Oxymetazoline ototoxicity in a chinchilla animal model

Conceptual Model for Using Imidazoline Derivative Solutions in Pulpal Management

Alpha-adrenergic agonists, such as the Imidazoline derivatives (ImDs) of oxymetazoline and xylometazoline, are highly effective hemostatic agents. ImDs have not been widely used in dentistry but their use in medicine, specifically in ophthalmology and otolaryngology, warrants consideration for pulpal hemostasis. This review presents dental healthcare professionals with an overview of ImDs in medicine. ImD solutions have the potential to be more effective and biocompatible than existing topical hemostatic compounds in pulpal management. Through a comprehensive analysis of the pharmacology of ImDs and the microphysiology of hemostasis regulation in oral tissues, a conceptual model of pulpal management by ImD solutions is presented.

Oxymetazoline, Mupirocin, Clotrimazole-Safe, Effective, Off-Label Agents for Tympanostomy Tube Care

OBJECTIVES

Only a few medications have a United States Food and Drug Administration indications for prevention and/or treatment of infections in patients with tympanic perforations or tympanostomy tubes. We examined 3 off-label agents that have become important in tympanostomy tube care hoping to demonstrate the effectiveness and safety of each in experimental assays and human application.

METHODS

Computerized literature review.

RESULTS

(1) Oxymetazoline nasal spray applied at the time of surgery is equivalent to fluoroquinolone ear drops in the prevention of early postsurgical otorrhea and tympanostomy tube occlusion at the first postoperative visit. (2) Topical mupirocin 2% ointment is effective alone or in combination with culture-directed systemic therapy for the treatment of tympanostomy tube otorrhea caused by community-acquired, methicillin-resistant Staphylococcus aureus. (3) Topical clotrimazole 1% cream is highly active against the common yeast and fungi that cause otomycosis. A single application after microscopic debridement will cure fungal tympanostomy tube otorrhea in most cases. None of these 3 agents is ototoxic in animal histological or physiological studies, and each has proved safe in long-term clinical use.

CONCLUSIONS

Oxymetazoline nasal spray, mupirocin ointment, and clotrimazole cream are safe and effective as off-label medications for tympanostomy tube care in children.

The Safety Pharmacology of Auditory Function

Safety pharmacology satisfies a key requirement in the process of drug development. Safety pharmacology studies are required to assess the impact of a new chemical entity (NCE) or biotechnology-derived product for human use on vital systems, such as those subserving auditory function. Safety pharmacology studies accordingly are defined as those studies that investigate the potential undesirable effects of a substance on auditory functions in relation to exposure in and above the therapeutic range. Auditory safety studies should be designed with the primary objective of determining how administration of a compound influences normal hearing. If an effect on hearing is identified, then it is necessary to determine through histopathology the underlying mechanism for the observed hearing loss. Since the auditory system contains a heterogeneous mixture of structural and cellular components that are organized in a very complex and integrated manner, it is necessary to clearly identify the underlying primary mechanism or target of the new chemical entity that produced the hearing loss. This chapter will highlight major components of auditory function with regard to potential opportunities for drug interaction. Aspects of designing ototoxicity studies will be discussed with an emphasis on standards deemed necessary by the US Food and Drug Administration. Additionally, classes of ototoxic compounds and their proposed mechanisms of action are described in depth.

Earigate™ for softening ear wax: is it safe when the eardrum is perforated?

OBJECTIVE

To determine the safety of Earigate™ as an ear wax softening product.

STUDY DESIGN

Prospective, controlled animal study.

METHODS

Bilateral wide myringotomies were performed in eleven chinchillas. In each animal, Earigate™ was delivered to a randomly selected experimental ear canal as 2 puffs twice a day. Auditory brainstem response (ABR) was used to assess the hearing of the animals before, 3 days and 10 days following the local application of Earigate™. The ABR threshold shifts were compared for both experimental and control ears.

RESULTS

The mean hearing threshold shifts in the experimental animals were comparable at all frequencies and at days 3 and 10. No statistically significant differences were observed in the mean threshold shifts for all of the frequencies evaluated, between the control and experimental ears.

CONCLUSIONS

The administration of Earigate™ to the middle ear of chinchillas did not cause any ototoxicity as assessed by ABR.

Ototoxicity of olive oil in a chinchilla animal model

OBJECTIVES/HYPOTHESIS

Olive oil is often used by patients to soften ear wax or to relieve ear canal obstruction. It is also sold in drugstores as a cerumenolytic. To date, no study has assessed the safety of ototopical olive oil on hearing in the presence of tympanic membrane perforation. The present study aimed to assess the safety of ototopic olive oil on hearing in the presence of tympanic membrane perforation.

STUDY DESIGN

Prospective, randomized, controlled trial in a chinchilla animal model.

MATERIALS AND METHODS

Eleven chinchillas underwent bilateral myringotomy. In each animal, one ear was randomly assigned to receive olive oil (experimental ear), while the contralateral control ear received normal saline. Auditory brain response (ABR) test was performed at baseline and then 7, 14, and 30 days following the application.

RESULTS

At 30 days follow-up, there was no significant change in auditory brain response thresholds at 8, 16, 20, or 25 kHz. Scanning electron microscope imaging showed no damage to the hair cells.

CONCLUSION

Olive oil does not seem to cause hearing loss in chinchillas with perforated tympanic membranes. Future clinical studies are required.

Topical treatment of chronic suppurative otitis media

Chronic suppurative otitis media (CSOM) is a chronic inflammation of the middle ear and mastoid cavity presenting with ear discharge or otorrhea through a non-intact tympanic membrane. CSOM is the most common cause of childhood hearing impairment in developing countries. Accurate diagnosis depends on a high index of suspicion, micro-otoscopic examination, and judicious use of imaging as required. CSOM can be classified into 3 types: tubotympanic, atticoantral, and post-tympanostomy tube insertion. Aerobes, anaerobes and fungi are all potential pathogens in CSOM. This review summarizes the results of recent studies on the bacteriology of CSOM, biofilms, and the role of the nasopharynx pathogens that may have important implications for the treatment of this important pathology; that is often associated with misdiagnosis or delayed diagnosis. Particular emphasis will be placed on topical treatment options including choices of antibiotic, antifungal, and antiseptic agents, delivery technique, spectrum of activity, and risk of ototoxicity.

Ototoxicity of baby oil in a chinchilla animal model

OBJECTIVE

Baby oil is commonly used to soften ear wax in order to aid its removal. The aim of this study was to determine the potential ototoxicity of baby oil.

METHOD

A prospective controlled animal study was conducted using ten chinchillas with normal hearing function. Each had bilateral myringotomies. One ear was randomly assigned to receive 1 ml of baby oil while the other ear received an equal volume of 0.45% NaCl. Distortion product otoacoustic emissions (DPOAEs) and Auditory Brainstem Response (ABR) measurements were recorded at baseline (post myringotomy and pre application of product) and on days 5 and 15 after application. Two months after application of baby oil, the cochleae were processed for light microscopy and qualitative comparisons were made between the cochleae of both control and experimental ears.

RESULTS

There was no statistically significant difference in DPOAE between experimental and control ears at 5 and 15 days after treatment. ABR results did not reveal ototoxicity at days 5 and 15 post treatment. None of the animals developed facial paralysis or any signs of vestibular toxicity. There were no overt mucosal changes in the middle ear of the ears exposed to baby oil compared to the control ears. Light microscopy showed comparable features in the organ of Corti, stria vascularis, spiral ligament and the spiral ganglion cells of both groups of cochleae.

CONCLUSION

Baby oil did not produce ototoxic effects when applied ototopically in chinchillas with non-intact tympanic membrane.