Efinaconazole 10% and Tavaborole 5% Penetrate Across Poly-ureaurethane 16%: Results of In Vitro Release Testing and Clinical Implications of Onychodystrophy in Onychomycosis Chris G. Adigun MD,a Tracey C. Vlahovic DPM,b Michael B. McClellan MS,c Kailas D. Thakker PhD,c Ryan R. Klein PhD,c Tuan A. Elstrom BS,d and Daniel B. Ward, Jr., MDdaDermatology & Laser Center of Chapel Hill, Chapel Hill, NC • bTemple University School of Podiatry, Philadelphia, PA • cTergus Pharma, LLC, Durham, NC • , Charleston, SC REFERENCES Supported by: ABSTR ACT INTRODUCTION DISCUSSION STUDY DESIGNMETHODS & RESULTS BACKGROUND: Poly-ureaurethane has been previously described for the management of dry, brittle, and in gen- eral, dystrophic nails. The polymer yields a waterproof, breathable barrier to protect the nail plate and prevent further damage to the nail, while regulating transonychial water loss (TOWL). Because nail dystrophy and dessication are contributing factors to onychomycosis, a barrier that protects the nail but also allows a topical antifungal to per- meate its shield is potentially an advantageous combina- tion. Oral antifungals such as terbinafine, itraconazole, and fluconazole, as well as the newer topical antifungals efinac- onazole and tavaborole (although formulated to penetrate the nail unit and work with the porosity and inherent elec- trical charge of the nail plate), do not take into account nail damage that has been created from years of harboring a dermatophyte infection. Up to 50% of cases presumed to be onychomycosis are in fact onychodystrophy without fun- gal infection, and laboratory testing for fungus should be obtained prior to initiating antifungal treatment. Whether a nail has onychomycosis, or onychodystrophy due to other causes, barrier function and structural integrity are compromised in diseased nails, and should be addressed. A poly-ureaurethane barrier that protects against wetting/ drying, fungal reservoirs, and microtrauma, followed by the addition of oral or topical antifungals after laboratory fun- gal confirmation may optomize outcomes in the treatment of onychomycosis. OBJECTIVE: The purpose of this work was to determine through in vitro release testing (IVRT) whether poly-ure- aurethane 16% allows for penetration of efinaconazole 10% or tavaborole 5%. Results could spur subsequent clinical studies which would have implications for the addition of an antifungal based on fungal confirmation, after addresss- ing the underlying nail dystrophy primarily. METHODS: A vertical diffusion cell system was used to eval- uate the ability of efinaconazole 10% and tavaborole 5% to Approximately half of all nail cases suspected to be ony- chomycosis, are in fact onychodystrophy due to other causes.1-4 A multitude of other disorders and diseases can lead to onychodystrophy, and for this reason, it is impor- tant to ensure an accurate diagnosis of the nail disease pri- or to beginning treatment. Prescribing antifungal therapy for suspected, but not confirmed nail fungus is therefore not recommended, and fungal confirmation or exclusion is an important initial step to ensure that patients are correct- ly treated. However, whether a nail has onychomycosis, or onychodystrophy due to other causes, barrier function and structural integrity are compromised in diseased nails,5,6 and should be addressed. If fungus is indeed confirmed, oral and topical antifungal options are available. The new- er topical products efinaconazole 10% and tavabarole 5%, were approved for the treatment of onychomycosis of toe- nails due to Trichophyton rubrum or Trichophton mentagro- phytes.7,8 The efficacy in the phase III trials was better than previously available topical antifungals, but remains below that of oral agents such as terbinafine and itraconazole,9-18 Even with oral therapy in onychomycosis, recurrence rates The following equations were used to calculate flux and permeability: The flux and permeability of efinaconazole 10% and tavaborole 5% across poly-ureaurethane 16% were determined, and the data are summarized in Table 1. Based on the determined values, the experimental flux of both efinaconazole and tavaborole across poly-ureaurethane 16% was greater than previously reported values for the flux of these molecules across the nail alone.31,32 These results demonstrate that the flux of both efinaconazole and tavaborole across poly-ureaurethane would not be a limiting factor during concomitant use. Results revealed greater vari- ability in the tavaborole 5% data than in the efinaconazole 10% data, and may be due to physiochemical differences between the molecules. The mass of tavaborole (151.93 Da) is less than half that of efinaconazole (348.39 Da), and molecular size has an important effect on penetration. The smaller molecular size could influence variability in flux and perme- ability. In addition, the experimental time course for each compound was set based on previously noted differences in flux. The shorter sam- pling intervals for tavaborole as compared to efinaconazole could have contributed to the greater variability observed in tavaborole permeabil- ity. The key finding, however, is that poly-ureaurethane would not be limiting in the flux of these molecules during combination use. Initial experiments to develop appropriate conditions guided the study design and suggested that the permeability of tavaborole across poly-ureaurethane 16% was much greater than efinacon- azole; therefore, the sampling intervals were set accordingly for the two compounds. Apparatus: vertical diffusion cells Replicates: 12 vertical diffusion cells per formulation Surface Area: 1.0 cm2 Poly-ureaurethane Application Method: applicator brush Coats: one Receptor Volume: approximately 8 mL Sampling Intervals (tavaborole 5%): 5, 10, 15, 20, 25, 30, 40 and 60 minutes Sampling Intervals (efinaconazole 10%): 0.5, 1, 2, 4, 6, 20, 24, and 28 hours Temperature: 32°C ± 0.5°C Sample Aliquot: 300 μL Membrane: nylon, 0.45µm Application Method: positive displacement pipette Application Amount: 50 µL Receiving Medium (tavaborole): phosphate buffer, pH 7.0 Receiving Medium (efinaconazole): 10% hydroxypropyl-β-cyclodextrin Sufficient poly-ureaurethane 16% was applied to the membrane extending outside the area defined by the donor chamber such that no exposed membrane remained when the vertical diffusion cell was fully assembled. Polyureaurethane was applied and allowed to dry for 30 minutes prior to use. 1. Allevato MAJ. Diseases Mimicking Onychomycosis. Clinics in Dermatology. 2010; 28:164-177. 2. Ghannoum MA, Hajjeh RA, Scher R, et al. A large-scale North American study of fungal isolates from nails: the frequency of onychomycosis, fungal distribution, and antifungal susceptibility patterns. J AmAcad Dermatol. 2000; 43:641-648. 3. Gupta AK, Jain HC, Lynde CW, et al. Prevalence and epidemiology of onychomycosis in patients visiting physicians’ offices: a multicenter Canadian survey of 15,000 patients. J Am Acad Dermatol. 2000; 43:244-248. 4. American Academy of Dermatology. Choosing Wisely. http://www.choosingwisely.org/societies/ameri- can-academy-of-dermatology/. Accessed July 27, 2016. 5. McAuley WJ, Jones SA, Traynor MJ, et al. An investigation of how fungal infection influences drug pene- tration through onychomycosis patient’s nail plates. Eur J Pharm Biopharm. 2016; 102:178-84. doi: 10.1016/j. ejpb.2016.03.008 6. Kitamori K, Koyabashi M, Akamatsu et al. Weakness in intercellular association of keratinocytes in severely brittle nails. Ach Histol Cytol. 2006; 69:323-328. 7. Jublia [package insert]. Bridgewater, NJ: Valeant Pharmaceuticals North America LLC; 2014. 8. Kerydin [package insert]. Palo Alto, CA: Anacor Pharmaceuticals; 2014. 9. Brautigam M, Nolting S, Schopf RE, Weidinger G. Randomised double blind comparison of terbinafine and itraconazole for treatment of toenail tinea infection. Seventh Lamisil German Onychomycosis Study Group. BMJ. 1995; 311:919-22. Erratum in: BMJ 1995; 311:1350. 10. Drake LA, Shear NH, Arlette JP, et al. Oral terbinafine in the treatment of toenail onychomycosis: North American multicenter trial. J Am Acad Dermatol. 1997; 37:740-745. 11. Scher RK, Breneman D, Rich P, et al. Once-weekly fluconazole (150, 300, or 450 mg) in the treatment of distal subungual onychomycosis of the toenail. J Am Acad Dermatol. 1998; 38:S77-86. 12. Evans EGV, Sigurgeirsson B, for the LION Study Group. Double blind, randomised study of continuous terbinafine compared with intermittent itraconazole in treatment of toenail onychomycosis. BMJ. 1999; 318:1031-1035. 13. Gupta AK, Lynde CW, Konnikov N. Single-blind, randomized, prospective study of sequential itracon- azole and terbinafine pulse compared with terbinafine pulse for the treatment of toenail onychomycosis. J Am Acad Dermatol. 2001; 44:485-91. 14. Warshaw EM, Fett DD, Bloomfield HE, Grill JP, Nelson DB, Quintero V, Carver SM, Zielke GR, Lederle FA. Pulse versus continuous terbinafine for onychomycosis: a randomized, double-blind, controlled trial. J Am Acad Dermatol. 2005; 53:578-84. 15. Penlac® (ciclopirox 8%) [package insert]. Bridgewater, NJ: Dermik Laboratories; 2006. 16. Sporanox® (itraconazole) [package insert]. Raritan, NJ: PriCara, Division of Ortho-McNeil-Janssen Pharmaceuticals, Inc; 2011. 17. Elewski BE, Rich P, Pollak R, et al. Efinaconazole 10% solution in the treatment of toenail onychomycosis: Two phase III multicenter, randomized, double-blind studies. J Am Acad Dermatol. 2013; 68:600-608. 18. Elewski BE, Aly R, Baldwin SL, et al. Efficacy and safety of tavaborole topical solution, 5%, a novel boron- based antifungal agent, for the treatment of toenail onychomycosis: Results from 2 randomized phase III studies. J Am Acad Dermatol. 2015; 73:62-69. 19. Tosti A, Piraccini BM, Stinchi C, Colombo MD. Relapses of onychomycosis after successful treatment with systemic antifungals: a three-year follow-up. Dermatol. 1998; 197:162-166. 20. Sigurgeirsson B, Olafsson JH, Steinsson JB, et al: Long-term effectiveness of treatment with terbinafine vs itraconazole in onychomycosis: a 5-year blinded prospective follow-up study. Arch Dermatol. 2002; 138:353. 21. Scher RK, Tavakkol A, Sigurgeirsson B, et al. Onychomycosis: diagnosis and definition of cure. J Am Acad Dermatol. 2007; 56:939-944. 22. Sigurgeirsson B, Olafsson J, Steinsson J, Kerrouche N, Sidou F. Efficacy of amorolfine nail lacquer for the prophylaxis of onychomycosis over 3 years. J Eur Acad Dermatol Venereol. 2010; 24:910-915. 23. Gupta AK, Cooper EA, Paquet M: Recurrences of dermatophyte toenail onychomycosis during long-term follow-up after successful treatments with mono- and combined therapy of terbinafine and itraconazole. J Cutan Med Surg. 2013; 17:201. 24. Scher RK, Baran R. Onychomycosis in clinical practice: factors contributing to recurrence. Br. J Dermatol. 2003; 149(S65):5-9. 25. Vlahovic T. The Use of Poly-Ureaurethane, 16% for Dystrophic Nails. Podiatry Management. 2013; 32:91-94. 26. Daniel C, Jellinek J. The pedal fungus reservoir. Arch Dermatol. 2006; 142:1344–1346. 27. Bakotic BW, Shavelson DS. The Pathogeneis of Nail Unit “Dystrophy.” Podiatry Management. 2006; 8:149-160. 28. Szepietowski JC, Reich A, Garlowska E, et al. Onychomycosis Epidemiology Study Group. Factors influ- encing coexistence of toenail onychomycosis with tinea pedis and other dermatomycoses: a survey of 2761 patients. Arch Dermatol. 2006; 142:1279-1284. 29. Cozzani E, Agnoletti AF, Speziari S, et al. Epidemiological study of onychomycosis in older adults with onychodystrophy. Geriatrics & Gerontology International. 2016; 16:486–491. doi: 10.1111/ggi.12496. 30. Nuvail [package insert]. Charleston, SC: Cipher Pharmaceuticals; June 2012. 31. Baker SJ, Hui X, and Sanders V, et al. Nail Penetration of AN2690: Efficacy Coefficient and Effect of Formulation. Poster. Anacor Pharmaceuticals; 2006. http://investor.anacor.com/releasedetail. cfm?releaseid=285008. Accessed July 8, 2016. 32. Pillai R, Korotzer A, Olin JT. In Vitro Nail Penetration of 14C-Efinaconazole Topical Solution, 10%. Supplement to the Journal of Clinical and Aesthetic Dermatology. 2014; 7:S15. 33. Nasir A, Goldstein B, Van Cleef M, Swick L. Clinical Evaluation of a New Topical Treatment for Onychomycosis. JDD. 2011; 10:1186-1191. 34. Poulakos M, Grace Y, Machin JD, Dorval E. Efinaconazole and Tavaborole: Emerging Antifungal Alternatives for the Topical Treatment of Onychomycosis. Journal of Pharmacy Practice. 2016; February 11 [Epub ahead of print]. doi: 10.1177/0897190016630904. 35. Elias PM, “Barrier-repair therapy for atopic dermatitis: corrective lipid biochemical therapy,” Expert Review of Dermatology. 2008; 3:441–452. 36. Elias PM, Hatano Y, Williams ML. Basis for the barrier abnormality in atopic dermatitis: outside-inside- outside pathogenic mechanisms. Journal of Allergy and Clinical Immunology. 2008; 121:1337–1343. Download a copy of this poster onto your mobile device at the QR code below: penetrate across poly-ureaurethane 16%. The diffusion cells had a 1.0 cm2 surface area and approximately 8 mL receptor volume. Poly-ureaurethane 16% was applied to a 0.45µm ny- lon membrane and allowed to dry before use. Efinaconazole 10% or tavaborole 5% was then applied to the poly-ure- aurethane 16% coated membrane, and samples were pulled from the receptor chamber at various times. Reverse phase chromatography was then used to assess the penetration of each active ingredient across the membrane. RESULTS: The flux and permeability of efinaconazole or tavaborole across poly-ureaurethane 16% were determined from efinaconazole 10% or tavaborole 5%, respectively. The flux and permeability of efinaconazole were determined to be 503.9 +/- 31.9 µg/cm2/hr and 14.0 +/- 0.9 nm/sec. The flux and permeability of tavaborole were determined to be 755.5 +/- 290.4 µg/cm2/hr and 42.0 +/- 16.1 nm/sec. CONCLUSION: In addition to the treatment of onychoschiz- ia, onychorrhexis, and other signs of severe dessication of the nail plate, a barrier that regulates TOWL should be consid- ered in the management onychomycosis to address barrier dysfunction and to promote stabilization of the damaged nail. Previously published flux values across the nail are re- ported to be 1.4 µg/cm2/day for efinaconazole and 204 µg/ cm2/day for tavaborole. These values are substantially lower than the herein determined flux for both molecules across poly-ureaurethane 16%. A comparison of the data suggests that poly-ureaurethane 16%, if used prior to efinaconazole or tavaborole, would not limit the ability of either active ingre- dient to access the nail, and therefore, would be unlikely to reduce their antifungal effect. Onychodystrophy is inherent in, and often precedes onychomycosis, and consideration should be given for initiation of treatment in the same se- quence: stabilizing and protecting the nail plate barrier pri- marily, and subsequently adding oral or topical antifungals after laboratory confirmation. Future clinical studies will be needed to determine combination efficacy for in vivo use. Chris G. Adigun has served as a consultant for Cipher Pharmaceuticals. Tracey C. Vlahovic has served as a consultant for Cipher Pharmaceuticals. Tergus Pharma conducted the IVRT studies under contract for Cipher Pharmaceuticals. Daniel B. Ward, Jr. and Tuan A. Elstrom are employees of Cipher Pharmaceuticals. DISCLOSURES Figure 1. PermeGear Vertical Diffusion Cell Figure 2. Average Penetration Profile of Efinaconazole 10% across Poly-ureaurethane 16% when Dosed with 50 uL of Efinaconazole 10% Figure 3. Average Penetration Profile of Tavaborole Across Poly-ureaurethane 16% When Dosed With 50 uL of Tavaborole 5% Efinaconazole 10%a Tavaborole 5%b Flux (µg/cm2/hr) 503.9 +/- 31.9 755.5 +/- 290.4 Permeability (nm/sec) 14.0 +/- 0.9 42.0 +/- 16.1 Table 1. Flux and Permeability of Efinaconazole and Tavaborole Across Poly-ureaurethane 16% aValues for efinaconazole are calculated based on linear regression using data from 1-6 hours. bValues for tavaborole are calculated based on linear regression using data from 5-60 minutes. FPO have been reported to be as high as 57%,19-24 and with anti- fungal therapy alone (whether oral or topical), the underly- ing onychodystrophy that preceded or followed as a result of the fungal disease is not primarily addressed. In reality, onychomycosis is most often an end result of environmen- tal conditions affecting the nails involving microtrauma, nail dystrophy (any alteration of nail morphology25), and a “pedal fungus reservoir” in a susceptible host. 26,27 Although treating the fungi, if present, is necessary; addressing the underlying onychodystrophy, barrier dysfunction, and structural integ- rity of the nail plate are also of paramount importance. In fact, onychodystrophy, along with concomitant tinea pedis, are the precursors to onychomycosis.26-29 Therefore, through in vitro release testing (IVRT) we sought to evaluate the pen- etration of efinaconazole 10% and tavaborole 5% across poly-ureaurethane 16%, which is FDA cleared for onycho- dystrophy.30 Poly-ureaurethane 16%, is a waterproof barrier that protects against the adverse effects of moisture, while preventing abrasion and friction,30 and now has been shown to allow in vitro penetration of efinaconazole or tavaborole to the nail when used in combination. Poly-ureaurethane 16% has been previously described and employed successfully for the management of nail dystro- phy including onychoschizia, onychorrhexis, and other signs of severe desiccation of the nail plate, collectively re- ferred to as brittle nails. Its ability to create a breathable shield on the nail by allowing oxygen permeability, but not water permeability,33 optimally regulates transonychial water loss (TOWL). Because nail desiccation and onycho- dystrophy are contributing factors in onychomycosis, a wa- terproof barrier that protects the nail plate from wetting/ drying, fungal reservoirs, and microtrauma but also allows a topical antifungal to permeate its shield is potentially an advantageous combination. Although formulated to pen- etrate the nail unit and work with the porosity and inher- ent electrical charge of the nail plate, the newer topical an- tifungals do not address nail plate damage that has been created from years of harboring a dermatophyte infection. The oral antifungals, terbinafine and itraconazole, likewise do not address this damage, and structural damage to the nail has been noted as a difficult complicating factor in the treatment and high recurrence rates of onychomycosis.24,34 Poly-ureaurethane 16% has demonstrated its place in the management of the multifactorial disease of onychomyco- sis, through barrier protection and structural stabilization of a nail plate that has been compromised by onychodys- trophy. Primary therapy with poly-ureaurethane 16% aims to protect the diseased nail from further insult and desic- cation, much as barrier formulations for compromised skin are foundational in promoting barrier repair.35,36 These IVRT study results reveal that this foundational barrier indeed allows penetration of the topical antifungal agents efina- conazole 10% and tavaborole 5%. Dual therapy with po- ly-ureaurethane 16% and these agents or oral antifungal therapy, may have the potential to augment outcomes by stabilizing the compromised nail plate primarily and sub- sequently addressing fungus if present on laboratory anal- ysis. Up to 50% of cases of suspected onychomycosis are in fact due to onychodystrophy of other etiologies,1-4 and these patients will not benefit from anti-fungal therapy. For confirmed cases of onychomycosis, a goal of future com- bination studies with poly-ureaurethane 16% would be to evaluate rates of complete cure, which often lag behind mycological cure in trials. Recurrence rates with continued weekly or bi-weekly use of poly-ureaurethane could also be assessed. Future clinical studies of poly-ureaurethane 16% in combination with oral or topical antifungals are of course necessary to determine both in vivo efficacy and the validity of these assumptions. However, whether a nail has onychomycosis, or onychodystrophy due to other causes, barrier function and structural integrity are compromised in diseased nails,5,6 and should be addressed. METHODS The in vitro vertical diffusion cell model is a valu- able tool for the study of drug release and pen- etration across specific test barriers. This model uses inert membranes, biological, or other barri- ers mounted in specially designed diffusion cham- bers allowing the system to be maintained at a controlled temperature, and was used in this ex- periment to evaluate the ability of efinaconazole 10% and tavaborole 5% to penetrate across poly- ureaurethane 16%. During the experiments, one coat of poly-ureaurethane 16% was applied evenly onto a 0.45µm nylon membrane with the applica- tor brush and allowed to dry prior to inserting the membrane on top of the receptor chamber. The donor chamber was then added to the apparatus, clamped in place securely, and the drug product administered on top of the poly-ureaurethane 16% within the donor chamber. A finite dose (50 µL) of either efinaconazole 10% or tavaborole 5% was applied, and drug penetration was measured by monitoring the appearance of the active compo- nent into the receptor chamber. The diffusion cells had a 1.0 cm2 surface area and approximately 8 mL receptor volume. Samples were pulled from the re- ceptor chamber at various times to assess the pen- etration of each active ingredient into the chamber by using reverse phase chromatography analysis. A diagram of a vertical diffusion cell is presented in Figure 1. Details are presented in the Study Design section. RESULTS Efinaconazole 10% and tava- borole 5% penetrated across poly-ureaurethane 16%, and the flux and permeability are listed in Table 1. Appropriate method parameters were es- tablished to ensure the sys- tem was compatible with po- ly-ureaurethane 16% and to ensure adequate solubility of tavaborole and efinaconazole to maintain sink conditions throughout the experiment. The flux and permeability of efinaconazole 10% were de- termined to be 503.9 ± 31.9 µg/cm2/hr and 14.0+/-0.9 nm/ sec, respectively. The flux and permeability of tavaborole 5% were determined to be 755.5 ± 290.4 µg/cm2/hr and 42.0+/- 16.1 nm/sec, respectively. CLINICAL IMPLICATIONS Flat Ground Joint FC17PosterEPIHealthAdigunEfinaconazole.pdf