Dataset Information

Cyclodextrins and Iatrogenic Hearing Loss: New Drugs with Significant Risk.

ABSTRACT: Cyclodextrins are a family of cyclic oligosaccharides with widespread usage in medicine, industry and basic sciences owing to their ability to solubilize and stabilize guest compounds. In medicine, cyclodextrins primarily act as a complexing vehicle and consequently serve as powerful drug delivery agents. Recently, uncomplexed cyclodextrins have emerged as potent therapeutic compounds in their own right, based on their ability to sequester and mobilize cellular lipids. In particular, 2-hydroxypropyl-?-cyclodextrin (HP?CD) has garnered attention because of its cholesterol chelating properties, which appear to treat a rare neurodegenerative disorder and to promote atherosclerosis regression related to stroke and heart disease. Despite the potential health benefits, use of HP?CD has been linked to significant hearing loss in several species, including humans. Evidence in mice supports a rapid onset of hearing loss that is dose-dependent. Ototoxicity can occur following central or peripheral drug delivery, with either route resulting in the preferential loss of cochlear outer hair cells (OHCs) within hours of dosing. Inner hair cells and spiral ganglion cells are spared at doses that cause ~85% OHC loss; additionally, no other major organ systems appear adversely affected. Evidence from a first-to-human phase 1 clinical trial mirrors animal studies to a large extent, indicating rapid onset and involvement of OHCs. All patients in the trial experienced some permanent hearing loss, although a temporary loss of function can be observed acutely following drug delivery. The long-term impact of HP?CD use as a maintenance drug, and the mechanism(s) of ototoxicity, are unknown. ?-cyclodextrins preferentially target membrane cholesterol, but other lipid species and proteins may be directly or indirectly involved. Moreover, as cholesterol is ubiquitous in cell membranes, it remains unclear why OHCs are preferentially susceptible to HP?CD. It is possible that HP?CD acts upon several targets-for example, ion channels, tight junctions (TJ), membrane integrity, and bioenergetics-that collectively increase the sensitivity of OHCs over other cell types.

SUBMITTER: Crumling MA

PROVIDER: S-EPMC5676048 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Cyclodextrins and Iatrogenic Hearing Loss: New Drugs with Significant Risk.

Crumling Mark A MA King Kelly A KA Duncan R Keith RK

Frontiers in cellular neuroscience 20171108

Cyclodextrins are a family of cyclic oligosaccharides with widespread usage in medicine, industry and basic sciences owing to their ability to solubilize and stabilize guest compounds. In medicine, cyclodextrins primarily act as a complexing vehicle and consequently serve as powerful drug delivery agents. Recently, uncomplexed cyclodextrins have emerged as potent therapeutic compounds in their own right, based on their ability to sequester and mobilize cellular lipids. In particular, 2-hydroxypr ...[more]

PMID: 29163061

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Project description:An estimated 466 million people suffer from hearing loss worldwide. Sensorineural hearing loss is characterized by degeneration of key structures of the sensory pathway in the cochlea such as the sensory hair cells, the primary auditory neurons and their synaptic connection to the hair cells - the ribbon synapse. Various strategies to protect or regenerate these sensory cells and structures are the subject of intensive research. Yet despite recent advances in our understandings of the capacity of the cochlea for repair and regeneration there are currently no pharmacological or biological interventions for hearing loss. Current research focusses on localized cochlear drug, gene and cell-based therapies. One of the more promising drug-based therapies is based on neurotrophic factors for the repair of the ribbon synapse after noise exposure, as well as preventing loss of primary auditory neurons and regrowth of the auditory neuron fibers after severe hearing loss. Drug therapy delivery technologies are being employed to address the specific needs of neurotrophin and other therapies for hearing loss that include the need for high doses, long-term delivery, localised or cell-specific targeting and techniques for their safe and efficacious delivery to the cochlea. Novel biomaterials are enabling high payloads of drugs to be administered to the cochlea with subsequent slow-release properties that are proving to be beneficial for treating hearing loss. In parallel, new gene therapy technologies are addressing the need for cell specificity and high efficacy for the treatment of both genetic and acquired hearing loss with promising reports of hearing recovery. Some biomaterials and cell therapies are being used in conjunction with the cochlear implant ensuring therapeutic benefit to the primary neurons during electrical stimulation. This review will introduce the auditory system, hearing loss and the potential for repair and regeneration in the cochlea. Drug delivery to the cochlea will then be reviewed, with a focus on new biomaterials, gene therapy technologies, cell therapy and the use of the cochlear implant as a vehicle for drug delivery. With the current pre-clinical research effort into therapies for hearing loss, including clinical trials for gene therapy, the future for the treatment for hearing loss is looking bright.

Project description:BACKGROUND:Fabry disease (FD) is a lysosomal storage disorder resulting in systemic accumulation of globotriaosylceramide resulting in multi-organ dysfunction e.g. cerebral, cardiac, renal and audiologic complications. The audiologic involvement in FD has often been neglected; while not a lethal aspect of the disease, hearing loss can have a significantly negative impact on quality of life. OBJECTIVES:To investigate baseline hearing status of the Danish Fabry cohort prior to treatment, compared to sex- and age-expected hearing levels and correlating hearing to renal and cerebral findings. MATERIAL AND METHODS:Retrospective study of baseline hearing status of the Danish Fabry cohort (n = 83, 9-72 years). Air conduction and speech discrimination scores were assessed at 6 frequencies between 0.25-8 kHz bilaterally. Data were collected between 2001-2014 and compiled in STATA using multilinear mixed modelling for statistical evaluation. RESULTS:Hearing thresholds at all frequencies deviated from the expected thresholds of an otologically normal cohort (p<0.001) and ranged 0.5 to 1.5 standard deviations below expected values. In total 29 males and 54 females were included. Hearing loss was more pronounced in the higher frequencies. There was a trend of association between hearing loss and measured glomerular filtration rate (mGFR) (p = 0.084). No association was present between hearing loss and albuminuria (p = 0.90), Fabry related cerebral abnormalities (p = 0.84) and cardiac left ventricular mass index, (LVMi) (p = 0.67) independent of sex. Hearing thresholds were poorer for men compared to women (p = 0.001). Sex differences were present at 0.25, 4 and 8 kHz. CONCLUSION:Our findings demonstrated significant hearing loss in Danish FD patients before treatment initiation, being more profound than in otologically healthy individuals at all frequencies. Additionally, we observed no association between hearing loss and LVMi, albuminuria or FD cerebral abnormalities, with a trend of association to mGFR. SYNOPSIS:Patients with Fabrys disease have hearing loss of all frequencies and most prominently at high frequencies (4-8 kHz), with no association between the hearing loss and cerebral abnormalities, and cardiac mass but with a trend of association to measured glomerular filtration rate.

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Cyclodextrins and Iatrogenic Hearing Loss: New Drugs with Significant Risk.

Publications

Cyclodextrins and Iatrogenic Hearing Loss: New Drugs with Significant Risk.

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