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1.
Anaesthesia ; 67(8): 906-16, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22607613

RESUMO

Systemic toxicity through overdose of local anaesthetic agents is a real concern. By encapsulating local anaesthetics in biodegradable carriers to produce a system for prolonged release, their duration of action can be extended. This encapsulation should also improve the safety profile of the local anaesthetic as it is released at a slower rate. Work with naturally occurring local anaestheticss has also shown promise in the area of reducing systemic and neurotoxicity. Extended duration local anaesthetic formulations in current development or clinical use include liposomes, hydrophobic based polymer particles such as Poly(lactic-co-glycolic acid) microspheres, pasty injectable and solid polymers like Poly(sebacic-co-ricinoleic acid) P(SA:RA) and their combination with synthetic and natural local anaesthetic. Their duration of action, rationale and limitations are reviewed. Direct comparison of the different agents is limited by their chemical properties, the drug doses encapsulated and the details of in vivo models described.


Assuntos
Anestésicos Locais/administração & dosagem , Química Farmacêutica , Ensaios Clínicos como Assunto , Preparações de Ação Retardada , Injeções , Ácido Láctico/administração & dosagem , Lipossomos , Microesferas , Ácido Poliglicólico/administração & dosagem , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Polímeros
2.
J Travel Med ; 28(2)2021 02 23.
Artigo em Inglês | MEDLINE | ID: mdl-33480414

RESUMO

BACKGROUND: Nearly a year into the COVID-19 pandemic, we still lack effective anti-SARS-CoV-2 drugs with substantial impact on mortality rates except for dexamethasone. As the search for effective antiviral agents continues, we aimed to review data on the potential of repurposing antiparasitic drugs against viruses in general, with an emphasis on coronaviruses. METHODS: We performed a review by screening in vitro and in vivo studies that assessed the antiviral activity of several antiparasitic agents: chloroquine, hydroxychloroquine (HCQ), mefloquine, artemisinins, ivermectin, nitazoxanide (NTZ), niclosamide, atovaquone and albendazole. RESULTS: For HCQ and chloroquine we found ample in vitro evidence of antiviral activity. Cohort studies that assessed the use of HCQ for COVID-19 reported conflicting results, but randomized controlled trials (RCTs) demonstrated no effect on mortality rates and no substantial clinical benefits of HCQ used either for prevention or treatment of COVID-19. We found two clinical studies of artemisinins and two studies of NTZ for treatment of viruses other than COVID-19, all of which showed mixed results. Ivermectin was evaluated in one RCT and few observational studies, demonstrating conflicting results. As the level of evidence of these data is low, the efficacy of ivermectin against COVID-19 remains to be proven. For chloroquine, HCQ, mefloquine, artemisinins, ivermectin, NTZ and niclosamide, we found in vitro studies showing some effects against a wide array of viruses. We found no relevant studies for atovaquone and albendazole. CONCLUSIONS: As the search for an effective drug active against SARS-CoV-2 continues, we argue that pre-clinical research of possible antiviral effects of compounds that could have antiviral activity should be conducted. Clinical studies should be conducted when sufficient in vitro evidence exists, and drugs should be introduced into widespread clinical use only after being rigorously tested in RCTs. Such a search may prove beneficial in this pandemic or in outbreaks yet to come.


Assuntos
Antiparasitários/farmacologia , Tratamento Farmacológico da COVID-19 , Reposicionamento de Medicamentos , Hidroxicloroquina/farmacologia , Ivermectina/farmacologia , SARS-CoV-2/efeitos dos fármacos , Animais , Antiparasitários/uso terapêutico , COVID-19/epidemiologia , Humanos , Hidroxicloroquina/uso terapêutico , Ivermectina/uso terapêutico , Pandemias , Ensaios Clínicos Controlados Aleatórios como Assunto
3.
Int J Clin Pharmacol Ther ; 48(4): 250-8, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20353746

RESUMO

OBJECTIVE: The aim of the present study was to evaluate the in-vitro dissolution and in-vivo pharmacokinetic profile of a novel two-phase modified-release formulation for diltiazem hydrochloride, as a water-soluble drug. MATERIALS AND METHODS: The delivery system consisted of two tablets inserted into a capsule. Both tablets comprised a coated drug core-matrix. The coating of the first tablet was intended to produce a first phase with a relatively fast release profile, while that of the second tablet included a unique controlling membrane designed to achieve a delayed controlled-release profile. Three different formulations were tested for their dissolution profiles both in water media and in buffer with a pH of 6.8. These formulations were also evaluated for their pharmacokinetic profile in healthy volunteers after single administration of a 240 mg dose. Serial venous blood samples were collected over 36 h post administration to measure diltiazem levels by HPLC. In addition the in-vivo /in-vitro correlation (IVIVC) was calculated for these formulations. RESULTS: The in-vitro characteristics of these formulations demonstrated a controlled release profile in both media but with different characteristics, as in Formulation 3 where faster dissolution profile obtained in water but slower one in pH 6.8 buffer. In-vivo the pharmacokinetic profile of these formulations showed that arabinogalactan containing formulations achieved plasma levels which allow a once daily administration. IVIVC calculation demonstrated that dissolution tested in buffer 6.8 media better correlates with the percent absorbed in-vivo and the best results were achieved with the formulation containing the highest amount of polysaccharide in the coating. CONCLUSION: It is concluded that the developed formulations achieved a controlled release profile both in-vitro and in-vivo which are suitable for once-daily administration.


Assuntos
Bloqueadores dos Canais de Cálcio/administração & dosagem , Química Farmacêutica/métodos , Diltiazem/administração & dosagem , Sistemas de Liberação de Medicamentos , Adulto , Área Sob a Curva , Bloqueadores dos Canais de Cálcio/química , Bloqueadores dos Canais de Cálcio/farmacocinética , Cápsulas , Cromatografia Líquida de Alta Pressão , Estudos Cross-Over , Preparações de Ação Retardada , Diltiazem/química , Diltiazem/farmacocinética , Método Duplo-Cego , Feminino , Humanos , Masculino , Solubilidade , Espectrofotometria Ultravioleta , Comprimidos , Adulto Jovem
4.
Int J Clin Pharmacol Ther ; 46(4): 165-71, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18397689

RESUMO

OBJECTIVE: Deximune soft-gelatin capsules (Dexcel Ltd., Hadera, Israel), the test preparation and Sandimmun Neoral (Novartis Inc., Basel, Switzerland), the reference preparation, are two cyclosporine (CyA) formulations widely used after stem cells and solid organ transplantation. A post-marketing, retrospective, parallel, comparative, multicenter survey study in transplant patients receiving these two formulations after transplantation was carried out in order to compare the toxicity profile and bioavailability. MATERIALS AND METHODS: The study was conducted in the five main leading transplantation centers in Israel and included 174 patients. A total of 1-3 CyA serum levels at different periods after transplantation were measured in each subject and the bioavailability, efficacy and toxicity profile were assessed. The blood concentrations were compared using a statistical model after adjustment for type of transplantation, dose and time after transplantation as confounding factors. RESULTS: No distinct differences were observed between the two CyA formulations. Using model-derived least squares means (LSM) of the CyA blood levels and adjusting for relevant confounding factors, no significant difference could be found between the blood levels of the test and reference formulations. Most of the side effects were mild and transient with both formulations, whereas 23% of the patients reported serious adverse events (mainly hypertension, 15%). 20% of the patients developed infectious complications during the therapy. CONCLUSIONS: Deximune administration is safe. The toxicity profile of the product, incidence and type of side effects and bioavailability are similar to those of Sandimmun Neoral.


Assuntos
Ciclosporina/efeitos adversos , Ciclosporina/farmacocinética , Imunossupressores/efeitos adversos , Imunossupressores/farmacocinética , Transplante de Órgãos , Transplante de Células-Tronco , Adolescente , Adulto , Disponibilidade Biológica , Cápsulas , Criança , Pré-Escolar , Ciclosporina/sangue , Monitoramento de Medicamentos , Feminino , Gelatina , Rejeição de Enxerto/prevenção & controle , Humanos , Imunossupressores/sangue , Lactente , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos
5.
Biomaterials ; 28(14): 2339-49, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17298842

RESUMO

In this study, we compared two systems which can be applied for transfection in vitro and in vivo: polyplexes based on the polymer dextran-spermine (D-SPM) and lipoplexes based on 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)/cholesterol. The carriers differ in (1) solubility in aqueous media, (2) source of the positive charges (quaternary amines for DOTAP and primary plus secondary amines for D-SPM), (3) electrostatics, i.e., for lipid and polymer, respectively: zeta-potential (81.0 and 48.1 mV), surface potential (180 and 92 mV), and surface pH (10.47 and 8.97), and (4) charge distribution (ordered versus non-ordered). The stability of the complex upon interaction with serum proteins was studied by means of fluorescence resonance energy transfer (FRET) between rhodamine-labeled cationic carriers and fluorescein-labeled DNA. Addition of serum increases the lipid-DNA average distance and decreases the polymer-DNA distance. However, FRET efficiency indicates that serum proteins do not induce a major DNA dissociation for either polyplexes or lipoplexes. Comparing the biodistribution of rhodamine-labeled complexes and the transgene expression after intravenous (i.v.), intramuscular (i.m.), and intranasal (i.n.) administration, we found that local administration of lipoplexes resulted in the lipoplexes remaining at the site of injection, whereas the polyplexes showed systemic distribution, accompanied by transgene expression in lungs and liver. It is suggested that the high water-solubility of the polymer combined with its lower positive charge (compared to DOTAP), which makes its association with the cells at the site of injection weaker, enables the polymer to reach and transfect distant organs through the blood stream. Using chemically modified D-SPM, we demonstrated the importance of high density of positive charges and a sufficient level of secondary amines for achieving efficient transgene expression in vivo.


Assuntos
Colesterol/metabolismo , Dextranos/metabolismo , Ácidos Graxos Monoinsaturados/metabolismo , Lipossomos/metabolismo , Compostos de Amônio Quaternário/metabolismo , Espermina/metabolismo , Administração por Inalação , Animais , Colesterol/administração & dosagem , Colesterol/química , DNA/química , Dextranos/administração & dosagem , Dextranos/química , Ácidos Graxos Monoinsaturados/administração & dosagem , Ácidos Graxos Monoinsaturados/química , Feminino , Fluoresceína , Transferência Ressonante de Energia de Fluorescência , Corantes Fluorescentes , Técnicas de Transferência de Genes , Concentração de Íons de Hidrogênio , Injeções Intramusculares , Injeções Intravenosas , Lipossomos/química , Lipossomos/farmacocinética , Fígado/metabolismo , Pulmão/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Plasmídeos , Compostos de Amônio Quaternário/administração & dosagem , Compostos de Amônio Quaternário/química , Rodaminas , Solubilidade , Organismos Livres de Patógenos Específicos , Espermina/administração & dosagem , Espermina/química , Eletricidade Estática , Distribuição Tecidual , Transgenes , Água/química
6.
Int J Clin Pharmacol Ther ; 45(2): 126-32, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17323793

RESUMO

OBJECTIVE: A study was conducted to establish the bioequivalence between a newly developed cyclosporin A (CsA) oral formulation, Deximune soft-gelatin capsules (Dexcel Ltd.) and Sandimmune Neoral (Novartis Inc.). MATERIALS AND METHODS: The clinical investigation was designed as a randomized, open-labeled, two-period, two-treatment crossover study, in 24 healthy fasted male volunteers. The subjects were administered a single 200 mg CsA dose of either formulation. Serial venous blood samples were obtained over 24 hours after each administration to measure CsA in whole blood by a specific TDx-immunoassay. In addition, the comparative drug release rate was assessed using a dissolution apparatus test according to the USP-24 method. RESULTS: For both treatments, a mean maximum blood concentration (Cmax) of approximately 1,200 ng/ml was obtained at about 1.6 hours (tmax) after administration and the geometric mean of the area under the blood concentration-time curve (AUC) both for test and reference was approximately 4,900 ng x h/ml. Bioequivalence was conclusively demonstrated for both rate (Cmax and tmax) and extent (AUC) of CsA absorption, between the two treatments. Moreover, the CsA blood concentration measurement at 2 hours after administration (C2), demonstrated equivalent results between the two products. The point estimates and their 90% confidence intervals were within the respective equivalence ranges for the pharmacokinetic parameters and were included in the range for drugs with a narrow therapeutic index. The comparative dissolution test for both formulations showed an in vitro release rate of more than 90% within 15 minutes. CONCLUSIONS: Based on the results, the two oral CsA formulations compared are bioequivalent and can be interchanged without need for dosage adjustment.


Assuntos
Ciclosporina , Imunossupressores , Administração Oral , Adulto , Área Sob a Curva , Cápsulas , Estudos Cross-Over , Ciclosporina/administração & dosagem , Ciclosporina/química , Ciclosporina/farmacocinética , Gelatina , Humanos , Imunossupressores/administração & dosagem , Imunossupressores/química , Imunossupressores/farmacocinética , Masculino , Taxa de Depuração Metabólica , Solubilidade , Equivalência Terapêutica
7.
Mini Rev Med Chem ; 6(2): 153-62, 2006 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16472184

RESUMO

The clinical treatment of leishmaniasis is based on a limited number of drugs, which are associated with adverse effects and have already induced resistance. Amphotericin B (AmB), a polyene antibiotic produced by Streptomyces sp, is the only anti-leishmanial drug which has not induced clinical resistance since its discovery in 1956. The limiting factor in the use of AmB is its toxic effects, mainly nephrotoxicity. The maximal dose of AmB for human use is 1.5 mg/kg which sometimes is not sufficient for cure. The mode of action of AmB is associated with its toxicity: it selectively binds to parasite membrane ergosterol but also, to a lesser extent, to human cholesterol. Apart from this mechanism, AmB has immunomodulatory effects, some of them are deleterious. Reduction of the toxic effects by using lipid formulations allows the infusion of higher doses of AmB. Unfortunately, these formulations are relatively expensive and therefore out of reach for patients in need, in the endemic areas. All the existing formulations are given parenterally, which has obvious disadvantages; most important is the need for hospitalization or multiple visits in the clinic. The current efforts to improve AmB are directed at the production of AmB aggregates in liquid solutions, encapsulation with lipid components, and solubilization by binding to soluble polymers. The expected improved treatment resulting from use of the new formulations is based on better pharmacokinetics, reduced toxicity originating from slow release, targeting to the infected organ and an altered pattern of immune responses (related to AmB). Of particular importance are the attempts to produce derivatives for oral treatment, which will decrease costs of hospitalization and improve applicability for children and the elderly population.


Assuntos
Anfotericina B/uso terapêutico , Antiprotozoários/uso terapêutico , Leishmaniose/tratamento farmacológico , Anfotericina B/efeitos adversos , Anfotericina B/farmacocinética , Animais , Antiprotozoários/efeitos adversos , Antiprotozoários/farmacocinética , Química Farmacêutica , Humanos , Camundongos , Solubilidade
8.
Eur J Pharm Biopharm ; 64(3): 277-86, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16846724

RESUMO

Pharmaceutical grade D,L-lactic acid, which is rather an economic source in comparison to lactide monomer, was utilized for synthesis of a series of copolymers with sebacic acid. Polymers were characterized by GPC, FTIR, NMR and DSC techniques, and formulated into blank and methotrexate (MTX) loaded microspheres by emulsion-solvent evaporation method. In vitro degradation of blank microspheres was studied by FTIR, GPC and SEM analysis. MTX loaded microspheres showed the encapsulation efficiency of 44-64% and were in the size range of 40-60 microm. These were used to study the release profile of the encapsulated drug. The release was found to be affected by the pH and buffer concentration of the release medium which was in turn revealed by solubility studies of MTX. The overall study demonstrates significance of drug as well as polymer properties on release. Biocompatibility of polymer was evaluated by injecting microspheres subcutaneously into Sprague-Dawley (SD) rat and no local histopathological abnormalities were found.


Assuntos
Materiais Biocompatíveis/síntese química , Ácidos Decanoicos/química , Ácidos Dicarboxílicos/química , Portadores de Fármacos , Ácido Láctico/química , Metotrexato/química , Polímeros/síntese química , Animais , Materiais Biocompatíveis/administração & dosagem , Materiais Biocompatíveis/efeitos adversos , Soluções Tampão , Química Farmacêutica , Ácidos Decanoicos/administração & dosagem , Ácidos Decanoicos/efeitos adversos , Ácidos Dicarboxílicos/administração & dosagem , Ácidos Dicarboxílicos/efeitos adversos , Composição de Medicamentos , Feminino , Concentração de Íons de Hidrogênio , Inflamação/induzido quimicamente , Inflamação/patologia , Injeções Subcutâneas , Cinética , Ácido Láctico/administração & dosagem , Ácido Láctico/efeitos adversos , Microesferas , Tamanho da Partícula , Polímeros/administração & dosagem , Polímeros/efeitos adversos , Ratos , Ratos Sprague-Dawley , Solubilidade , Fatores de Tempo
9.
Cancer Res ; 54(8): 2207-12, 1994 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-7909720

RESUMO

Taxol is a novel antitumor agent with demonstrated efficacy against ovarian, breast, and non-small cell lung cancers in Phase II clinical trials, but which has been shown not to cross the blood-brain barrier. To adapt taxol as a therapy for brain tumors, we have incorporated it into a biodegradable polyanhydride matrix for intracranial implantation and evaluated this formulation in a rat model of malignant glioma. Fischer 344 rats bearing intracranial 9L glioma tumors were treated with 10 mg poly[bis(p-carboxyphenoxy)propane-sebacic acid] (20:80) copolymer discs, containing 20-40% taxol by weight, 5 days after tumor implantation. The taxol-loaded polymers doubled (38 days, 40% taxol loading, P < 0.02) to tripled (61.5 days, 20% taxol loading, P < 0.001) the median survival of rats bearing tumor relative to control rats (19.5 days). Drug loadings of 20-40% taxol by weight released intact taxol for up to 1000 h in vitro. In rats followed up to 30 days postimplant, the polymer maintained a taxol concentration of 75-125 ng taxol/mg brain tissue (100-150 microM taxol) within a 1-3-mm radius of the disc. At points more distant from the disc (up to 8 mm away, the size limit of the rat brain), the polymer maintained a taxol concentration of greater than 4 ng taxol/mg brain tissue (5 microM). We conclude that taxol shows promise as a therapy for malignant glioma when delivered interstitially from a biodegradable polymer.


Assuntos
Glioma/tratamento farmacológico , Paclitaxel/administração & dosagem , Animais , Biopolímeros , Encéfalo/metabolismo , Ensaios Clínicos Fase II como Assunto , Ácidos Decanoicos , Implantes de Medicamento , Glioma/metabolismo , Humanos , Masculino , Paclitaxel/farmacocinética , Paclitaxel/uso terapêutico , Poliésteres , Ratos , Ratos Endogâmicos F344 , Análise de Sobrevida , Distribuição Tecidual
10.
Mini Rev Med Chem ; 5(5): 441-7, 2005 May.
Artigo em Inglês | MEDLINE | ID: mdl-15892686

RESUMO

Heparin is a biogenic anionic charged sulfated polysaccharide that has a range of desired activities including inhibition of tumor metastasis and inhibition of restenosis. However, its clinical use is limited to treating blood-clotting disorders. Anionic macromolecules called heparinoids have been investigated with the objective of developing heparin-like molecules with reduced anti-coagulant activity and selective anti-metastasis and anti-restenosis activity. This mini-review summarizes the synthesis and biological activity of the main synthetic heparinoids reported in the past three decades.


Assuntos
Antineoplásicos/farmacologia , Inibidores Enzimáticos/farmacologia , Heparinoides/farmacologia , Aminoácidos/química , Aminoácidos/farmacologia , Animais , Anticoagulantes/química , Anticoagulantes/farmacologia , Antineoplásicos/química , Reestenose Coronária/tratamento farmacológico , Reestenose Coronária/prevenção & controle , Inibidores Enzimáticos/química , Fatores de Crescimento de Fibroblastos/metabolismo , Glucuronidase/antagonistas & inibidores , Heparina/química , Heparina/farmacologia , Heparinoides/química , Heparitina Sulfato/metabolismo , Humanos , Metástase Neoplásica/tratamento farmacológico , Metástase Neoplásica/prevenção & controle
11.
J Control Release ; 103(3): 541-63, 2005 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-15820403

RESUMO

Many drugs that are administered in an unmodified form by conventional systemic routes fail to reach target organs in an effective concentration, or are not effective over a length of time due to a facile metabolism. Various types of targeting delivery systems and devices have been tried over a long period of time to overcome these problems. Targeted delivery or localized drug delivery offers an advantage of reduced body burden and systemic toxicity of the drugs, especially useful for highly toxic drugs like anticancer agents. Local drug delivery via polymer is a simple approach and hypothesized to avoid the above stated problems. Polyanhydrides are a unique class of polymer for drug delivery because some of them demonstrate a near zero order drug release and relatively rapid biodegradation in vivo. Further, the release rate of polyanhydride fabricated device can be altered over a thousand fold by simple changes in the polymer backbone. Hence, these are one of the best-suited polymers for drug delivery, with biodegradability and biocompatibility. The review focuses on the advantages of polyanhydride carriers in localized drug delivery along with their degradability behavior, toxicological profile and role in various disease conditions.


Assuntos
Portadores de Fármacos/química , Polianidridos/química , Antineoplásicos/administração & dosagem , Antineoplásicos/farmacocinética , Sistemas de Liberação de Medicamentos , Humanos , Polianidridos/toxicidade
12.
Molecules ; 10(1): 34-64, 2005 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-18007276

RESUMO

Nucleic acid delivery has many applications in basic science, biotechnology, agriculture, and medicine. One of the main applications is DNA or RNA delivery for gene therapy purposes. Gene therapy, an approach for treatment or prevention of diseases associated with defective gene expression, involves the insertion of a therapeutic gene into cells, followed by expression and production of the required proteins. This approach enables replacement of damaged genes or expression inhibition of undesired genes. Following two decades of research, there are two major methods for delivery of genes. The first method, considered the dominant approach, utilizes viral vectors and is generally an efficient tool of transfection. Attempts, however, to resolve drawbacks related with viral vectors (e.g., high risk of mutagenicity, immunogenicity, low production yield, limited gene size, etc.), led to the development of an alternative method, which makes use of non-viral vectors. This review describes non-viral gene delivery vectors, termed "self-assembled" systems, and are based on cationic molecules, which form spontaneous complexes with negatively charged nucleic acids. It introduces the most important cationic polymers used for gene delivery. A transition from in vitro to in vivo gene delivery is also presented, with an emphasis on the obstacles to achieve successful transfection in vivo.


Assuntos
Técnicas de Transferência de Genes , Polímeros/química , Polímeros/farmacologia , Animais , Células Cultivadas , DNA/administração & dosagem , Dendrímeros/química , Dendrímeros/farmacologia , Técnicas de Transferência de Genes/efeitos adversos , Vetores Genéticos/química , Humanos , Lipídeos/química , Lipídeos/farmacologia , Modelos Biológicos , Polietilenoimina/química , Polietilenoimina/farmacologia , Polilisina/química , Polilisina/farmacologia , Polissacarídeos/química , Vírus/genética
13.
Adv Drug Deliv Rev ; 53(1): 23-44, 2001 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-11733116

RESUMO

Recently, block copolymers have got tremendous impetus on the ongoing research in the area of drug delivery technology, due to their capability to provide a biomaterial having a broad range of amphiphilic characteristics, as well as targeting the drugs to specific site. This article is an attempt to review applications of block copolymers in surface modification, drug targeting, nano and microparticles, hydrogels, micelles etc. The physicochemical properties of block copolymers and various synthetic routes for block copolymers are also discussed.


Assuntos
Materiais Biocompatíveis/síntese química , Lactatos/síntese química , Polietilenoglicóis/síntese química , Animais , Materiais Biocompatíveis/farmacocinética , Biodegradação Ambiental , Sistemas de Liberação de Medicamentos/métodos , Humanos , Lactatos/farmacocinética , Polietilenoglicóis/farmacocinética
14.
J Med Chem ; 43(13): 2591-600, 2000 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-10891119

RESUMO

Poly(N-acryl amino acids) bearing side groups with a lipophilic character or having charged functional groups (i.e. -NH(2), -COOH, -SH, -OH, and phenols) were synthesized from the radical polymerization of N-acryl amino acid monomers. Monomers were prepared from the reaction of acryloyl chloride and amino acid esters in dry solvents. Polymers of a broad molecular weight ranging from 3 000 to 60 000 Da were obtained. The polymers were optically active, and their structures were confirmed by (1)H NMR and IR spectra and elemental analysis. Hydroxyl-containing polymers were sulfated in high conversion yields by SO(3)/pyridine complex. The newly synthesized linear homopolyanions were tested for heparin-like activities: (i) inhibition of heparanase enzyme, (ii) release of basic fibroblast growth factor (bFGF) from the extracellular matrix (ECM), and (iii) inhibition of smooth muscle cell (SMC) proliferation. Polymers based on tyrosine and leucine were highly active in all three tests (microgram level). Polymers based on phenylalanine, tert-leucine, and proline were active as heparanase inhibitors and FGF release, and polymers of trans-hydroxyproline, glycine, and serine were active only as heparanase inhibitors. The polymer of cis-hydroxyproline was inactive. It was found that a net anionic charge (i.e. carboxylic acid) is essential for biological activity. Thus, methyl ester derivatives of the active polymers, zwitterionic amino acid dependent groups (lysine, histidine), and decarboxylated amino acids (tyramine, ethanolamine) were inactive. The above active polymers did not exhibit anticoagulation activity which is considered the main limitation of heparin and heparinomimetics for clinical use. These synthetic poly(N-acryl amino acids) may have potential use in the inhibition of heparanase-mediated degradation of basement membranes associated with tumor metastasis, inflammation, and autoimmunity.


Assuntos
Resinas Acrílicas/síntese química , Aminoácidos/síntese química , Inibidores Enzimáticos/síntese química , Resinas Acrílicas/química , Resinas Acrílicas/farmacologia , Aminoácidos/química , Aminoácidos/farmacologia , Animais , Ânions , Anticoagulantes/síntese química , Anticoagulantes/química , Anticoagulantes/farmacologia , Bovinos , Divisão Celular/efeitos dos fármacos , Células Cultivadas , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Matriz Extracelular/metabolismo , Fator 2 de Crescimento de Fibroblastos/metabolismo , Heparina/química , Heparina/farmacologia , Heparina Liase/antagonistas & inibidores , Humanos , Espectroscopia de Ressonância Magnética , Peso Molecular , Músculo Liso Vascular/citologia , Músculo Liso Vascular/efeitos dos fármacos , Espectrofotometria Infravermelho , Relação Estrutura-Atividade
15.
Artigo em Inglês | MEDLINE | ID: mdl-1868550

RESUMO

The delivery of drugs to the brain has been a major challenge to the scientist developing drugs designed for central nervous system (CNS) activity. One of the obstacles to the progress is the transport of drug through the blood brain barrier (BBB). The criteria for effective drug delivery to the CNS include the following: (a) the drug must have access to the brain, (b) the effect of the drug should be localized, (c) the drug must be stable, and (d) the effective dose should be sustained and controlled. To meet some of the above criteria, two approaches have been used: systemic administration of drugs, and direct delivery of drugs into the brain. The systemic administration of drugs relies on passive diffusion of drug through the BBB, formation of lipid soluble prodrugs and the use of monoclonal antibodies for targeting the drug to the CNS. The other approach includes the use of implantable polymer systems and infusion pumps. Both of the approaches have some advantages and disadvantages. Because of the enormous amount of literature on drug delivery to the brain, the following review focuses on the use of polymer-based implantable systems. The review includes nondegradable and biodegradable polymer implants from the conceptual phase to the clinic.


Assuntos
Encéfalo/metabolismo , Bombas de Infusão Implantáveis , Polímeros , Animais , Antineoplásicos/administração & dosagem , Biodegradação Ambiental , Barreira Hematoencefálica , Neoplasias Encefálicas/tratamento farmacológico , Humanos
16.
Biochem Pharmacol ; 62(9): 1221-7, 2001 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-11705455

RESUMO

The effect of dermal application of halofuginone-an inhibitor of collagen type I synthesis-on skin collagen and collagen alpha1(I) gene expression in an animal model of scleroderma and chronic graft versus host disease (cGvHD) was evaluated. Halofuginone-containing cream was applied on the tight-skin mouse (Tsk) and skin biopsies were taken for collagen staining by sirius red and for collagen alpha1(I) gene expression by in situ hybridization. In addition, cell proliferation was evaluated by immunostaining for proliferation cell nuclear antigen (PCNA) alone or in combination with collagen alpha1(I) probe. The number of mast cells was assessed by toluidine blue. Dermal application of halofuginone (0.01%) for 60 days was as good as systemic administration (1 microg/mouse/day) in reducing collagen alpha1(I) gene expression in skin biopsy and almost as good in reducing skin width. Halofuginone was stable and effective only at acidic pH. The effect of halofuginone (0.03%) was time-dependent. After 40 days of daily treatment, a significant reduction in the collagen alpha1(I) gene expression was observed and further decrease was observed after 60 days. The reduction in collagen alpha1(I) gene expression and the reduction in the proliferation of dermal fibroblasts probably occur in the same subset of cells. No effect of halofuginone on the proliferation of keratinocytes or on mast cell number was observed. These results suggest that target-oriented application of halofuginone may become a novel therapy for fibrotic disorders in general and for scleroderma in particular.


Assuntos
Fibrose/tratamento farmacológico , Inibidores da Síntese de Proteínas/uso terapêutico , Quinazolinas/uso terapêutico , Administração Tópica , Animais , Divisão Celular/efeitos dos fármacos , Colágeno/biossíntese , Colágeno/efeitos dos fármacos , Modelos Animais de Doenças , Fibrose/patologia , Masculino , Mastócitos/efeitos dos fármacos , Mastócitos/fisiologia , Camundongos , Piperidinas , Quinazolinonas , Pele/efeitos dos fármacos , Pele/metabolismo
17.
Biomaterials ; 11(9): 686-9, 1990 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-2090303

RESUMO

This report describes general methods for the synthesis of biodegradable poly(amide anhydrides) and poly(amide esters) based on naturally occurring amino acids. The polymers were synthesized from dicarboxylic acids prepared by amidation of the amino group of an amino acid with a cyclic anhydride, or by amide coupling of two amino acids with a diacid chloride. This approach was demonstrated by the synthesis of polymers based on alanine and proline. Homo- and copolyanhydrides with sebacic acid of beta-alanyl succinamide, and N,N'-bis (beta-alanine)-1,3-benzene dicarboxamide, were synthesized by melt or solution polymerization. The copolymers prepared in solution had molecular weights up to 4500, while the copolymers prepared by melt condensation had higher molecular weights of about 30,000. Polymers were also prepared directly from the reaction of an amino acid and a diacid chloride. These polymers were soluble in dichloromethane and had molecular weights in the range 800-4800. A polyester of L-prolyl succinamide was prepared by melt condensation of the methyl ester derivative of the diacid and propylene glycol with acid catalysis. The polymer was transparent and pliable, and had a weight average molecular weight of 33,000. The poly(amide anhydrides) based on alanine and sebacic acid display a nearly linear degradation pattern with complete degradation in vitro after 5-10 d (phosphate buffer, pH 7.4 at 37 degrees C).


Assuntos
Aminoácidos/química , Polímeros/síntese química , Materiais Biocompatíveis , Biodegradação Ambiental , Preparações de Ação Retardada , Hidrólise , Peso Molecular
18.
Biomaterials ; 16(4): 319-23, 1995 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-7772672

RESUMO

The hydrolysis and elimination processes of biopolyanhydrides has been studied using a polymer series of linear aliphatic diacids. This polymer series degrade into their monomer counterparts at about the same rate but differ in the water solubility of their degradation products. Polymers based on natural diacids of the general structure -[OOC-(CH2)x-CO]n- where x is between 4 and 12 were implanted subcutaneously in rats and the elimination of the polymers from the implantation site was observed. The in vitro hydrolysis of this polymer series was studied by monitoring the weight loss, release of monomer degradation products and the content of anhydride bonds in the polymer as a function of time. A dependence was found between the monomer solubility and the rate of polymer elimination in both in vivo and in vitro. The elimination time for polymers based on soluble monomers (x = 4-8) was 7-14 days, while the polymers based on low monomer solubility (x = 10-12) were eliminated only after 8 weeks. The in vitro degradation of polyanhydrides in the presence of several common hydrolytic enzymes found around implants did not affect polymer degradation. All polymers were biocompatible and found to be useful as carriers for drug delivery.


Assuntos
Anidridos/metabolismo , Ácidos Carboxílicos/metabolismo , Anidridos/química , Animais , Materiais Biocompatíveis/química , Materiais Biocompatíveis/metabolismo , Biodegradação Ambiental , Bovinos , Cromatografia em Gel , Sistemas de Liberação de Medicamentos/normas , Enzimas/química , Concentração de Íons de Hidrogênio , Hidrólise , Técnicas In Vitro , Masculino , Peso Molecular , Polímeros/metabolismo , Próteses e Implantes , Ratos , Ratos Sprague-Dawley , Espectrofotometria Infravermelho , Temperatura
19.
Biomaterials ; 23(22): 4389-96, 2002 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12219829

RESUMO

Diastereoisomeric complexes of insulin with D-poly(lactic acid) (D-PLA) or stereocomplexes of D- and L-PLA entrapping insulin were discovered. The complexes were spontaneously formed when insulin and D-PLA were mixed together in acetonitrile solution. Complexes of insulin-D-PLA formed a microparticulate precipitate after a few hours in the solution. The porous 1-3 microm precipitate, which contained both insulin and D-PLA, was insoluble in solvents that dissolve isotactic PLA, and had an additional transition temperature at 169 degrees C. When suspending these particles in buffer solution of pH 7.4, 37 degrees C, insulin was constantly released for a few weeks. L-PLA or D,L-PLA did not form a precipitate with insulin, which indicates stereospecificity to the complex formation. Microparticulates were also obtained when L-PLA was added to the D-PLA-insulin solution. In this case two types of complexes, D-PLA-insulin and D-PLA-L-PLA complexes, were formed. These macromolecular stereocomplexes may form the onset of the development of a new generation of controlled release systems for peptides and proteins, by molecular complexation with enantiomeric polymers.


Assuntos
Materiais Biocompatíveis/química , Insulina/química , Insulina/farmacocinética , Ácido Láctico/química , Ácido Láctico/farmacocinética , Polímeros/química , Polímeros/farmacocinética , Acetonitrilas/farmacologia , Varredura Diferencial de Calorimetria , Etanol/farmacologia , Congelamento , Hexanos/química , Concentração de Íons de Hidrogênio , Cloreto de Metileno/química , Microscopia Eletrônica de Varredura , Peptídeos/química , Poliésteres , Solventes/farmacologia , Estereoisomerismo , Temperatura , Fatores de Tempo , Água/química
20.
Biomaterials ; 17(4): 411-7, 1996 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-8938235

RESUMO

The synthesis of biodegradable bone cement compositions is presented. These bone cement compositions can be applied as a putty-like mixture and harden to a strong material in a bone fracture. They degrade from the site of application to allow the ingrowth of new bone for complete healing of the bone fracture. The bone cement is composed of a solid particulate phase dispersed in an initially liquid polymeric phase, which can be hardened by cross-linking. The polymeric phase is a low-molecular-weight liquid poly(propylene fumarate) (PPF) containing double bonds available for cross-linking. The solid particulate phase consists of calcium carbonate and tricalcium phosphate. PPF oligomers of Mw = 1800 and Mn = 750 were prepared from the condensation of non-volatile bis(2-hydroxypropyl fumarate) and propylene-bis(hydrogen maleate) trimers. PPF terminated divinyl and diepoxide derivatives were obtained from the reactions between PPF diol and acryloyl chloride or epichlorhydrin, respectively. Putty-like cement compositions were prepared from a mixture of 30 wt% polymer phase containing benzoyl peroxide-dimethyl toluidine as polymerization catalyst and 70 wt% calcium salts. The divinyl and diepoxide terminated PPF oligomers provided a high strength composition of between 30 and 129 MPa which is suitable for bone cement applications. In vitro hydrolysis of the composites showed little weight loss with the compressive strength remaining above 20 MPa after 4 weeks in buffer solution. Compositions of the PPF oligomers cross-linked without calcium salts showed a gradual weight loss (10-65 wt% after 4 weeks) when placed in buffer solution followed by high water absorption (18-200 wt% after 4 weeks), with the epoxide terminated PPF being the least to degrade or absorb water.


Assuntos
Acrilatos/química , Materiais Biocompatíveis/química , Cimentos Ósseos/química , Cálcio/química , Compostos de Epóxi/química , Fumaratos/química , Polipropilenos/química , Acrilatos/síntese química , Materiais Biocompatíveis/síntese química , Cimentos Ósseos/síntese química , Compostos de Epóxi/síntese química , Fumaratos/síntese química , Metilmetacrilatos/síntese química , Metilmetacrilatos/química , Polipropilenos/síntese química , Sais/química
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