Multiple Intravitreal Liposomal Amphotericin B for a Case of Candida glabrata Endophthalmitis

We report a case of Candida glabrata endophthalmitis which was effectively treated by intravitreal liposomal amphotericin B (L-AMB) injection. A 72-year-old man was referred to our department for positive blood culture of Candida glabrata. First ophthalmologic examination revealed a chorioretinal lesion in left eye, and the patient was diagnosed as possible candida chorioretinitis. Despite systemic antifungal therapy, his chorioretinal lesion increased in both eyes and complicated by vitritis. Intravitreal administration of L-AMB was introduced for probable candida endophthalmitis. Finally, improvement of vitritis and regression of chorioretinal lesions were obtained by total of 9 times intravitreal injection. Our case suggests the safety and efficacy of intravitreal L-AMB injection for Candida glabrata endophthalmitis

Liposomes as delivery systems in the prevention and treatment of infectious diseases

Research on the potential application of liposomes in the prevention and treatment of infectious diseases has focussed on improvement of the therapeutic index of antimicrobial drugs and immunomodulators and on stimulation of the immune response to otherwise weak antigens in vaccines composed of purified micro-organism subunits. In this review current approaches in this field are outlined. The improved therapeutic index of antimicrobial drugs after encapsulation in liposomes is a result of enhanced drug delivery to infected tissue or infected cells and/or a reduction of drug toxicity of potentially toxic antibiotics. Liposomal encapsulation of immunomodulators that activate macrophages aims at reducing the toxicity of these agents and targeting them to the cells of the mononuclear phagocyte system in order to increase the nonspecific resistance of the host against infections. Studies on the immunogenicity of liposomal antigens have demonstrated that liposomes can potentiate the humoral and cell mediated immunity to a variety of antigens

Imaging, quantitation and kinetic modelling of intravitreal nanomaterials

In this study, the intravitreal pharmacokinetics of nanomaterials were investigated in vivo in rats and rabbits. Impact of particle size and shape (spherical, longitudinal) on ocular particle distribution and elimination was investigated with fundus camera, optical coherence tomography and ocular fluorophotometry. Differently sized particles showed prolonged ocular retention and remarkable differences in vitreal elimination, but size dependence was consistent, suggesting that other features have influence on their vitreal kinetics. We also demonstrate that liposomes are eliminated from the rabbit vitreous mainly via the anterior route. Simulation of drug concentrations after injection of intravitreal particles shows the importance of synchronized particle retention and drug release rate for efficient drug delivery. In conclusion, we provide kinetic insights in intravitreally administered nanoparticles to improve retinal drug delivery.Peer reviewe

PEGylated Nanostructured Lipid Carries for Amphotericin B Ocular Delivery

The Chapter II focuses on formulation of an optimized and robust amphotericin B ocular formulation with prolonged precorneal residence and ocular tissue concentration at par or superior to the marketed preparations. Additionally, demonstrating stability of amphotericin B formulations in presence of preservative in comparison to marketed preparation, making it an ideal choice of formulation for multi-dosing. As mentioned earlier, we optimized PEGylated nanostructured lipid carriers (PEG-NLC-AmB) for ocular delivery of amphotericin B. The formulations could be autoclaved with at least one-month stability and in vivo ocular biodistribution was statistically insignificantly different compared to AmBisome®. To accomplish the aim, strategies such as mucoadhesion and/or viscosity enhancement were investigated. In this regard, PEG-NLC-AmB entrapped in ion triggered hydrogels using gellan gum (mucoadhesive) and chitosan (mucoadhesive and permeation enhancer) coated PEG-NLC-AmB were formulated and characterized

Drug delivery systems for the posterior segment of the eye : in vitro evaluation of light triggered and pH-sensitive liposomes with gold nanoparticles

The leading causes of vision loss in developed countries are related to the impairment of the posterior segment of the eye. The drug delivery to the posterior segment with topical or systemic methods is challenging due to the protective barriers of the eye. The conventional and effective technique to deliver therapeutic concentrations of drugs to the posterior segment is intravitreal injection. Since naked molecules usually have a rapid vitreal clearance, the invasive injections need repeated administration in chronic conditions, resulting to increased risk of complications and poor patient compliance. The growing field of research of drug delivery systems, such as implants, nano- and microparticles and liposomes emphasizes to answer these challenges by enhancing time-controlled and targeted drug release to retinal and choroidal tissues, enabling less frequent administration and reduced off-target side effects. Liposomal drug delivery systems have potential in delivering therapeutics to posterior eye tissues in sustained and targeted manner. The experimental part of the thesis focused on studying the cell uptake, content release and cytotoxicity of light triggered pH-sensitive gold nanoparticle liposomes in human retinal pigment epithelial (ARPE-19), human umbilical vein endothelial (HUVEC) and monkey choroidal endothelial (RF/6A) cell lines. To enhance the cell differentiation to resemble the in vivo morphology, ARPE-19 cells were also used as a filter-cultured model. HUVEC cells were cultured on an artificial basement membrane matrix and induced with vascular endothelial growth factor (VEGF) to form capillary like tube structures. The liposomes were not cytotoxic during 24-hour incubation. All cells internalized liposomes to some extent, but in HUVEC capillary tubes the uptake seemed to be negligible. The light induced calcein release was variable between the experiments, possibly due to the study setting related factors, such as difficulties in temperature control. The liposomal carrier system has promising attributes to posterior eye drug delivery. Liposome-encapsulation prolongs the half-live of a drug. Light triggered release and pH-sensitivity enables highly targeted intracellular drug release decreasing the off-target side effects. Optimization of the study arrangement and liposome production procedure is needed in order to get more reliable results and further assess the future potential of these liposomes in the treatment of posterior eye diseases.Silmän takaosan sairaudet ovat merkittävimpiä sokeutumisen aiheuttajia teollisuusmaissa. Lääkkeen kuljetus silmän takaosan kudoksiin topikaalisilla tai systeemisillä antotavoilla on hankalaa silmän anatomisten ja fysiologisten suojamekanismien takia. Lasiaisinjektio on yleisesti käytetty ja tehokas tapa saavuttaa hoidollinen lääkeainepitoisuus silmän takaosassa. Lasiaisinjektiot ovat invasiivisia ja epämiellyttäviä potilaille, ja lääkeaineiden takakammion nopean puhdistuman takia injektioita täytyy toistaa säännöllisesti kroonisessa lääkehoidossa. Tämä lisää komplikaatioiden ja haittavaikutusten riskiä. Erilaisilla lääkemuodoilla, kuten implanteilla, liposomeilla sekä nano- ja mikropartikkeleilla voidaan mahdollistaa pitkäaikainen lääkeaineen vapautuminen ja kohdennus kudoksiin siten vähentäen haittavaikutuksia ja harventaen annosväliä. Kokeellisessa osassa tutkittiin valoaktivoituvien ja pH-herkkien kultananopartikkeleita sisältävien liposomien soluunottoa, liposomeihin kapseloidun kalseiinin vapautumista solun sisällä sekä toksisuutta ihmisen verkkokalvon pigmenttiepiteeli- (ARPE-19), ihmisen napanuoralaskimon endoteeli- (HUVEC) sekä apinan suonikalvon endoteelisolulinjoissa (RF/6A). ARPE-19-soluja kasvatettiin puoliläpäisevillä suodatinkalvoilla morfologian erilaistumisen tehostamiseksi. HUVEC-soluja viljeltiin keinotekoisella soluväliainematriisilla sekä indusoitiin verisuonien kasvutekijällä (VEGF) muodostamaan kapillaariverisuonia muistuttavia putkimaisia rakenteita. Liposomit eivät olleet solutoksisia 24 tunnin inkubaation aikana. Kaikki solulinjat ottivat liposomeja sisäänsä jossain määrin, mutta HUVEC-solujen muodostamissa kapillaariputkissa soluunotto oli erittäin vähäistä. Valotuksen aikaansaama kalseiinin solunsisäinen vapautuminen oli vaihtelevaa eri kokeiden välillä, mikä voi osittain johtua koeasetteluun liittyvistä tekijöistä, muun muassa vaikeuksista lämpötilan säädössä. Tällä liposomisysteemillä on lupaavia ominaisuuksia silmän takaosan lääkinnässä. Liposomikapselointi pidentää lääkkeen puoliintumisaikaa. Valoaktivoitu ja pH-riippuva vapautuminen mahdollistaa hyvin kohdennetun solunsisäisen lääkkeen vapautumisen vähentäen sivuvaikutuksia muissa kudoksissa. Koejärjestelyn ja liposomien valmistusmenetelmän optimointia tarvitaan, jotta voitaisiin luotettavammin arvioida formulaation tulevaisuuden mahdollisuuksia silmän takaosan sairauksien hoitamisessa

Nano and microtechnologies for ophthalmic administration. An overview

Ocular drug delivery is one of the most challenging fields of pharmaceutical research. They are generally employed to overcome the static (different layers of cornea, sclera, and retina including blood aqueous and blood-retinal barriers) and dynamic barriers (choroidal and conjunctival blood flow, lymphatic clearance, and tear dilution) of the eye. Ophthalmic formulations must be sterile, and the biomaterials used in the preparation of pharmaceutical systems completely compatible and extremely well tolerated by ocular tissues. The location of the target tissue in the eye will determine the route of administration. Ophthalmic administration systems are intended for topical, intraocular and periocular administration. In this review we describe the main pharmaceutical nano- and microsystems currently under study to administrate drugs in the eye, covering microparticles, nanoparticles, liposomes, microemulsions, niosomes and dendrimers. We have performed the corresponding revision of the published scientific literature always emphasizing the technological aspects. The review discusses also the biomaterials used in the preparation of the nano and microsystems of ophthalmic drug delivery, fabrication techniques, therapeutic significances, and future possibilities in the field

Desarrollo de un nuevo tratamiento para el ojo seco basado en la terapia génica con sistemas nanoparticulares

El principal objetivo de la presente memoria ha sido el diseño de nuevos sistemas nanoparticulares capaces de proporcionar una aproximación terapéutica totalmente novedosa al tratamiento del síndrome del ojo seco. En una primera etapa se ha evaluado el potencial de proteínas cationizadas como biomateriales constitutivos de nanopartículas desarrolladas mediante gelificación ionotrópica. Después de caracterizar los diferentes sistemas desarrollados, se seleccionaron nanopartículas híbridas elaboradas empleando combinaciones de gelatina cationizada con espermina y el biopolímero aniónico natural sulfato de condroitino, en base a su versatilidad, perfil de toxicidad y potencial de transfección en células del epitelio ocular. Seguidamente, se incorporó a dichas nanopartículas un plásmido que codifica la proteína MUC5AC, mucina secretada por las células caliciformes de la conjuntiva. Esta mucina es una de las principales responsables de la homeostasis del fluido lacrimal, presentándose en niveles anormalmente disminuidos en determinados procesos inflamatorios de la superficie ocular, como el síndrome del ojo seco. El tratamiento tópico en ratones sometidos a un modelo de síndrome de ojo seco con dichos nanosistemas ha permitido restablecer la producción normal de lágrimas y mejorar capacidad de protección de la superficie ocular en los animales enfermos. Estos resultados suponen la prueba de concepto sobre la aplicación clínica de las nanopartículas diseñadas al desarrollo de la terapia génica de diferentes patologías oculares como el síndrome de ojo seco