Distribution of Dexamethasone and Preservation of Inner Ear Function following Intratympanic Delivery of a Gel-Based Formulation

Intratympanic (IT) delivery of drugs to the ear is increasingly used for both clinical and research purposes. One limitation of IT delivery is that drugs are rapidly lost from the middle ear by a number of processes, so that prolonged delivery of drug is technically difficult. In the present study, the delivery characteristics of a poloxamer hydrogel formulation containing dexamethasone (dex) were evaluated. The gel is liquid at room temperature, allowing IT injection, but transitions to a gel at body temperature, providing a prolonged residence time in the middle ear. A 50-μl volume of control or dex-containing gel (dex-gel) was injected through the tympanic membrane of guinea pigs. Cochlear function was assessed with cochlear action potential and acoustic emission thresholds measured immediately, 6 or 24 h after IT gel injection. After 6- or 24-hour treatment with dex-gel, perilymph drug gradients along the cochlea were assessed by taking samples sequentially from the apex, and endolymph was sampled from the basal turn. Control gel injections caused small changes in sound field calibrations and functional measures for low-frequency stimuli, consistent with an induced conductive loss. Within 24 h, responses returned to normal. Twenty-four hours after dex-gel injection, low-frequency changes remained as the dex-gel was retained better in the middle ear, but there was no indication of high-frequency loss. While perilymph sample data showed that dex gradients were substantially lower than after single injections of dex solution, quantitative analysis of this result suggests that some dex may have entered the perilymph through the thin bone in the apical region of the cochlea. Endolymph levels of dex remained lower than those in the perilymph. This study confirms that a poloxamer hydrogel-based dex formulation provides an effective method for a prolonged delivery, providing a more uniform distribution of drug in the inner ear

Overexpression of c-jun, junB, or JunD affects cell growth differently

The coding sequences of murine c-jun, junB, or junD, which code for proteins with practically identical dimerization and DNA binding properties, were introduced into a nondefective retroviral vector, and the phenotype of primary avian fibroblasts chronically infected with each of these viruses was studied. Cells expressing c-jun grew in low-serum medium and developed into colonies in agar, two properties characteristic of in vitro transformation. Cells expressing junB grew in agar, with a reduced efficiency as compared to c-jun, but did not grow in low-serum medium. Finally, no effect of junD expression on cell growth was observed. These different phenotypes suggest that these three closely related transcription factors play distinct roles during normal cell growth. Analysis of c-jun deletion mutants and of c-jun/junB and c-jun/junD chimeric genes showed that the N-terminal portion (amino acids 2-168) of the c-Jun protein that is involved in transcriptional activation is required for efficient transformation. On the contrary, cells expressing a truncated mouse c-Jun lacking this N-terminal domain grew slower than normal embryo fibroblasts. The reduced growth rate may be related to the finding that expression of the intact or the truncated mouse c-jun repressed the endogenous avian c-Jun homologue, suggesting that functional c-Jun product is required for normal cell growth

Design, synthesis, and structure-activity analysis of isoform-selective retinoic acid receptor ß ligands

We recently discovered the isoform selective RARβ2 ligand 4′-octyl-4-biphenylcarboxylic acid (3, AC-55649). Although 3 is highly potent at RARβ2 and displays excellent selectivity, solubility issues make it unsuitable for drug development. Herein we describe the exploration of the SAR in a biphenyl and a phenylthiazole series of analogues of 3. This ultimately led to the design of 28, a novel, orally available ligand with excellent isoform selectivity for the RARβ2

Intratympanic Administration of OTO-313 Reduces Tinnitus in Patients with Moderate to Severe, Persistent Tinnitus: A Phase 1/2 Study

Objective: To evaluate the safety and exploratory efficacy of intratympanic administration of OTO-313 in patients with tinnitus.Study Design: Single intratympanic injection of OTO-313 evaluated in a randomized, double-blind, placebo-controlled Phase 1/2 clinical study.Setting: Tertiary referral centers.Patients: Patients with unilateral tinnitus (moderate–severe) with tinnitus duration 1 to 6 months.Interventions: Intratympanic OTO-313.Main Outcome Measures: Safety and change from baseline in tinnitus functional index (TFI), daily ratings of tinnitus loudness and annoyance, and patient global impression of change (PGIC).Results: OTO-313 was well-tolerated with lower incidence of adverse events than placebo. Mean TFI reduction from baseline favored OTO-313 at Week 2, 4, and 8. A clinically meaningful, 13-point improvement on the TFI was observed in 43% (6/14) of OTO-313 patients at both Weeks 4 and 8 versus 13% (2/16) of placebo patients (ad hoc responder analysis, p-value < 0.05). Reductions in daily ratings of tinnitus loudness and annoyance favored OTO-313 compared with placebo. In OTO-313 responders, a strong correlation existed between change from baseline in TFI score and changes in tinnitus loudness, tinnitus annoyance, and PGIC.Conclusions: OTO-313 was well-tolerated and demonstrated a higher proportion of responders than placebo across consecutive visits (Weeks 4 and 8) supporting further clinical development of OTO-313 for the treatment of tinnitus