
25
|
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]
|
26
|
Hu T, Le Q, Wu Z, Wu W. Determination of doxorubicin in rabbit ocular tissues and pharmacokinetics after intravitreal injection of a single dose of doxorubicin-loaded poly-β-hydroxybutyrate microspheres. J Pharm Biomed Anal 2007; 43:263-9. [PMID: 16884884 DOI: 10.1016/j.jpba.2006.06.032] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2006] [Revised: 06/14/2006] [Accepted: 06/20/2006] [Indexed: 11/17/2022]
Abstract
A validated HPLC method was developed for the quantification of doxorubicin in rabbit ocular tissues using solid phase extraction and ultraviolet detection. Chromatographic separation of doxorubicin in various ocular tissues was performed on a C18 column. The mobile phase was composed of 0.2 M KH2PO4 buffer solution, acetonitrile and triethylamine in volumetric ratio of 70/30/0.2, adjusted to pH 4.0 with orthophosphoric acid. The calibration curve was linear over the range of 0.03-10, 0.03-10, 0.05-10 and 0.05-10 microg/ml in vitreous body, iris, retina/choroids and sclera, respectively. The intra-day and inter-day precisions in all ocular tissues were smaller than 4.95% and 5.73%, and the accuracies were about 100%. The extraction recoveries of doxorubicin in all of the ocular tissues were between 83.47% and 96.33%. After intravitreal administration of doxorubicin-loaded poly-beta-hydroxybutyrate microspheres, doxorubicin level in ocular tissues was much lower than that for administration of free doxorubicin, which was helpful to reduce the associated toxicity to surrounding tissues. Doxorubicin was detectable even after tens of days in the studied ocular tissues.
Collapse
Affiliation(s)
- Tao Hu
- School of Pharmacy, Fudan University, Shanghai 200032, China
| | | | | | | |
Collapse
|
27
|
Haesslein A, Ueda H, Hacker MC, Jo S, Ammon DM, Borazjani RN, Kunzler JF, Salamone JC, Mikos AG. Long-term release of fluocinolone acetonide using biodegradable fumarate-based polymers. J Control Release 2006; 114:251-60. [PMID: 16872709 DOI: 10.1016/j.jconrel.2006.05.024] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Revised: 05/06/2006] [Accepted: 05/31/2006] [Indexed: 10/24/2022]
Abstract
Intraocular drug delivery systems made from biodegradable polymers hold great potential to effectively treat chronic diseases of the posterior segment of the eye. This study is based on the hypothesis that crosslinked poly(propylene fumarate) (PPF)-based matrices are suitable long-term delivery devices for the sustained release of the anti-inflammatory drug fluocinolone acetonide (FA) due to their hydrophobicity and network density. FA-loaded rods of 10 mm length and 0.6 mm diameter were fabricated by photo-crosslinking PPF with N-vinyl pyrrolidone (NVP). The released amounts of FA and NVP were determined by HPLC analysis. The effects of drug loading and the ratio of PPF to NVP on the release kinetics were investigated using a 2(3-1) factorial design. Overall, FA release was sustained in vitro over almost 400 days by all tested formulations. Low burst release was followed by a dual modality release controlled by diffusion and bulk erosion with release rates up to 1.7 microg/day. The extent of the burst effect and the release kinetics were controlled by the drug loading and the matrix composition. Matrix water content and degradation were determined gravimetrically. Micro-computed tomography was used to image structural and dimensional changes of the devices. The results show that photo-crosslinked PPF-based matrices are promising long-term delivery devices for intraocular drug delivery.
Collapse
Affiliation(s)
- A Haesslein
- Department of Bioengineering, Rice University, Houston, TX 77251-1892, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Ng EWM, Shima DT, Calias P, Cunningham ET, Guyer DR, Adamis AP. Pegaptanib, a targeted anti-VEGF aptamer for ocular vascular disease. Nat Rev Drug Discov 2006; 5:123-32. [PMID: 16518379 DOI: 10.1038/nrd1955] [Citation(s) in RCA: 1019] [Impact Index Per Article: 56.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Aptamers are oligonucleotide ligands that are selected for high-affinity binding to molecular targets. Pegaptanib sodium (Macugen; Eyetech Pharmaceuticals/Pfizer) is an RNA aptamer directed against vascular endothelial growth factor (VEGF)-165, the VEGF isoform primarily responsible for pathological ocular neovascularization and vascular permeability. After nearly a decade of preclinical development to optimize and characterize its biological effects, pegaptanib was shown in clinical trials to be effective in treating choroidal neovascularization associated with age-related macular degeneration. Pegaptanib therefore has the notable distinction of being the first aptamer therapeutic approved for use in humans, paving the way for future aptamer applications.
Collapse
Affiliation(s)
- Eugene W M Ng
- Eyetech Pharmaceuticals, Inc., 3 Times Square, 12th Floor, New York, New York 10036, USA
| | | | | | | | | | | |
Collapse
|
29
|
Fournier E, Passirani C, Montero-Menei CN, Benoit JP. Biocompatibility of implantable synthetic polymeric drug carriers: focus on brain biocompatibility. Biomaterials 2003; 24:3311-31. [PMID: 12763459 DOI: 10.1016/s0142-9612(03)00161-3] [Citation(s) in RCA: 254] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Numerous polymeric biomaterials are implanted each year in human bodies. Among them, drug delivery devices are potent novel powerful therapeutics for diseases which lack efficient treatments. Controlled release systems are in direct and sustained contact with the tissues, and some of them degrade in situ. Thus, both the material itself and its degradation products must be devoid of toxicity. The knowledge and understanding of the criteria and mechanisms determining the biocompatibility of biomaterials are therefore of great importance. The classical tissue response to a foreign material leads to the encapsulation of the implant, which may impair the drug diffusion in the surrounding tissue and/or cause implant failure. This tissue response depends on different factors, especially on the implantation site. Indeed, several organs possess a particular immunological status, which may reduce the inflammatory and immune reactions. Among them, the central nervous system is of particular interest, since many pathologies still need curative treatments. This review describes the classical foreign body reaction and exposes the particularities of the central nervous system response. The recent in vivo biocompatibility studies of implanted synthetic polymeric drug carriers are summarized in order to illustrate the behavior of different classes of polymers and the methodologies used to evaluate their tolerance.
Collapse
Affiliation(s)
- E Fournier
- Inserm ERIT-M 0104, Ingénierie de la Vectorisation Particulaire, 10, rue André Bocquel, 49100 Angers, France
| | | | | | | |
Collapse
|
30
|
Abdekhodaie MJ. Diffusional release of a solute from a spherical reservoir into a finite external volume. J Pharm Sci 2002; 91:1803-9. [PMID: 12115807 DOI: 10.1002/jps.10165] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
An exact solution has been obtained for the release kinetics of a solute from a spherical reservoir with the burst effect initial condition into a finite external volume. The exact solution is derived based on the time Laplace transform method. The results presented here indicate that as the external fluid volume increases, the cumulative release at any time and the releasable amount of the solute at infinite time increase. In addition, for a given external volume, as the polymeric coat thickness increases the fractional release at any time decreases. Experimentally, cumulative release profiles of theophylline microspheres coated with ethylene vinyl acetate copolymer into different external volumes agreed with the mathematical predictions.
Collapse
|
31
|
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.
Collapse
Affiliation(s)
- S Kawakami
- School of Pharmaceutical Sciences, Nagasaki University, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
32
|
Abdekhodaie MJ. Diffusional release of a solute from a rectangular polymer reservoir into a finite external volume. J Memb Sci 2000. [DOI: 10.1016/s0376-7388(00)00366-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
33
|
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.
Collapse
Affiliation(s)
- M J Colthurst
- Department of Medicine, University of Liverpool, UK.
| | | | | | | |
Collapse
|
34
|
|
35
|
Diffusional release of a dispersed solute from planar and spherical matrices into finite external volume. J Control Release 1997. [DOI: 10.1016/s0168-3659(96)01482-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|