FDA-Approved MEK1/2 Inhibitor, Trametinib, Protects Mice from Cisplatin and Noise-Induced Hearing Loss.

Hearing loss is one of the most common types of disability; however, there is only one FDA-approved drug to prevent any type of hearing loss. Treatment with the highly effective chemotherapy agent, cisplatin, and exposure to high decibel noises are two of the most common causes of hearing loss. The mitogen activated protein kinase (MAPK) pathway, a phosphorylation cascade consisting of RAF, MEK1/2, and ERK1/2, has been implicated in both types of hearing loss. Pharmacologically inhibiting BRAF or ERK1/2 is protective from noise and cisplatin-induced hearing loss in multiple mouse models. Trametinib, a MEK1/2 inhibitor, protects from cisplatin induced outer hair cell death in mouse cochlear explants; however, to the best of our knowledge, inhibiting MEK1/2 has not yet been shown to be protective from hearing loss in vivo. In this study, we demonstrate that trametinib protects from cisplatin-induced hearing loss in a translationally relevant mouse model and does not interfere with cisplatin's tumor killing efficacy in cancer cell lines. Higher doses of trametinib were toxic to mice when combined with cisplatin but lower doses of the drug were protective from hearing loss without any known toxicity. Trametinib also protected mice from noise-induced hearing loss and synaptic damage. This study shows that MEK1/2 inhibition protects from both insults of hearing loss and that targeting all three kinases in the MAPK pathway protect from cisplatin and noise-induced hearing loss in mice.

Trametinib, a MEK1/2 Inhibitor, Protects Mice from Cisplatin- and Noise-Induced Hearing Loss.

Hearing loss is one of the most common types of disability; however, there is only one FDA-approved drug to prevent any type of hearing loss. Treatment with the highly effective chemotherapy agent, cisplatin, and exposure to high-decibel noises are two of the most common causes of hearing loss. The mitogen-activated protein kinase (MAPK) pathway, a phosphorylation cascade consisting of RAF, MEK1/2, and ERK1/2, has been implicated in both types of hearing loss. Pharmacologically inhibiting BRAF or ERK1/2 is protective against noise- and cisplatin-induced hearing loss in multiple mouse models. Trametinib, a MEK1/2 inhibitor, protects from cisplatin-induced outer hair cell death in mouse cochlear explants; however, to the best of our knowledge, inhibiting MEK1/2 has not yet been shown to be protective against hearing loss in vivo. In this study, we demonstrate that trametinib protects against cisplatin-induced hearing loss in a translationally relevant mouse model and does not interfere with cisplatin's tumor-killing efficacy in cancer cell lines. Higher doses of trametinib were toxic to mice when combined with cisplatin, but lower doses of the drug were protective against hearing loss without any known toxicity. Trametinib also protected mice from noise-induced hearing loss and synaptic damage. This study shows that MEK1/2 inhibition protects against both insults of hearing loss, as well as that targeting all three kinases in the MAPK pathway protects mice from cisplatin- and noise-induced hearing loss.

Oseltamivir (Tamiflu), a Commonly Prescribed Antiviral Drug, Mitigates Hearing Loss in Mice.

Hearing loss affects up to 10% of all people worldwide, but currently there is only one FDA-approved drug for its prevention in a subgroup of cisplatin-treated pediatric patients. Here, we performed an unbiased screen of 1,300 FDA-approved drugs for protection against cisplatin-induced cell death in an inner ear cell line, and identified oseltamivir phosphate (brand name Tamiflu), a common influenza antiviral drug, as a top candidate. Oseltamivir phosphate was found to be otoprotective by oral delivery in multiple established cisplatin and noise exposure mouse models. The drug conferred permanent hearing protection of 15-25 dB SPL for both female and male mice. Oseltamivir treatment reduced in mice outer hair cells death after cisplatin treatment and mitigated cochlear synaptopathy after noise exposure. A potential binding protein, ERK1/2, associated with inflammation, was shown to be activated with cisplatin treatment and reduced by oseltamivir cotreatment in cochlear explants. Importantly, the number of infiltrating immune cells to the cochleae in mice post noise exposure, were significantly reduced with oseltamivir treatment, suggesting an anti-inflammatory mechanism of action. Our results support oseltamivir, a widespread drug for influenza with low side effects, as a promising otoprotective therapeutic candidate in both cisplatin chemotherapy and traumatic noise exposure.

KSR1 Knockout Mouse Model Demonstrates MAPK Pathway's Key Role in Cisplatin- and Noise-induced Hearing Loss.

Hearing loss is a major disability in everyday life and therapeutic interventions to protect hearing would benefit a large portion of the world population. Here we found that mice devoid of the protein kinase suppressor of RAS 1 (KSR1) in their tissues (germline KO mice) exhibit resistance to both cisplatin- and noise-induced permanent hearing loss compared with their wild-type KSR1 littermates. KSR1 is a scaffold protein that brings in proximity the mitogen-activated protein kinase (MAPK) proteins BRAF, MEK1/2 and ERK1/2 and assists in their activation through a phosphorylation cascade induced by both cisplatin and noise insults in the cochlear cells. KSR1, BRAF, MEK1/2, and ERK1/2 are all ubiquitously expressed in the cochlea. Deleting the KSR1 protein tempered down the MAPK phosphorylation cascade in the cochlear cells following both cisplatin and noise insults and conferred hearing protection of up to 30 dB SPL in three tested frequencies in male and female mice. Treatment with dabrafenib, an FDA-approved oral BRAF inhibitor, protected male and female KSR1 wild-type mice from both cisplatin- and noise-induced hearing loss. Dabrafenib treatment did not enhance the protection of KO KSR1 mice, providing evidence dabrafenib works primarily through the MAPK pathway. Thus, either elimination of the KSR1 gene expression or drug inhibition of the MAPK cellular pathway in mice resulted in profound protection from both cisplatin- and noise-induced hearing loss. Inhibition of the MAPK pathway, a cellular pathway that responds to damage in the cochlear cells, can prove a valuable strategy to protect and treat hearing loss.

Dabrafenib protects from cisplatin-induced hearing loss in a clinically relevant mouse model.

The widely used chemotherapy cisplatin causes permanent hearing loss in 40%-60% of patients with cancer. One drug, sodium thiosulfate, is approved by the FDA for use in pediatric patients with localized solid tumors for preventing cisplatin-induced hearing loss, but more drugs are desperately needed. Here, we tested dabrafenib, an FDA-approved BRAF kinase inhibitor and anticancer drug, in a clinically relevant multidose cisplatin mouse model. The protective effects of dabrafenib, given orally twice daily with cisplatin, were determined by functional hearing tests and cochlear outer hair cell counts. Toxicity of the drug cotreatment was evaluated, and levels of phosphorylated ERK were measured. A dabrafenib dose of 3 mg/kg BW, twice daily, in mice, was determined to be the minimum effective dose, and it is equivalent to one-tenth of the daily FDA-approved dose for human cancer treatment. The levels of hearing protection acquired, 20-25 dB at the 3 frequencies tested, in both female and male mice, persisted for 4 months after completion of treatments. Moreover, dabrafenib exhibited a good in vivo therapeutic index (> 25), protected hearing in 2 mouse strains, and diminished cisplatin-induced weight loss. This study demonstrates that dabrafenib is a promising candidate drug for protection from cisplatin-induced hearing loss.

KSR1 knockout mouse model demonstrates MAPK pathway's key role in cisplatin- and noise-induced hearing loss.

Hearing loss is a major disability in everyday life and therapeutic interventions to protect hearing would benefit a large portion of the world population. Here we found that mice devoid of the protein kinase suppressor of RAS 1 (KSR1) in their tissues (germline KO mice) exhibit resistance to both cisplatin- and noise-induced permanent hearing loss compared to their wild-type KSR1 littermates. KSR1 is expressed in the cochlea and is a scaffold protein that brings in proximity the mitogen-activated protein kinase (MAPK) proteins BRAF, MEK and ERK and assists in their activation through a phosphorylation cascade induced by both cisplatin and noise insults in the cochlear cells. Deleting the KSR1 protein tempered down the MAPK phosphorylation cascade in the cochlear cells following both cisplatin and noise insults and conferred hearing protection of up to 30 dB SPL in three tested frequencies in mice. Treatment with dabrafenib, an FDA-approved oral BRAF inhibitor, downregulated the MAPK kinase cascade and protected the KSR1 wild-type mice from both cisplatin- and noise-induced hearing loss. Dabrafenib treatment did not enhance the protection of KO KSR1 mice, as excepted, providing evidence dabrafenib works primarily through the MAPK pathway. Thus, either elimination of the KSR1 gene expression or drug inhibition of the MAPK cellular pathway in mice resulted in profound protection from both cisplatin- and noise-induce hearing loss. Inhibition of the MAPK pathway, a cellular pathway that responds to damage in the cochlear cells, can prove a valuable strategy to protect and treat hearing loss.

Nanoemulsion-Loaded Hydrogels for Topical Administration of Pentyl Gallate.

The aim of this study is to describe the development of nanoemulsion-loaded hydrogels to deliver pentyl gallate (PG), a gallic acid n-alkyl ester, through the skin. PG is an antioxidant agent; however, it seems to be a promising agent for herpis labialis treatment. Aristoflex AVC® and chitosan were used as gelling agents for nanoemulsion thickening. The developed formulations presented suitable PG content (94.4-100.3% w/w), nanometric droplet sizes (162-297 nm), high zeta potentials, and a non-Newtonian pseudoplastic behavior. Both vehicles neither enhanced PG penetration nor delayed its release from the nanoemulsion. Formulations remained physically stable at 8°C during 3 months of storage.

Pentyl Gallate Nanoemulsions as Potential Topical Treatment of Herpes Labialis.

Previous studies have demonstrated the antiherpes activity of pentyl gallate (PG), suggesting that it could be a promising candidate for the topical treatment of human herpes labialis. PG low aqueous solubility represents a major drawback to its incorporation in topical dosage forms. Hence, the feasibility of incorporating PG into nanoemulsions, the ability to penetrate the skin, to inhibit herpes simplex virus (HSV)-1 replication, and to cause dermal sensitization or toxicity were evaluated. Oil/water nanoemulsions containing 0.5% PG were prepared by spontaneous emulsification. The in vitro PG distribution into porcine ear skin after topical application of nanoemulsions was assessed, and the in vitro antiviral activity against HSV-1 replication was evaluated. Acute dermal toxicity and risk of dermal sensitization were evaluated in rat model. Nanoemulsions presented nanometric particle size (from 124.8 to 143.7 nm), high zeta potential (from -50.1 to -66.1 mV), loading efficiency above 99%, and adequate stability during 12 months. All formulations presented anti-HSV-1 activity. PG was able to reach deeper into the dermis more efficiently from the nanoemulsion F4. This formulation as well as PG were considered safe for topical use. Nanoemulsions seem to be a safe and effective approach for topically delivering PG in the treatment of human herpes labialis infection.

Citotoxic activity evaluation of essential oils and nanoemulsions of Drimys angustifolia and D. brasiliensis on human glioblastoma (U-138 MG) and human bladder carcinoma (T24) cell lines in vitro

The species Drimys angustifolia Miers and D. brasiliensis Miers, commonly known as "casca-de-anta", have in their leaves essential oils that can confer cytotoxic effects. In this study, we evaluated the citotoxic effects of the volatile oils from these two species. We also proposed a nanoemulsion formulation for each of the species and assessed the in vitro cytotoxicity on U-138 MG (human glioblastoma) and T24 (human bladder carcinoma) cell lines. The plant chemical composition was evaluated by gas chromatography coupled to mass spectrometer. Furthermore, the nanoemulsions were prepared and characterized. Our results showed that; bicyclogermacrene (19.6%) and cyclocolorenone (18.2%) were the most abundant for the D angustifolia oil and D brasiliensis oil, respectively. Both nanoemulsions, D angustifolia and D brasiliensis appeared macroscopically homogeneous and opalescent bluish liquids, with nanometric mean diameters of 168 nm for D brasiliensis and 181 nm for D angustifolia. The polydispersity indices were below 0.10, with an acid pH of 4.7-6.3, and negative zeta potentials about -34 mV. The results of transmission electron microscopy showed that droplets are present in the nanometer range. Only the D brasiliensis oil was efficient in reducing the cell viability of both U-138 MG (42.5%±7.0 and 67.8%±7.8) and T24 (33.2%±2.8, 60.3%±1.6 and 80.5%±8.8) cell lines, as assessed by MTT assay. Noteworthy, similar results were obtained with cell counting. Finally, D brasiliensis oil incubation caused an increase of annexin-V and propidium iodite population, according to evaluation by cytometry analysis, what is characteristic of late apoptosis. The results presented herein lead us to consider the potential therapeutic effects of the essential oils and nanoformulations as novel strategies to inhibit tumor growth.

Optimization of headspace solid-phase microextraction for analysis of ß-caryophyllene in a nanoemulsion dosage form prepared with copaiba (Copaifera multijuga Hayne) oil.

Recent studies have shown the anti-inflammatory activity of Copaiba oils may be addressed to the high content of ß-caryophyllene, the most common sesquiterpene detected, especially in the Copaifera multijuga Hayne species. In the present study, nanoemulsions were proposed as a delivery system for copaiba oil in view to treat locally inflamed skin. This article describes the optimization and validation of a stability-indicating SPME-GC method, for ß-caryophyllene analysis in the nanoemulsions produced by high pressure homogenization. SPME methods are performed with PDMS (polydimethylsiloxane) fiber (100 µm). Three SPME parameters were evaluated by a three-level-three-factor Box-Behnken factorial design as potentially affecting the technique efficiency. According to the results obtained, the best conditions to extract ß-caryophyllene were: (i) sampling temperature of 45°C, (ii) sampling time of 20 min and (iii) no NaCl addition. Results coming from the forced degradation tests showed a reduction of ß-caryophyllene peak area when both caryophyllene methanolic solution and nanoemulsions were exposed to acid hydrolysis, UV-A irradiation, oxidative (H(2)O(2)) and thermolitic (60°C) conditions. Such reduction occurred in lower extent in the nanoemulsions, suggesting a protective effect of the formulation to ß-caryophyllene content. Since no degradation products were detected in the same retention time of ß-caryophyllene, the specificity of the method was demonstrated. The method was linear in the range of 0.14-0.68 µg mL(-1) of ß-caryophyllene (r(2)>0.999), and was also validated for precision (R.S.D.≤5.0%), accuracy (97.85-101.87%) and robustness. Finally, the method was applied to quantification of ß-caryophyllene content in the developed formulations.

Pharmacokinetic study of a carbamazepine nanoemulsion in beagle dogs.

This work describes the pharmacokinetics of a novel carbamazepine nanoemulsion. The plasma concentration profiles were determined in beagle dogs after i.v. bolus administration of a 5 mg/kg carbamazepine nanoemulsion and compared to the corresponding carbamazepine/hydroxypropyl-beta-cyclodextrin complex solution. Both formulations showed similar pharmacokinetic profiles and could represent valuable formulations in case of emergencies, when a rapid action in the central nervous system is desirable.

Preliminary study on the development of nanoemulsions for carbamazepine intravenous delivery: an investigation of drug polymorphic transition.

Carbamazepine (CBZ) is available on the pharmaceutical market as tablets, capsules, and oral suspensions, but not as a parenteral formulation for clinical use. Parenteral emulsions are a good alternative to poorly water-soluble drugs such as CBZ. In this way, four different emulsions containing 3 mg/mL of CBZ were developed, but during a period of storage, drug crystal precipitates appeared. To investigate this phenomenon, differential scanning calorimetry, infrared spectroscopy, and light microscopy were employed. The results suggested a polymorphic transition from beta form to dehydrate form, resulting in drug precipitation, although the emulsions themselves remained stable for at least three months.

Carbamazepine parenteral nanoemulsions prepared by spontaneous emulsification process.

Carbamazepine (CBZ), a widely used anticonvulsant drug, is a poorly soluble drug with no parenteral treatment available for patients. This study was aimed at developing a nanoemulsion for CBZ intravenous delivery. The spontaneous emulsification method was used to prepare different formulations containing 2mg/mL CBZ. Likewise, a 2(2) full factorial experimental design was applied to study the influence of two independent variables (type of oil and type of lipophilic emulsifier) on emulsion physicochemical characteristics. The nanoemulsions were evaluated concerning droplet size, zeta potential, viscosity, drug content and association to oily phase. The formulation, which presented the best characteristics required for intravenous administration was selected and refined with respect to the lipophilic emulsifier content (increase from 5% to 6% of soy lecithin). This formulation was characterized and kept its properties in a satisfactory range over the evaluated period (3 months), i.e. droplet size around 150 nm, drug content around 95% and zeta potential around -40 mV. The transmission electron microscopy revealed emulsion droplets almost spherical in shape with an amorphous core, whereas the in vitro release profile assessed by dialysis bags demonstrated a release kinetics square root time dependent, with 95% of ca. having been released within 11h.