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Efficacy and safety of 1.5% levofloxacin otic solution for the treatment of otitis media in a multicenter, randomized, double-blind, parallel-group, placebo-controlled, phase III study

Open AccessPublished:January 02, 2023DOI:https://doi.org/10.1016/j.anl.2022.12.013

      Abstract

      Objective

      The present study aimed to evaluate the efficacy and safety of 1.5% levofloxacin (LVFX) otic solution for the treatment of patients with otitis media.

      Methods

      This multicenter, randomized, double-blind, parallel-group, placebo-controlled phase 3 trial was conducted at 34 institutions in Japan. A total of 202 patients with chronic suppurative otitis media (CSOM) or acute otitis media (AOM) were randomized into either the LVFX group or placebo group. A total of 6–10 drops of 1.5% otic solution of LVFX or its matching placebo were administered in the diseased ear twice daily, in the morning and evening for up to 10 days. Images corresponding to three clinical findings—purulent otorrhea, hyperemia (redness), and granulation tissue formation in the middle ear and tympanic membrane—for each diseased ear were evaluated using digital endoscopy by a blinded central independent review committee (BICRC) at each visit after treatment administration.

      Results

      In total, the data of 201 participants (LVFX group, 99; placebo group, 102) were analyzed. The proportion of patients with disappearance (improvement rate) of all three clinical findings at the end of treatment or discontinuation by the BICRC was 46.5% (46/99) in the LVFX group and 23.5% (24/102) in the placebo group, and the difference (95% confidence interval) between the groups was 22.0% (8.7, 34.2), with a significantly higher improvement rate in the LVFX group than in the placebo group (p = 0.001; Cochran–Mantel–Haenszel test), demonstrating the efficacy of LVFX. The bacterial eradication rates were 93.9% (77/82) and 12.5% (11/88) in the LVFX and placebo groups, respectively, and the rate was significantly higher in the LVFX group than in the placebo group (p < 0.001). Treatment-related adverse events (AEs) occurred in 5.1% (5/99) and 7.8% (8/102) of the patients in the LVFX and placebo groups, respectively, and no significant difference was noted in incidence rate between the groups.

      Conclusion

      The clinical efficacy of 1.5% LVFX otic solution for CSOM and AOM was demonstrated by the resolution of inflammation in the middle ear and tympanic membrane as well as through the high bacterial eradication rate observed. No deaths or serious treatment-related AEs were observed. The study provided confirmation that 1.5% LVFX otic solution is a safe, well-tolerated, and effective treatment for CSOM and AOM.

      Keywords

      1. Introduction

      Administration of antibiotics is the most common treatment method for chronic suppurative otitis media (CSOM) and acute otitis media (AOM). Antibiotics can be administered either systemically or topically, and topical usage is considered to be advantageous in terms of achieving higher topical concentration of these drugs. Clinically, achievement of a higher concentration of antibiotic per dose in the middle ear is a key factor that can reduce bacterial resistance among community- and hospital-acquired pathogens, which is associated with the inappropriate use of systemic antibiotics.
      As a topical antibiotic treatment method for CSOM and AOM, five otic solutions have been approved as prescription drugs in Japan: ofloxacin, lomefloxacin hydrochloride, cefmenoxime hydrochloride, fosfomycin sodium, and chloramphenicol. Among these, ofloxacin (Tarivid® Otic Solution 0.3%), which is indicated for many bacterial species, is racemic, whereas its optically active (S-(-)) form, levofloxacin (LVFX), has approximately twice the antibacterial activity of ofloxacin in vitro. Despite this theoretical advantage of LVFX, no otic solution has been developed [
      • Hayakawa I
      • Atarashi S
      • Yokohama S
      • Imamura M
      • Sakano K
      • Furukawa M.
      Synthesis and antibacterial activities of optically active ofloxacin.
      ,
      • Une T
      • Fujimoto T
      • Sato K
      • Osada Y.
      In vitro activity of DR-3355, an optically active ofloxacin.
      ,
      • Tanaka M
      • Otsuki M
      • Une T
      • Nishino T.
      In-vitro and in-vivo activity of DR-3355, an optically active isomer of ofloxacin.
      ,
      • Takahashi H
      • Hayakawa I
      • Akimoto T.
      [The history of the development and changes of quinolone antibacterial agents].
      ]. Application of higher topical concentrations of the active agent is typically important for quinolone otic solutions because it is hypothesized that the “area under the blood concentration-time curve (AUC) to minimum inhibitory concentration (MIC) ratio (AUC/MIC)” is mostly correlated with therapeutic efficacy and that the “maximum blood concentration (Cmax) to MIC ratio (Cmax/MIC)” is mostly correlated with inhibiting resistance [
      • Craig WA.
      Does the dose matter?.
      ,
      • Totsuka K
      • Kohno S
      • Matsumoto T
      • Sunakawa K
      • Shiba K.
      Overview of new dosage and administration of levofloxacin, 500 mg once a day.
      ,
      • Fujihara K
      • Hotomi M
      • Yamanaka N.
      An appropriate selection of antimicrobial agents for intractable otitis media.
      ].
      Recently, CEOLIA Pharma Co. Ltd. (Tokyo, Japan) developed a new otic solution, which contains 1.5% LVFX, as a treatment option for CSOM and AOM. Theoretically, this solution provides a 10-fold higher concentration (five times more concentration and two times due to racemization) of the active agent than of the existing ofloxacin otic solutions. Herein, we reported a multicenter, randomized, double-blind, placebo-controlled, parallel-group study to objectively evaluate the efficacy and safety of 1.5% LVFX otic solution for the treatment of otitis media.

      2. Patients and methods

      2.1 Study design

      This multicenter, randomized, double-blind, placebo-controlled, parallel-group, phase 3 trial was conducted at 34 institutions in Japan from May 2019 to June 2021 in compliance with Good Clinical Practice. The study protocol and other relevant documents were reviewed and approved by the institutional review boards at all participating centers.
      A blinded central independent review committee (BICRC), excluding the trial investigators, was established to evaluate the digital endoscopic images of the tympanic membrane and tympanic cavity.

      2.2 Population

      Patients who were diagnosed with AOM or CSOM and who presented with perforation of the tympanic membrane, persistent purulent otorrhea, with or without ventilation tubes, granulation tissue formation, or erosion were included. All participants aged ≥ 15 years who provided written informed consent to participate in this study were enrolled. For patients aged < 20 years, written informed consent was also obtained from their parents or guardians. Patients who met the following criteria were excluded from this study: (i) patients who were not eligible for antibiotic treatment, such as patients with eosinophilic otitis media, cholesteatoma, chronic otitis media with effusion, or otitis media with antineutrophil cytoplasmic antibody-associated vasculitis; (ii) patients with otitis media with signs of fungal infection, Mycobacterium tuberculosis, or viral infection; (iii) patients with mastoiditis or patients who have already demonstrated progressive pure-tone bone-conducting threshold elevation; (iv) patients with cochlear implants or other implantable hearing devices; (v) patients with a history of allergy to LVFX hydrate or quinolone antibiotic agents; and (vi) patients judged as ineligible by the trial investigators.

      2.3 Randomization and masking

      The randomization code was prepared by the allocation manager (EPS Corp., Tokyo, Japan). Patients who met the eligibility criteria were enrolled via an Internet-based registration system and were randomly allocated to either the investigational drug (i.e., LVFX) or placebo group in a 1:1 ratio using dynamic allocation with a minimization approach with the facility and diseased ear as allocation factors to minimize bias. All trial investigators, patients, and study personnel, including the sponsor and their representatives, remained blinded to details about treatment allocation during the study period and until after database lock. The investigational drug was 1.5% LVFX otic solution, and the placebo drug was a 5-mL otic solution without the active ingredient. Both solutions were provided in a green translucent polyethylene container used for otic application. The label of the randomization numbers was affixed to the outer box containing six containers, and they were visually identical.

      2.4 Procedures

      A total of 6 to 10 drops of 1.5% LVFX otic solution or the matching placebo were administered in the diseased ear twice daily, in the morning and evening. After applying the ear drops into the ear, the patients were advised to keep their head tilted for 10 min. The number of drops at the initial dose for participants in whom pharmacokinetics (PK) (i.e., blood transferability) was evaluated was set to 10 drops per dose. The study drug was administered for up to 10 days. The application of the drug was discontinued when the investigators judged that the treatment had been successful and further treatment was not required.

      2.5 Study discontinuation

      The participants were free to withdraw from the study at any time. Those who met the following criteria were withdrawn from this study: (1) patients in whom symptoms worsened, with the trial investigators considering that an alternative treatment was required (discontinuation due to lack of efficacy); (2) patients in whom a moderate or severe treatment-related adverse event (AE) occurred; (3) patients in whom a major violation of the protocol was recorded; and (4) patients who required to discontinue this study per investigators’ discretion.

      2.6 Concomitant therapy

      During the study period, suction was permitted for otorrhea only, and irrigation of the tympanic cavity was prohibited. Otology-related surgery (except for insertion of a ventilation tube and tympanostomy) was also prohibited. In addition, suction was not performed prior to the completion of digital endoscopy of the tympanic membrane and tympanic cavity. The concomitant use of any otic solutions, systemic antibiotics, and corticosteroids was prohibited.

      2.8 Assessment

      2.8.1 Tympanic membrane and tympanic cavity findings

      The trial investigators evaluated the resolution of inflammation using digital endoscopy based on the following findings: purulent otorrhea, hyperemia (redness), and granulation tissue formation in the middle ear and tympanic membrane for each diseased ear. Assessments were made at screening, at visit 1 (the day of initial administration), visit 2 (days 3 to 6 of administration), visit 3 (days 7 to 9 of administration), visit 4 (1 to 4 days after completion of administration, including patients in whom treatment was discontinued or terminated), and visit 5 (9 to 14 days after completion of administration). In addition, disappearance or persistence of all findings was evaluated according to the “resolution criteria” (overall evaluation).
      Imaging findings of the tympanic membrane and tympanic cavity obtained using digital endoscopy at screening and each visit (including patients who had discontinued or terminated treatment) were submitted to the BICRC. The BICRC evaluated the efficacy of the drug based on digital endoscopic findings in a blinded manner. Findings were evaluated for each measurement using the criteria listed in Table 1.
      Table 1Criteria for evaluation of purulent otorrhea and findings in the middle ear mucosa and tympanic membrane.
      SymptomsFindings in middle ear mucosa and tympanic membrane
      Purulent otorrheaHyperemia (redness)Granuloma
      Criteria for evaluationNoneNoneNone
      Otorrhea other than purulentPartialWithout purulent otorrhea
      Purulent otorrheaWholeWith purulent otorrhea
      If the findings of the middle ear mucosa and the tympanic membrane could not be confirmed and/or the images could not be acquired using digital endoscopy due to a large amount of otorrhea, it was judged as "unassessable."

      2.8.2 Time to cessation of purulent otorrhea

      The first date was defined as the date of treatment initiation, and the event was defined as the date of cessation of purulent otorrhea collected via a patient diary (ear subjective symptoms). If the participant had bilateral disease, the event was defined as the later date of cessation. If cessation was confirmed using the patient diary, the trial investigator confirmed the absence of purulent otorrhea by digital endoscopy on the most recent patient visit. If this could not be confirmed by the trial investigator, the study was continued. If cessation was not confirmed by the patient diary and the trial investigator confirmed the absence of purulent otorrhea by digital endoscopy at any visit, that visit date was considered as the event. For participants whose otorrhea had not stopped at the end of the study, the last observation date when the trial investigator confirmed presence of the purulent otorrhea by digital endoscopy was considered the censoring date. For those who discontinued treatment owing to lack of efficacy, the discontinuation date or the last observation date was also considered the censoring date.

      2.8.3 Bacteriological tests

      Middle ear secretions (otorrhea) were collected at screening and at the end of treatment or discontinuation (EOT) (if middle ear secretions remained) by placing the tip of a swab into the middle ear cavity and then directly into the transport culture medium (BD BBL Culture Swab Plus, Becton Dickinson Japan, Inc., Tokyo, Japan). Samples were sent to BML Corp. (Saitama, Japan). The pathogenic microorganisms were isolated and identified, and the MIC of LVFX was determined using frozen plates according to the trace liquid dilution method, the standard method of the Japanese Society of Chemotherapy [
      • Goto S
      • Okada J
      • Oguri T
      • Kanno S
      • Yamaguchi K
      • Watanabe K.
      MIC assay by the micro-dilution (Broth micro-dilution method).
      ]. If otorrhea was present within the external ear canal with a perforated tympanic membrane, the pre-existing otorrhea was first cleaned by suction or wiping, and the newly leaked otorrhea from the middle ear cavity was collected to avoid contaminating the normal bacterial flora and other organisms.

      2.8.4 Plasma concentrations of levofloxacin

      Blood samples were collected from patients who provided written informed consent to measure their plasma concentrations of LVFX before the first (morning) administration and at 30, 60, 120, 240, and 360 min after administration. After collection, blood was centrifuged immediately at 4°C for 10 min at 3000 rpm, and plasma components were separated and frozen in a freezer below –20°C pending analysis. Plasma concentrations of LVFX were determined using validated liquid chromatography at a central laboratory (SNBL Ltd., Kagoshima, Japan).

      2.8.5 Audiometry

      Audiologic assessments by means of pure-tone audiometry were performed at screening and at study completion or discontinuation of treatment. The thresholds for each frequency using the standard 5-dB adaptive method were determined at 125, 250, 500, 1000, 2000, 4000, and 8000 Hz.

      2.8.6 Equilibrium function test

      Gaze and non-gaze nystagmus (seated frontal examination under Frenzel goggles) were assessed at screening and at study completion or discontinuation.

      2.8.7 Safety assessment

      Safety was assessed based on AEs, which included clinical findings and abnormal changes in laboratory tests during the study period. Among AEs, those judged to be “related” to the study drug were considered to be treatment-related AEs.

      2.9 Outcomes

      2.9.1 Primary endpoint

      The primary endpoint was the proportion of patients with disappearance of all three clinical findings of purulent otorrhea, hyperemia (redness), and granulation tissue formation in the middle ear mucosa and tympanic membrane, assessed by the BICRC at EOT (improvement rate). If bilaterally diseased, the resolution of all findings bilaterally was required.

      2.9.2 Resolution criteria (clinical efficacy)

      The clinical efficacy of each symptom was determined according to the following criteria.
      • (1) Purulent otorrhea resolved: When purulent otorrhea was improved to “none” or “otorrhea other than purulent” in the symptom evaluation after treatment, the case was classified as “resolved.”
      • (2) Hyperemia (redness) resolved in the middle ear mucosa and tympanic membrane:
      • 1)
        If there were no findings at screening or visit 1 and no new findings had developed after the treatment, the case was classified as “none.”
      • 2)
        If findings were “partial” or “whole” at screening or visit 1 and the findings had improved to “none” after the treatment, the case was classified as “resolved.”
      • 3)
        Findings were unassessable at screening and visit 1 owing to otorrhea, and the evaluation of findings was assessable after the treatment; if the findings were “none,” the case was classified as “resolved.”
      • (3) Granulation resolved in the middle ear mucosa and tympanic membrane:
      • 1)
        If there was no granulation tissue formation at screening or visit 1, and no new granulation tissue had developed after the treatment, the case was classified as “none.”
      • 2)
        If the patient had “granulation tissue formation without purulent otorrhea” at screening or visit 1 and the granulation remained “granulation tissue without purulent otorrhea” and there was no increase in granulation lesions after the treatment, the case was classified as “unchanged”; and if there was “no granulation,” the case was classified as “resolved.”
      • 3)
        If the patient had “granulation tissue formation with purulent otorrhea” at screening or visit 1 and the evaluation of findings after the treatment showed “granulation tissue without purulent otorrhea” and no increase in granulation lesions, the case was classified as “improved”; if the patient had “no granulation tissue formation” after the treatment, the case was classified as “resolved.”
      • 4)
        If findings at screening and visit 1 were unassessable and the evaluation of findings became assessable after the treatment because of the disappearance of purulent otorrhea, and if the findings were “granulation tissue formation without purulent otorrhea” or “no granulation,” the case was classified as “resolved.”
      The overall evaluation was determined according to the criteria shown in Table 2.
      Table 2Overall evaluation criteria for clinical efficacy.
      SymptomsResolution criteria (Clinical efficacy)
      • (1)
        Purulent otorrhea resolved
      None, otorrhea other than purulent
      • (2)
        Hyperemia (redness) resolved in the middle ear mucosa and tympanic membrane
      None, resolved
      • (3)
        Granuloma resolved in the middle ear mucosa and tympanic membrane
      Unchanged, improved, resolved or none
      Overall evaluationIf all symptoms met the above criteria, classified as “Disappearance”

      2.9.3 Secondary endpoints

      The secondary endpoints included clinical efficacy based on the resolution of middle ear and tympanic membrane assessed by the trial investigators at EOT, clinical efficacy at visit 5 (9 to 14 days after the treatment termination), the time to cessation of purulent otorrhea, the bacterial eradication rate, MIC for pathogenic organisms, and the rate of change in the nature of otorrhea.

      2.10 Statistical analyses

      The improvement rates in CSOM for the LVFX and placebo groups were assumed to be 60% and 35%, respectively, with a difference of 25% with reference to a previously published study [
      • Macfadyen C
      • Gamble C
      • Garner P
      • Macharia I
      • Mackenzie I
      • Mugwe P
      • et al.
      Topical quinolone vs. antiseptic for treating chronic suppurative otitis media: a randomized controlled trial.
      ]. Based on the assumption of an alpha level of 0.5 and a power of 0.9 and allowing for withdrawal of 20% of participants, a total of 200 participants (100 per group) were estimated to be required.
      Data management and statistical analyses were performed by an independent vendor (EPS Corp.). The analysis population for the primary endpoint and similar secondary endpoints was the full analysis set (FAS). The analysis population for the bacterial eradication was microbial FAS. Data are summarized with descriptive statistics. The rate and corresponding two-sided 95% confidence interval (CI) for each treatment group were calculated. Differences between treatment groups and their two-sided 95% CIs were also calculated. In addition, for the primary analysis, the difference in the rate and its two-sided 95% CI adjusted by the Mantel–Haenszel method using the diseased ear as a stratification factor were calculated and compared between the two groups using the Cochran–Mantel–Haenszel test.
      The analysis population for the time to cessation of purulent otorrhea was intention-to-treat. The Kaplan–Meier method was used to estimate the time to cessation of otorrhea. Stratified log-rank tests, with the diseased ear as the stratum, were used for between-group comparisons.
      The analysis set of MICs for pathogenic organisms was microbial intention-to-treat. A list of characteristics (frequency, MICrange, MIC50, MIC80, and MIC90 by pathogenic organisms) of MICs for LVFX was prepared.
      Statistical analyses were performed using SAS version 9.4 (SAS Institute Inc., Cary, NC, USA), and PK analyses were performed using WinNonlin version 8.1 (Certara Inc., Princeton, NJ, USA). AEs were classified according to the Medical Dictionary for Regulatory Activities Japanese translation version 24.0.

      3. Results

      3.1 Participants

      A total of 202 patients were enrolled in this study, with 99 patients randomized into the LVFX group and 103 into the placebo group. One patient in the placebo group did not receive placebo drug; therefore, 201 patients (LVFX group, 99; placebo group, 102) were finally included in this study. In total, 96 and 97 patients in the LVFX and placebo groups, respectively, completed the treatment. Finally, 89 and 66 patients in the LVFX and placebo groups, respectively, completed the follow-up (visit 5) (Fig. 1).
      Fig 1
      Fig. 1Consolidated Standards of Reporting Trials flow diagram.
      a If the patient's treatment was completed and an alternative treatment was required, the follow-up visit is not performed.
      Abbreviations: AE, adverse event; MIC, minimum inhibitory concentration; FAS, full analysis set; ITT, intention-to-treat; mFAS, microbial full analysis set; SAF, safety analysis set
      Three and five patients in the LVFX and placebo groups, respectively, discontinued treatment during the study. Among the discontinuations in the LVFX group, one patient experienced a moderate adverse drug reaction, and, regarding the remaining two patients, the study investigator deemed that it was inappropriate to continue the study. In the placebo group, four patients experienced worsening symptoms, and the trial investigator chose to pursue alternative treatment. Moreover, the remaining one patient in the placebo group experienced a moderate or severe AE, and the trial investigator opted to discontinue the treatment. The demographic characteristics and other baseline values for the FAS are shown in Table 3.
      Table 3Demography and baseline characteristics of the subjects involved in the study
      CharacteristicsLevofloxacin groupPlacebo group
      (n = 99)(n = 102)
      Sex, n (%)
       Male55 (55.6)50 (49.0)
       Female44 (44.4)52 (51.0)
      Age, mean (SD), y65.1 (16.2)66.8 (15.1)
      Diseased ear
       One side96 (97.0)96 (94.1)
       Both sides3 (3.0)6 (5.9)
      Diagnosis
       Acute otitis media8 (8.1)7 (6.9)
       Chronic otitis media91 (91.9)95 (93.1)
      Microbiologic culture
       Positive82 (82.8)88 (86.3)
       Negative17 (17.2)14 (13.7)
      Abbreviations: SD, standard deviation.

      3.2 Efficacy

      The primary endpoint of this study, the proportions of patients with disappearance of all three clinical findings of purulent otorrhea, hyperemia (redness), and granulation tissue formation in the middle ear mucosa and tympanic membrane, assessed by the BICRC at EOT, were 46.5% (46/99) in the LVFX group and 23.5% (24/102) in the placebo group. The difference (95% CI) in the improvement rate between the LVFX and placebo groups, adjusted by the Mantel–Haenszel method with the diseased ears as a stratification factor, was 22.0% (8.7, 34.2), with statistical significance confirmed by the Cochran–Mantel–Haenszel test (p = 0.001) (Fig. 2A).
      Fig 2
      Fig. 2A) Improvement rate evaluated by the BICRC. B) Improvement rate evaluated by a trial investigator.
      The mean improvement rates and two-sided 95% CIs (Wilson score) in the FAS population in each group are indicated.
      The improvement rate of the overall clinical effect is calculated based on the resolution of inflammation in the middle ear and tympanic membrane at the EOT in each group: purulent otorrhea, hyperemia, and granuloma.
      The differences in the improvement rate and its two-sided 95% CI adjusted by the Mantel–Haenszel method, using the diseased ear as a stratification factor, were calculated. The Cochran–Mantel–Haenszel method, with diseased ears as a stratification factor, is used to compare the two groups.
      Regarding improvement in granulation, the incidence rates of no granulation tissue formation and “unassessable” at screening were 57.8% (57/99) and 21.2% (21/99) in the LVFX group and 58.8% (60/102) and 22.5% (23/102) in the placebo group, respectively. The term “unassessable” can contain some indication of no granulation cases. In particular, this is because granulation was not present at screening; therefore, high improvement rates were considered to be relatively noted in both groups.
      Abbreviations: FAS, full analysis set; CI, confidence interval; EOT, end of treatment or discontinuation; BICRC, blinded central independent review committee
      In addition, according to the trial investigator's assessment, the improvement rates at EOT were 62.6% (62/99) in the LVFX group and 24.5% (25/102) in the placebo group. With the diseased ears as stratification factors, the difference (95% CI) in the improvement rate between both groups, adjusted by the Mantel–Haenszel method, was 38.0% (24.5, 49.6), with a statistically significant difference (p < 0.001), and this was a greater improvement than that of the BICRC evaluation (Fig. 2B). Further, the improvement rates for each individual finding, such as purulent otorrhea, hyperemia, and granuloma, by the BICRC and the trial investigator, are shown in Fig. 2A and B. The improvement rate of purulent otorrhea and hyperemia in the LVFX group, as evaluated by the trial investigator, was higher than that evaluated by the BICRC.
      Regarding the clinical efficacy at visit 5 (follow-up) by the BICRC, the improvement rate of 61.8% (55/89) in the LVFX group was significantly higher than the 31.8% in the placebo group (21/66) (p < 0.001).
      The median (95% CI) time to cessation of purulent otorrhea in the BICRC assessment estimated by the Kaplan–Meier method was significantly different between the two groups (7.0 [7.0, 8.0] days in the LVFX group vs. 22.0 [14.0, not estimable] days in the placebo group, log-rank test, p < 0.001). In addition, the hazard ratio (95% CI) estimated using Fine–Gray modeling with study withdrawal as a competing risk was 2.949 (2.099, 4.143) by the BICRC. The Gray test showed statistically significant differences between the two groups (p < 0.001) (Fig. 3).
      Fig 3
      Fig. 3Time to cessation of purulent otorrhea estimated by the Kaplan–Meier method (evaluation by the BICRC).
      The median (95% confidence interval) time to cessation of purulent otorrhea estimated by the Kaplan–Meier method in the intention-to-treat population in each group is indicated. Gray test is used to compare the two groups.
      Abbreviations: BICRC, blinded central independent review committee
      The characteristics (frequency, MICrange, MIC50, MIC80, and MIC90 of MICs by pathogens) of MICs for LVFX in both groups are presented in Table 4. The bacterial eradication rates were 93.9% (77/82) in the LVFX group and 12.5% (11/88) in the placebo group. The difference (95% CI) in bacterial eradication rates between both groups was 81.4% (70.1, 87.8), with significantly higher bacterial eradication rates in the LVFX group than in the placebo group (p < 0.001) (Table 5). In the LVFX group, 83.3% of the methicillin-resistant Staphylococcus aureus (MRSA) strains and 88.9% of P. aeruginosa strains were eradicated. When viewed by the MIC of LVFX, only one out of the four strains with an MIC of 16 μg/mL and only one out of the five strains with an MIC of > 64 μg/mL were not eradicated, whereas all strains with an MIC of ≤ 8 μg/mL were eradicated. When examined by species, for MRSA, all three strains with MICs ≤ 4 μg/mL, one out of one strain with MICs > 64 μg/mL, and one out of two strains with MICs ≤ 16 μg/mL were eradicated. For P. aeruginosa, all six strains with MICs ≤ 2 μg/mL and two of the three strains with MICs > 64 μg/mL were eradicated. In the placebo group, the bacterial eradication rates by species ranged from 0.0% to 100.0%. Among the bacterial pathogens detected in both the LVFX and placebo groups, the bacterial eradication rate was higher in the LVFX than in the placebo group at ≥ 60% for Achromobacter sp., Acinetobacter baumannii, Klebsiella pneumoniae, MRSA, methicillin-susceptible S. aureus, P. aeruginosa, Serratia marcescens, and Staphylococcus lugdunensis. In contrast, 66.7% to 100% eradication rates were observed in coagulase-negative Staphylococci, such as Staphylococcus capitis, Staphylococcus epidermidis, and Staphylococcus caprae, in the placebo group, with differences as small as 0% to 33.3% from the values observed in the LVFX group.
      Table 4Minimal Inhibitory Concentration (MIC) of Levofloxacin for each Pathogen (MITT)
      The analysis population of MICs for each pathogen was set as MITT. A list of characteristic (frequency, MICrange, MIC50, MIC80 and MIC90 of MICs by pathogens) of MICs for levofloxacin was prepared by both groups in MITT population.
      .
      Organisms (Number of strains)Number of isolatesMICrange
      MICrange, minimal, and maximum inhibitory concentrations at which isolates were inhibited. If the minimum and maximum values are the same, only one is displayed.


      (μg/mL)
      MIC50
      MIC50, minimal inhibitory concentration at which 50% of isolates were inhibited.


      (μg/mL)
      MIC80
      MIC80: the minimal inhibitory concentration at which 80% of isolates were inhibited.


      (μg/mL)
      MIC90
      MIC90: the minimal inhibitory concentration at which 90% of isolates were inhibited.


      (μg/mL)
      Gram-positive bacteriaStaphylococcus (146)
       MSSA (S.aureus)820.06 - 640.250.54
       MRSA (S.aureus)130.125 - >6481664
      Staphylococcus capitis160.125 - >6448>64
      Staphylococcus caprae130.06 - 648832
      Coagulase(-)staphylococcus100.125 - >6421664
      Staphylococcus epidermidis60.06 - 640.256464
      Staphylococcus lugdunensis40.25 - 10.2511
      Staphylococcus auricularis10.060.060.060.06
      Staphylococcus haemolyticus10.1250.1250.1250.125
      Streptococcus (1)
      Streptococcus dysgalactiae11111
      Gram-negative bacteriaPseudomonas (22)
      Pseudomonas aeruginosa190.06 - >640.5>64>64
      Pseudomonas sp.21 - 2122
      Pseudomonas fluorescens10.50.50.50.5
      Pseudomonas stutzeri10.030.030.030.03
      Serratia (7)
      Serratia marcescens70.06 - 0.250.060.1250.25
      Enterobacter (7)
      Enterobacter cloacae50.03 - 0.250.060.060.25
      Enterobacter aerogenes10.060.060.060.06
      Enterobacter gergoviae1<=0.015<=0.015<=0.015<=0.015
      Acinetobacter (5)
      Acinetobacter sp.30.06 - 0.250.060.250.25
      Acinetobacter baumannii20.03 - 0.060.030.060.06
      Achromobacter (2)
      Achromobacter sp.22 - 4244
      Citrobacter (2)
      Citrobacter koseri20.03 - 0.060.030.060.06
      Klebsiella (2)
      Klebsiella pneumoniae20.06 - 0.1250.060.1250.125
      Stenotrophomonas (1)
      Stenotrophomonas maltophilia11111
      a The analysis population of MICs for each pathogen was set as MITT. A list of characteristic (frequency, MICrange, MIC50, MIC80 and MIC90 of MICs by pathogens) of MICs for levofloxacin was prepared by both groups in MITT population.
      b MICrange, minimal, and maximum inhibitory concentrations at which isolates were inhibited. If the minimum and maximum values are the same, only one is displayed.
      c MIC50, minimal inhibitory concentration at which 50% of isolates were inhibited.
      d MIC80: the minimal inhibitory concentration at which 80% of isolates were inhibited.
      e MIC90: the minimal inhibitory concentration at which 90% of isolates were inhibited.
      Table 5Bacterial eradication rates.
      Outcome, n (%)
      The percentage of subjects with bacterial eradication at the end of treatment or discontinuation (EOT) (bacterial eradication rate) was calculated in the microbial FAS population in each group.
      Levofloxacin group n=82Placebo group n=88
      Eradication77 (93.9)11 (12.5)
      Difference in eradication rate
      Differences in eradication rate and its two-sided 95% CI (Newcombe score) were calculated, and the chi-square test was used for comparison of two groups. The eradication rate was significantly higher in the levofloxacin group than in the placebo group.
      81.4%
      95% CI70.1 to 87.8
      p valuep < 0.001
      Abbreviations: CI, confidence interval.
      a The percentage of subjects with bacterial eradication at the end of treatment or discontinuation (EOT) (bacterial eradication rate) was calculated in the microbial FAS population in each group.
      b Differences in eradication rate and its two-sided 95% CI (Newcombe score) were calculated, and the chi-square test was used for comparison of two groups. The eradication rate was significantly higher in the levofloxacin group than in the placebo group.
      The rates of change in the nature of otorrhea were 85.9% (85/99) in the LVFX group and 32.4% (33/102) in the placebo group, with a difference (95% CI) of 53.5% (40.9, 63.5) in the total population. The chi-squared test showed that this difference was statistically significant (p < 0.001) (Table 6).
      Table 6Percentage changes in the nature of otorrhea.
      Levofloxacin group n = 99Placebo group n = 102
      Percent change (%)
      FAS population was used as the analysis set to calculate the percentage of change in the nature of otorrhea from the time of screening to the end of treatment or discontinuation: percentage of subjects whose nature of otorrhea changed from purulent to mucinous, serous, or no otorrhea. In cases where both ears were affected, the one with the most severe symptoms was adopted in the order of "purulent > mucinous > serous > no otorrhoea ".
      85.932.4
      95% CI
      Two-sided 95% CI (Wilson score) in each group is indicated.
      77.7 to 91.424.1 to 41.9
      Difference in percent change
      Differences in the percentage of change in the nature of otorrhea between the two groups and its two-sided 95% CI (Newcombe score) were calculated, and the chi-square test was used for comparison between the two groups.
      53.5%
      95% CI40.9 to 63.5
      p valuep < 0.001
      Abbreviations: CI, confidence interval.
      a FAS population was used as the analysis set to calculate the percentage of change in the nature of otorrhea from the time of screening to the end of treatment or discontinuation: percentage of subjects whose nature of otorrhea changed from purulent to mucinous, serous, or no otorrhea. In cases where both ears were affected, the one with the most severe symptoms was adopted in the order of "purulent > mucinous > serous > no otorrhoea ".
      b Two-sided 95% CI (Wilson score) in each group is indicated.
      C Differences in the percentage of change in the nature of otorrhea between the two groups and its two-sided 95% CI (Newcombe score) were calculated, and the chi-square test was used for comparison between the two groups.
      There were no significant differences between the LVFX and placebo groups in the audiometric test at EOT, both in air and bone conduction.

      3.3 Pharmacokinetic analysis

      LVFX was detected in the plasma of all six patients in the LVFX group. Four of the six patients had Cmax 30 min after administering the otic solution, with a mean (standard deviation [SD]) of 9.9 (14.5) ng/mL for Cmax. The mean (SD) of LVFX concentration in plasma 360 min after administration of the otic solution was 5.1 (7.5) ng/mL, indicating a gradual decrease, and the means (SDs) of AUC0-t and AUC0-inf were 40.2 (59.4) ng∙h/mL and 98.7 (125.5) ng∙h/mL, respectively.

      3.4 Safety

      A summary of reported AEs is presented in Table 7. AEs occurred in 24 of 99 patients (30 events) in the LVFX group and in 23 of 102 patients (27 events) in the placebo group, while the incidence rates (95% CI) were 24.2% (16.2, 33.9) and 22.5% (14.9, 31.9), respectively. Treatment-related AEs occurred in five of 99 patients (five events) in the LVFX group and in eight of 102 patients (eight events) in the placebo group, with incidence rates of 5.1% (1.7, 11.4) and 7.8% (3.4, 14.9), respectively. The differences (95% CI) in incidence rate between the groups were 1.7% (–12.1, 15.7) for AEs and –2.8% (–16.7, 10.9) for treatment-related AEs; the difference in the incidence of AEs and treatment-related AEs between the groups was not significant.
      Table 7Summary of reported adverse events (SAF).
      Levofloxacin group

      (n = 99)
      Placebo group

      (n = 102)
      Adverse eventSubjects, n (%)
      The number of subjects experienced more than 1 event and incidence of AEs in each group was indicated.
      Any AE24 (24.2)23(22.5)
      Any treatment-related AE
      AEs considered related to study drug.
      5 (5.1)8 (7.8)
      AE by preferred term
      Adverse events were classified using MedDRA version 24.0.
      Otic events
      Otitis media chronic2 (2.0)5 (4.9)
      Otitis media bacterial01 (1.0)
      Otitis media01 (1.0)
      Tinnitus2 (2.0)2 (2.0)
      Otitis externa3 (3.0)0
      Ear pain2 (2.0)1 (1.0)
      Otitis externa fungal1 (1.0)1 (1.0)
      Ear canal injury1 (1.0)1 (1.0)
      Ear pruritus02 (2.0)
      Nonotic events
      Nasopharyngitis2 (2.0)1 (1.0)
      Vertigo1 (1.0)2 (2.0)
      Dizziness1 (1.0)2 (2.0)
      Headache2 (2.0)0
      Pharyngitis1 (1.0)1(1.0)
      Impetigo1 (1.0)0
      Tonsillitis1 (1.0)0
      Insomnia1 (1.0)0
      Haematoma1 (1.0)0
      Diarrhoea1 (1.0)0
      Abdominal pain1 (1.0)0
      Stomatitis1 (1.0)0
      Neck pain1 (1.0)0
      Swelling1 (1.0)0
      Chronic eosinophilic rhinosinusitis01 (1.0)
      Gingivitis01 (1.0)
      Nausea01 (1.0)
      Vomiting01 (1.0)
      Dermatitis01 (1.0)
      Muscle spasms01 (1.0)
      Contusion01 (1.0)
      Abbreviation: AE, adverse event; SAF, safety analysis set.
      a The number of subjects experienced more than 1 event and incidence of AEs in each group was indicated.
      b AEs considered related to study drug.
      c Adverse events were classified using MedDRA version 24.0.
      The most common AE was otitis externa, which occurred in 3.0% (3/99) of patients in the LVFX group and 0% (0/102) in the placebo group. It was determined that this was not related to treatment.
      In the LVFX group, the incidence rate of treatment-related AEs, including fungal otitis externa, dizziness, vertigo, diarrhea, and pain at the application site, was 1.0% (1/99). All treatment-related AEs were mild, except for diarrhea, which was moderate in one patient. This patient with moderate diarrhea, which was treated as a significant adverse drug reaction prespecified in the protocol, was excluded from this study, and the diarrhea resolved after treatment discontinuation. In the placebo group, dizziness, vertigo, and ear pruritus occurred in 2.0% of the patients (2/102), and fungal otitis externa and tinnitus occurred in 1.0% of the patients (1/102), all of which were mild treatment-related AEs. Vertigo and ear pruritus occurred in both groups as treatment-related AEs, possibly caused by otic solution administration, at rates of 1.0% (1/99) and 2.0% (2/102) in the LVFX and placebo groups, respectively. No differences were observed in treatment-related AEs related to the application site.

      4. Discussion

      This study was aimed to evaluate the efficacy of a 1.5% LVFX otic solution for the treatment of patients with CSOM and AOM, based on the resolution of inflammation in the middle ear and tympanic membrane, and its safety and PK.
      The primary endpoint of this study was the proportion of patients with disappearance (improvement rate) of all three clinical findings of purulent otorrhea, hyperemia (redness), and granulation tissue formation in the middle ear mucosa and tympanic membrane on digital endoscopy findings. Finally, the improvement rates at EOT according to the BICRC were 46.5% in the LVFX group and 23.5% in the placebo group, with a significantly higher improvement rate in the LVFX group than in the placebo group (p = 0.001), demonstrating the efficacy of LVFX.
      There have been no prior Japanese clinical trials that have investigated similar endpoints to those adopted in this study. In conventional Japanese evaluations of the efficacy of therapeutic agents for CSOM, CSOM symptoms, such as a closed feeling in the ear and middle ear mucosa and tympanic membrane hyperemia (redness), nature of otorrhea, and degree of otorrhea are scored, and the improvement of findings is determined by the degree of score reduction [
      • Baba S
      • Kobayashi T
      • Saito S
      • Unno T
      • Yanagiuchi T
      • Watanabe A
      • et al.
      [Double-blind comparative study results of ofloxacin otic solution for patients with chronic suppurative otitis media or acute exacerbation of chronic suppurative otitis media.].
      ]. As only one physician examines the otoscopy findings, this makes it difficult to quantify “resolution.” In other words, this makes standardization of the evaluations theoretically difficult. In that case, the possibility that differences in evaluation among participants may have affected the results cannot be ruled out, and this may also make it difficult to verify results in the future. Hence, in this study, the tympanic membrane images were captured by digital endoscopy, and the results were evaluated by a central evaluation committee. The advantage of this method is that evaluation by a neutral and independent evaluation committee can reduce some of biases caused by individual evaluation. In contrast, evaluations may differ depending on the imaging conditions; thus, unifying the evaluation method in advance was an important process.
      Previous studies have reported an improvement rate of 65% to 95% for the efficacy of quinolone otic solutions for CSOM [
      • Macfadyen C
      • Gamble C
      • Garner P
      • Macharia I
      • Mackenzie I
      • Mugwe P
      • et al.
      Topical quinolone vs. antiseptic for treating chronic suppurative otitis media: a randomized controlled trial.
      ,
      • Kasemsuwan L
      • Clongsuesuek P.
      A double blind, prospective trial of topical ciprofloxacin versus normal saline solution in the treatment of otorrhoea.
      ,
      • De Miguel Martínez I
      • Vasallo Morillas JR
      • Ramos Macías A
      Antimicrobial therapy in chronic suppurative otitis media.
      ,
      • Ramos A
      • Ayudarte F
      • de Miguel I
      • Cuyás JM
      • Cenjor C.
      Use of topical ciprofloxacin in chronic suppurating otitis media.
      ,
      • Esposito S
      • D'Errico G
      • Montanaro C
      Topical and oral treatment of chronic otitis media with ciprofloxacin. A preliminary study.
      ,
      • Kaygusuz I
      • Karlidağ T
      • Gök U
      • Yalçin S
      • Keleş E
      • Demirbağ E
      • et al.
      Efficacy of topical ciprofloxacin and tobramycin in combination with dexamethasone in the treatment of chronic suppurative otitis media.
      ,
      • Lorente J
      • Sabater F
      • Maristany M
      • Jimenez R
      • Menem J
      • Vinas J
      • et al.
      [Multicenter study comparing the efficacy and tolerance of topical ciprofloxacin (0.3%) versus topical gentamicin (0.3%) in the treatment of simple, non-cholesteatomatous chronic otitis media in the suppurative phase.].
      ,
      • Nawasreh O
      • Fraihat A.
      Topical ciprofloxacin versus topical gentamicin for chronic otitis media.
      ,
      • Tutkun A
      • Ozagar A
      • Koc A
      • Batman C
      • Uneri C
      • Sehitoglu MA.
      Treatment of chronic ear disease. Topical ciprofloxacin vs topical gentamicin.
      ]. Here, the primary endpoint results were lower than the improvement rates reported in those studies. The reason for the lower improvement rate in the present dataset could be attributed to stricter evaluation criteria, namely, (1) “resolved,” defined as the disappearance of all three clinical findings described above, and (2) the primary evaluation being assessed by the BICRC based on digital endoscopy findings. Digital endoscopic images provide a wider angle of view than conventional visual inspection or surgical microscopy and allow the visualization of the blind area, such as the corners of a bent external auditory canal. Evaluation based on the images may lead to more rigorous observation of tympanic membrane findings. An assessment for cure by an independent reviewer who is not involved in the treatment generally tends to be more stringent. In the present study, the improvement rate (95% CI) of purulent otorrhea at EOT assessed by the trial investigators was 85.9% (77.7, 91.4) in the LVFX group. This rate was similar to the rates reported in previous studies [
      • Macfadyen C
      • Gamble C
      • Garner P
      • Macharia I
      • Mackenzie I
      • Mugwe P
      • et al.
      Topical quinolone vs. antiseptic for treating chronic suppurative otitis media: a randomized controlled trial.
      ,
      • Kasemsuwan L
      • Clongsuesuek P.
      A double blind, prospective trial of topical ciprofloxacin versus normal saline solution in the treatment of otorrhoea.
      ,
      • De Miguel Martínez I
      • Vasallo Morillas JR
      • Ramos Macías A
      Antimicrobial therapy in chronic suppurative otitis media.
      ,
      • Ramos A
      • Ayudarte F
      • de Miguel I
      • Cuyás JM
      • Cenjor C.
      Use of topical ciprofloxacin in chronic suppurating otitis media.
      ,
      • Esposito S
      • D'Errico G
      • Montanaro C
      Topical and oral treatment of chronic otitis media with ciprofloxacin. A preliminary study.
      ,
      • Kaygusuz I
      • Karlidağ T
      • Gök U
      • Yalçin S
      • Keleş E
      • Demirbağ E
      • et al.
      Efficacy of topical ciprofloxacin and tobramycin in combination with dexamethasone in the treatment of chronic suppurative otitis media.
      ,
      • Lorente J
      • Sabater F
      • Maristany M
      • Jimenez R
      • Menem J
      • Vinas J
      • et al.
      [Multicenter study comparing the efficacy and tolerance of topical ciprofloxacin (0.3%) versus topical gentamicin (0.3%) in the treatment of simple, non-cholesteatomatous chronic otitis media in the suppurative phase.].
      ,
      • Nawasreh O
      • Fraihat A.
      Topical ciprofloxacin versus topical gentamicin for chronic otitis media.
      ,
      • Tutkun A
      • Ozagar A
      • Koc A
      • Batman C
      • Uneri C
      • Sehitoglu MA.
      Treatment of chronic ear disease. Topical ciprofloxacin vs topical gentamicin.
      ]. Further, the possibility that these previously reported results were affected by individual evaluation bias cannot be ruled out.
      The median (95% CI) times to cessation of purulent otorrhea estimated by the Kaplan–Meier method were 7.0 (7.0, 8.0) days in the LVFX group and 22.0 (14.0, not estimable) days in the placebo group, representing a three-fold reduction in time. This fact is expected to lead to two clinical benefits. First, it shortens the waiting period before surgery. The curative treatment for CSOM is reconstruction of the tympanic membrane or tympanoplasty, but surgery must be performed after the active CSOM infection has been resolved. Moreover, as rapid cessation of otorrhea is expected to shorten the waiting time for surgery, this can reduce the social burden, including a reduction in the frequency or length of hospital visits. In addition, this may prevent the development of sensorineural hearing loss, which can be the result of long-standing middle ear problems. As sensorineural hearing loss is irreversible, its prevention is significantly important. The risk of damage to the inner ear is increased by the proliferation of pyogenic inflammation in the middle ear region. Therefore, prompt resolution of prolonged inflammation is important to improve patients’ quality of life and future [
      • Luntz M
      • Yehudai N
      • Haifler M
      • Sigal G
      • Most T.
      Risk factors for sensorineural hearing loss in chronic otitis media.
      ]. Given these points, rapid resolution of otorrhea with LVFX is an important clinical goal from a long-term perspective.
      Staphylococcus and Pseudomonas were the most frequently detected pathogenic organisms in otorrhea, and although the MIC90 for LVFX against MRSA and P. aeruginosa was high at 64 μg/mL and > 64 μg/mL, respectively, the eradication rates were high at 83.3% for MRSA and 88.9% for P. aeruginosa, indicating the efficacy of topical administration. Although Streptococcus pyogenes, Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae, the major pathogenic organisms of AOM, were not isolated in this study, the MIC90 of LVFX against these species were 4, 1, ≤ 0.06, and ≤ 0.06 μg/mL in 2015, 2016, and 2017, respectively [
      • Suzuki K
      • Kurono Y
      • Ikeda K
      • Hotomi M
      • Yano H.
      The sixth nationwide surveillance of clinical isolates from patients with six otolaryngological field infections and antimicrobial susceptibility pattern in the isolated pathogens in Japan.
      ]. Therefore, bacterial eradication is expected to be sufficient.
      In terms of PK, the mean ± SD plasma LVFX concentrations increased to 9.8 ± 14.5 ng/mL at 30 min after administration of the drug and then decreased gradually. We considered that LVFX was partially absorbed from the middle ear mucosa or gastrointestinal tract through the Eustachian tube due to the tympanic membrane perforation. Another study of healthy adults demonstrated that the Cmax and AUC0–72 h of a single oral administration of one (500 mg) tablet of LVFX in a fasting state were 8.04 ± 1.98 μg/mL and 50.86 ± 6.46 μg-h/mL, respectively, and the Cmax and AUC0–72 h were 8.05 ± 1.54 μg/mL and 51.96 ± 4.96 μg/h/mL, respectively, after a single intravenous infusion of LVFX 500 mg over 60 min [
      The interview forms of CRAVIT® Tablets, fine granules.
      ,
      The interview forms of CRAVIT® intravenous drip infusion.
      ]. Compared to these results, the Cmax and AUC0-t of 1.5% LVFX otic solution in this study were as low as approximately 1/1000, and the concentration transported into the blood was considered to be significantly low and unlikely to cause the AEs that have been reported in systemic formulations.
      Regarding safety, there were five treatment-related AEs in five patients in the LVFX group in this study, with an incidence rate (95% CI) of 5.1% (1.7 to 11.4), and this rate was not significantly different to that of the placebo group. These AEs included fungal otitis externa, dizziness, vertigo, diarrhea, and pain at the application site.
      All treatment-related AEs were mild, except for diarrhea, which was moderate in one patient who was excluded from this study, and the diarrhea resolved after discontinuation. The treatment-related AEs in the placebo group were dizziness, vertigo, and ear pruritus in 2.0% (2/102) and fungal otitis externa and tinnitus in 1.0% (1/102) of the patients, and all AEs were mild.
      Vertigo or dizziness occurred in both groups as a treatment-related AE, possibly caused by cold ear drop administration. No significant differences were observed in treatment-related AEs related to the application site. No serious treatment-related AEs were observed in either of the groups. AEs in the LVFX group were generally similar to those in the placebo group.
      There was no apparent skin effect or damage in the external ear in either group resulting from the drugs. The drugs (both LVFX and placebo) used in this study did not contain benzalkonium chloride (BAK). The lack of BAK in both the LVFX and the placebo otic solutions may be related to the reduced frequency of skin AEs. BAK has been used as an antiseptic for more than 50 years in many products. However, skin irritation and the possibility of subsequent contact sensitization have been observed after BAK use. Hence, BAK has been considered a causative agent of allergic contact dermatitis (ACD) [
      • Wentworth AB
      • Yiannias JA
      • Davis MD
      • Killian JM.
      Benzalkonium chloride: a known irritant and novel allergen.
      ]. Therefore, another advantage of this LVFX formulation is that it will not cause ACD. Furthermore, possible ototoxicity derived from BAK, which has not been investigated, may be avoided.
      No other clinically significant changes were observed in the laboratory, audiometry, or equilibrium function tests.
      In a previous study about ototoxicity in guinea pigs, 0% (vehicle), 1.5%, 3.0%, 6.0% solutions of LVFX and 4.0% gentamicin solution (positive control) were administered in the middle ear cavity at a dose of 0.1 mL/body, once daily for 10 days. The auditory brainstem response (ABR), inner and middle ear histopathology using an optical microscope, and cochlear hair cells by scanning electron microscopy were assessed. The results showed that 1.5%, 3.0%, and 6.0% LVFX solutions did not deteriorate ABR, with no significant difference observed in histological examination findings of the inner and middle ear and electron microscopy findings of cochlear hair cells compared with that noted for the vehicle, indicating that there was no ototoxicity. Therefore, 1.5% LVFX otic solution was considered to be safe and well-tolerated for otic administration.
      This study has some limitations, such as difficulty in evaluating inflammatory findings in the tympanic membrane and tympanic cavity on some images due to poor visibility due to otorrhea, out-of-focus images, or the use of different color tones at each visit because the digital endoscopic images were acquired before otorrhea aspiration and autofocus, and auto-exposure were used.

      5. Conclusions

      The present study demonstrated that 1.5% LVFX otic solution is clinically effective for the successful treatment of CSOM and AOM. This was demonstrated by the resolution of inflammation in the middle ear and tympanic membrane and the high bacterial eradication rate observed. No deaths or serious treatment-related AEs were observed. Although a moderate treatment-related AE (diarrhea) was observed in one patient, the patient recovered after discontinuation of the drug. All other treatment-related AEs were mild. It is concluded that application of 1.5% LVFX otic solution is a safe, well-tolerated, and effective treatment method for CSOM and AOM.

      Disclosure statement

      This study was funded by CEOLIA Pharma Co., Ltd. (Tokyo, Japan) and NanoCarrier Co., Ltd. (Tokyo, Japan).

      Declaration of Competing Interest

      All the authors have declared that there are no conflicts of interest in connection with this manuscript.

      Acknowledgements

      The authors are thankful to Dr. Kunihiro Fukushima for his support in the study as a medical professional. The authors acknowledge the following investigators for their participation in the study: Dr. Hidetoshi Ohshima (Sen-En Rifu Hospital), Chihiro Nakagawa (Yokohama Sakae Kyosai Hospital), Makiko Mori (Hiratsuka Kyosai Hospital), Osamu Shiono (Yokohama Rosai Hospital), Takatoshi Yashima (Oomori Otolaryngology Clinic), Yutaka Fujimaki (Fujimaki Otolaryngology Clinic), Yusuke Akagi (National Hospital Organization Okayama Medical Center), Arata Horii (Niigata University Medical & Dental Hospital), Ryusuke Hori, Tsuyoshi Kojima (Tenri Hospital), Katsumi Doi (Kindai University Hospital), Kikuko Naka (Fukuyama City Hospital), Ikuo Inoguchi (Hiroshima City Hiroshima Citizens Hospital), Nobuhiko Kimura (National Hospital Organization Iwakuni Clinical Center), Seiichiro Makihara (Kagawa Rosai Hospital), Naotaka Aizawa, Kohei Honda (Uonuma Kikan Hospital), Kyoko Chujo (St. Luke's International Hospital), Seiji Horibe (Miyanomori Clinic), Sho Kanzaki (Keio University Hospital), Masatoki Takahashi (Tokyo Metropolitan Geriatric Medical Center), Kanetaka Horibe (Daido Clinic), Muneki Hotomi (Wakayama Medical University Hospital), Hiromitsu Hatakeyama (Yokohama City University Medical Center), Takahide Taguchi (Yokohama City Minato Red Cross Hospital), Yuuji Tanigaki (Fujisawa City Hospital), Tomoyasu Tachibana (Japanese Red Cross Society Himeji Hospital), Kazunori Nishizaki (Okayama University Hospital), and Misato Hirai (Okayama Saiseikai Outpatient Center Hospital). The authors express their sincere gratitude to Dr. Yukihiko Kanda, Dr. Haruo Yoshida, Minoru Hara, Ryuichiro Yoshimi, and Shigeharu Yamanobe for contributing as members of blinded central independent review committee. The authors would like to thank Dr. Yasuo Oohashi and Dr. Kohei Uemura for their assistance in statistical analysis.

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