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Yu Y, Kim DH, Suh EY, Jeong SH, Kwon HC, Le TP, Kim Y, Shin SA, Park YH, Huh KM. Injectable glycol chitosan thermogel formulation for efficient inner ear drug delivery. Carbohydr Polym 2022; 278:118969. [PMID: 34973784 DOI: 10.1016/j.carbpol.2021.118969] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 11/08/2021] [Accepted: 11/30/2021] [Indexed: 01/09/2023]
Abstract
We prepared a new injectable thermogel to enhance the efficiency of inner ear delivery of dexamethasone (DEX). Hexanoyl glycol chitosan (HGC) was synthesized and evaluated as an amphiphilic thermogel (Tgel ~ 32 °C) for use as a solubilizing agent as well as an injectable carrier for intratympanic delivery of the hydrophilic and hydrophobic forms of DEX. Various thermogel formulations with different drug types and concentrations were prepared, and their physicochemical and thermogelling properties were characterized by 1H NMR, ATR-FTIR, and rheometer. They exhibited versatile release kinetics from several hours to more than 2 weeks, depending on drug type and concentration. Our formulations further showed good residual stability for more than 21 days without any cytotoxicity or inflammation in the middle and inner ear and could deliver a considerably high drug concentration into the inner ear. Therefore, HGC thermogel has great potential as an effective and safe formulation for inner ear drug delivery.
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Affiliation(s)
- Yang Yu
- Department of Otolaryngology-Head and Neck Surgery, College of Medicine, Chungnam National University, Daejeon 35015, South Korea
| | - Da Hae Kim
- Polymer Science and Engineering, Chungnam National University, 99 Daehakro, Yuseonggu, Daejeon 34134, South Korea
| | - Eun Yeong Suh
- Polymer Science and Engineering, Chungnam National University, 99 Daehakro, Yuseonggu, Daejeon 34134, South Korea
| | - Seong-Hun Jeong
- Department of Medical Science, College of Medicine, Chungnam National University, Daejeon 35015, South Korea
| | - Hyuk Chan Kwon
- Department of Medical Science, College of Medicine, Chungnam National University, Daejeon 35015, South Korea
| | - Thi Phuc Le
- Polymer Science and Engineering, Chungnam National University, 99 Daehakro, Yuseonggu, Daejeon 34134, South Korea
| | - Yugyeong Kim
- Polymer Science and Engineering, Chungnam National University, 99 Daehakro, Yuseonggu, Daejeon 34134, South Korea
| | - Sun-Ae Shin
- Department of Otolaryngology-Head and Neck Surgery, College of Medicine, Chungnam National University, Daejeon 35015, South Korea; Brain Research Institute, College of Medicine, Chungnam National University, Daejeon 35015, South Korea
| | - Yong-Ho Park
- Department of Otolaryngology-Head and Neck Surgery, College of Medicine, Chungnam National University, Daejeon 35015, South Korea; Department of Medical Science, College of Medicine, Chungnam National University, Daejeon 35015, South Korea; Brain Research Institute, College of Medicine, Chungnam National University, Daejeon 35015, South Korea.
| | - Kang Moo Huh
- Polymer Science and Engineering, Chungnam National University, 99 Daehakro, Yuseonggu, Daejeon 34134, South Korea.
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A Review on Recent Advancement on Age-Related Hearing Loss: The Applications of Nanotechnology, Drug Pharmacology, and Biotechnology. Pharmaceutics 2021; 13:pharmaceutics13071041. [PMID: 34371732 PMCID: PMC8309044 DOI: 10.3390/pharmaceutics13071041] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 07/01/2021] [Accepted: 07/01/2021] [Indexed: 11/30/2022] Open
Abstract
Aging is considered a contributing factor to many diseases such as cardiovascular disease, Alzheimer’s disease, and hearing loss. Age-related hearing loss, also termed presbycusis, is one of the most common sensory impairments worldwide, affecting one in five people over 50 years of age, and this prevalence is growing annually. Associations have emerged between presbycusis and detrimental health outcomes, including social isolation and mental health. It remains largely untreatable apart from hearing aids, and with no globally established prevention strategies in the clinical setting. Hence, this review aims to explore the pathophysiology of presbycusis and potential therapies, based on a recent advancement in bile acid-based bio-nanotechnologies. A comprehensive online search was carried out using the following keywords: presbycusis, drugs, hearing loss, bile acids, nanotechnology, and more than 150 publications were considered directly relevant. Evidence of the multifaceted oxidative stress and chronic inflammation involvement in cellular damage and apoptosis that is associated with a loss of hair cells, damaged and inflamed stria vascularis, and neuronal signalling loss and apoptosis continues to emerge. New robust and effective therapies require drug delivery deeper into the various layers of the cochlea. Bile acid-based nanotechnology has gained wide interest in its permeation-enhancing ability and potential for numerous applications in treating presbycusis.
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Poly-Lactic Acid-Based Biopolymer Formulations Are Safe for Sustained Intratympanic Dexamethasone Delivery. Otol Neurotol 2020; 40:e739-e746. [PMID: 31295207 DOI: 10.1097/mao.0000000000002305] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
HYPOTHESIS AND BACKGROUND The clinical treatment of sudden sensorineural hearing loss currently relies on the administration of steroids, either systemically or via intratympanic injections. Intratympanic injections bypass the hemato-cochlear barrier, reducing its systemic side effects. The efficacy of the injections is limited through rapid drug clearance via the Eustachian tube, and through nonoptimal properties of slow-release drug carriers. A new slow-release drug delivery vehicle based on hexyl-substituted-poly-lactic-acid (HexPLA), with the highest possible safety profile and complete bio-degradability, has been evaluated for safety and efficacy in a standardized guinea pig model of intratympanic injection. METHODS A total of 83 animals received through retrobullar injection either empty Nile-red-colored HexPLA vehicle, 5%-dexamethasone-HexPLA, 5%-dexamethasone suspension, or a sham operation. Long-term residence time of vehicle, biocompatibility, click- and pure-tone hearing thresholds, and dexamethasone levels in the perilymph were prospectively assessed. RESULTS At 1 week after injection, HexPLA vehicle was morphologically present in the middle ear and perilymph levels in the 5%-dexamethasone-HexPLA were on average 2 to 3 μg/ml and one order of magnitude higher compared with those of the 5%-dexamethasone suspension group. No significant postoperative morphological or functional changes were observed up to 3 months postdelivery. CONCLUSIONS HexPLA is safe, fully biocompatible, and efficient for sustained high-dose, intratympanic delivery of dexamethasone at least for 1 week and therefore of high interest for the treatment of sudden sensorineural hearing loss and other acute inner ear diseases. Due to the favorable chemical properties, a wide range of other drugs can be loaded into the vehicle further increasing its potential value for otological applications.
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Videhult Pierre P, Fransson A, Kisiel MA, Damberg P, Nikkhou Aski S, Andersson M, Hällgren L, Laurell G. Middle Ear Administration of a Particulate Chitosan Gel in an in vivo Model of Cisplatin Ototoxicity. Front Cell Neurosci 2019; 13:268. [PMID: 31293387 PMCID: PMC6603134 DOI: 10.3389/fncel.2019.00268] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 05/29/2019] [Indexed: 11/13/2022] Open
Abstract
Background Middle ear (intratympanic, IT) administration is a promising therapeutic method as it offers the possibility of achieving high inner ear drug concentrations with low systemic levels, thus minimizing the risk of systemic side effects and drug-drug interactions. Premature elimination through the Eustachian tube may be reduced by stabilizing drug solutions with a hydrogel, but this raises the secondary issue of conductive hearing loss. Aim This study aimed to investigate the properties of a chitosan-based particulate hydrogel formulation when used as a drug carrier for IT administration in an in vivo model of ototoxicity. Materials and Methods Two particulate chitosan-based IT delivery systems, Thio-25 and Thio-40, were investigated in albino guinea pigs (n = 94). Both contained the hearing protecting drug candidate sodium thiosulfate with different concentrations of chitosan gel particles (25% vs. 40%). The safety of the two systems was explored in vivo. The most promising system was then tested in guinea pigs subjected to a single intravenous injection with the anticancer drug cisplatin (8 mg/kg b.w.), which has ototoxic side effects. Hearing status was evaluated with acoustically evoked frequency-specific auditory brainstem response (ABR) and hair cell counting. Finally, in vivo magnetic resonance imaging was used to study the distribution and elimination of the chitosan-based system from the middle ear cavity in comparison to a hyaluronan-based system. Results Both chitosan-based IT delivery systems caused ABR threshold elevations (p < 0.05) that remained after 10 days (p < 0.05) without evidence of hair cell loss, although the elevation induced by Thio-25 was significantly lower than for Thio-40 (p < 0.05). Thio-25 significantly reduced cisplatin-induced ABR threshold elevations (p < 0.05) and outer hair cell loss (p < 0.05). IT injection of the chitosan- and hyaluronan-based systems filled up most of the middle ear space. There were no significant differences between the systems in terms of distribution and elimination. Conclusion Particulate chitosan is a promising drug carrier for IT administration. Future studies should assess whether the physical properties of this technique allow for a smaller injection volume that would reduce conductive hearing loss.
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Affiliation(s)
- Pernilla Videhult Pierre
- Division of Audiology, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
| | - Anette Fransson
- Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | | | - Peter Damberg
- Karolinska Experimental Research and Imaging Center, Karolinska University Hospital, Stockholm, Sweden
| | - Sahar Nikkhou Aski
- Karolinska Experimental Research and Imaging Center, Karolinska University Hospital, Stockholm, Sweden
| | - Mats Andersson
- Division of Bioscience and Materials, RISE Research Institutes of Sweden, Södertälje, Sweden
| | - Lotta Hällgren
- Division of Bioscience and Materials, RISE Research Institutes of Sweden, Södertälje, Sweden
| | - Göran Laurell
- Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
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Piu F, Bishop KM. Local Drug Delivery for the Treatment of Neurotology Disorders. Front Cell Neurosci 2019; 13:238. [PMID: 31213983 PMCID: PMC6557301 DOI: 10.3389/fncel.2019.00238] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 05/13/2019] [Indexed: 02/01/2023] Open
Abstract
Neurotology disorders such as vertigo, tinnitus, and hearing loss affect a significant proportion of the population (estimated 39 million in the United States with moderate to severe symptoms). Yet no pharmacological treatments have been developed, in part due to limitations in effective drug delivery to the anatomically protected inner ear compartment. Intratympanic delivery, a minimally invasive injection performed in the office setting, offers a potential direct route of administration. Currently, off-label use of therapeutics approved to treat disorders via systemic administration are being injected intratympanically, mostly in the form of aqueous solutions, but provide variable levels of drug exposure for a limited time requiring repeated injections. Hence, current drug delivery approaches for neurotology disorders are sub-optimal. This review, following a description of pharmacokinetic considerations of the inner ear, explores the merits of novel delivery approaches toward the treatment of neurotology disorders. Methodologies employing local delivery to the inner ear are described, including direct intracochlear delivery as well as intratympanic methods of infusion and injection. Intratympanic injection delivery formulation strategies including hydrogels, polymers and nanoparticulate systems are explored. These approaches represent progress toward more effective delivery options for the clinical treatment of a variety of neurotology disorders.
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Hao J, Li SK. Inner ear drug delivery: Recent advances, challenges, and perspective. Eur J Pharm Sci 2019; 126:82-92. [DOI: 10.1016/j.ejps.2018.05.020] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 05/17/2018] [Accepted: 05/20/2018] [Indexed: 10/16/2022]
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Salt AN, Hirose K. Communication pathways to and from the inner ear and their contributions to drug delivery. Hear Res 2018; 362:25-37. [PMID: 29277248 PMCID: PMC5911243 DOI: 10.1016/j.heares.2017.12.010] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 11/08/2017] [Accepted: 12/05/2017] [Indexed: 01/04/2023]
Abstract
The environment of the inner ear is highly regulated in a manner that some solutes are permitted to enter while others are excluded or transported out. Drug therapies targeting the sensory and supporting cells of the auditory and vestibular systems require the agent to gain entry to the fluid spaces of the inner ear, perilymph or endolymph, which surround the sensory organs. Access to the inner ear fluids from the vasculature is limited by the blood-labyrinth barriers, which include the blood-perilymph and blood-strial barriers. Intratympanic applications provide an alternative approach in which drugs are applied locally. Drug from the applied solution enters perilymph through the round window membrane, through the stapes, and under some circumstances, through thin bone in the otic capsule. The amount of drug applied to the middle ear is always substantially more than the amount entering perilymph. As a result, significant amounts of the applied drug can pass to the digestive system, to the vasculature, and to the brain. Drugs in perilymph pass to the vasculature and to cerebrospinal fluid via the cochlear aqueduct. Conversely, drugs applied to cerebrospinal fluid, including those given intrathecally, can enter perilymph through the cochlear aqueduct. Other possible routes in or out of the ear include passage by neuronal pathways, passage via endolymph and the endolymphatic sac, and possibly via lymphatic pathways. A better understanding of the pathways for drug movements in and out of the ear will enable better intervention strategies.
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Affiliation(s)
- Alec N Salt
- Department of Otolaryngology, Washington University School of Medicine, 660 South Euclid Avenue, St Louis, MO, USA.
| | - Keiko Hirose
- Department of Otolaryngology, Washington University School of Medicine, 660 South Euclid Avenue, St Louis, MO, USA
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Mäder K, Lehner E, Liebau A, Plontke SK. Controlled drug release to the inner ear: Concepts, materials, mechanisms, and performance. Hear Res 2018; 368:49-66. [PMID: 29576310 DOI: 10.1016/j.heares.2018.03.006] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 02/21/2018] [Accepted: 03/06/2018] [Indexed: 12/01/2022]
Abstract
Progress in drug delivery to the ear has been achieved over the last few years. This review illustrates the main mechanisms of controlled drug release and the resulting geometry- and size-dependent release kinetics. The potency, physicochemical properties, and stability of the drug molecules are key parameters for designing the most suitable drug delivery system. The most important drug delivery systems for the inner ear include solid foams, hydrogels, and different nanoscale drug delivery systems (e.g., nanoparticles, liposomes, lipid nanocapsules, polymersomes). Their main characteristics (i.e., general structure and materials) are discussed, with special attention given to underlining the link between the physicochemical properties (e.g., surface areas, glass transition temperature, microviscosity, size, and shape) and release kinetics. An appropriate characterization of the drug, the excipients used, and the formulated drug delivery systems is necessary to achieve a deeper understanding of the release process and decrease variability originating from the drug delivery system. This task cannot be solved by otologists alone. The interdisciplinary cooperation between otology/neurotology, pharmaceutics, physics, and other disciplines will result in improved drug delivery systems for the inner ear.
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Affiliation(s)
- Karsten Mäder
- Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, D-06120 Halle (Saale), Germany.
| | - Eric Lehner
- Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, D-06120 Halle (Saale), Germany
| | - Arne Liebau
- Department of Otorhinolaryngology, Head & Neck Surgery, Martin Luther University Halle-Wittenberg, University Medicine Halle, Ernst-Grube-Str. 40, 06120 Halle (Saale), Germany
| | - Stefan K Plontke
- Department of Otorhinolaryngology, Head & Neck Surgery, Martin Luther University Halle-Wittenberg, University Medicine Halle, Ernst-Grube-Str. 40, 06120 Halle (Saale), Germany
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