Safety of cidofovir by intratympanic delivery technique

Congenital cytomegalovirus (CMV) for the pediatric otolaryngologist

Cytomegalovirus (CMV) is a double-stranded DNA virus and a member of the herpesvirus family. It is the most common congenital viral infection. For symptomatic infections, symptoms can vary widely but tends to have a predilection for the central nervous system and for the reticuloendothelial system. Sensorineural hearing loss (SNHL) is by far the most common sequelae of congenital CMV infection. For this reason, it is imperative to understand the screening, diagnosis, and possible treatment options for congenital CMV induced SNHL. This literature review explores the association of CMV with hearing loss, screening for congenital CMV infections, possible treatments options, and the development of a possible vaccine.

A Controlled Antibiotic Release System for the Development of Single-Application Otitis Externa Therapeutics

Ear infections are a commonly-occurring problem that can affect people of all ages. Treatment of these pathologies usually includes the administration of topical or systemic antibiotics, depending on the location of the infection. In this context, we sought to address the feasibility of a single-application slow-releasing therapeutic formulation of an antibiotic for the treatment of otitis externa. Thixotropic hydrogels, which are gels under static conditions but liquefy when shaken, were tested for their ability to act as drug controlled release systems and inhibit Pseudomonas aeruginosa and Staphylococcus aureus, the predominant bacterial strains associated with outer ear infections. Our overall proof of concept, including in vitro evaluations reflective of therapeutic ease of administration, formulation stability, cytocompatibility assessment, antibacterial efficacy, and formulation lifespan, indicate that these thixotropic materials have strong potential for development as otic treatment products.

Combination therapies using an intratympanic polymer gel delivery system in the guinea pig animal model: A safety study

OBJECTIVES

High dose antivirals have been shown to cause hearing loss when applied via the intratympanic route. The aim of this study was to determine if a combination therapy using dexamethasone (DXA) with either Cidofovir (CDV) or Ganciclovir (GCV), in solution or in PLGA-PEG-PLGA (PPP) hydrogel, is innocuous to the inner ear.

METHODS

Cytomegalovirus (CMV)-free guinea pigs were separated into four principal study groups and treated via intratympanic injection (IT) of CDV/DXA solution, CDV/DXA Hydrogel, GCV/DXA solution and GCV/DXA hydrogel. Hearing thresholds were evaluated with pretreatment ABR and post injection weekly ABRs for a total follow up of 28 days. Temporal bone tissue was harvested and stained with Hematoxylin and Eosin for histologic analysis.

RESULTS

ABR analysis revealed that GCV/DXA in solution and in hydrogel led to a mild hearing loss at days 7-21 but returned to baseline by day 28 When administered via PPP hydrogel, CDV/DXA demonstrated mild persistent hearing loss at 32kHz at 28 days. An inflammatory response was identified in the cochlear specimen of the CDV/DXA/PPP hydrogel group, in concert with mild hearing loss, at days 21 and 28.

CONCLUSION

Results of this study support the safe intratympanic use of higher concentrations of antivirals when combined with DXA, both in solution and when applied via PPP hydrogel.

Recent advances in local drug delivery to the inner ear

Inner ear diseases are not adequately treated by systemic drug administration mainly because of the blood-perilymph barrier that reduces exchanges between plasma and inner ear fluids. Local drug delivery methods including intratympanic and intracochlear administrations are currently developed to treat inner ear disorders more efficiently. Intratympanic administration is minimally invasive but relies on diffusion through middle ear barriers for drug entry into the cochlea, whereas intracochlear administration offers direct access to the colchlea but is rather invasive. A wide range of drug delivery systems or devices were evaluated in research and clinic over the last decade for inner ear applications. In this review, different strategies including medical devices, hydrogels and nanoparticulate systems for intratympanic administration, and cochlear implant coating or advanced medical devices for intracoclear administration were explored with special attention to in vivo studies. This review highlights the promising systems for future clinical applications as well as the current hurdles that remain to be overcome for efficient inner ear therapy.