RESUMO
An innovative and sensitive HPLC-UV method for the extraction and quantification of methotrexate (MTX) in skin layers was developed and validated. Owing to the physico-chemical characteristics of the drug and the nature of the tissue, it was necessary to use folic acid (FA) as an internal standard for MTX quantification in the dermis. MTX (and FA) analysis was performed on a Phenomenex Jupiter C18 column, using a 50 mm sodium acetate buffer (pH 3.6) and methanol mixture (87:13, v/v) as mobile phase, pumped at 1 ml/min. The absorbance was monitored at 290 nm. The method was selective, linear in the range 0.11-8.49 µg/ml for extraction solvent and 0.05-8.94 µg/ml for pH 7.4 phosphate-buffered saline, precise and accurate, with lower limits of quantitation of 0.11 µg/ml (extraction solvent) and 0.05 µg/ml (pH 7.4 phosphate-buffered saline). The method developed is suitable for the quantification of MTX in skin layers at the end of in vitro permeation experiments; the overall mass balance was 96.5 ± 1.4%, in line with the requirements of the Organisation for Economic Co-operation and Development guideline for the testing of the chemicals (Skin absorption: in vitro method).
Assuntos
Metotrexato , Fosfatos , Cromatografia Líquida de Alta Pressão/métodos , Metotrexato/análise , Reprodutibilidade dos Testes , SolventesRESUMO
Crisaborole is a boron compound recently approved by the US Food and Drug Administration as a 2% ointment for the treatment of mild to moderate atopic dermatitis. This work describes a simple method for the quantification of the drug in the skin layers at the end of in-vitro permeation experiments. Chromatographic separation was carried out on a reverse-phase C18 column using a mixture of trifluoroacetic acid 0.05%-acetonitrile (55:45, v/v) as mobile phase, pumped at 1 ml/min. Column temperature was 35°C and UV detection was performed at 250 nm. The method was linear in the range of concentration from 0.06 to 6 µg/ml (R2 = 1) and was selective, precise and accurate. Depending on the solvent used, the LOQ ranged from 0.014 to 0.030 µg/ml and the LOD from 0.005 to 0.010 µg/ml. The extraction from all the skin layers was quantitative. The developed method was successfully tested in an in-vitro permeation study, proving to be an effective tool in the development of new formulations containing crisaborole.
Assuntos
Compostos de Boro/análise , Compostos de Boro/isolamento & purificação , Compostos Bicíclicos Heterocíclicos com Pontes/análise , Compostos Bicíclicos Heterocíclicos com Pontes/isolamento & purificação , Pele/química , Animais , Compostos de Boro/química , Compostos Bicíclicos Heterocíclicos com Pontes/química , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia de Fase Reversa/métodos , Dermatite Atópica , Limite de Detecção , Modelos Lineares , Reprodutibilidade dos Testes , Espectrofotometria Ultravioleta , SuínosRESUMO
Cyclosporine is an immunosuppressant agent approved for the treatment of dry eye disease and used off-label for other ocular pathologies. Its formulation and ocular bioavailability present a real challenge due to the large molecular weight (1.2 kDa), high lipophilicity, and low water solubility. The aim of the work was to develop an aqueous micellar formulation for an efficient cyclosporine delivery to the ocular tissues, using a water-soluble derivative of vitamin E (TPGS: d-α-tocopheryl polyethylene glycol 1000 succinate) and poloxamer 407 (Pluronic ®F127) as excipients. The mixed micelles were characterized in terms of particle size, zeta potential, rheology, and stability upon dilution and freeze-drying. Additionally, the enzymatic-triggered release of vitamin E and vitamin E succinate from TPGS was investigated in vitro in the presence of esterase. Compared to the commercially available ophthalmic formulation, the poloxamer 407:TPGS 1:1 molar ratio micellar formulation significantly improved cyclosporine solubility, which increased proportionally to surfactant concentration reaching 0.4% (w/v) for 20 mM surfactant total concentration. Cyclosporine-loaded mixed micelles efficiently retained the drug once diluted in simulated lachrymal fluid and, in the presence of a 20 mM surfactant concentration, were stable upon freeze-drying. The drug-loaded mixed micelles were applied ex vivo on porcine cornea and compared to Ikervis®. Drug accumulation in the cornea resulted proportional to drug concentration (6.4 ± 1.9, 17.6 ± 5.4, and 26.9 ± 7.4 µgdrug/gcornea, after 3 h for 1, 2.5, and 4 mg/mL cyclosporine concentration respectively). The formulation containing cyclosporine 4 mg/mL (20 mM surfactant) was also evaluated on the sclera, with a view to targeting the posterior segment. The results demonstrated the capability of mixed micelles to diffuse into the sclera and sustain cyclosporine delivery (28 ± 7, 38 ± 10, 57 ± 9, 145 ± 27 µg/cm2 cyclosporine accumulated after 3, 6, 24, and 48 h respectively). Reservoir effect experiments demonstrated that the drug accumulated in the sclera can be slowly released into the underlying tissues. Finally, all the formulations developed in this work successfully passed the HET-CAM assay for the evaluation of ocular irritability.
Assuntos
Ciclosporina/administração & dosagem , Portadores de Fármacos/química , Síndromes do Olho Seco/tratamento farmacológico , Imunossupressores/administração & dosagem , Administração Oftálmica , Animais , Linhagem Celular Tumoral , Embrião de Galinha , Córnea/efeitos dos fármacos , Córnea/metabolismo , Ciclosporina/uso terapêutico , Portadores de Fármacos/farmacocinética , Liberação Controlada de Fármacos , Síndromes do Olho Seco/imunologia , Excipientes/química , Feminino , Humanos , Imunossupressores/uso terapêutico , Masculino , Micelas , Poloxâmero/química , Solubilidade , Sus scrofa , Vitamina E/química , Vitamina E/farmacocinéticaRESUMO
The aim of this work was to develop an innovative microemulsion with gel-like properties for the cutaneous delivery of imiquimod, an immunostimulant drug employed for the treatment of cutaneous infections and neoplastic conditions. A pseudoternary phase diagram was built using a 1/1 TPGS (d-α-tocopheryl polyethylene glycol 1000 succinate)/Transcutol mixture as surfactant system, and oleic acid as oil phase. Eight microemulsions-selected from the 1.25/8.75 oil/surfactants ratio, along the water dilution line (from 20 to 56% w/w)-were characterized in terms of rheological behavior, optical properties via polarized microscopy, and supramolecular structure using X-ray scattering. Then, these formulations were loaded with imiquimod and the uptake and distribution into the skin was evaluated on full-thickness porcine skin. X-ray scattering experiments revealed the presence of disconnected drops in the case of microemulsion with 20% water content. Diluting the system up to 48% water content, the structure turned into an interconnected lamellar microemulsion, reaching a proper disconnected lamellar structure for the highest water percentages (52-56%). Upon water addition, also the rheological properties changed from nearly Newtonian fluids to gel-like structures, displaying the maximum of viscosity for the 48% water content. Skin uptake experiments demonstrated that formulation viscosity, drug loading, and surfactant concentration did not play an important role on imiquimod uptake into the skin, while the skin penetration was related instead to the microemulsion mesostructure. In fact, drug uptake became enhanced by locally lamellar interconnected structures, while it was reduced in the presence of disconnected structures, either drops or proper lamellae. Finally, the data demonstrated that mesostructure also affects the drug distribution between the epidermis and dermis. In particular, a significantly higher dermal accumulation was found when disconnected lamellar structures are present, suggesting the possibility of tuning both drug delivery and localization into the skin by modifying microemulsions composition.
Assuntos
Adjuvantes Imunológicos/farmacologia , Aminoquinolinas/farmacologia , Absorção Cutânea , Pele/metabolismo , Vitamina E/química , Administração Cutânea , Animais , Portadores de Fármacos/química , Emulsões/química , Etilenoglicóis/química , Imiquimode , Ácido Oleico/química , Espalhamento de Radiação , Suínos , Distribuição Tecidual , ViscosidadeRESUMO
The aim of the present paper was the development of semi-solid (hydrogels) and solid (film) ophthalmic formulations for the controlled release of two mydriatics: phenylephrine and tropicamide. The formulations - based on polyvinylalcohol and hyaluronic acid - were characterized, and release studies were performed with three different in vitro set-ups, i.e. Franz-type diffusion cell, vial method and inclined plane; for comparison, a solution and a commercial insert, both clinically used to induce mydriasis, were evaluated. Both gels and film allowed for a controlled release of drugs, appearing a useful alternative for mydriatics administration. However, the release kinetic was significantly influenced by the method used, highlighting the need for optimization and standardization of in vitro models for the evaluation of drug release from ophthalmic dosage forms.
Assuntos
Olho/efeitos dos fármacos , Midriáticos/farmacocinética , Soluções Oftálmicas/farmacologia , Fenilefrina/farmacocinética , Pupila/efeitos dos fármacos , Tropicamida/farmacocinética , Química Farmacêutica , Combinação de Medicamentos , Humanos , Técnicas In Vitro , Midriáticos/administração & dosagem , Midriáticos/farmacologia , Soluções Oftálmicas/administração & dosagem , Soluções Oftálmicas/química , Fenilefrina/administração & dosagem , Fenilefrina/farmacologia , Tropicamida/farmacologiaRESUMO
The role of cell penetrating peptides (CPPs) has been challenged in recent years for drug delivery to ocular tissues for the targeting of both anterior and posterior segments. The enhancement of trans-corneal transport for anterior segment targeting is a very important issue possibly leading to important outcomes on efficacy and to the opportunity of topical administration of molecules with unfavorable penetration properties. The aim of the present work was the design and synthesis of new CPPs, deriving from the structure of PEP-1 peptide. Synthesized peptides were labeled with 5-carboxyfluorescein (5-FAM), and their diffusion behavior and distribution inside the cornea were evaluated by a validated ex vivo model and a confocal microscopy approach. Newly synthesized peptides showed similar corneal permeation profiles as PEP-1 (Papp = 0.75 ± 0.56 × 10-6 cm/s), about 2.6-fold higher than 5-FAM (Papp = 0.29 ± 0.08 × 10-6 cm/s) despite the higher molecular weight. Confocal microscopy experiments highlighted the tendency of PEP-1 and its derived peptides to localize in the intercellular space and/or in the plasma membrane. Noteworthy, using penetratin as positive control, a higher trans-corneal permeation (Papp = 6.18 ± 1.46 × 10-6 cm/s) was evidenced together with a diffusion by intracellular route and a different accumulation between wings and basal epithelial cells, probably depending on the stage of cell development. Finally, PEP-1 and pep-7 proved to be safe and well tolerated when tested on human conjuctival cell line.
Assuntos
Peptídeos Penetradores de Células/metabolismo , Córnea/metabolismo , Animais , Proteínas de Transporte/metabolismo , Sobrevivência Celular/fisiologia , Cromatografia Líquida de Alta Pressão , Cisteamina/análogos & derivados , Cisteamina/metabolismo , Fluoresceínas/química , Células HeLa , Humanos , Microscopia Confocal , Micro-Ondas , Peptídeos/metabolismo , SuínosRESUMO
The aim of this work was to assess in vivo the anti-inflammatory efficacy and tolerability of clobetasol propionate (CP) loaded lecithin/chitosan nanoparticles incorporated into chitosan gel for topical application (CP 0.005%). As a comparison, a commercial cream (CP 0.05% w/w), and a sodium deoxycholate gel (CP 0.05% w/w) were also evaluated. Lecithin/chitosan nanoparticles were prepared by self-assembling of the components obtained by direct injection of soybean lecithin alcoholic solution containing CP into chitosan aqueous solution. Nanoparticles obtained had a particle size around 250 nm, narrow distribution (polydispersity index below 0.2) and positive surface charge, provided by a superficial layer of the cationic polymer. The nanoparticle suspension was then loaded into a chitosan gel, to obtain a final CP concentration of 0.005%. The anti-inflammatory activity was evaluated using carrageenan-induced hind paw edema test on Wistar rats, the effect of formulations on the barrier property of the stratum corneum were determined using transepidermal water loss measurements (TEWL) and histological analysis was performed to evaluate the possible presence of morphological changes. The results obtained indicate that nanoparticle-in-gel formulation produced significantly higher edema inhibition compared to other formulations tested, although it contained ten times less CP. TEWL measurements also revealed that all formulations have no significant disturbance on the barrier function of skin. Furthermore, histological analysis of rat abdominal skin did not show morphological tissue changes nor cell infiltration signs after application of the formulations. Taken together, the present data show that the use of lecithin/chitosan nanoparticles in chitosan gel as a drug carrier significantly improves the risk-benefit ratio as compared with sodium-deoxycholate gel and commercial cream formulations of CP.
Assuntos
Anti-Inflamatórios/administração & dosagem , Clobetasol/administração & dosagem , Glucocorticoides/administração & dosagem , Nanopartículas/efeitos adversos , Pele/efeitos dos fármacos , Animais , Anti-Inflamatórios/farmacologia , Quitosana/química , Clobetasol/farmacologia , Glucocorticoides/farmacologia , Lecitinas/química , Masculino , Nanopartículas/química , Ratos , Ratos WistarRESUMO
Trazodone is a triazolpyridine derivative approved for the treatment of depression, and currently marketed as oral formulations. The transdermal administration of this drug could reduce side effects, related to peak plasma concentration, and improve patient adherence due to a reduced administration frequency. The aims of this work were: (a) the evaluation of the effect of pH vehicle and permeation enhancers on trazodone permeability across porcine skin ex-vivo; (b) the development and optimization of a transdermal drug delivery system containing trazodone hydrochloride. From the results obtained, it was found that the effect of pH of the vehicle on the permeation of trazodone across the skin is quite complex, because it influences both solubility and partitioning and that the presence of fatty acids in the vehicle has a notable effect on permeation (the enhancement factor obtained was approx. 100). For both the fatty acid selected (oleic and lauric) a parabolic relationship between the transdermal flux and the concentration was found, with an optimum activity in the range 2-3 %. In the second part of the work, different patches were prepared and tested ex-vivo. Overall, the results obtained seem to highlight that drug loading, rather than the components of the adhesive matrix, plays the most relevant role for the permeation of trazodone. The addition of lauric acid, which produced a considerable enhancement in solution, was not effective when included in the patch. The obtained data are promising although probably not clinically relevant for the treatment of depression, but might be interesting for the treatment of insomnia and anxiety disorder, which require much lower doses.
Assuntos
Administração Cutânea , Absorção Cutânea , Trazodona , Trazodona/administração & dosagem , Trazodona/farmacocinética , Animais , Suínos , Absorção Cutânea/efeitos dos fármacos , Pele/metabolismo , Pele/efeitos dos fármacos , Permeabilidade , Ácido Oleico/química , Solubilidade , Concentração de Íons de Hidrogênio , Ácidos Láuricos/química , Ácidos Láuricos/administração & dosagem , Adesivo Transdérmico , Química Farmacêutica/métodos , Antidepressivos de Segunda Geração/administração & dosagem , Antidepressivos de Segunda Geração/farmacocinética , Sistemas de Liberação de Medicamentos/métodosRESUMO
TPGS (D-α-tocopheryl polyethylene glycol 1000 succinate) polymeric micelles show interesting properties for ocular administration thanks to their solubilization capability, nanometric size and tissue penetration ability. However, micelles formulations are generally characterized by low viscosity, poor adhesion and very short retention time at the administration site. Therefore, the idea behind this work is the preparation and characterization of a crosslinked film based on xanthan gum that contains TPGS micelles and is capable of controlling their release. The system was loaded with melatonin and cyclosporin A, neuroprotective compounds to be delivered to the posterior eye segment. Citric acid and heating at different times and temperatures were exploited as crosslinking approach, giving the possibility to tune swelling, micelles release and drug release. The biocompatibility of the platform was confirmed by HET-CAM assay. Ex vivo studies on isolated porcine ocular tissues, conducted using Franz cells and two-photon microscopy, demonstrated the potential of the xanthan gum-based platform and enlightened micelles penetration mechanism. Finally, the sterilization step was approached, and a process to simultaneously crosslink and sterilize the platform was developed.
Assuntos
Administração Oftálmica , Preparações de Ação Retardada , Liberação Controlada de Fármacos , Micelas , Fármacos Neuroprotetores , Polissacarídeos Bacterianos , Vitamina E , Polissacarídeos Bacterianos/química , Animais , Suínos , Fármacos Neuroprotetores/administração & dosagem , Fármacos Neuroprotetores/química , Fármacos Neuroprotetores/farmacocinética , Vitamina E/química , Vitamina E/administração & dosagem , Preparações de Ação Retardada/química , Ciclosporina/administração & dosagem , Ciclosporina/química , Melatonina/administração & dosagem , Melatonina/química , Melatonina/farmacologia , Melatonina/farmacocinética , Esterilização , Reagentes de Ligações Cruzadas/química , Portadores de Fármacos/química , Olho/efeitos dos fármacos , Olho/metabolismo , Sistemas de Liberação de Medicamentos/métodosRESUMO
Contact lenses (CLs) have been suggested as drug delivery platforms capable of increasing the drug residence time on the cornea and therefore its bioavailability. However, when targeting the posterior segment of the eye, the drug released from CLs still encounters the barrier effect of the ocular tissues, which considerably reduces the efficacy of administration. This work aims at the development of CLs able to simultaneously deliver an anti-inflammatory drug (dexamethasone sodium phosphate) and a cell-penetrating peptide (penetratin), the latter acting as a drug carrier across the tissues. Hydroxyethyl methacrylate (HEMA)-based hydrogels were functionalized with acrylic acid (AAc) and/or aminopropyl methacrylamide (APMA) to serve as CL materials with increased affinity for the drug and peptide. APMA-functionalized hydrogels sustained the dual release for 8 h, which is compatible with the wearing time of daily CLs. Hydrogels demonstrated suitable light transmittance, swelling capacity and in vitro biocompatibility. The anti-inflammatory activity of the drug was not compromised by the presence of the peptide nor by sterilization. The ocular distribution of the drug after 6 h of CL wearing was evaluated in vivo in rabbits and revealed that the amount of drug in the cornea and aqueous humor significantly increased when the drug was co-delivered with penetratin.
Assuntos
Peptídeos Penetradores de Células , Lentes de Contato , Animais , Coelhos , Sistemas de Liberação de Medicamentos , Portadores de Fármacos , Dexametasona , Anti-Inflamatórios , Permeabilidade , HidrogéisRESUMO
The upper airways represent the point of entrance from where Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection spreads to the lungs. In the present work, α-tocopheryl-polyethylene-glycol succinate (TPGS) micelles loaded with cyclosporine A (CSA) were developed for nasal administration to prevent or treat the viral infection in the very first phases. The behavior of the micelles in presence of simulated nasal mucus was investigated in terms of stability and mucopenetration rate, evidencing long-term stability and fast diffusion across the glycoproteins matrix. Moreover, the spray characteristics of the micellar formulation and deposition profile in a silicon nasal model were studied using three nasal spray devices. Results allowed to identify the nasal spray pump (BiVax, Aptar) able to provide the wider and uniform deposition of the nasal cavity. The cyclosporine A micelles antiviral activity against SARS-CoV-2 was tested on the Omicron BA.1 variant using Vero E6 cells with protocols simulating treatment before, during and after the infection of the upper airways. Complete viral inactivation was observed for the cyclosporine-loaded micelles while a very low activity was evidenced for the non-formulated drug, suggesting a synergistic activity of the drug and the formulation. In conclusion, this work showed that the developed cyclosporine A-loaded micellar formulations have the potential to be clinically effective against a wide spectrum of coronavirus variants.
Assuntos
COVID-19 , Ciclosporina , Humanos , Ciclosporina/farmacologia , Micelas , SARS-CoV-2 , Sprays Nasais , Portadores de Fármacos , Polietilenoglicóis , Antivirais/farmacologiaRESUMO
The aim of this study was the optimization of a lidocaine-based film formulation for the prevention of pain from needle prick during the injection of local anesthetic in dentistry. Film performances were evaluated in vitro by studying lidocaine permeation across pig esophageal epithelium as model for nonkeratinized buccal mucosa. The results obtained showed that the molecular weight of the film-forming polymer had no effect on lidocaine transport. The introduction of the adhesive Plastoid® into the film determined a significant increase of drug permeation rate, which was further improved by the addition of Azone®. On the contrary, the effect of sodium taurocholate was negligible.
Assuntos
Anestésicos Locais/administração & dosagem , Gengiva/metabolismo , Lidocaína/administração & dosagem , Administração Bucal , Algoritmos , Animais , Bochecha , Cromatografia Líquida de Alta Pressão , Sistemas de Liberação de Medicamentos , Epitélio/metabolismo , Esôfago/metabolismo , Técnicas In Vitro , Modelos Estatísticos , Mucosa Bucal/metabolismo , Permeabilidade , Resinas Sintéticas , Suínos , Adesivos TeciduaisRESUMO
Ocular drug delivery is challenging due to the poor drug penetration across ocular barriers and short retention time of the formulation at the application site. Films, applied as inserts or implants, can be used to increase residence time while controlling drug release. In this work, hydrophilic films made of hyaluronic acid and two kinds of PVA were loaded with dexamethasone (included as hydroxypropylcyclodextrin complex) and levofloxacin. This association represents one of the main treatments for the post cataract surgery management, and it is also promising for eye infections with pain and inflammation. Films were characterized in terms of swelling and drug release and were then applied to porcine eye bulbs and isolated ocular tissues. Film swelling leads to the formation of either a gel (3D swelling) or a larger film (2D swelling) depending on the type of PVA used. Films, prepared in an easy and scalable method, demonstrated high loading capacity, controlled drug release and the capability to deliver dexamethasone and levofloxacin to the cornea and across the sclera, to potentially target also the posterior eye segment. Overall, this device can be considered a multipurpose delivery platform intended for the concomitant release of lipophilic and hydrophilic drugs.
Assuntos
Ácido Hialurônico , Levofloxacino , Suínos , Animais , Sistemas de Liberação de Medicamentos , Córnea , DexametasonaRESUMO
Corticosteroids, although highly effective for the treatment of both anterior and posterior ocular segment inflammation, still nowadays struggle for effective drug delivery due to their poor solubilization capabilities in water. This research work aims to develop nanostructured lipid carriers (NLC) intended for periocular administration of dexamethasone acetate to the posterior segment of the eye. Pre-formulation studies were initially performed to find solid and liquid lipid mixtures for dexamethasone acetate solubilization. Pseudoternary diagrams at 65 °C were constructed to select the best surfactant based on the macroscopic transparency and microscopic isotropy of the systems. The resulting NLC, obtained following an organic solvent-free methodology, was composed of triacetin, Imwitor® 491 (glycerol monostearate >90%) and tyloxapol with Z-average = 106.9 ± 1.2 nm, PDI = 0.104 ± 0.019 and zeta potential = -6.51 ± 0.575 mV. Ex vivo porcine sclera and choroid permeation studies revealed a considerable metabolism in the sclera of dexamethasone acetate into free dexamethasone, which demonstrated higher permeation capabilities across both tissues. In addition, the NLC behavior once applied onto the sclera was further studied by means of multiphoton microscopy by loading the NLC with the fluorescent probe Nile red.
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The greatest achievement in the advanced drug delivery field should be the optimization of non-invasive formulations for the delivery of high molecular weight compounds. Peptides, proteins, and other macromolecules can have poor membrane permeation, principally due to their large molecular weight. The aim of this work was to explore the possibility of administering fluorescently labeled dextrans (molecular weight 4-150 kDa) across the buccal mucosa. Permeation experiments across pig esophageal mucosa were carried out using fatty acids and bile salts as penetration enhancers. The data obtained show that it is possible to increase or promote the mucosa permeation of high molecular weight dextrans by using caprylic acid or sodium taurocholate as the chemical enhancers. With these enhancers, dextrans with molecular weight of 70 and 150 kDa, that in passive conditions did not permeate, could cross the mucosa in detectable amounts. FD-70 and FD-150 showed comparable permeability values, despite the molecular weight difference. The results obtained in the present work suggest that the buccal administration of high molecular weight compounds is feasible.
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Cyclosporine is an immunomodulatory drug commonly used for the treatment of mild-to-severe dry eye syndrome as well as intermediate and posterior segment diseases as uveitis. The ocular administration is however hampered by its relatively high molecular weight and poor permeability across biological barriers. The aim of this work was to identify a micellar formulation with the ability to solubilize a considerable amount of cyclosporine and promote its transport across ocular barriers. Non-ionic amphiphilic polymers used for micelles preparation were tocopherol polyethylene glycol 1000 succinate (TPGS) and Solutol® HS15. Furthermore, the addition of alpha-linolenic acid was assessed. A second aim was to evaluate micelles fate in the ocular tissues (cornea and sclera) to shed light on penetration mechanisms. This was possible by extracting and quantifying both drug and polymer in the tissues, by studying TPGS hydrolysis in a bio-relevant environment and by following micelles penetration with two-photon microscopy. Furthermore, TPGS role as permeation enhancer on the cornea, with possible irreversible modifications of tissue permeability, was analyzed. Results showed that TPGS micelles (approx. 13 nm in size), loaded with 5 mg/ml of cyclosporine, promoted drug retention in both the cornea and the sclera. Data demonstrated that micelles behavior strictly depends on the tissue: micelles disruption occurs in contact with the cornea, while intact micelles diffuse in the interfibrillar pores of the sclera and form a reservoir that can sustain over time drug delivery to the deeper tissues. Finally, cornea quickly restore the barrier properties after TPGS removal from the tissue, demonstrating its potential good tolerability for ocular application.
Assuntos
Ciclosporina , Micelas , Córnea , Portadores de Fármacos , Polietilenoglicóis , Polímeros , Solubilidade , Succinatos , Tocoferóis , Vitamina E , Ácido alfa-LinolênicoRESUMO
The topical use of imiquimod (IMQ), a non-specific immune response modifier, showed to be a promising therapeutic option for the early-stage treatment of some type of oral cancer, even when performed with a formulation (Aldara®) developed and approved for skin application. The aim of this work was the development of buccal formulations for the topical administration of IMQ with improved mucosal retention and reduced trans-mucosal permeation when compared to the reference formulation. Three different hydrogels based on carboxymethyl chitosan (CMChit), sodium alginate (A), and xanthan gum (X) in different combinations were prepared, and the loading of imiquimod was successfully performed by using a micellar formulation based on d-α-tocopheril polyethylene glycol 100 succinate (TPGS). Except for CMChit formulation, in all the other cases, the performance in vitro on the mucosa resulted comparable to the commercial formulation, despite the drug loading being 50-fold lower. Converting the gels in films did not modify the IMQ accumulated with respect to the correspondent gel formulation but produced as a positive effect a significant reduction in the amount permeated. Compared to the commercial formulation, this reduction was significant (p < 0.01) in the case of X film, resulting in an improvement of the retained/permeated ratio from 1 to 5.44. Mucoadhesion evaluation showed similar behavior when comparing the developed gels and the commercial formulation, and an excellent bioadhesion was observed for the films.
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Nanotherapeutics based on biocompatible lipid matrices allow for enhanced solubility of poorly soluble compounds in the treatment of ophthalmic diseases, overcoming the anatomical and physiological barriers present in the eye, which, despite the ease of access, remains strongly protected. Micro-/nanoemulsions, solid lipid nanoparticles (SLN) or nanostructured lipid carriers (NLC) combine liquid and/or solid lipids with surfactants, improving drug stability and ocular bioavailability. Current research and development approaches based on try-and-error methodologies are unable to easily fine-tune nanoparticle populations in order to overcome the numerous constraints of ocular administration routes, which is believed to hamper easy approval from regulatory agencies for these systems. The predictable quality and specifications of the product can be achieved through quality-by-design (QbD) implementation in both research and industrial environments, in contrast to the current quality-by-testing (QbT) framework. Mathematical modelling of the expected final nanoparticle characteristics by variation of operator-controllable variables of the process can be achieved through adequate statistical design-of-experiments (DoE) application. This multivariate approach allows for optimisation of drug delivery platforms, reducing research costs and time, while maximising the understanding of the production process. This review aims to highlight the latest efforts in implementing the design of experiments to produce optimised lipid-based nanocarriers intended for ophthalmic administration. A useful background and an overview of the different possible approaches are presented, serving as a starting point to introduce the design of experiments in current nanoparticle research.
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There is increasing consensus in considering statins beneficial for age-related macular degeneration and in general, for immune and inflammatory mediated diseases affecting the posterior segment of the eye. However, all available data relate to oral administration, and safety and effectiveness of statins directly administered to the eye are not yet known, despite their ophthalmic administration could be beneficial. The aim was the development and the characterization of polymeric micelles based on TPGS or TPGS/poloxamer 407 to increase simvastatin solubility and stability and to enhance the delivery of the drug to the posterior segment of the eye via trans-scleral permeation. Simvastatin was chosen as a model statin and its active hydroxy acid metabolite was investigated as well. Results demonstrated that polymeric micelles increased simvastatin solubility at least 30-fold and particularly TPGS/poloxamer 407 mixed micelles, successfully stabilized simvastatin over time, preventing the hydrolysis when stored for 1 month at 4 °C. Furthermore, both TPGS (1.3 mPas) and mixed micelles (33.2 mPas) showed low viscosity, suitable for periocular administration. TPGS micelles resulted the best performing in delivery simvastatin either across conjunctiva or sclera in ex vivo porcine models. The data pave the way for a future viable ocular administration of statins.
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A simple and sensitive HPLC method for the quantification of budesonide in skin layers was developed and validated. Budesonide was extracted from stratum corneum, epidermis and dermis by means of a mixture of acetonitrile:water (recovery > 90%). Budesonide quantification was performed with a RP-C18 column using methanol and water mixture (69:31, v/v) as mobile phase, pumped at 0.8 ml/min. The absorbance was monitored at 254 nm. The method resulted to be selective, linear in the range 0.05-5 or 10 µg/ml, precise and accurate. LLOQ resulted to be 0.05 µg/ml. The developed method appeared to be appropriate for the quantification of budesonide in skin layers at the end of in vitro permeation experiments since the recovery of the applied dose was 97 ± 1%, in line with requirement of the OECD guideline for the testing of the chemicals (Skin absorption: in vitro method).