The Experts below are selected from a list of 198 Experts worldwide ranked by ideXlab platform
David; Attwood - One of the best experts on this subject based on the ideXlab platform.
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in situ gelling xyloglucan formulations for sustained release ocular delivery of Pilocarpine hydrochloride
International Journal of Pharmaceutics, 2001Co-Authors: Shozo Miyazaki, N. Kawasaki, K. Endo, A Takahashi, S. Suzuki, David; AttwoodAbstract:Abstract Thermoreversible gels formed in situ by aqueous solutions of an enzyme-degraded xyloglucan polysaccharide were evaluated as sustained release vehicles for the ocular delivery of Pilocarpine hydrochloride. In vitro release of Pilocarpine from gels formed by warming xyloglucan sols (1.0, 1.5 and 2.0% w/w) to 34 °C followed root-time kinetics over a period of 6 h. The miotic responses in rabbit following administration of xyloglucan sols were compared with those from in situ gelling Pluronic F127 sols and from an aqueous buffer solution containing the same drug concentration. Sustained release of Pilocarpine was observed with all gels, the duration of miotic response increasing with increase of xyloglucan concentration. The degree of enhancement of miotic response following sustained release of Pilocarpine from the 1.5% w/w xyloglucan gel was similar to that from a 25% w/w Pluronic F127 gel.
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In situ gelling xyloglucan formulations for sustained release ocular delivery of Pilocarpine hydrochloride
International Journal of Pharmaceutics, 2001Co-Authors: Shuichi Miyazaki, N. Kawasaki, K. Endo, A Takahashi, S. Suzuki, David; AttwoodAbstract:Thermoreversible gels formed in situ by aqueous solutions of an enzyme-degraded xyloglucan polysaccharide were evaluated as sustained release vehicles for the ocular delivery of Pilocarpine hydrochloride. In vitro release of Pilocarpine from gels formed by warming xyloglucan sols (1.0, 1.5 and 2.0% w/w) to 34°C followed root-time kinetics over a period of 6 h. The miotic responses in rabbit following administration of xyloglucan sols were compared with those from in situ gelling Pluronic F127 sols and from an aqueous buffer solution containing the same drug concentration. Sustained release of Pilocarpine was observed with all gels, the duration of miotic response increasing with increase of xyloglucan concentration. The degree of enhancement of miotic response following sustained release of Pilocarpine from the 1.5% w/w xyloglucan gel was similar to that from a 25% w/w Pluronic F127 gel. © 2001 Elsevier Science B.V. All rights reserved.
Shiping Yu - One of the best experts on this subject based on the ideXlab platform.
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characterization of Pilocarpine loaded chitosan carbopol nanoparticles
Journal of Pharmacy and Pharmacology, 2006Co-Authors: Yuli Lo, Shiping YuAbstract:Patients using ophthalmic drops are faced with frequent dosing schedules and difficult drop instillation. Therefore, a long-lasting Pilocarpine-loaded chitosan (CS)/Carbopol nanoparticle ophthalmic formulation was developed. The physicochemical properties of the prepared nanoparticles were investigated using dynamic light scattering, zeta-potential, transmission electron microscopy, Fourier transform infrared ray spectroscopy (FT-IR) and differential scanning calorimetry (DSC). The sustained-release effects of Pilocarpine-loaded nanoparticles were evaluated using in-vitro release and in-vivo miotic tests, and compared with Pilocarpine in solution, gel and liposomes. We found that the prepared nanoparticles were about 294 nm in size. DSC and FT-IR studies suggested that an electrostatic interaction between CS and Carbopol contributes at least in part to the stabilization of Pilocarpine/CS/Carbopol nanoparticles. When compared with Pilocarpine in solution, gel or liposomes, the best slow-release profile of Pilocarpine from the prepared nanoparticles occurred in a dissolution test. In the in-vivo miotic study, Pilocarpine-loaded CS/Carbopol nanoparticles showed the most significant long-lasting decrease in the pupil diameter of rabbits. The advantages of CS and Carbopol are good biocompatibility, biodegradability and low toxicity. CS is also a mucoadhesive polymer. Thus, Pilocarpine/CS/Carbopol nanoparticles may provide an excellent potential alternative ophthalmic sustained-release formulation of Pilocarpine for clinical use. CS/Carbopol nanoparticles may also be useful for a variety of other therapeutic delivery systems.
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Characterization of Pilocarpine‐loaded chitosan/Carbopol nanoparticles
Journal of Pharmacy and Pharmacology, 2006Co-Authors: Yuli Lo, Shiping YuAbstract:Patients using ophthalmic drops are faced with frequent dosing schedules and difficult drop instillation. Therefore, a long-lasting Pilocarpine-loaded chitosan (CS)/Carbopol nanoparticle ophthalmic formulation was developed. The physicochemical properties of the prepared nanoparticles were investigated using dynamic light scattering, zeta-potential, transmission electron microscopy, Fourier transform infrared ray spectroscopy (FT-IR) and differential scanning calorimetry (DSC). The sustained-release effects of Pilocarpine-loaded nanoparticles were evaluated using in-vitro release and in-vivo miotic tests, and compared with Pilocarpine in solution, gel and liposomes. We found that the prepared nanoparticles were about 294 nm in size. DSC and FT-IR studies suggested that an electrostatic interaction between CS and Carbopol contributes at least in part to the stabilization of Pilocarpine/CS/Carbopol nanoparticles. When compared with Pilocarpine in solution, gel or liposomes, the best slow-release profile of Pilocarpine from the prepared nanoparticles occurred in a dissolution test. In the in-vivo miotic study, Pilocarpine-loaded CS/Carbopol nanoparticles showed the most significant long-lasting decrease in the pupil diameter of rabbits. The advantages of CS and Carbopol are good biocompatibility, biodegradability and low toxicity. CS is also a mucoadhesive polymer. Thus, Pilocarpine/CS/Carbopol nanoparticles may provide an excellent potential alternative ophthalmic sustained-release formulation of Pilocarpine for clinical use. CS/Carbopol nanoparticles may also be useful for a variety of other therapeutic delivery systems.
Rivelilson Mendes De Freitas - One of the best experts on this subject based on the ideXlab platform.
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the evaluation of effects of lipoic acid on the lipid peroxidation nitrite formation and antioxidant enzymes in the hippocampus of rats after Pilocarpine induced seizures
Neuroscience Letters, 2009Co-Authors: Rivelilson Mendes De FreitasAbstract:It has been suggested that Pilocarpine-induced seizures is mediated by increases in oxidative stress. Current researches have suggested that antioxidant compounds may afford some level of neuroprotection against the neurotoxicity of seizures in cellular level. The objective of the present study was to evaluate the neuroprotective effects of lipoic acid (LA) in rats, against the observed oxidative stress during seizures induced by Pilocarpine. Wistar rats were treated with 0.9% saline (i.p., control group), LA (10 mg/kg, i.p., LA group), Pilocarpine (400 mg/kg, i.p., Pilocarpine group), and the association of LA (10 mg/kg, i.p.) plus Pilocarpine (400 mg/kg, i.p.), 30 min before of administration of LA (LA plus Pilocarpine group). After the treatments all groups were observed for 6 h. The enzyme activities as well as the lipid peroxidation and nitrite concentrations were measured using spectrophotometric methods and the results compared to values obtained from saline and Pilocarpine-treated animals. Protective effects of LA were also evaluated on the same parameters. In Pilocarpine group there was a significant increase in lipid peroxidation and nitrite level. However, no alteration was observed in superoxide dismutase and catalase activities. Antioxidant treatment significantly reduced the lipid peroxidation level and nitrite content as well as increased the superoxide dismutase and catalase activities in hippocampus of rats after seizures induced by Pilocarpine. Our findings strongly support the hypothesis that oxidative stress in hippocampus occurs during seizures induced by Pilocarpine, proving that brain damage induced by the oxidative process plays a crucial role in seizures pathogenic consequences, and also imply that strong protective effect could be achieved using lipoic acid as an antioxidant.
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neuroprotective actions of vitamin c related to decreased lipid peroxidation and increased catalase activity in adult rats after Pilocarpine induced seizures
Pharmacology Biochemistry and Behavior, 2008Co-Authors: Lucia F L Santos, Rizângela Lyne Mendes De Freitas, Sarah M L Xavier, Glaucio Barros Saldanha, Rivelilson Mendes De FreitasAbstract:Abstract In the present study, we examined the neuroprotective effects of vitamin C in adult rats after Pilocarpine-induced seizures. Vitamin C is an exogenous antioxidant that can be used in treatment of seizures. It can alter oxidative stress and damage neuronal induced by seizures. Its antioxidant properties can be proved in epilepsy models, such as Pilocarpine-induced seizures in adult rats. In order to investigate neuroprotective effects of vitamin C, adult male rats (2 months-old) were pretreated with vitamin C (VIT C 250 mg/kg, i.p.) 30 min before receiving Pilocarpine (400 mg/kg, s.c., P400 group). The other three groups were treated with vitamin C (VIT C group) and saline 0.9 (control group) alone. The pretreatment with vitamin C increased the latency to first seizures and reduced mortality rate after Pilocarpine-induced seizures. Pretreatment with vitamin C alone decrease lipid peroxidation levels when compared to Pilocarpine group and P400 + VIT C. In P400, P400 + VIT C and VIT C groups were observed an increased hippocampal catalase activity when compared to control group. Our results can suggest that neuroprotective effects of vitamin C in adult rats can be the result of reduced lipid peroxidation levels and increase of catalase activity after seizures and status epilepticus induced by Pilocarpine.
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effects of the vitamin e in catalase activities in hippocampus after status epilepticus induced by Pilocarpine in wistar rats
Neuroscience Letters, 2007Co-Authors: D O Barros, Rivelilson Mendes De Freitas, Rizângela Lyne Mendes De Freitas, S M Xavier, C O Barbosa, Rui F M Silva, F D Maia, A A Oliveira, Reinaldo N TakahashiAbstract:Abstract Experimental manipulations suggest that in vivo administration of exogenous antioxidants agents decreases the concentration of free radical in the brain. Neurochemical studies have proposed a role for catalase in brain mechanisms responsible by development to status epilepticus (SE) induced by Pilocarpine. The present study was aimed at was investigating the changes in catalase activities after Pilocarpine-induced SE. Animals were treated with vitamin E (VIT E) 200 mg/kg (intraperitoneally (i.p.)) and, 30 min later, they received Pilocarpine hydrochloride, 400 mg/kg, subcutaneous (s.c.) (P400). Other three groups received VIT E (200 mg/kg, i.p.), Pilocarpine (400 mg/kg, s.c.) or 0.9% NaCl (control) alone. Animals were closely observed for behavioral changes, tremors, stereotyped movements, seizures, SE and death, for 24 h following the Pilocarpine injection. The brains were dissected after decapitation. The results have shown that Pilocarpine administration and resulting SE produced a significant increase in hippocampal catalase activity of (88%). In the group pre-treated which VIT E in hippocampal catalase activity was increase of 67% and 214% when compared with P400 and control group, respectively. Our results demonstrated a direct evidence of an increase in the activity of the hippocampal catalase of rat adults during seizure activity and after the pre-treated which VIT E that could be responsible by regulation of free radical levels during the establishment of SE.
Massimo Avoli - One of the best experts on this subject based on the ideXlab platform.
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the Pilocarpine model of temporal lobe epilepsy
Journal of Neuroscience Methods, 2008Co-Authors: Giulia Curia, Daniela Longo, Giuseppe Biagini, Roland S G Jones, Massimo AvoliAbstract:Understanding the pathophysiogenesis of temporal lobe epilepsy (TLE) largely rests on the use of models of status epilepticus (SE), as in the case of the Pilocarpine model. The main features of TLE are: (i) epileptic foci in the limbic system; (ii) an “initial precipitating injury”; (iii) the so-called “latent period”; and (iv) the presence of hippocampal sclerosis leading to reorganization of neuronal networks. Many of these characteristics can be reproduced in rodents by systemic injection of Pilocarpine; in this animal model, SE is followed by a latent period and later by the appearance of spontaneous recurrent seizures (SRSs). These processes are, however, influenced by experimental conditions such as rodent species, strain, gender, age, doses and routes of Pilocarpine administration, as well as combinations with other drugs administered before and/or after SE. In the attempt to limit these sources of variability, we evaluated the methodological procedures used by several investigators in the Pilocarpine model; in particular, we have focused on the behavioural, electrophysiological and histopathological findings obtained with different protocols. We addressed the various experimental approaches published to date, by comparing mortality rates, onset of SRSs, neuronal damage, and network reorganization. Based on the evidence reviewed here, we propose that the Pilocarpine model can be a valuable tool to investigate the mechanisms involved in TLE, and even more so when standardized to reduce mortality at the time of Pilocarpine injection, differences in latent period duration, variability in the lesion extent, and SRS frequency.
Yuli Lo - One of the best experts on this subject based on the ideXlab platform.
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characterization of Pilocarpine loaded chitosan carbopol nanoparticles
Journal of Pharmacy and Pharmacology, 2006Co-Authors: Yuli Lo, Shiping YuAbstract:Patients using ophthalmic drops are faced with frequent dosing schedules and difficult drop instillation. Therefore, a long-lasting Pilocarpine-loaded chitosan (CS)/Carbopol nanoparticle ophthalmic formulation was developed. The physicochemical properties of the prepared nanoparticles were investigated using dynamic light scattering, zeta-potential, transmission electron microscopy, Fourier transform infrared ray spectroscopy (FT-IR) and differential scanning calorimetry (DSC). The sustained-release effects of Pilocarpine-loaded nanoparticles were evaluated using in-vitro release and in-vivo miotic tests, and compared with Pilocarpine in solution, gel and liposomes. We found that the prepared nanoparticles were about 294 nm in size. DSC and FT-IR studies suggested that an electrostatic interaction between CS and Carbopol contributes at least in part to the stabilization of Pilocarpine/CS/Carbopol nanoparticles. When compared with Pilocarpine in solution, gel or liposomes, the best slow-release profile of Pilocarpine from the prepared nanoparticles occurred in a dissolution test. In the in-vivo miotic study, Pilocarpine-loaded CS/Carbopol nanoparticles showed the most significant long-lasting decrease in the pupil diameter of rabbits. The advantages of CS and Carbopol are good biocompatibility, biodegradability and low toxicity. CS is also a mucoadhesive polymer. Thus, Pilocarpine/CS/Carbopol nanoparticles may provide an excellent potential alternative ophthalmic sustained-release formulation of Pilocarpine for clinical use. CS/Carbopol nanoparticles may also be useful for a variety of other therapeutic delivery systems.
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Characterization of Pilocarpine‐loaded chitosan/Carbopol nanoparticles
Journal of Pharmacy and Pharmacology, 2006Co-Authors: Yuli Lo, Shiping YuAbstract:Patients using ophthalmic drops are faced with frequent dosing schedules and difficult drop instillation. Therefore, a long-lasting Pilocarpine-loaded chitosan (CS)/Carbopol nanoparticle ophthalmic formulation was developed. The physicochemical properties of the prepared nanoparticles were investigated using dynamic light scattering, zeta-potential, transmission electron microscopy, Fourier transform infrared ray spectroscopy (FT-IR) and differential scanning calorimetry (DSC). The sustained-release effects of Pilocarpine-loaded nanoparticles were evaluated using in-vitro release and in-vivo miotic tests, and compared with Pilocarpine in solution, gel and liposomes. We found that the prepared nanoparticles were about 294 nm in size. DSC and FT-IR studies suggested that an electrostatic interaction between CS and Carbopol contributes at least in part to the stabilization of Pilocarpine/CS/Carbopol nanoparticles. When compared with Pilocarpine in solution, gel or liposomes, the best slow-release profile of Pilocarpine from the prepared nanoparticles occurred in a dissolution test. In the in-vivo miotic study, Pilocarpine-loaded CS/Carbopol nanoparticles showed the most significant long-lasting decrease in the pupil diameter of rabbits. The advantages of CS and Carbopol are good biocompatibility, biodegradability and low toxicity. CS is also a mucoadhesive polymer. Thus, Pilocarpine/CS/Carbopol nanoparticles may provide an excellent potential alternative ophthalmic sustained-release formulation of Pilocarpine for clinical use. CS/Carbopol nanoparticles may also be useful for a variety of other therapeutic delivery systems.
