Papers by Armando Silva-cunha
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright Keywords: Rabies Adjuvants Microemulsion W/O/W multiple emulsion a b s t r a c t Water-in-oil-in-water (W/O/W) multiple emulsions and microemulsions have been studied as potential candidates to be formulated as adjuvants. In this work their application as adjuvants for rabies virus immunization was studied. The humoral response, the effective dose 50 and histology for the developed formulations were evaluated in mice and compared with those from traditional adjuvants. The micro-emulsion and W/O/W multiple emulsion adjuvants developed were able to induce humoral response in mice and the serum showed good in vivo protection. Compared to the other adjuvants evaluated, microemulsion was shown to be the best candidate for rabies immunization as it presented good potency against the virus and did not appear to cause any local reaction.
Documenta Ophthalmologica, 2015
To determine the in vivo release profile and retinal safety of cyclosporine A (CsA) delivered fro... more To determine the in vivo release profile and retinal safety of cyclosporine A (CsA) delivered from a biodegradable poly-lactide-co-glycolide (PLGA) device in the vitreous cavity of rabbits' eyes. A total of 60 animals (60 eyes) divided into two groups were used. For the in vivo release study, 32 eyes received PLGA implants containing 350 µg of CsA, and 16 eyes received the implants without drug (control). Four animals of CsA group and two of the control group were killed weekly until 8 weeks; the vitreous was removed, and CsA concentration was evaluated. Ophthalmological examination was performed in the animals prior to implant placement and weekly during the study period. Electroretinography (ERG) was performed in other six animals for each group, treated and control, at the beginning and at the end of the study (8 weeks) when they were killed and had their eyes processed for histology. No sign of inflammation was noticed on slit lamp examinations and the IOP maintained stable during the study period in CsA and control groups. CsA concentration in the vitreous (ng/ml) was 257.07 ± 117.23, 271.15 ± 98.96, 296.66 ± 86.25, 256.27 ± 99.22, 304.50 ± 88.18, 326.35 ± 105.24, 491.25 ± 119.90 and 589.93 ± 132.55 after 1, 2, 3, 4, 5, 6, 7 and 8 weeks of implantation, respectively. At the end of the study, 21.67 % of mass loss was found. The retina did not show any histological alteration in either group, but a significant reduction in dark-adapted b-wave amplitude was observed in the CsA group, with no changes in a-wave amplitude. These data show that the PLGA system is safe, but the selective reduction in ERG b-wave amplitude indicates that the PLGA with 350 µg CsA causes retinal function impairment, specifically on the rod postreceptor pathway, 8 weeks after implantation. These ERG changes were not associated with any histological damage as seen at the light microscopy level.
Clinical and Experimental Ophthalmology, 2004
Eye drops are the most used dosage form by the ocular route, in spite of their low bioavailabilit... more Eye drops are the most used dosage form by the ocular route, in spite of their low bioavailability. Due to their properties and numerous advantages, microemulsions are promising systems for topical ocular drug delivery. They can increase water solubility of the drug and enhance drug absorption into the eye. The present study describes the development and characterization of an oil-in-water microemulsion containing dexamethasone and the evaluation of its pharmacokinetics in rabbits after topical ocular application. The microemulsion was prepared by the titration technique. Its physico-chemical characteristics and stability were determined. The ocular irritation test and the pharmacokinetics of this system were studied in white rabbits. The developed system showed an acceptable physico-chemical behaviour and presented good stability for 3 months. The ocular irritation test used suggested that the microemulsion did not provide significant alteration to eyelids, conjunctiva, cornea and iris. This formulation showed greater penetration of dexamethasone in the anterior segment of the eye and also release of the drug for a longer time when compared with a conventional preparation. The area under the curve obtained for the microemulsion system was more than twofold higher than that of the conventional preparation (P < 0.05). The microemulsion-based dexamethasone eye drop is advantageous for ophthalmic use because it is well-tolerated in the eye and seemed to provide a higher degree of bioavailability. The developed system shows greater penetration in the eye, allowing the possibility of decreasing the number of applications of eye drops per day.
A terapia farmacológica convencional para tratamentos oftálmicos apresenta inúmeros efeitos colat... more A terapia farmacológica convencional para tratamentos oftálmicos apresenta inúmeros efeitos colaterais. Um dos maiores problemas consiste em manter a concentração adequada de fármaco no local de administração por um tempo prolongado sem, no entanto, ser drenado pelo ducto lacrimal. A síntese de polímeros conjugados com fármacos pode produzir sistemas eficazes para controlar a concentração do fármaco no sítio de ação e aumentar a retenção da droga no local de administração. O presente trabalho relata o desenvolvimento e caracterização de sistema de liberação controlada de dexametasona por conjugação com polímero natural (quitosana). A reação foi procedida em duas etapas e os polímeros conjugados obtidos foram caracterizados por espectrometria no IR, Análises Calorimétricas e Estabilidade Química. Os ésteres obtidos foram susceptíveis a hidrolise alcalina e a cinética de degradação dos conjugados foi mensurada em função do pH e da temperatura. Os resultados obtidos demonstram que as p...
Brazilian Journal of Pharmaceutical Science
Interferon-alpha (IFN-alpha) is one of the main drugs used in the treatment of hepatitis C. Use o... more Interferon-alpha (IFN-alpha) is one of the main drugs used in the treatment of hepatitis C. Use of IFN-alpha has some limitations that result in poor treatment efficacy and low patient compliance. Therefore, the aim of this study was to develop poly-ε-caprolactone (PCL) microspheres containing IFN-alpha as an alternative for the treatment of chronic hepatitis C. Microspheres were prepared using the multiple emulsion followed by solvent evaporation technique. Particle size, surface morphology, drug content and encapsulation efficiency of the microspheres produced were evaluated. The stability of the formulation was assessed after 90 days at -20ºC. An in vitro release study was performed in PBS. In vitro cytotoxicity of the formulation was studied using hepatic cell line. The freeze-dried microspheres had mean particle size, IFN-alpha content, and encapsulation efficiency of 38.52 ± 4.64 µm, 15.52 ± 3.28% and 83.93 ± 5.76%, respectively. There were no significant changes during storag...
European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences, Jan 20, 2015
Biocompatibility is a requirement for the development of nanofibers for ophthalmic applications. ... more Biocompatibility is a requirement for the development of nanofibers for ophthalmic applications. In this study, nanofibers were elaborated using poly(ε-caprolactone) via electrospinning. The ocular biocompatibility of this material was investigated. MIO-M1 and ARPE-19 cell cultures were incubated with nanofibers and cellular responses were monitored by viability and morphology. The in vitro biocompatibility revealed that the nanofibers were not cytotoxic to the ocular cells. These cells exposed to the nanofibers proliferated and formed an organized monolayer. ARPE-19 and MIO-M1 cells were capable of expressing GFAP, respectively, demonstrating their functionality. Nanofibers were inserted into the vitreous cavity of the rat's eye for 10days and the in vivo biocompatibility was investigated using Optical Coherence Tomography (OCT), histology and measuring the expression of pro-inflammatory genes (IL-1β, TNF-α, VEGF and iNOS) (real-time PCR). The OCT and the histological analyzes ...
SUMMARY. W/O/W multiple emulsions containing naltrexone (NTX) hydrochloride were prepared by a tw... more SUMMARY. W/O/W multiple emulsions containing naltrexone (NTX) hydrochloride were prepared by a two-step emulsification method at 20 ºC. Characterization of the developed system was evaluated and the release kinetics of the drug was determined. The tissue response to the injection of the multiple emulsion in mice was observed by histological analysis. The entrapment efficiency of NTX hydrochloride in W/O/W multiple
Biomedicine & Pharmacotherapy, 2015
To develop thalidomide-loaded poly-lactide-co-glycolide implants and evaluate its in vivo release... more To develop thalidomide-loaded poly-lactide-co-glycolide implants and evaluate its in vivo release and biological activity against inflammation and angiogenesis after subcutaneous administration. Implants were prepared by the hot molding technique and characterized using stereomicroscopy, thermal analysis and X-ray diffraction. Swiss mice, divided in groups 1-3, received a subcutaneous implant containing 25% (w/w), 50% (w/w) or 75% (w/w) of thalidomide, respectively (n = 6). The drug levels were determined during a 28-day study period. The toxicity associated with the implants was evaluated by light microscopy. The potential of the developed implant in the inhibition of inflammation and angiogenesis was evaluated in vivo using the sponge model. Thalidomide implant was developed and its characterization proved the stability of the drug and the polymer during preparation. Release profiles in vivo demonstrated an extended release of thalidomide from the implants during the 28 days. Histological evaluation did not show any sign of intense local inflammatory response to the presence of the implants in the subcutaneous pouch. The thalidomide implant reduced the number of vessels and N-acetyl-b-glucosaminidase (NAG) in vivo. The biodegradable implants delivered safe doses of thalidomide that were also effective to induce angiogenesis and inflammation regression.
Journal of Drug Delivery Science and Technology, 2007
ABSTRACT
The International Journal of Oral & Maxillofacial Implants, 2013
To evaluate the effect of surgical placement of an aminoguanidine (AG)-loaded chitosan membrane, ... more To evaluate the effect of surgical placement of an aminoguanidine (AG)-loaded chitosan membrane, which allows slow local release of AG, over an endosseous implant on mechanical retention of the implant in nondiabetic and diabetic rats. Forty-eight male Wistar rats were randomly divided into six groups of eight animals each and subjected to three different treatment modalities: (1) implant placement in the femur, (2) placement of implant + chitosan membrane without AG at the surgical site, or (3) placement of implant + AG-loaded chitosan membrane (AG concentration of 7.35 mmol/kg body weight) at the surgical site. Groups 1, 2, and 3 were nondiabetic (control groups), and groups 4, 5, and 6 had chemically induced type 1 diabetes (test groups). At 4 weeks after implant placement, the animals were sacrificed and the countertorque force (CTF) required to disrupt the bone-implant interface was measured. Analyses of variance were performed, and the mean CTF values were compared between groups by using the Student t test. The mean CTF values were significantly lower in diabetic groups not treated with AG than in the corresponding nondiabetic animals that had received the same treatment modality. In groups that received AG locally, the mean CTF values were not statistically significantly different, regardless of diabetes status. Induced diabetes (type 1) negatively affected the CTF necessary for disrupting the bone-implant interface. Local availability of AG in diabetic animals led to an increase in the CTF values to the same level as that in nondiabetic animals.
Journal of Pharmaceutical and Biomedical Analysis, 2015
Current Eye Research, 2014
Purpose: Excessive subconjunctival scarring is associated with increased angiogenesis and leads t... more Purpose: Excessive subconjunctival scarring is associated with increased angiogenesis and leads to filtration failure in glaucoma surgery. In this study, we describe that rosmarinic acid (RA) has anti-angiogenic activity during wound healing in a rabbit model of glaucoma surgery. Methods: Forty New Zealand rabbits underwent an experimental trabeculectomy and were randomly allocated into two treatment groups: RA group -treated with subconjunctival injections of 0.1 ml RA (15 mg/ml; n = 20)and control group -treated with subconjunctival injections of 0.1 ml balanced salt solution (n = 20). The in vivo effect of RA was investigated after 5 and 15 d by measuring the intraocular pressure (IOP; with Tonopen) and bleb area and vascularity (using the Moorfields Bleb Grading System). Vascularization was also studied by counting histological blood vessels and by immunohistochemistry of vascular endothelial growth factor (VEGF) at the surgical site and by quantification of vessels in chicken's chorioallantoic membrane (CAM), treated with AR 500 mg/ml for 48 h. Results: On the fifth day, eyes of RA group displayed higher bleb area (3.6 ± 0.2 versus 1.8 ± 0.2; p = 0.004) and lower vascularity (3.0 ± 0.5 versus 4.0 ± 0.4; p = 0.009) than controls; however, difference in IOP reduction was not significant (À1.4 ± 0.3 versus À0.8 ± 0.3 mmHg; p = 0.226). Proportion of vessels/field (4.6 ± 0.5 versus 10.4 ± 0.9; p = 0.008) and VEGF immunostaining (15,347 ± 3788 versus 31,043 ± 3230; p = 0.019) also declined with RA treatment. However, at the 15th day, none of the parameters were different between the groups, except for vessels/field proportion (5.4 ± 1.0 versus 10.6 ± 1.6; p = 0.035). CAM exposed to AR inhibited vascularization (À45.67 ± 4.74%; p50.001). Conclusion: These data indicate RA has a short-term anti-angiogenic effect and could be a potential modulator of neovascularization during subconjunctival healing at glaucoma filtration surgical sites. 1 Curr Eye Res Downloaded from informahealthcare.com by 189.63.226.196 on 12/15/14 For personal use only.
Journal of materials science. Materials in medicine, 2014
The present work developed a biomaterial (HA/SBA-16) based on the growth of calcium phosphate (HA... more The present work developed a biomaterial (HA/SBA-16) based on the growth of calcium phosphate (HA) particles within an organized silica structure (SBA-16) to evaluate its application as a drug delivery system. The samples were charged with ciprofloxacin as a model drug and in vitro release assays were carried out. The samples were characterized by elemental analysis (CHN), Fourier transform infrared spectroscopy, nitrogen adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), small angle X-ray scattering (SAXS) and X-ray diffraction. The results obtained by TEM, SEM and SAXS reveal a well-defined cubic arrangement of a uniform spherical mesoporous structure, an intrinsic characteristic of these materials, which indicated that SBA-16 and HA/SBA-16 could potentially encapsulate bioactive molecules by means of ordered mesopores. It was found that both surface interaction and pore volume affect the rate and amount of ciprofloxacin released from the mesop...
International Journal of Pharmaceutics, 1998
ABSTRACT
Materials Science and Engineering: C, 2011
The treatment of posterior segment ocular diseases, such as uveitis, by using eye drops and oral ... more The treatment of posterior segment ocular diseases, such as uveitis, by using eye drops and oral drugs is usually not effective due to the body's natural barriers to drug penetration. In this study, ocular implants to treat uveitis were synthesized by incorporating dexamethasone acetate, an important type of corticoid used in the treatment of some uveitis, into a biodegradable polyurethane
Journal of Pharmaceutical and Biomedical Analysis, 2012
Ofloxacin, second-generation fluoroquinolone derivative, is one of the most commonly used to trea... more Ofloxacin, second-generation fluoroquinolone derivative, is one of the most commonly used to treat and prevent superficial ocular infection in animals and human beings. However, poor bioavailability, rapid elimination, and non compliance by patients are several problems associated with ocular route. Ophthalmic controlled drug delivery offers the potential to enhance the efficacy of treatment for pathological conditions, while reducing the side effects and the toxicity associated with frequent applications. Specific analytical methods to determine drugs in eye are needed to analyze and compare the new controlled release ocular devices with those conventional eye drops. The topical eye administration of ophthalmic drugs induces lachrymation, and the tear promotes a drug wash out. Quantify drugs in tear is a good tool to study their kinetic comportment in the eye. A liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) method for quantitation of ofloxacin in rabbits' tears was developed and validated. The tear was collected with tear strips, extracted by a liquid extraction procedure and then separated on an ACE C 18 column with a mobile phase composed of 0.15% aqueous formic acid and methanol (60:40, v/v). Calibration curve was constructed over the range of 10-5000 ng/mL for ofloxacin. The mean R.S.D. values for the intra-run and inter-run precision were 5.15% and 4.35%, respectively. The mean accuracy value was 100.16%. The validated method was successfully applied to determine the ofloxacin concentration in tears of rabbits treated with a mucoadhesive chitosan films and a conventional eye drop formulation.
Journal of Ocular Pharmacology and Therapeutics, 2012
Purpose: Chitosan, a cationic polysaccharide biopolymer with mucoadhesive properties, presents a ... more Purpose: Chitosan, a cationic polysaccharide biopolymer with mucoadhesive properties, presents a promising future in the prolonged ocular delivery of drugs. The present study compared the efficacy and safety of chitosancoated timolol maleate (TM) mucoadhesive film, using a 0.5% TM commercial ophthalmic solution in a rabbit model. In addition, this study investigates the maximum release time of these implants in vivo. Methods: The mucoadhesive films were prepared by means of a casting and solvent evaporation technique performed in a 2 wt% acetic acid solution and distilled water. Physical properties were characterized by release and swelling studies, differential scanning calorimetry, and attenuated total reflectance fourier transformed infrared spectroscopy (ATR-FTIR). The developed formulations were evaluated for their pharmacodynamics in ocular normotensive albino rabbits, in which the intraocular pressure (IOP) was measured by means of applanation tonometer on alternative days (13 h) for 11 weeks. For 15 days, 0.5% TM commercial ophthalmic solution was administered twice a day (n = 5) and compared to chitosan-coated TM (n = 5). In the control group (n = 5), saline was used twice a day. The maximum TM release time from chitosan films were also recorded. After euthanasia, the right eyes were removed from the 3 groups for histological analyses. Results: In an in vitro study, TM was released over a 4-week period, in which 85% of the drug was released over the first 2 weeks. However, the film's release of TM lowered the in vivo IOP levels over a 10-week period. No significant difference in the lowering of IOP in rabbits treated with 0.5% TM commercial ophthalmic solution, as compared to those that received the films (P < 0.05), could be observed. No signs of ocular discomfort or irritations could be identified upon ophthalmic examination by slit-lamp biomicroscopy. Ophthalmic structures that came in direct contact with the films revealed no alterations within the histopathological studies. Moreover, the animals showed no signs of ocular discomfort during the experimental assays. Conclusion: These findings suggest that the TM-loaded chitosan film is safe and efficient and presents a promising future as an ocular drug delivery system in the treatment and prevention of glaucoma.
Journal of Ocular Pharmacology and Therapeutics, 2014
Tacrolimus is a potent immunosuppressive agent with limited corneal penetration. Microemulsions c... more Tacrolimus is a potent immunosuppressive agent with limited corneal penetration. Microemulsions can increase the drug solubility and enhance drug absorption in the eye. This work aimed to develop a tacrolimus microemulsion as well as to characterize and to evaluate its ocular tolerance and pharmacokinetics after topical application in rabbits. The microemulsion was prepared by the titration with the cosurfactant technique and its physical-chemical parameters and stability were determined. The cytotoxicity was evaluated using the corneal epithelium and conjunctiva cell lines. The ocular pharmacokinetic parameters in rabbits were determined and compared with that obtained after instillation of tacrolimus suspension. The microemulsion containing tacrolimus was successfully developed. It was nonirritating to rabbits&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; eyes and it was also not toxic to the corneal and conjunctival cells. When compared to the suspension, the microemulsion containing tacrolimus presented higher values of AUC (2,912.5±245.4 min.ng/mL vs. 1,669.8±93 min.ng/mL) and Cmax (26.8±2.3 ng/mL vs. 20.7±2.8 ng/mL). On the other hand, the Cl/F value was smaller when compared to the suspension that may decrease the number of applications of eye drops. The developed microemulsion could be an alternative to reduce the systemic adverse effects of tacrolimus and, consequently, increase the patient compliance to the treatment.
Journal of Materials Science: Materials in Medicine, 2013
The subretinal transplantation of retinal pigment epithelial cells (RPE cells) grown on polymeric... more The subretinal transplantation of retinal pigment epithelial cells (RPE cells) grown on polymeric supports may have interest in retinal diseases affecting RPE cells. In this study, montmorillonite based polyurethane nanocomposite (PU-NC) was investigated as substrate for human RPE cell growth (ARPE-19 cells). The ARPE-19 cells were seeded on the PU-NC, and cell viability, proliferation and differentiation were investigated. The results indicated that ARPE-19 cells attached, proliferated onto the PU-NC, and expressed occludin. The in vivo ocular biocompatibility of the PU-NC was assessed by using the HET-CAM; and through its implantation under the retina. The direct application of the nanocomposite onto the CAM did not compromise the vascular tissue in the CAM surface, suggesting no ocular irritancy of the PU-NC film. The nanocomposite did not elicit any inflammatory response when implanted into the eye of rats. The PU-NC may have potential application as a substrate for RPE cell transplantation.
Journal of Drug Targeting, 2009
Polyurethanes and polyurethane nanocomposites can be applied to control the release of drugs prev... more Polyurethanes and polyurethane nanocomposites can be applied to control the release of drugs previously incorporated into these materials. In this study, dexamethasone acetate (ACT) was incorporated into biodegradable and biocompatible polyurethane and polyurethane containing montmorillonite nanoparticles. Fourier transform infrared spectroscopic technique showed no strong interactions between drug and polymers. Data obtained from X-ray diffraction and small angle X-ray scattering indicated that the incorporation of ACT did not disturb the polymer morphology, but montmorillonite led to a less defined phase separation between hard and soft segments of polyurethane. The in vitro release studies demonstrated that nanoparticles increased the rate of ACT release possibly because these particles have a hydrophilic surface that increases the absorption of water and accelerates the hydrolysis of the polymer. The in vivo short-term biocompatibility studies demonstrated adequate interfacial interaction between polyurethane and subcutaneous tissue and a discreet inflammatory response which was completely resolved in 14 days.
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Papers by Armando Silva-cunha