Ototoxicity of otic drops applied to the middle ear in the chinchilla

Structural Integrity of Absorbable Gelatin Sponges for Middle Ear Packing in Otologic Surgery

OBJECTIVE

This study investigates the physical properties upon immersion of two gelatin sponges commonly used in otologic surgery.

BACKGROUND

Absorbable gelatin sponges are often used in middle ear surgery to achieve hemostasis and, perhaps more importantly, to provide a "scaffolding" to support ossicular chain and/or tympanic membrane reconstructions. Their rate of dissolution may therefore affect the success of tympanic membrane closure.

METHODS

An in vitro study was conducted to quantify the material changes of two absorbable gelatin sponges, a standard-density sponge and one with fewer collagen cross-linkages (low-density sponge). Volume loss (%) in 0.9% saline, 0.3% ciprofloxacin, and/or 0.1% dexamethasone as single-agent otic drops in a combination formulation was measured at 15-minute intervals for the first hour and at days 1, 3, and 5 postimmersion. Secondary end points included compressibility, porosity under microscopy, and infrared spectroscopy analysis.

RESULTS

The low-density sponge immersed in any of the three otic solutions showed a statistically significant greater volume loss at all time points when compared with the standard-density sponge (27.2% ± 5.4% vs. 15.4% ± 6.0% at 15 minutes and 44.8% ± 5.1% vs. 34.6% ± 2.9% at 5 days, p < 0.001). Interestingly, both sponges immersed in normal saline had lost almost half of their original volume after 15 minutes when compared with samples immersed in an otic solution (48.3% ± 4.6% vs. 21.3% ± 8.3%, respectively, p < 0.001).

CONCLUSION

The standard-density sponge immersed in an otic solution of ciprofloxacin, dexamethasone, or a combination formulation best maintained its structural integrity. Ancillary in vivo studies are required to assess the hemostatic properties, surgical outcomes, and middle ear synechiae of the above study conditions.

LEVEL OF EVIDENCE

Foundational evidence.

[External otitis: clinical diagnostics and treatment tactics]

OBJECTIVE

To summarize modern data about the epidemiology, etiology, clinical course and diagnosis of otitis externa.

MATERIAL AND METHODS

Materials of scientific publications included in the Cochrane Library, information bases of the RSCI, MEDLINE, PubMed were used as a data source. The choice of material was carried out according to the keywords: otitis externa, etiology, diagnosis, treatment, local treatment.

RESULTS

The role of combined drugs in the main etiopathogenetic mechanisms of the external ear inflammatory process is shown.

CONCLUSION

Analysis of published data from clinical trials indicates the importance of a fixed antibacterial agents and anesthetic combination in increasing the effectiveness of topical therapy for otitis externa.

Non-autonomous Cellular Responses to Ototoxic Drug-Induced Stress and Death

The first major recognition of drug-induced hearing loss can be traced back more than seven decades to the development of streptomycin as an antimicrobial agent. Since then at least 130 therapeutic drugs have been recognized as having ototoxic side-effects. Two important classes of ototoxic drugs are the aminoglycoside antibiotics and the platinum-based antineoplastic agents. These drugs save the lives of millions of people worldwide, but they also cause irreparable hearing loss. In the inner ear, sensory hair cells (HCs) and spiral ganglion neurons (SGNs) are important cellular targets of these drugs, and most mechanistic studies have focused on the cell-autonomous responses of these cell types in response to ototoxic stress. Despite several decades of studies on ototoxicity, important unanswered questions remain, including the cellular and molecular mechanisms that determine whether HCs and SGNs will live or die when confronted with ototoxic challenge. Emerging evidence indicates that other cell types in the inner ear can act as mediators of survival or death of sensory cells and SGNs. For example, glia-like supporting cells (SCs) can promote survival of both HCs and SGNs. Alternatively, SCs can act to promote HC death and inhibit neural fiber expansion. Similarly, tissue resident macrophages activate either pro-survival or pro-death signaling that can influence HC survival after exposure to ototoxic agents. Together these data indicate that autonomous responses that occur within a stressed HC or SGN are not the only (and possibly not the primary) determinants of whether the stressed cell ultimately lives or dies. Instead non-cell-autonomous responses are emerging as significant determinants of HC and SGN survival vs. death in the face of ototoxic stress. The goal of this review is to summarize the current evidence on non-cell-autonomous responses to ototoxic stress and to discuss ways in which this knowledge may advance the development of therapies to reduce hearing loss caused by these drugs.

Topical otic drugs in a multi-purpose manufacturing facility: a guide on determination and application of permitted daily exposure (PDE)

Due to newly introduced EU GMP (Good Manufacturing Practice) guideline for Medicinal Products for Human and Veterinary use, product specific permitted daily exposure (PDE) for toxicological evaluation in multi-purpose facilities are required within a documented process for risk assessment. European Medicines Agency (EMA) guidance on setting PDE limits so far focused on systemic administration routes such as intravenous (IV), oral or inhalation. This article provides guidance on setting PDE values for risk management purposes in multi-purpose facilities for active pharmaceutical ingredients (APIs) applied as topical otic drugs to the outer ear canal. The therewith determined PDE otic, is used for the calculation of maximum safe carry-over (MSC) in manufacturing scenarios where a topical otic product is manufactured followed by another topical otic product.

Earache

Earache, a common emergency department presentation, may be caused by a variety of conditions, some distant from the ear. This article discusses the diagnosis and treatment of acute otitis media, otitis media with effusion, otitis externa, otitis media with ruptured tympanic membrane or tympanostomy tubes, malignant otitis externa, mastoiditis and petrositis, traumatic ruptured tympanic membrane, cerumen impactions, and foreign bodies in the ears.

The effect of topical ciprofloxacin and steroid-containing ear drops for chronic suppurative otitis media on the internal ear

Aim of the study is to evaluate the effects of topical ciprofloxacin and prednisolone-containing ear drops for chronic suppurative otitis media on hearing threshold, cochlear reserve and cochlea morphology in healthy subjects and to determine the proper drug dose. Sixty-eight guinea pigs, all of which had healthy hearing, were used for the study. The first group (n = 30) was administered ciprofloxacin three times a day, the second group (n = 30) was administered prednisolone three times a day and the third group (n = 8) was administered sterile distilled water three times a day. The therapies lasted for 7 days and were administered intratympanically. The first group and second group were divided into three sub-groups of ten subjects. The first sub-group (n = 10) was administered an equivalent dose per kilogram as in humans, the second sub-group (n = 10) was administered one-third of the human-equivalent dose and the third sub-group (n = 10) was administered tenfold the human-equivalent dose. All subjects underwent brainstem evoked response audiometry (BERA) and distortion product otoacoustic emission (DPOAE) testing on the seventh and twenty-first days following the therapy. Following the tests, two subjects from each group were decapitated and examined under electron microscope. BERA and DPOAE testing results of the sub-group (n = 10) which was administered tenfold the human-equivalent dose were significantly different from the control group and other groups (P < 0.05). According to electron microscopic examination of the cochlea, the group which was administered a tenfold human-equivalent dose of intratympanic ciprofloxacin and prednisolone showed atrophy in cells and degenerations in cilia. This case was statistically significant when compared with the control group and other groups (P < 0.05). Ciprofloxacin and prednisolone applied at a human-equivalent dose per kilogram did not affect the hearing and cochlear histology of subjects.

Differences in bacteriologic treatment failures in acute otitis externa between ciprofloxacin/dexamethasone and neomycin/polymyxin B/hydrocortisone: results of a combined analysis

OBJECTIVE

To compare treatment failure rates for the two major acute otitis externa (AOE) pathogens, Pseudomonas aeruginosa and Staphylococcus aureus, by topical therapy with ciprofloxacin 0.3%/dexamethasone 0.1% (CDex) or neomycin 0.35%/polymyxin B 10,000 IU/mL/hydrocortisone 1% (Cort) based on clinical and microbiological failure in patients positive for these pathogens at baseline.

RESEARCH DESIGN AND METHODS

A combined analysis was conducted from two similar, but non-identical clinical trials involving CDex vs. Cort. Outcomes of the combined efficacy analysis were treatment failure rates and antibiotic susceptibility values for P. aeruginosa and S. aureus. The raw data for the treatment failure rates from the two studies were combined to calculate the overall treatment failure rates of each treatment group. Chi-square tests of independence were conducted to assess differences in treatment failure rates between treatment groups.

RESULTS

Of the 789 patients with culture-positive ears prior to the initiation of therapy, 61.0% (n = 481) were positive for P. aeruginosa and 8.9% (n = 70) were positive for S. aureus. While treatment failure rates for S. aureus were similar for the two therapies, CDex had a significantly lower treatment failure rate than Cort (5.1 vs. 13.0%; p = 0.0044) for P. aeruginosa. All of the persisting P. aeruginosa and S. aureus isolates were susceptible to fluoroquinolones and neomycin/polymyxin B.

LIMITATIONS

The analysis strength is dependent on pooled data from similar studies.

CONCLUSIONS

Ototopical ciprofloxacin 0.3%/dexamethasone 0.1% more effectively eradicates P. aeruginosa compared to Cort. Eradication of S. aureus by either drug was similar. These results favor CDex as a better first-line choice in the treatment of AOE compared to Cort.

Topical antibiotic ear drops: are they safe?

A discharging ear is a very common condition for the general practitioner and the ENT surgeon. Oral and intravenous antibiotics have potential complications, are costly, and exhibit increasing resistance. This study explores the advantages and disadvantages of all common otic preparations and compares effectiveness, safety, cost and complication rates. In chronic otitis media (chronic discharging ears), topical antibiotics seem to be the treatment of choice by comparison with oral or intravenous antibiotics. Cultures and antibiograms do not correspond directly to clinical efficacy, as laboratory determination of resistance does not take into account the high concentration of antibiotics in local preparations. It is safer to use quinolone drops as a first-line treatment, but it is still possible to use short courses of other drops if quinolones are either unavailable or contraindicated (e.g. allergy), or when bacteria are resistant to them. However, in such a situation, a round window membrane involved in an established inflammatory process and therefore less permeable to the passage of topical preparations is the preferred setting, as ototoxicity is a potential complication, especially in the case of gentamicin, in which case patients should be warned accordingly.

Preventive therapy for postoperative purulent otorrhea after ventilation tube insertion

OBJECTIVE

Treatment modalities which are intraoperative irrigation of the middle ear with isotonic saline, postoperative oral antibiotic treatment, and postoperative topical antibiotic use have been compared with each other and with control group regarding their efficiency in preventing postoperative purulent otorrhea after ventilation tube insertion. Moreover, the costs of the treatment modalities were analyzed.

STUDY DESIGN

Each group consisted of 70 patients, and a total of 280 patients were followed up for purulent otorrhea 2 weeks after the surgery. The study was a single-blind randomized clinical trial.

RESULTS

Ten (14.28%) patients in the oral antibiotic group, 11 (15.71%) patients in the isotonic saline irrigation group, 6 (8.57%) patients in the topical antibiotic drops group, and 21 (30%) patients in the control group had postoperative purulent otorrhea. Statistical analysis determined a significant difference between each treatment modalities and control group but did not show any significant difference between the treatment groups. When the treatment options were compared according to their cost, however, the cost per successfully treated patient was significantly lower in the saline irrigation group.

CONCLUSION

Intraoperative saline irrigation of the middle ear provides an effective, easy, and cheap treatment in preventing postoperative purulent otorrhea.

Management of the draining ear in children

There are a variety of causes of otorrhea in children. The most important factor in reaching the proper diagnosis and providing relief of the problem is aural toilet. Once adequate debridement has been performed, the diagnosis is usually clearer, and treatment with ototopicals is significantly more effective. Most cases of otorrhea are due to infection or granulation tissue and can be managed initially with appropriately selected ototopical medication, thereby avoiding the risks and side effects of systemic therapy and the need for referral to a specialist. However, otorrhea in children that is refractory to medical therapy may be due to retained tympanostomy tubes or insidious pathology such as cholesteatoma or malignancy. In such cases, prompt referral to the otolaryngologist can facilitate accurate diagnosis and successful management.

[Use of topical ciprofloxacin in chronic suppurating otitis media]

OBJECTIVE

A prospective study is presented. We carry out an analysis of the results obtained after treatment with different protocols of administration of ciprofloxacin, during the active phase in chronic otitis media and in chronic otorrhea.

MATERIAL AND METHOD

A multicenter, prospective study is carried out, in 3 ENT departments, corresponding to 3 reference tertiary hospitals. 300 patients were included ranging from 5 to 73 years old, all were diagnosed of chronic disease of the middle ear: simple chronic otitis media (n = 128), chronic otitis with bone reabsorption (n = 57), cholesteatoma infection (n = 42) and postsurgery ear infection (n = 73). Patients were placed in 5 treatment groups: ciprofloxacin (oral administration) (only adults were included), topical ciprofloxacin (0.5%), topical ciprofloxacin (0.2%), topical ciprofloxacin (0.2%) plus oral ciprofloxacin and ciprofloxacin (0.3%) plus topical fluocinolone. There was a control group treated with polimixin plus neomicine and hidrocortison.

RESULTS

The most common isolated bacterias were: Pseudomonas aeruginosa and S. aureus. We found 19 resistant strains to ciprofloxacin. A better therapeutic response was observed in the topical administration groups. In topical administration, a difference was only observed in the cholesteatoma and chronic middle ear infection with bone reabsorption groups, in those patients that were administered the ciprofloxacin with fluocinolone.

CONCLUSION

Forms of topical treatment, with ciprofloxacin, in active infection of chronic disease of the middle ear, improve the results compared to oral administration. The association with of topical fluocinolone improves the results in the cases with cholesteatoma infection and chronic middle ear infection.

The use of otic powder in the treatment of acute external otitis

BACKGROUND

Acute external otitis (AEO) is a painful condition that results as a secondary infection of macerated skin and subcutaneous tissues of the external auditory canal. The most commonly causative microorganisms are Pseudomonas aeruginosa and Staphylococcus aureus. Classic management strategies include moisture prevention, cleansing of the canal and administration of topical antimicrobial agents in drop form, such as aminoglycosides and quinolones, at times in combination with steroid solutions. The objective of this study was to evaluate and compare the efficacy of topical otic powder, tobramycin drops and ciprofloxacin drops in patients suffering from AEO. MATERIALS AND MEASURES: A randomized prospective trial was performed to determine the efficacy of Auricularum powder (dexamethasone 10 mg, oxytetracycline HCl 90,000 U, polymyxin B Sulfate 100,000 U, nystatin 1,000,000 U; Trima, Serolam Laboratories, Germany) compared with ciprofloxacin (Ciloxan, Alcon Laboratories, Fort Worth, TX) and tobramycin (Tobrex, Alcon Laboratories) drops for the treatment of AEO. One hundred twenty patients who presented with signs and symptoms of AEO were enrolled. Inclusion criteria were: AEO diagnosed by an otolaryngologist, patient age 18 years, no prior treatment with other drops or systemic antibiotics, no sensitivity to any of the drugs used or their contents, and no perforation of the tympanic membrane. All patients were instructed to avoid moisture and wetness of the ear during the course of their treatment. After we received informed consent, a swab culture was taken, and the patient was randomly assigned topical treatment for 14 days.

RESULTS

Eighty-six percent of those treated with Auricularum powder were cured at day 3-4 after initial treatment. Seventy-seven percent of those treated with ciprofloxacin drops, and fifty-six percent of those treated with tobramycin were cured at that time. All 120 patients were cured by day 14.

CONCLUSION

The results show that topical treatment with Auricularum powder is an effective and rapid method for the treatment of AEO. Ciloxan also was effective in the treatment of AEO and relieved symptoms quickly and efficiently in a short period of time. Tobrex was effective in treating AEO, but our results show that relief of symptoms was slower than with the other drugs.

Vascular occlusion in the endolymphatic sac in Meniere's disease

In 2 patients with severe Meniere's disease (MD), there was histologic evidence of occlusion of the vein of the vestibular aqueduct (VVA). This finding coincided with total or partial occlusion of numerous small vessels around the endolymphatic sac (ES), flattening of epithelium, extensive perisaccular fibrosis, and signs of new bone formation. Ultrastructural analysis of the occluding material showed foci with dense connective tissue, calcification, lipid deposits, and layers of basement membrane, sometimes concentrically arranged. The exact nature of the occluding material was unknown. In another 2 MD patients, the VVA was not visualized, and the ES vessels showed no signs of occlusion. Seven controls with acoustic schwannoma or meningioma had normal vasculature. The presence of vascular impairment in the ES in MD patients indicated that altered hemodynamics may contribute to the pathogenesis of endolymphatic hydrops and MD.

Determination of ototoxicity of common otic drops using isolated cochlear outer hair cells

OBJECTIVES

Otic drops are commonly used not only for otitis externa, but also for otorrhea in the presence of tympanostomy tubes or tympanic membrane perforations. Many studies have demonstrated the ototoxicity of common otic preparations such as Cortisporin otic drops (Monarch Pharmaceuticals, Bristol, TN). The purpose of this study was to assess the relative ototoxicity of common otic preparations by direct exposure to isolated cochlear outer hair cells (OHCs).

METHODS

OHCs from adult chinchilla cochlea were exposed to standard bathing solution (control), acetic acid, Acetasol HC (Alpharma USPD Inc., Baltimore, MD), Gentacidin (CIBA Vision Ophthalmics, Atlanta, GA), and Tobradex (Alcon, Fort Worth, TX). The cells were observed using an inverted microscope, and the images were recorded in digital still-frame and video, and analyzed on the Image Pro-Plus 3.0 program (Media Cybernetics, Silver Spring, MD).

RESULTS AND CONCLUSIONS

As measured by time to cell death and change in morphology of OHCs, acetic acid with or without hydrocortisone was most toxic to OHCs. Cortisporin was more cytotoxic than gentamicin and Tobradex.

Are some ear drops ototoxic or potentially ototoxic?

In this article we review the literature concerning the capacity of certain substances to cause ototoxicity when administered topically. The ototoxicity experimentally observed in animals only occurs in humans under certain circumstances. It is concluded that many of these products. which are commonly used for treatment in humans, are ototoxic in animals and may also be ototoxic in humans. Therefore, the use of other substances which have the same action but are not ototoxic

Efficacy of ofloxacin and other otic preparations for acute otitis media in patients with tympanostomy tubes

Otorrhea occurs in 21 to 50% of all children with tympanostomy tubes in the United States. More than 1 million children annually undergo tubomyringotomy, constituting placement of more than 2 million tympanostomy tubes each year. The organisms typically responsible for otorrhea are the same as those that cause otitis media in very young children, including Streptococcus pneumonia, Haemophilus influenzae and Moraxella catarrhalis. Drainage from tympanostomy tubes in older children involves organisms that colonize the external auditory canal, the most common being Pseudomonas aeruginosa and Staphylococcus aureus. Ofloxacin (Floxin otic), a newer fluoroquinalone antibiotic, has several advantages over other agents available for the treatment of otorrhea caused by acute otitis media in patients with tympanostomy tubes. The twice daily dosing regimen encourages better patient adherence to therapy, which is likely to improve treatment efficacy. Ofloxacin has not been associated with ototoxicity in animal models or in children participating in the clinical trials. It provides coverages for a wide range of pathogens, including Pseudomonas sp., and is indicated for use in children > or =1 year old and currently approved for patients > or =12 years with chronic suppurative otitis media. Ofloxacin applied topically in children with tympanostomy tubes in place and purulent otorrhea is as efficacious as oral amoxicillin/clavulanate (Augmentin) therapy. Other currently available therapeutic options are discussed.

Effects of common topical otic preparations on the morphology of isolated cochlear outer hair cells

Otic drops are commonly used not only for otitis externa but also for otorrhea in the presence of tympanostomy tube or tympanic membrane perforation. Many studies have demonstrated the ototoxicity of common otic preparations such as Cortisporin otic drops. Recent studies have suggested the use of fluoroquinolone antibiotic drops as an alternative owing to their excellent antimicrobial coverage and no ototoxic effect. The purpose of this study was to assess the relative ototoxicity of four common otic preparations by direct exposure to isolated cochlear outer hair cells (OHCs). OHCs from adult chinchilla cochlea were exposed to standard bathing solution (control), Cortisporin, Cipro HC, Ciloxan, and Floxin. The cells were observed using an inverted microscope, and the images recorded in digital still-frame and video, and analyzed on the Image Pro-Plus 3.0 program. As measured by time to cell death and change in morphology of OHCs, Cortisporin was most toxic to OHCs. Among the fluoroquinolone drops, Floxin was more toxic than Ciloxan or Cipro HC.

Effect of transgenic GDNF expression on gentamicin-induced cochlear and vestibular toxicity

Gentamicin administration often results in cochlear and/or vestibular hair cell loss and hearing and balance impairment. It has been demonstrated that adenovirus-mediated overexpression of glial cell line-derived neurotrophic factor (GDNF) can protect cochlear hair cells against ototoxic injury. In this study, we evaluated the protective effects of adenovirus-mediated overexpression of GDNF against gentamicin ototoxicity. An adenovirus vector expressing the human GDNF gene (Ad.GDNF) was administered into the scala vestibuli as a rescue agent at the same time as gentamicin, or as a protective agent, 7 days before gentamicin administration. Animals in the Rescue group displayed hearing thresholds that were significantly better than those measured in the Gentamicin or Ad.LacZ/Gentamicin groups. In the Protection group, Ad.GDNF afforded significant preservation of utricular hair cells. The data demonstrated protection of the inner ear structure, and rescue of the inner ear structure and function against ototoxic insults. These experiments suggest that inner ear gene therapy may be developed as a clinical tool for protecting the ear against environmentally induced insults.

Ototoxicity of common topical antimycotic preparations

OBJECTIVE

To determine the ototoxic effects of five commonly used topical antimycotic agents-clotrimazole, miconazole, nystatin, tolnaftate, and gentian violet-in the guinea pig.

DESIGN

A controlled animal study in which the ototoxicity of commonly used topical antifungal agents was investigated by measurement of hair cell loss.

METHODS

Several readily available topical antimycotic preparations were instilled into the middle ears of female Hartley guinea pigs over a 1-week period. Two weeks after the last instillation, the animals were euthanized. An active control group was treated with neomycin to confirm the adequacy of the treatment in delivering a known ototoxin; an untreated control group defined the normal distribution of hair cells. The temporal bones were removed, and the cochleas were fixed and dissected. The basilar membranes were examined under the scanning electron microscope. A map of hair cell survival was made for each row in segments of each turn.

RESULTS

The untreated control animals had no discernible hair cell loss in the two lower turns. In the apical turn and sometimes the third turn, loss of hair cells was a common finding, this is a known effect of aging in this species. The animals treated with neomycin had damage consistently in the basal turn, sometimes extending into the second turn, as well as the expected hair cell loss in the apical turn. Clotrimazole, miconazole, or tolnaftate did not cause any hair cell loss in the first two turns. Hair cell loss in the third and fourth turns was similar to that of the untreated control group. Likewise, nystatin exhibited no evidence of ototoxicity. Of note, however, the preparation used in this study left a persistent residue in the round window niche. Of the first four animals treated with gentian violet, three developed pronounced behavioral signs of vestibular damage, and three demonstrated extensive middle ear inflammation and extensive new bone growth. Hair cell counts were not attempted because the extreme bone growth interfered with successful perfusion and dissection.

CONCLUSIONS

Extrapolating from guinea pigs to humans requires caution. However, it is likely that guinea pigs are, if anything, more susceptible to topical ototoxins than are humans. The specific antimycotics clotrimazole, miconazole, and tolnaftate appear to be safe. Gentian violet has the potential for severe damage. The persistent residue left by the nystatin preparation is cause for concern and is a reminder that both the active ingredient and vehicle must be considered in evaluation of safety.

How easily do topical antibiotics pass through tympanostomy tubes?--an in vitro study

BACKGROUND

Despite potential ototoxicity, eardrops containing aminoglycosides remain in widespread use in the presence of indwelling tympanostomy tubes (grommets). It is unclear how readily they pass into the middle ear during administration, nor whether this is affected by middle ear secretions.

MATERIALS AND METHODS

The trans-tympanic pressure required to force antibiotic solutions through a tympanostomy tube in an artificial middle ear model was investigated with six ototopical preparations and two sizes of tube. To assess the effect of middle ear secretions, tympanostomy tubes removed from patients ears were investigated in addition to new tubes. The intra-canal pressure generated during tragal massage was also measured.

RESULTS

Pressures required for leakage of solutions differed significantly between solutions (P=0.001) and tube sizes, smaller lumen tubes requiring higher trans-tympanic pressure for leakage to occur. The presence of middle ear secretions reduced the pressure required for leakage of solution. Tragal massage generated pressures of over 20 cm of H20 which would be enough to force solution into the middle ear in all tube/solution combinations.

DISCUSSION

Some antibiotic solution is likely to leak into the middle ear during most applications of antibiotic solution. Although the risk is small, this suggests the possibility of ototoxicity, previously demonstrated in animal experiments. The relatively low incidence of this occurrence in clinical practice is thought to be related to inter-species anatomical variations.

Topical ofloxacin versus systemic amoxicillin/clavulanate in purulent otorrhea in children with tympanostomy tubes

Acute otitis media (AOM) in children with tympanostomy tubes in place typically presents with otorrhea (draining ear). Because therapy is not standardized, various topical and systemic antibiotics of unproven efficacy and safety have been used in this indication. This study compared the safety and efficacy of ofloxacin otic solution, 0.3% (OFLX) with that of Augmentin oral suspension (AUG) in pediatric subjects 1-12 years of age with tympanostomy tubes and acute purulent otorrhea. Subjects were randomized to receive 10d of OFLX, 0.25 ml topically bid, or of AUG, 40 mg/kg per day. Audiometry was performed in subjects > or =4 years of age. Overall cure rate for clinically evaluable subjects was 76% with OFLX (n = 140) and 69% with AUG (n = 146; P = 0.169). Overall eradication rates for OFLX and AUG were similar for Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis and were superior with OFLX for Staphylococcus aureus and Pseudomonas aeruginosa (P<0.05 for both). OFLX had a greater overall pathogen eradication rate (96% vs. 67%; P<0.001). Treatment-related adverse event rates were 31% for AUG and 6% for OFLX (P<0.001). Neither treatment significantly altered hearing acuity. Topical ofloxacin 0.3% otic solution 0.25 ml bid was as effective and better tolerated than systemic therapy with Augmentin oral suspension 40 mg/kg per day in treating AOM in children with tympanostomy tubes.

Investigation of topical ciprofloxacin ototoxicity in guinea pigs

Antibiotic eardrops mostly contain potentially ototoxic aminoglycosides. Ciprofloxacin is an alternative, and there is limited experience in its topical use. To investigate the topical ototoxicity of ciprofloxacin, 11 guinea pigs have been operated on. Transbullae silicone drug delivery tubes were placed to both ears of the animals. After the operation the guinea pigs were divided into two groups. The first group of animals received 0.2 ml of 4% gentamicin in one ear and 0.2 ml of 0.9% sodium chloride solution in the other. The second group received 0.2 ml of 0.2% ciprofloxacin in the test ear and 0.2 ml of 0.9% sodium chloride solution in the control ear. All drugs were given once a day on 7 consecutive days. Auditory brainstem response thresholds were recorded using click, 4 and 8 kHz logon stimuli before and after the operation, and after topical drug application. Results were statistically compared using Wilcoxon matched pairs signed-ranks test. Comparison of the thresholds before and after the operation, physiological saline application, as well as ciprofloxacin application yielded no statistically significant differences, whereas application of gentamicin resulted in total hearing loss. The results indicate that topical use of 0.2% ciprofloxacin is not ototoxic in guinea pigs.

Treatment of chronic suppurative otitis media with topical ciprofloxacin

To date, only ofloxacin has been approved by the US Food and Drug Administration for treatment of ears with a nonintact tympanic membrane. The purpose of this study was to determine the safety and efficacy of topical ciprofloxacin hydrochloride in the treatment of experimental chronic suppurative otitis media caused by Pseudomonas aeruginosa infection in cynomolgus monkeys. Forty adult cynomolgus monkeys were divided into 4 equal groups, and their ears were challenged with P aeruginosa, drained for 3 weeks, then treated twice daily for 4 weeks with 1 of 4 randomly assigned agents: 1) ciprofloxacin, 2) saline, 3) Cortisporin, or 4) vehicle. The animals were followed up with auditory brain stem response testing, culture, otoscopy, and histopathology. Both ciprofloxacin and Cortisporin treatment resulted in a significantly more rapid rate of clearance of P aeruginosa as compared to treatment with saline (100% versus 20%). Eradication was not associated with resolution of otorrhea after a 4-week period of treatment. There were no significant changes in auditory brain stem response wave latencies for any of the treatment groups. Histopathologic data revealed that there was no statistically significant difference in the amount of outer hair cell loss for the ciprofloxacin group as compared to the control ear and other treatment groups. We conclude, therefore, that topical ciprofloxacin is not ototoxic and is effective in sterilizing the otorrhea, but does not promote resolution of the drainage, in this animal model.

Topical gentamicin and ethacrynic acid: effects on cochlear function

OBJECTIVE

To determine whether concurrent intravenous administration of the loop diuretic ethacrynic acid potentiates the toxicity of the aminoglycoside antibiotic gentamicin applied topically on the round window.

STUDY DESIGN

The authors studied the effects on cochlear sensitivity of co-administered intracardiac ethacrynic acid (40 mg/kg) and high-dose topical gentamicin solution (100%) applied to the round window. Comparisons were made with animals receiving ethacrynic acid plus systemic gentamicin (100 mg/kg); topical gentamicin alone; systemic gentamicin alone; and intravenous ethacrynic acid alone.

METHODS

Experiments were carried out on pigmented guinea pigs weighing 400 to 500 g. Changes in cochlear function were characterized by monitoring shifts in compound action potential (CAP) thresholds by use of chronic indwelling electrodes implanted at the round window, vertex, and contralateral mastoid.

RESULTS

After 20 days animals receiving ethacrynic acid in combination with topical gentamicin to the round window failed to demonstrate a significant deterioration in cochlear sensitivity, whereas all animals receiving systemic gentamicin plus ethacrynic acid experienced profound increases in CAP thresholds.

CONCLUSIONS

This study supports the contention that ethacrynic acid potentiates aminoglycoside ototoxicity by facilitating the entry of the antibiotics from the systemic circulation into the endolymph. In addition, this study answers important clinical concerns regarding the safety of the use of topical aminoglycoside agents in combination with loop diuretics.

Care of the child with tympanostomy tubes

More than two million tympanotomy tubes are placed annually in the United States, making this operation the most common performed on children. This article provides an overview of the applications of tympanotomy tubes for the treatment for otitis media in childhood. The indications for tube placement are discussed; a visual guide for managing children with tympanostomy tubes is presented; an approach to dealing with tube complications is outlined; and guidelines for referral to a pediatric otolaryngologist are suggested.

Effect of cortisporin otic suspension on cochlear function and efferent activity in the guinea pig

To predict cochlear receptor cell insult from therapeutic aminoglycoside antibiotics, we sought to determine whether the presence of subtoxic concentrations of Cortisporin otic suspension in the cochlea can be detected by measuring changes in efferent suppression of compound action potentials recorded from the round window. Olivocochlear efferent suppression in an earlier study was reversibly inhibited by injections of gentamicin in guinea pigs. Using that same technique, we found that 2.0 microliter of Cortisporin otic suspension (neomycin, polymyxin B, hydrocortisone) placed on the round window of guinea pigs in varying concentrations causes a rapid, permanent alteration in thresholds. Solutions of Cortisporin otic suspension diluted to a concentration of 1:20 yield a reversible loss of efferent suppression without measurable changes in compound action potential. These data suggest that the presence of Cortisporin otic suspension can be detected functionally in the cochlea at very low concentrations prior to the development of a threshold shift.

A double-blind comparative study of ofloxacin otic drops versus neomycin-polymyxin B-hydrocortisone otic drops in the medical treatment of chronic suppurative otitis media

Active chronic suppurative otitis media poses a management problem when patients are being considered for surgical treatment. Topical antibiotics have demonstrated varying degrees of success in the management of discharging ears. The introduction of quinolones has revived interest in these topical agents. This double-blind study compares two antibiotics, namely ofloxacin and neomycin-polymyxin B, with similar in vitro sensitivities to Gram positive and Gram negative organisms. Fifty-two patients were selected randomly and the results show that ofloxacin eardrops have marginal benefits in symptomatic improvement (89 per cent versus 79 per cent, p = 0.27) and bacterial eradication (81 per cent versus 75 per cent, p = 0.81) in active chronic suppurative otitis media. Significantly fewer patients (seven per cent versus 29 per cent, p = 0.04) in the ofloxacin group had active disease at the end of the two-week treatment. We recommend the use of ofloxacin eardrops in managing active chronic suppurative otitis media since it has high clinical efficacy, contains no steroid component and has no demonstrated risk of ototoxicity.

Safety of ototopical antibiotics

A prospective randomized study analyzing the safety and efficacy of a single dose of ototopical antibiotics following human middle ear tympanostomy tube insertion was performed. Fifty children undergoing bilateral tympanostomy tube insertion were studied by the placement of 0.5 mL of Cortisporin Otic Suspension (COS; Burroughs Wellcome Co., Research Triangle Park, N.C.) to one middle ear space by random assignment. Preoperative and postoperative audiograms were obtained, and the presence of otorrhea was noted. In one patient sensorineural hearing loss of 6 dB developed bilaterally, which was symmetric in both the treated and the untreated ear. This preliminary study showed no statistical difference in hearing loss or postoperative otorrhea associated with a single application of Cortisporin to the middle ear space.

Therapeutic management of chronic suppurative otitis media with otic drops

The use of potentially ototoxic topical drugs is controversial. Few experimental reports of audiometric data from human subjects exist. The purpose of this study is to determine if a significant difference between bone conduction hearing sensitivity before and after otic drop treatment for children with chronic suppurative otitis media and patent ventilation tubes exists. A statistical analysis of sensorineural threshold status after treatment of chronic suppurative otitis media with otic drops is presented.

Interactive inner-ear/middle-ear disease, including perilymphatic fistula

Pathologic interactions between the middle ear and inner ear occur with 1) congenital anomalies, 2) trauma, 3) infection/inflammation, 4) tumors, 5) granulomas, 6) ototoxic eardrops, 7) cochlear implants, 8) otosclerosis, 9) Meniere's disease (decompensated) and Meniere's disease (with perilymphatic fistula), and 10) perilymphatic hypertension. Clinical and pathological characteristics are briefly categorized in this survey. Comments are made concerning the clinical utility of exploratory tympanotomy in diagnosis and treatment of pathologic conditions in the middle ear and pathologic conditions that are interactive between middle ear and inner ear.

Toxicity of ototopical drugs: animal modeling

It is important to be aware of the potential ototoxicity of any drug, vehicle, or antiseptic that is used in the middle ear. Frequently used ear drops (Cortisporin otic suspension, Coly-Mycin S Otic, and VoSoL otic solution) were studied for their ototoxicity. Compound action potentials were measured before and at 1, 2, and 24 hours following drug application on the round window membranes of chinchillas. Each drug was applied for 10 minutes and then was removed by rinsing. The sound pressure in decibels sound pressure level that produced a compound action potential amplitude of 10 microV was defined as the threshold. The change in threshold was interpreted as hearing loss. On the basis of the short-term results at 24 hours following drug application, the ototoxicity of Coly-Mycin was calculated to be twice that of Cortisporin, and the ototoxicity of VoSoL four times that of Cortisporin.

Experimental induction of middle ear cholesteatoma in rats

We induced cholesteatoma in two groups of rats by instilling different concentrations of propylene glycol into the middle ear cavity. Fifteen rats were exposed to 50% propylene glycol (group I), while pure propylene glycol was applied to six others (group II). The group I rats were killed 1 month after instillation. Seven of the 15 showed cholesteatoma in the middle ear with accumulation of keratin debris. The group II rats were killed 3 months after instillation. All six animals showed inflammation in the experimental ears, and five of the six experimental ears showed cholesteatoma in the middle ear cavity. Six experimental ears in group I and five in group II revealed retraction of the tympanic membrane, possibly due to eustachian tube obstruction. Bone resorption was seen along with cholesteatoma and inflammatory cells and osteoclasts in the middle ear of all 11 of these rats. The seventh cholesteatoma of group I can be classified as a microcholesteatoma, a pearl-like cyst within the tympanic membrane. The microcholesteatoma was formed by an invasion of basal cells from the tympanic epidermis and the proliferation of these cells in the fibrous layer of the tympanic membrane. Our findings suggest that cholesteatoma in the middle ear cavity is a response to the inflammation produced by high concentrations of propyleme glycol.

Inflammatory effects of topical antibiotic suspensions containing propylene glycol in chinchilla middle ears

This study examines the occurrence of inflammatory changes and cholesteatoma in the middle ears of seven chinchillas after the application of topical antibiotic suspensions containing two different concentrations of propylene glycol. The preparations used were Cortisporin otic suspension, which contains neomycin, polymyxin B, hydrocortisone, and 10.5% propylene glycol, and Cortisporin ophthalmic suspension, containing the same ingredients, but only a 2% concentration of propylene glycol. Six weeks after the administration of the Cortisporin preparations, applied to the middle ear through a transbulla approach, no cholesteatomas were found in the seven ears treated with the ophthalmic suspension. Evidence of mild inflammation was present in only two of these ears. In the seven contralateral ears treated with the otic suspension, middle ear adhesions were found in six, cholesteatoma was present in four, serous effusions were found in three, and one had a large tympanic membrane perforation. The ears that showed cholesteatomas also had histologic evidence of squamous metaplasia, granulation tissue, and erosion of the underlying bone. We submit that the pathologic responses of the middle ear mucosa treated with the otic suspension, were due to an inflammatory response to the higher concentration of propylene glycol compared to that of the ophthalmic suspension.

Survey of interactions between middle ear and inner ear

Diseases with interaction between the middle ear and inner ear include 1) congenital anomalies, 2) trauma, 3) infection/inflammation, 4) tumors, 5) granulomas, 6) ototoxic eardrops, 7) cochlear implants, 8) otosclerosis, 9) Meniere's disease-decompensated, and Meniere's disease with perilymphatic fistula, and 10) perilymphatic hypertension. Clinical and pathological characteristics are briefly categorized in this survey. The clinical utility of exploratory tympanotomy in diagnosis and treatment of middle ear pathology and middle ear/inner ear interactions is commented upon.

Toxic effects on inner ear of noxious agents passing through the round window membrane

The effects on inner ear of Xylocain, EMLA, phenol, endotoxin and hydrocortisone were analysed before treatment and 24 h-6 months after instillation of each drug into the round window (RW) niche, where the substance was left. Inner ear function was determined by repeated auditory brainstem recordings (ABR). All cochleae were analysed morphologically at the light microscopic level. Hydrocortisone, Xylocain and endotoxin caused functional changes without morphological correlates, even at long-term follow-up. In contrast, phenol and EMLA caused both functional impairment and graded morphological damage to the organ of Corti in the basal coil. Outer hair cells (OHC) were more vulnerable than inner hair cells (IHC).

Pigmented epithelial cells of the membranous saccular wall of the chinchilla

The posterior-superior portion of the membranous wall of the chinchilla saccule is lined by pigmented epithelial cells which contain golden brown granules having three components (lipid droplets, granular matrix, and dense globules). Histochemical and electronmicroscopic studies indicate that the dense component is a form of melanin. The pigmented cells show morphological features suggestive of fluid transport function; they are also involved in decalcification and phagocytosis of otoconial crystals. These findings provide evidence that the saccular wall epithelium plays an active role in regulating endolymph composition and in clearance of debris from the endolymphatic space.

Polymyxin-B-binding sites in the cochlea as demonstrated by polymyxin-B/gold labeling

A polymyxin-B/bovine-serum-albumin/gold complex was used as a probe to detect the binding sites of polymyxin B on thin sections of cochlea embedded in Spurr's resin. The binding sites were found to be mainly located on the stereocilia, the cuticular plate of hair cells, the head plate of Deiters' cells, the tonofilaments in pillar cells and Deiters' cells, fibrous structures in the spiral limbus, the tectorial membrane and the basilar membrane and neural elements such as nerve endings, fibers, and the myelin sheath. The mitochondria, plasma membrane, and chromatin of the nuclei of the cells observed also exhibited binding. Our results suggest that phospholipids, glycoconjugates, cytoskeletal proteins and nucleic acids are responsible for this binding activity.

Middle ear cholesteatoma: an animal model

Topical otic preparations now in clinical use contain a variety of antibiotics and solvents that may produce severe inflammation if they reach the middle ear cavity. This report describes the response of the chinchilla middle ear to direct application of one such preparation that appears to act as a nonspecific irritant. Cortisporin otic suspension (containing neomycin, polymyxin B, hydrocortisone, and propylene glycol) was introduced into the bullae of 32 chinchillas that were kept alive for four days to five months before histologic examination of their temporal bones. All the experimental animals had tissue damage and inflammation within the middle ear. The changes observed included proliferation of ciliated and secretory columnar cells, formation of granulation tissue, bone erosion, and osteoneogenesis. Some areas of the mucosa underwent metaplasia to stratified squamous epithelium; this metaplastic epithelium, however, did not produce keratin. In the majority of animals kept for two months or more, cholesteatoma was identified in the middle ear. The cholesteatomas appeared to develop as a result of penetration of external canal epidermis through intact tympanic membranes or as the result of migration of epidermis through perforations. The experimental cholesteatomas behaved like those seen clinically in humans, with extensive erosion of bony structures within the middle ear.

Surface morphology of the inner sulcus and related epithelial cells of the cochlea following acoustic trauma

When the organ of Corti is severely traumatized by intense (160 dB) blast waves, such that as much as 7 mm of Corti's organ is torn loose from the basilar membrane, the cells of the inner sulcus respond to the altered biochemical milieu of the endolymph by a profile elaboration of surface membrane, zeiosis and the development of numerous pseudopodia and microvilli. On the basis of our longitudinal study, this surface reaction appears to peak at approximately 10 days after trauma and may indicate that the inner sulcus cells are extremely active in the endocytosis of cellular debris. Signs of active changes on the surface of the inner sulcus cells occur immediately following trauma, and activity continues for as long as 30 days after exposure. The cells of Claudius, as well as other epithelial cells on the basilar membrane, are also capable of extreme membrane proliferation and mobility. Possible mechanisms for the unusual behavior and the role of the inner sulcus cells in the normal functioning cochlea are discussed.