Development of inert coatings to prevent drug retention in 3D-printed diffusion cells.

Diffusion cells play a crucial role in the pharmaceutical and cosmetic fields by assessing the release and permeation of active pharmaceutical ingredients across membranes. However, commercially available glass-based devices, such as Franz diffusion cells, are expensive and fragile. The emergence of three-dimensional (3D) printing technology enables the creation of diffusion cells with cost-effective polymeric materials and resins, offering exceptional precision and custom geometries. Nonetheless, there are challenges associated with interactions between 3D printing materials and drug molecules. This work aimed to develop inert coatings for 3D-printed diffusion models. Diffusion devices were designed and 3D-printed with a stereolithography (SLA) 3D printer, and different coatings were applied. Then, two model drugs were used to evaluate drug retention by coated devices. Among the tested coatings, one of them showed great potential in preventing drug retention and was selected for subsequent experiments with different drugs and conditions. Finally, voriconazole eyedrops were used to confirm the viability of 3D-printed Franz diffusion cells as a drug release diffusion model. The favourable results obtained with the coating promote the use of 3D printing as a cost-effective manufacturing technology, capable of producing diffusion cells tailored to specific study requirements.

Intravitreal implants manufactured by supercritical foaming for treating retinal diseases.

Chronic retinal diseases, such as age-related macular degeneration (AMD), are a major cause of global visual impairment. However, current treatment methods involving repetitive intravitreal injections pose financial and health burdens for patients. The development of controlled drug release systems, particularly for biological drugs, is still an unmet need in prolonging drug release within the vitreous chamber. To address this, green supercritical carbon dioxide (scCO2) foaming technology was employed to manufacture porous poly(lactic-co-glycolic acid) (PLGA)-based intravitreal implants loaded with dexamethasone. The desired implant dimensions were achieved through 3D printing of customised moulds. By varying the depressurisation rates during the foaming process, implants with different porosities and dexamethasone release rates were successfully obtained. These implants demonstrated controlled drug release for up to four months, surpassing the performance of previously developed implants. In view of the positive results obtained, a pilot study was conducted using the monoclonal antibody bevacizumab to explore the feasibility of this technology for preparing intraocular implants loaded with biologic drug molecules. Overall, this study presents a greener and more sustainable alternative to conventional implant manufacturing techniques, particularly suited for drugs that are susceptible to degradation under harsh conditions.

Design and biopharmaceutical preclinical characterisation of a new thermosensitive hydrogel for the removal of gastric polyps.

BACKGROUND AND AIMS: Submucosal injection agents are widely used solutions in gastric polyp resection techniques. Currently, many different solutions are used in clinical practice, but most are not authorised for this use or are not biopharmaceutical characterised. The objective of this multidisciplinary work is to test the efficacy of a novel thermosensitive hydrogel designed specifically for this indication. METHODS: A mixture design of various components (Pluronic®, hyaluronic acid and sodium alginate) was carried out to select the combination with optimal properties for this use. Three final thermosensitive hydrogels were selected on which biopharmaceutical characterisation was performed and stability and biocompatibility were analysed. Efficacy in maintaining elevation was tested ex vivo on pig mucosa and in vivo in pigs RESULTS: The mixture design allowed selection of the ideal combinations of agents for the characteristics sought. The thermosensitive hydrogels studied showed high values of hardness and viscosity at 37 °C, maintaining good syringeability. One of them demonstrated superiority in maintaining polyp elevation in the ex vivo assay and non-inferiority in the in vivo assay. CONCLUSION: The thermosensitive hydrogel specifically designed for this use is promising both for its biopharmaceutical characteristics and for its demonstrated efficacy. This study lays the foundation for evaluating the hydrogel in humans.

Mucoadhesive PLGA Nanospheres and Nanocapsules for Lactoferrin Controlled Ocular Delivery.

BACKGROUND: the present work describes the preparation, characterization and optimization of eight types of PLGA-based nanosystems (nanospheres and nanocapsules) as innovative mucoadhesive drug delivery systems of lactoferrin, in order to achieve a preclinical consistent base as an alternative pharmacological treatment to different ocular syndromes and diseases. METHODS: All different nanoparticles were prepared via two modified nanoprecipitation techniques, using a three-component mixture of drug/polymer/surfactant (Lf/PLGA/Poloxamer), as a way to overcome the inherent limitations of conventional PLGA NPs. These modified polymeric nanocarriers, intended for topical ophthalmic administration, were subjected to in vitro characterization, surface modification and in vitro and in vivo assessments. RESULTS: An appropriate size range, uniform size distribution and negative ζ potential values were obtained for all types of formulations. Lactoferrin could be effectively included into all types of nanoparticles with appropriate encapsulation efficiency and loading capacity values. A greater, extended, and controlled delivery of Lf from the polymeric matrix was observed through the in vitro release studies. No instability or cytotoxicity was proved for all the formulations by means of organotypic models. Additionally, mucoadhesive in vitro and in vivo experiments show a significant increase in the residence time of the nanoparticles in the eye surface. CONCLUSIONS: all types of prepared PLGA nanoparticles might be a potential alternative for the topical ophthalmic administration of lactoferrin.

Lactoferrin-loaded nanostructured lipid carriers (NLCs) as a new formulation for optimized ocular drug delivery.

Nanostructured lipid carriers (NLC) are novel lipidic nanosystems that provide significant improvements in terms of high drug loading capacity and controlled drug release. The purpose of the present work was based on the design, development, and physicochemical characterization of lactoferrin-loaded NLCs as a new therapeutic alternative for the keratoconus treatment. Lactoferrin-loaded NLCs were successfully prepared by a double emulsion/solvent evaporation method. The resultant NLC were assessed in terms of particle size, size distribution, surface charge, morphology, encapsulation efficiency (EE), loading capacity (LC), stability, cytotoxicity, in vitro release, and ocular surface retention. Resulting data showed a size of 119.45 ± 11.44 nm, a 0.151 ± 0.045 PDI value and a surface charge of -17.50 ± 2.53 mV. Besides, high EE and LC values were obtained (up to 75%). The in vitro release study demonstrated a lactoferrin controlled release pattern. NLCs were also stable, non-toxic and show mucoadhesive properties. Thus, a consistent preclinical base was obtained, where NLC may be considered as a potential controlled release novel drug delivery system of lactoferrin for the keratoconus treatment.

Antifungal Combination Eye Drops for Fungal Keratitis Treatment.

Fungal keratitis (FK) is a corneal mycotic infection that can lead to vision loss. Furthermore, the severity of FK is aggravated by the emergence of resistant fungal species. There is currently only one FDA-approved formulation for FK treatment forcing hospital pharmacy departments to reformulate intravenous drug preparations with unknown ocular bioavailability and toxicity. In the present study, natamycin/voriconazole formulations were developed and characterized to improve natamycin solubility, permanence, and safety. The solubility of natamycin was studied in the presence of two cyclodextrins: HPßCD and HPγCD. The HPßCD was chosen based on the solubility results. Natamycin/cyclodextrin (HPßCD) inclusion complexes characterization and a competition study between natamycin and voriconazole were conducted by NMR (Nuclear Magnetic Resonance). Based on these results, several eye drops with different polymer compositions were developed and subsequently characterized. Permeability studies suggested that the formulations improved the passage of natamycin through the cornea compared to the commercial formulation Natacyn®. The ocular safety of the formulations was determined by BCOP and HET-CAM. The antifungal activity assay demonstrated the ability of our formulations to inhibit the in vitro growth of different fungal species. All these results concluded that the formulations developed in the present study could significantly improve the treatment of FK.

Enhancement in corneal permeability of riboflavin using cyclodextrin derivates complexes as a previous step to transepithelial cross-linking.

Corneal cross-linking has been described as an effective treatment to slow the progression of keratoconus. The standard protocol entails corneal epithelial removal to allow the diffusion of riboflavin into the stroma. Although, de-epithelization can generate risks or complications that transepithelial cross-linking tries to solve or avoid. Different formulations were developed after verifying that hydroxypropyl-ß-cyclodextrin (HPßCD) and sulfobuthylether-ß-cyclodextrin (SBEßCD) in a 20% concentration, increased the solubility of practically insoluble in water drugs such as riboflavin from 0.12 mg/mL to 0.35 mg/mL and 0.29 mg/mL respectively. These values were higher when chitosan and arginine were added to the formulation, showing solubility of 0.78 mg/mL when HPßCD concentration was not modified. Ex vivo corneal permeability was measured after having kept in contact bovine corneas with intact epithelium for 5 h with the 0.1 mg/mL riboflavin solution, the formulations developed and a reproduced nanoemulsion from another work. Riboflavin's permeability was increased when cyclodextrins, chitosan, and arginine were part of the formulations, compared to the control drug solution. The best permeability coefficient was reached when riboflavin was combined with 40% (w/v) HPßCD, 0.5% (w/w) arginine, and 0.5% (w/w) chitosan. After having carried out toxicity studies as bovine corneal opacity and permeability (BCOP) and Hens Egg Test - Chorioallantoic Membrane Test (HET-CAM) it was verified that both, the active ingredients and the excipients of the different formulations were not harmful without generating irritation, loss of transparency or corneal permeability alterations. The results show the great potential of the ocular developed solution for their use in transepithelial cross-linking for keratoconus treatment.

In situ forming and mucoadhesive ophthalmic voriconazole/HPßCD hydrogels for the treatment of fungal keratitis.

Fungal keratitis is a severe infectious corneal disease. At present, no voriconazole ophthalmic formulations are approved by the FDA or EMA. This lack of therapeutic options leads to the reformulation of intravenous voriconazole preparations (VFEND®) by the hospital pharmacy departments to prepare the appropriate ophthalmic formulations (pharmacy compounding). However, the limited residence time of these formulations leads to an intensive treatment posology that may increase the occurrence of side effects. In the present study, two different hydrogels were developed and characterized in order to improve the voriconazole's ophthalmic solubility, permanence, and security. Voriconazole-cyclodextrin (HPßCD or HPÉ£CD) inclusion complexes in aqueous solutions were characterized by NMR and molecular modeling. Complexes were formed by encapsulation of voriconazole into the cyclodextrin's internal cavity which considerably increases its water solubility. Ocular safety was proven by ocular irritation studies. Permeability studies suggest both hydrogels have good corneal permeability. Furthermore, in vivo ocular permanence study by PET/CT showed a longer permanence time on the ocular surface (t1/2 = 58.91 ± 13.4 min and 96.28 ± 49.11 min for VZHAH and VZISH 0.65 respectively) compared to the voriconazole control formulation (VFEND® t1/2 = 32.27 ± 15.56 min). Results suggest these formulations are a good alternative for the treatment of fungal keratitis.

Development and Characterization of a Tacrolimus/Hydroxypropyl-ß-Cyclodextrin Eye Drop.

Uveitis is a vision inflammatory disorder with a high prevalence in developing countries. Currently, marketed treatments remain limited and reformulation is usually performed to obtain a tacrolimus eye drop as a therapeutic alternative in corticosteroid-refractory eye disease. The aim of this work was to develop a mucoadhesive, non-toxic and stable topical ophthalmic formulation that can be safely prepared in hospital pharmacy departments. Four different ophthalmic formulations were prepared based on the tacrolimus/hydroxypropyl-ß-cyclodextrin (HPßCD) inclusion complexes' formation. Phase solubility diagrams, Nuclear Magnetic Resonance (NMR) and molecular modeling studies showed the formation of 1:1 and 1:2 tacrolimus/HPßCD inclusion complexes, being possible to obtain a 0.02% (w/v) tacrolimus concentration by using 40% (w/v) HPßCD aqueous solutions. Formulations also showed good ophthalmic properties in terms of pH, osmolality and safety. Stability studies proved these formulations to be stable for at least 3 months in refrigeration. Ex vivo bioadhesion and in vivo ocular permanence showed good mucoadhesive properties with higher ocular permanence compared to the reference pharmacy compounding used in clinical settings (t1/2 of 86.2 min for the eyedrop elaborated with 40% (w/v) HPßCD and Liquifilm® versus 46.3 min for the reference formulation). Thus, these novel eye drops present high potential as a safe alternative for uveitis treatment, as well as a versatile composition to include new drugs intended for topical ophthalmic administration.

Design, Optimization, and Characterization of Lactoferrin-Loaded Chitosan/TPP and Chitosan/Sulfobutylether-ß-cyclodextrin Nanoparticles as a Pharmacological Alternative for Keratoconus Treatment.

This research study describes the design, optimization, and characterization of two different types of chitosan-based nanoparticles as novel drug delivery systems of a protein drug, lactoferrin. A preclinical consistent base was obtained for both nanosystems, being considered as the first pharmacological treatment for keratoconus as an alternative to current invasive clinical methods. Both types of nanoparticles were obtained via the ionotropic gelation technique. The size and morphology of the nanoparticles were studied as a function of the preparation conditions. A mean size of 180.73 ± 40.67 nm, a size distribution [polydispersity index (PDI)] of 0.170 ± 0.067, and positive ζ-potential values, ranging from 17.13 to 19.89 mV, were achieved. Lactoferrin was successfully incorporated into both types of nanocarriers. In vitro release profiles showed a lactoferrin enhanced, prolonged, and controlled delivery from the polymeric matrix. These formulations also demonstrated no stability or cytotoxicity problems, as well as appropriate mucoadhesive properties, with a high permanence time in the ocular surface. Thus, both types of nanoparticles may be considered as nanocarriers for the controlled release of lactoferrin as novel topical ophthalmic drug delivery systems.

Biopharmaceutical Assessment of Dexamethasone Acetate-Based Hydrogels Combining Hydroxypropyl Cyclodextrins and Polysaccharides for Ocular Delivery.

We previously developed two optimized formulations of dexamethasone acetate (DXMa) hydrogels by means of special cubic mixture designs for topical ocular administration. These gels were elaborated with hydroxypropyl-ß-CD (HPßCD) and hydroxypropyl-γ-CD (HPγCD) and commercial hydrogels in order to enhance DXMa water solubility and finally DXMa's ocular bioavailability and transcorneal penetration. The main objective of this study was to characterize them and to evaluate in vitro, ex vivo, and in vivo their safety, biopermanence, and transcorneal permeation. Gels A and B are Newtonian fluids and display a viscosity of 13.2 mPa.s and 18.6 mPa.s, respectively, which increases their ocular retention, according to the in vivo biopermanence study by PET/CT. These hydrogels could act as corneal absorption promoters as they allow a higher transcorneal permeation of DXMa through porcine excised cornea, compared to DEXAFREE® and MAXIDEX®. Cytotoxicity assays showed no cytotoxic effects on human primary corneal epithelial cells (HCE). Furthermore, Gel B is clearly safe for the eye, but the effect of Gel A on the human eye cannot be predicted. Both gels were also stable 12 months at 25 °C after sterilization by filtration. These results demonstrate that the developed formulations present a high potential for the topical ocular administration of dexamethasone acetate.

Novel Polymeric Formulation for Removal of Gastrointestinal Polyps by Digestive Endoscopy.

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are two techniques used in the resection of gastrointestinal mucosal polyps. The aim of this work is the development and evaluation of an innovative polymeric solution containing sodium carboxymethylcellulose and hyaluronic acid. For this purpose, several mixtures of these two main components, as well as other components such as fructose, citric acid, and zinc, are evaluated in terms of physicochemical and microbiological properties, rheological behavior, extensibility, syringeability, and stability at different storage conditions. Furthermore, the potential production of mucosal elevation and duration is also studied by an ex vivo model using porcine stomach and colon. Results show that the developed polymeric solutions possess optimal values of pH, from 4.58 to 6.63, for their use in the gastrointestinal tract. The formulations exhibit both Newtonian and pseudoplastic behaviors with different viscosity values as a function of their composition. All formulations exhibit high stability properties and no bacterial or fungal growth is detected. MCS01 and MCS05 are the polymeric solutions with the best syringeability results. In this line, MCS05 is the formulation that provides the highest, 2.20 ± 0.18 cm and 1.40 ± 0.11 cm, and longest-lasting, for more than 120 min, elevation effect on porcine submucosal stomach and colon tissues, respectively. Thus, it can be concluded that polymeric solution MCS05 might be considered as a promising tool for use in human EMR and ESD.

Drug Delivery to the Posterior Segment of the Eye: Biopharmaceutic and Pharmacokinetic Considerations.

The treatment of the posterior-segment ocular diseases, such as age-related eye diseases (AMD) or diabetic retinopathy (DR), present a challenge for ophthalmologists due to the complex anatomy and physiology of the eye. This specialized organ is composed of various static and dynamic barriers that restrict drug delivery into the target site of action. Despite numerous efforts, effective intraocular drug delivery remains unresolved and, therefore, it is highly desirable to improve the current treatments of diseases affecting the posterior cavity. This review article gives an overview of pharmacokinetic and biopharmaceutics aspects for the most commonly-used ocular administration routes (intravitreal, topical, systemic, and periocular), including information of the absorption, distribution, and elimination, as well as the benefits and limitations of each one. This article also encompasses different conventional and novel drug delivery systems designed and developed to improve drug pharmacokinetics intended for the posterior ocular segment treatment.

Ophthalmic Econazole Hydrogels for the Treatment of Fungal Keratitis.

Econazole is a feasible alternative treatment in the management of fungal keratitis. Nevertheless, its low water solubility is considered the main limitation to the incorporation into ophthalmic formulations. In this work, econazole nitrate is solubilized by using cyclodextrins to achieve an optimum therapeutic concentration. Phase solubility diagrams suggest α-cyclodextrin as the most effective cyclodextrin and later the inclusion complex formed with this one was characterized in solution by 1D, 2D-NMR, and molecular modeling. Econazole-α-cyclodextrin inclusion complex was included in 2 types of ocular hydrogels: a natural polysaccharides ion-sensitive hydrogel and a hyaluronic acid hydrogel. Both of them show no ocular irritation in the hen's egg test on chorioallantoic membrane assay and a controlled econazole release over time. Permeability studies suggest that hydrogels do not modify the econazole nitrate permeability through bovine cornea in comparison with an econazole-α-cyclodextrin inclusion complex solution. Finally, ocular biopermanence studies performed using positron emission tomography show these hydrogels present a high retention time on the eye. Results suggest the developed formulations have a high potential as vehicles for the econazole topical ocular administration as fungal keratitis treatment.

Hidrogel oftálmico de cisteamina para el tratamiento de la cistinosis ocular / Cysteamine ophthalmic hydrogel for the treatment of ocular cystinosis

La cistinosis ocular es una enfermedad rara que se caracteriza por el depósito de cristales de cistina a nivel corneal, los cuales dificultan la visión de los pacientes. La cisteamina oral se administra en forma de cisteamina, pero esta no alcanza la córnea debido a la falta de vascularización corneal, por lo que es necesaria la aplicación tópica ocular. El objetivo del presente trabajo es determinar la estabilidad de un hidrogel oftálmico de cisteamina, potencialmente formulable en servicios de farmacia hospitalaria, conservado este bajo diferentes condiciones de almacenamiento durante un periodo de 30 días. Los parámetros físicos y químicos evaluados han sido la osmolalidad, el pH y la concentración de cisteamina, siendo esta última valorada mediante un método de cromatografía líquida de ultra alta presión, empleando un detector de masas en tándem (UPLC-MS/MS). Los ensayos descriptivos se han basado en la medición de la transparencia y los ensayos microbiológicos en la realización de pruebas de esterilidad. Los resultados obtenidos permiten concluir que el hidrogel de cisteamina es estable durante un periodo de 30 días, recomendándose que su conservación sea en nevera (AU)

Ocular cystinosis is a rare disease characterised by the deposit of cystine crystals on the corneal surface, which hinder patients' eyesight. Oral cysteamine is given as cysteamine; however, it does not reach the cornea due to the lack of corneal vascularization making necessary its administration by the topical ocular route. The aim of the present study is to determine the stability of an ophthalmic hydrogel of cysteamine, which can be potentially prepared at hospital pharmacy departments, under different preservation conditions during a follow-up of 30 days. Different physical and chemical parameters were evaluated: osmolality, pH and cysteamine concentration, which has been measured by a method of ultra performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS). Descriptive assays were also performed, such as transparency measurement and microbiological assays in order to verify its sterility. The obtained results allow us to conclude that the cysteamine hydrogel is stable during 30 days, being recommendable its preservation in refrigerated conditions (AU)

[Cysteamine ophthalmic hydrogel for the treatment of ocular cystinosis]. / Hidrogel oftálmico de cisteamina para el tratamiento de la cistinosis ocular.

Ocular cystinosis is a rare disease characterised by the deposit of cystine crystals on the corneal surface, which hinder patients' eyesight. Oral cysteamine is given as cysteamine; however, it does not reach the cornea due to the lack of corneal vascularization making necessary its  administration by the topical ocular route. The aim of the present study is to  determine the stability of an ophthalmic hydrogel of cysteamine, which can be  potentially prepared at hospital pharmacy departments, under different preservation conditions during a follow-up of 30 days. Different physical  and chemical parameters were evaluated: osmolality, pH and  cysteamine concentration, which has been measured by a method of ultra  performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS).  Descriptive assays were also performed, such as transparency measurement and  microbiological assays in order to verify its sterility. The obtained results  allow us to conclude that the cysteamine hydrogel is stable during 30 days,  being recommendable its preservation in refrigerated conditions.

La cistinosis ocular es una enfermedad rara que se caracteriza por el depósito de  cristales de cistina a nivel corneal, los cuales dificultan la visión de  los pacientes. La cisteamina oral se administra en forma de cisteamina, pero  esta no alcanza la córnea debido a la falta de vascularización corneal, por lo que  es necesaria la aplicación tópica ocular. El objetivo del presente trabajo es  determinar la estabilidad de un hidrogel oftálmico de cisteamina, potencialmente  formulable en servicios de farmacia hospitalaria, conservado  este bajo diferentes condiciones de almacenamiento durante un periodo de 30  días. Los parámetros físicos y químicos evaluados han sido la osmolalidad, el pH  y la concentración de cisteamina, siendo esta última valorada mediante un  método de cromatografía líquida de ultra alta presión, empleando un detector de  masas en tándem (UPLC-MS/MS). Los ensayos descriptivos se han basado  en la medición de la transparencia y los ensayos microbiológicos en la realización  de pruebas de esterilidad. Los resultados obtenidos permiten  concluir que el hidrogel de cisteamina es estable durante un periodo de 30 días,  recomendándose que su conservación sea en nevera.

Cysteamine polysaccharide hydrogels: Study of extended ocular delivery and biopermanence time by PET imaging.

Cystinosis is a rare autosomal recessive disorder in which cystine crystals accumulate within the lysosomes of various organs, including the cornea. Ocular treatment is based on the administration of cysteamine eye drops, requiring its instillation several times per day. We have introduced the cysteamine in two types of previously developed ocular hydrogels (ion sensitive hydrogel with the polymers gellan gum and kappa-carrageenan and another one composed of hyaluronic acid), aiming at increasing the ocular retention in order to extend the dosing interval. The biopermanence studies (direct measurements and PET/CT) show that these formulations present a high retention time on the ocular surface of rats. From the in vitro release study we determined that both hydrogels can control the release of cysteamine over time, showing a zero order kinetics during four hours. At the same time, these hydrogels could act as corneal absorption promoters, as they allow a higher permeation of cysteamine through bovine cornea compared to a solution. HET-CAM test and cytotoxicity assays show no irritation on the ocular surface. These results demonstrate that the developed formulations present a high potential as vehicles for the topical ocular administration of cysteamine.

In Vitro Evaluation of the Ophthalmic Toxicity Profile of Chlorhexidine and Propamidine Isethionate Eye Drops.

PURPOSE: Acanthamoeba keratitis causes frequent epithelial lesions that fully expose the corneal stroma. The aim of this study was to determine the toxic profile of chlorhexidine and propamidine eye drops. METHODS: We used primary human keratocytes in cell culture in combination with a novel technology that evaluates dynamic real-time cytotoxicity through impedance analysis. Additional studies such as a classic cell viability test (WST-1®), a bovine corneal opacity and permeability assay, and an irritation eye study (Hen's Egg Test [HET]) have been made. RESULTS: Both eye drop formulations showed a time- and concentration-dependent toxicity profile, in which long periods and high concentrations were more detrimental to cells. In prolonged times of exposure, propamidine is more harmful to cells than chlorhexidine. On the contrary, no irritation has been detected in using the HET-chorioallantoic membrane test and no alterations in the corneal transparency nor permeability was produced by the treatment with both eye drops. CONCLUSIONS: In culture assay, chlorhexidine eye drops have proven to be less cytotoxic than Brolene® for a long contact period of time, but no signs of irritation or alterations in transparency or permeability have been observed in the cornea after both treatments.