Semifluorinated Alkane Eye Drops in Chronic Ocular Graft-versus-Host Disease: A Prospective, Multicenter, Noninterventional Study.

PURPOSE: Ocular graft-versus-host disease (oGvHD) following allogeneic hematopoietic stem cell transplantation develops as severe dry eye disease (DED) and is initially treated with lubricants, although no clinical trials are available using artificial tears in oGvHD. This trial was set up to test perfluorohexyloctane (NovaTears®) as nonpreserved layer-forming agent for the treatment of DED in oGvHD. METHODS: 25 patients with severe DED due to oGvHD received 1 drop perfluorohexyloctane 4 times daily during a prospective, multicenter, observational 12-week study on top of established topical therapy. Clinical parameters included Schirmer test, tear film breakup time, corneal staining, meibum secretion and ocular surface disease index. Adverse events, visual acuity and intraocular pressure were key safety parameters. RESULTS: From 25 patients recruited, 23 presented for the second visit. Perfluorohexyloctane treatment did not lead to any changes in clinical or safety parameters but led to fast relief in symptoms in 57% of the patients. One adverse reaction occurred. CONCLUSIONS: This study showed no change in clinical signs in severe DED due to oGvHD, which was not unexpected due to the underlying pathomechanisms. However, the study showed improvement of symptoms in individual patients allowing application of perfluorohexyloctane as an additional symptomatic therapy in oGvHD.

Influence of Perfluorohexane-Enriched Atmosphere on Viscoelasticity and Structural Order of Self-Assembled Semifluorinated Alkanes at the Air-Water Interface.

Semifluorinated alkanes FnHm self-assemble into nanometer-sized surface micelles at the air-water interface. In this study, we investigated how an atmosphere enriched with perfluorohexane (PFH) influences the interfacial viscoelasticity and structural order of a monolayer of FnHm by the combination of dilational rheology and grazing-incidence small-angle X-ray scattering (GISAXS). The monolayers behaved predominantly elastic which can be attributed to the strong dipole repulsions of the surface domains. Enrichment of the atmosphere with PFH lead to an increase of the compressibility and a decrease of the elastic modulus without altering the structural ordering of the FnHm molecules into highly correlated nanodomains, suggesting the adsorption of PFH molecules to the free spaces between the domains. The capability of FnHm domains to retain the structural integrity in the presence of PFH gas is promising for the fabrication of stable microbubbles for sonographic imaging.

Drug Product Characterization of High Concentration Non-Aqueous Protein Powder Suspensions.

High concentration protein formulations for subcutaneous injection represent a substantial number of development projects in the pharmaceutical industry. Such concentrated aqueous protein solutions face some specific challenges such as increased viscosity and aggregation propensity. Protein powder suspensions in non-aqueous vehicles could be an alternative providing lower viscosity than the respective aqueous solution. The choice of potential suspension vehicles is limited as traditional non-aqueous liquids, such as oils, show an inherent high viscosity. We studied suspensions prepared by dispersing spray-dried protein powder in different vehicles including sesame oil and medium chain triglycerides, as well as fluorinated and semifluorinated alkanes. We found, that semifluorinated alkanes enable formulations with high concentrations up to 280 mg/ml monoclonal antibody with a low viscosity of less than 10 mPa·s and low injection forces. The glide force of suspensions containing 210 mg/ml protein was not affected by the particle size of the spray-dried powders with medians ranging from 1 to 14 µm. In contrast, suspensions prepared with cryo-milled powder showed markedly higher viscosities and were not injectable at the same concentration. Protein powder suspensions were syringeable using a 25G needle. Vial filling using a peristaltic pump was possible and lead to a uniform filling. Sedimentation of the suspension was slow and does not lead to challenges upon vial filling during manufacturing or transfer of the suspension into syringes. Thus, we could show that dispersions of spray-dried protein powders in non-aqueous vehicles, such as semifluorinated alkanes, are a promising alternative to aqueous protein solutions at high concentrations.

Semifluorinated Alkanes as New Drug Carriers-An Overview of Potential Medical and Clinical Applications.

Fluorinated compounds have been used in clinical and biomedical applications for years. The newer class of semifluorinated alkanes (SFAs) has very interesting physicochemical properties including high gas solubility (e.g., for oxygen) and low surface tensions, such as the well-known perfluorocarbons (PFC). Due to their high propensity to assemble to interfaces, they can be used to formulate a variety of multiphase colloidal systems, including direct and reverse fluorocarbon emulsions, microbubbles and nanoemulsions, gels, dispersions, suspensions and aerosols. In addition, SFAs can dissolve lipophilic drugs and thus be used as new drug carriers or in new formulations. In vitreoretinal surgery and as eye drops, SFAs have become part of daily clinical practice. This review provides brief background information on the fluorinated compounds used in medicine and discusses the physicochemical properties and biocompatibility of SFAs. The clinically established use in vitreoretinal surgery and new developments in drug delivery as eye drops are described. The potential clinical applications for oxygen transport by SFAs as pure fluids into the lungs or as intravenous applications of SFA emulsions are presented. Finally, aspects of drug delivery with SFAs as topical, oral, intravenous (systemic) and pulmonary applications as well as protein delivery are covered. This manuscript provides an overview of the (potential) medical applications of semifluorinated alkanes. The databases of PubMed and Medline were searched until January 2023.

VEGF TrapR1R2 Suspended in the Semifluorinated Alkane F6H8 Inhibits Inflammatory Corneal Hem- and Lymphangiogenesis.

Purpose: Semifluorinated alkanes (SFAs) are used at the ocular surface as lubricants or vehicles for drugs. The purpose of this study was to test the effect of vascular endothelial growth factor (VEGF) TrapR1R2 suspended in the SFA perfluorohexyloctane (Trap/F6H8) on corneal neovascularization. Methods: Suture placement was used to induce inflammatory corneal neovascularization in mice. Treatment groups were: Trap/F6H8, VEGF TrapR1R2 as aqueous formulation dissolved in phosphate buffer (Trap), F6H8, and phosphate buffer (controls). Eye drops were applied 3×/daily for 2 weeks. Afterward, corneas were stained with CD31 and LYVE-1 to analyze corneal hem- and lymphangiogenesis. To investigate the effect of on inflammatory cell recruitment, corneal CD45+ cells were quantified. In addition, epithelial wound closure after debridement was assessed by corneal fluorescein staining. Results: Trap/F6H8 was as effective as Trap in inhibiting corneal hemangiogenesis and lymphangiogenesis after 2 weeks of treatment. After 3 days of treatment, Trap/F6H8 was even more effective than Trap in inhibiting corneal hemangiogenesis. Both treatment groups (Trap/F6H8 and Trap) significantly reduced corneal CD45+ cell recruitment. Epithelial closure after debridement was unaffected by Trap/F6H8 or Trap. Conclusions: In this study, we demonstrate that F6H8 is a potential carrier for VEGF TrapR1R2 to topically treat corneal neovascularization. Our findings might open new treatment avenues for local anti-angiogenic therapy at the cornea, as F6H8 is already approved for the usage at the ocular surface. Translational Relevance: With this study we show for the first time that SFAs can serve as carriers for anti-angiogenic drugs at the ocular surface.

Interactions of Perfluorohexyloctane With Polyethylene and Polypropylene Pharmaceutical Packaging Materials.

Semifluorinated alkanes (SFAs) are aprotic solvents, which may be used as drug solvents for topical ocular applications, for instance, in dry eye syndrome. Their physical properties suggest that they might be prone to interaction with plastic materials, such as, polyethylene (PE) and polypropylene (PP), which are commonly used as packaging materials for pharmaceutical products. In this study, we investigate interactions of PE and PP with a liquid SFA perfluorohexyloctane (PFHO) using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and cross-polarized light microscopy. Binary phase diagrams of PFHO-PE and PFHO-PP systems demonstrating interactions of PFHO with the polymeric materials were constructed based on DSC data. According to this data, PFHO tends to lower the melting temperatures of PE and PP. The equilibrium values of solubilities of the polymers in PFHO and PFHO in the polymers were obtained by extrapolation of melting enthalpy data. Absorption of PFHO by PE and PP materials at ambient conditions after 4 weeks of equilibration was also studied by TGA. From the presented results, it may be concluded that thorough studies of interactions of PE or PP with SFAs are required when these materials are used as packaging components in SFA-based formulations.

Perfluorohexyloctane (F6H8) as a delivery agent for cyclosporine A in dry eye syndrome therapy - Langmuir monolayer study complemented with infrared nanospectroscopy.

One of the key challenges in dry eye syndrome therapy is to find a suitable carrier for immunosuppressant drug - cyclosporine A (CsA) - delivery to the eye. To investigate this issue, herein we present a methodology based on the combined analysis in macro- (Langmuir monolayers), micro- (Brewster angle microscopy) and nanoscale (atomic force microscopy and infrared nano-spectroscopy). The applied approach proves that CsA affects the phospholipid part of the tear film lipid layer by loosening molecular packing. This effect can be reversed by the addition of perfluorohexyloctane (F6H8). We have highlighted that F6H8 increases the availability of CsA and therefore is appropriate carrier for CsA topical delivery to the eye in the dry eye syndrome. In addition, the applied herein procedure provides a simple, low-cost laboratory tool for preliminary studies involving membrane active pharmaceuticals, preceding in vivo tests.

Preclinical studies evaluating the effect of semifluorinated alkanes on ocular surface and tear fluid dynamics.

PURPOSE: Dry eye disease (DED) is one of the most prevalent ocular surface disorders that presents clinically. Recently, the semifluorinated alkane (SFA) perfluorohexyloctane (NovaTears®; EvoTears®) entered the market for the management of evaporative DED, while perfluorobutylpentane has been used as a vehicle to enhance ocular drug delivery. This study evaluated the mechanisms by which SFAs might improve therapeutic outcomes in DED. METHODS: Interactions of both SFAs with the corneal surface were evaluated ex vivo using high-speed photography. The in vivo influence of SFAs on tear fluid dynamics was evaluated in healthy rabbit eyes observing changes in lipid layer grade, tear evaporation rate, tear volume and tear osmolarity. Furthermore, ocular tolerability was confirmed by clinical scoring and sodium fluorescein staining. RESULTS: Ex vivo studies demonstrated that both SFAs rapidly spread on the ocular surface with their contact angle on the cornea being virtually zero. A significant improvement in lipid layer grade was observed immediately after instillation of both SFAs in vivo, although the improvement was more sustained upon instillation of perfluorohexyloctane with a statistically significant difference compared to saline instillation evident from day five onwards. No significant changes in tear evaporation rate, volume or osmolarity, nor any signs of ocular irritation were observed after application of either SFA over the seven-day study period. CONCLUSION: Both SFAs showed excellent spreading on the ocular surface. Perfluorohexyloctane improved the lipid layer grade significantly after topical application supporting its potential to stabilise the tear film lipid layer and thus provide symptomatic relief in evaporative DED.

Topical semifluorinated alkane-based azithromycin suspension for the management of ocular infections.

The management of ocular infections is challenging due to poor drug bioavailability and vehicle related adverse effects associated with current antibiotic eye drops. Semifluorinated alkanes (SFAs) are reportedly well-tolerated on the ocular surface and can enhance ocular drug bioavailability. Therefore, an SFA-based azithromycin suspension (SFA-AZM) was prepared and its antibacterial efficacy was compared to that of marketed azithromycin eye drops by monitoring the growth of bioluminescent Staphylococcus aureus in ex vivo ocular tissues. Corneal and conjunctival distribution of hydrophobic fluorescent dye particles from an SFA suspension (SFA-BODIPY) resulted in preferential dye localisation in the epithelial layers of both tissues. However, corneal dye absorption was significantly lower than conjunctival absorption, likely due to limited adhesion of suspended dye particles to the corneal compared to the conjunctival epithelium. In line with the dye distribution results, bacterial colonisation in the conjunctiva reduced significantly upon application of SFA-AZM with the efficacy being greater than or at least equal to the marketed azithromycin eye drops. In the cornea, all tested azithromycin eye drops reduced the rate of bacterial growth with similar efficacy. Overall, the SFA-AZM suspension tested here may provide a safe and effective alternative for the management of ocular infections by enhancing conjunctival drug absorption and thus drug efficacy.

Semifluorinated alkane based systems for enhanced corneal penetration of poorly soluble drugs.

Semifluorinated alkanes (SFAs) are amphiphilic liquids that can dissolve hydrophobic drugs to form clear solutions. This study evaluated the potential of two SFAs to act as vehicle for topical ocular drug delivery. After confirming ocular safety, an ex vivo corneal penetration model was developed to determine drug distribution and corneal bioavailability. Hydrophobic dye distribution in the different corneal layers was visualised under a confocal microscope. Corneal bioavailability of cyclosporine A (CsA) dissolved in perfluorobutylpentane (F4H5) or perfluorohexyloctane (F6H8) was compared to commercially available CsA ophthalmic emulsions, Restasis® and Ikervis®. Precorneal residence of the four test vehicles containing the hydrophobic dye was also compared using an ex vivo corneal tissue model. Preferential accumulation of the hydrophobic dye in the corneal epithelium was observed with higher amounts detectable when delivered via the SFAs compared to Restasis or Ikervis. A significant improvement in corneal CsA penetration was observed after application of a single dose of 0.05% CsA in F4H5 and F6H8 when compared to Restasis with the area under curve over 4 h (AUC(0-4h)) being at least 8-fold greater for both SFAs (p < .0001). Moreover, the AUC(0-4h) of 0.1% CsA in F4H5 was almost 5-fold greater than Ikervis (p < .0001). Finally, the precorneal residence time of both SFA solutions was significantly longer than that of the commercial emulsions with the AUC(0-60min) being 2- to 11-fold greater. This study demonstrated that SFAs can significantly improve the local bioavailability of hydrophobic drugs by increasing corneal penetration as well as prolonging precorneal residence. They therefore offer a promising new platform for topical drug delivery to the eye.

Semifluorinated Alkane Eye Drops for Treatment of Dry Eye Disease Due to Meibomian Gland Disease.

PURPOSE: Meibomian gland disease is generally accepted as the leading cause for evaporative dry eye disease (DED). In a previous study, perfluorohexyloctane, a semifluorinated alkane, has been demonstrated to significantly increase tear film breakup time and to reduce corneal fluorescein staining in patients with evaporative DED, thereby vastly reducing dry eye-related symptoms. This study was set up to evaluate perfluorohexyloctane in a larger population of patients with Meibomian gland dysfunction. METHODS: Seventy-two patients with Meibomian gland disease and associated dry eye received 1 drop of perfluorohexyloctane 4 times daily during an observational, prospective, multicenter, 6-8-week study. Clinical assessment included best-corrected visual acuity, intraocular pressure, Schirmer test I, tear film breakup time, anterior and posterior blepharitis assessment, number of expressible Meibomian glands, meibum quality and quantity, ocular surface fluorescein staining, lid margin and symptom assessment, and Ocular Surface Disease Index (OSDI©). RESULTS: From the 72 patients recruited, 61 completed the trial per protocol. Nine patients did not apply the medication as recommended and 2 patients were lost to follow-up. Tear film breakup time, corneal and conjunctival fluorescein staining, number of expressible Meibomian glands, and severity of anterior and posterior blepharitis significantly improved after 6-8 weeks of perfluorohexyloctane application. In addition, symptoms improved as demonstrated by a significant decrease of OSDI-values from 37 (±13) to 26 (±16). CONCLUSIONS: In concordance with previous findings, 6-8 weeks of topical application of perfluorohexyloctane significantly improves clinical signs of Meibomian gland disease and associated mild to moderate DED.

Surface and liquid-crystalline properties of FmHnFm triblock semifluorinated n-alkanes.

A series of triblock semifluorinated n-alkanes of the general formula: F(CF2)m(CH2)n(CF2)mF, (in short FmHnFm), where m=10, 12, and n=6, 8, and 12 have been synthesized and employed for liquid crystalline studies and Langmuir monolayer characterization. Differential scanning calorimetry (DSC) measurements together with texture observation with polarizing microscope (POM) revealed the presence of liquid crystalline smectic phases for all the investigated homologs. The behavior of the studied molecules spread at the free water surface has also been investigated. Our results show for the first time that these unusual film-forming materials, which are completely hydrophobic in nature and do not possess any polar group in their structure, are surface active and form insoluble (Langmuir) monolayers at the air/water interface. Due to the fact that these molecules are chemically inert and, similar to the semifluorinated diblocks, are not toxic, they may be destined for biomedical uses as gas carriers and contrast agents, as well as in drug delivery systems.

19F Oximetry with semifluorinated alkanes.

This work examines the variation of longitudinal relaxation rate R1(= 1/T1) of the 19F-CF3-resonance of semifluorinated alkanes (SFAs) with oxygen tension (pO2), temperature (T) and pH in vitro. Contrary to their related perfluorocarbons (PFCs), SFA are amphiphilic and facilitate stable emulsions, a prerequisite for clinical use. A linear relationship between R1 and pO2 was confirmed for the observed SFAs at different temperatures. Using a standard saturation recovery sequence, T1 has been successfully measured using fluorine 19F-MRI with a self-constructed birdcage resonator at 9.4 T. A calibration curve to calculate pO2 depending on T and R1 was found for each SFA used. In contrast to the commonly used PFC, SFAs are less sensitive to changes in pO2, but more sensitive to changes in temperature. The influence of pH to R1 was found to be negligible.

Semifluorinated thiols in Langmuir monolayers - a study by nonlinear and linear vibrational spectroscopies.

A series of semifluorinated thiols of the general formula CmF2m+1CnH2nSH (abbr. FmHnSH) have been synthesized and characterized in Langmuir monolayers with surface pressure-area isotherms, complemented with polarization-modulated reflection absorption spectroscopy (PM-IRRAS) and sum-frequency generation (SFG) techniques. A comparative analysis was performed for compounds having the same length of fluorinated segment (F10) and variable length of the hydrogenated part (H6, H10, H12), and having identical hydrogenated segment (H12) connected to a fluorinated moiety of different lengths (F6, F8, F10). For the sake of comparison, an alkanethiol (H18SH) was also examined, and F10H10COOH and F10H10OH molecules were used for helping the assignment of SFG spectra of CH stretches. SFG was applied to investigate the hydrocarbon chain and the terminal CF3 group, while PM-IRRAS was used to probe CF2 groups. The number of gauche defects in the hydrocarbon chain increased with the increasing length of the molecule, either by elongation of the hydrogenated or perfluorinated part. SFG measurements recorded at three polarization combinations (ppp, ssp, sps) enabled us to estimate the tilt angle of the terminal CF3 group in semifluorinated thiol molecules as ranging from 35° to 45°, which is consistent with nearly vertical fluorinated segments. Upon increasing the surface pressure, the fluorinated segment gets slightly more upright, but the hydrocarbon chain tilt increases while keeping the same average number of gauche defects. The extent of disorder in the hydrogenated segment may be controlled by varying the size of the fluorinated segment, and this could be exploited for designing functionalized surfaces with insertion of other molecules in the defect region.

Semifluorinated alkanes as a liquid drug carrier system for topical ocular drug delivery.

Semifluorinated alkanes (SFA, e.g. perfluorobutylpentane F4H5, perfluorohexyloctane F6H8) are inert, non-toxic fluids capable of dissolving lipophilic drugs. The aim of this study to assess the bioavailability and safety of SFAs as drug solvents for the topical ocular application of Cyclosporin A (CsA). A commercially available CsA formulation (Restasis, 0.05% CsA in castor oil) was tested against two novel formulations of 0.05% CSA in (a) F4H5 containing Ethanol (0.5 w/w%) and (b) F6H8 containing Ethanol (0.5 w/w%) with 0.05% CsA. Formulations were tested on rabbit corneas cultured on an artificial anterior chamber with a constant flow of an aqueous humour supplement (Ex Vivo Eye Irritation Test (EVEIT) system). Anterior chamber fluids were sampled at multiple time points to analyse the CsA concentration following single and repeated application regimes by HPLC. Photographs of fluorescein sodium-stained corneas were recorded for corneal toxicity evaluation. The impact of the formulations on the integrity of the corneal barrier function was tested after drug application by fluorescein sodium corneal diffusion experiments. The influence on the corneal metabolism was evaluated by analysis of the metabolic markers glucose and lactate. Restasis did not pass the corneal barrier after short term application, CsA in ethanolic F4H6 reached a maximum of 152.95 ng/ml in anterior chamber fluid samples whilst CsA in ethanolic F6H8 reached a maximum of 15.12 ng/ml. After repeated applications for 8h, Restasis reached 21.07 ng/ml compared to 247.62 ng/ml and 174.5 ng/ml for F4H5 and F6H8, respectively. No corneal toxicity was observed in following application of any of the formulations. In contrast to the commercially available castor oil-based formulation, CsA dissolved in SFAs reached therapeutic inner ocular concentrations after topical administration, possibly leading to the replacement of systemic applications of CsA for inflammatory ocular disease.