RESUMO
A simple, highly sensitive, and robust CE method applied to the determination of alendronate (ALN) was developed from matrices for tissue engineering, characterized by being highly complex systems. The novel method was based on the ALN derivatization with o-phthalaldehyde and 2-mercaptoethanol for direct ultraviolet detection at 254 nm. The BGE consisted of 20 mM sodium borate buffer at pH 10, and the electrophoretic parameters were optimized.The method was validated in terms of specificity, linearity, LOD, LOQ, precision, accuracy, and robustness. The LOD and LOQ obtained were 0.8 and 2.7 µg/mL, respectively. In addition, the method offers higher sensitivity and specificity compared to other CE and HPLC methods using UV-detectors, as well as low cost and simplicity that allowed the rapid and simple quantitation of ALN from bone regeneration matrices.
Assuntos
Alendronato/análise , Portadores de Fármacos/química , Eletroforese Capilar/métodos , Espectrofotometria Ultravioleta/métodos , Alendronato/farmacocinética , Materiais Biocompatíveis , Limite de Detecção , Modelos Lineares , Reprodutibilidade dos TestesRESUMO
Osteomyelitis is a progressive destruction of bones caused by microorganisms. Inadequate or absent treatment increases the risk of bone growth inhibition, fractures, and sepsis. Among the diagnostic techniques, functional images are the most sensitive in detecting osteomyelitis in its early stages. However, these techniques do not have adequate specificity. By contrast, radiolabeled antibiotics could improve selectivity, since they are specifically recognized by the bacteria. The incorporation of these radiopharmaceuticals in drug-delivery systems with high affinity for bones could improve the overall uptake. In this work, long-circulating and alendronate-coated liposomes containing (99m)technetium-radiolabeled ceftizoxime were prepared and their ability to identify infectious foci (osteomyelitis) in animal models was evaluated. The effect of the presence of PEGylated lipids and surface-attached alendronate was evaluated. The bone-targeted long-circulating liposomal (99m)technetium-ceftizoxime showed higher uptake in regions of septic inflammation than did the non-long-circulating and/or alendronate-non-coated liposomes, showing that both the presence of PEGylated lipids and alendronate coating are important to optimize the bone targeting. Scintigraphic images of septic or aseptic inflammation-bearing Wistar rats, as well as healthy rats, were acquired at different time intervals after the intravenous administration of these liposomes. The target-to-non-target ratio proved to be significantly higher in the osteomyelitis-bearing animals for all investigated time intervals. Biodistribution studies were also performed after the intravenous administration of the formulation in osteomyelitis-bearing animals. A significant amount of liposomes were taken up by the organs of the mononuclear phagocyte system (liver and spleen). Intense renal excretion was also observed during the entire experiment period. Moreover, the liposome uptake by the infectious focus was significantly high. These results show that long-circulating and alendronate-coated liposomes containing (99m)technetium-radiolabeled ceftizoxime have a tropism for infectious foci.
Assuntos
Alendronato , Ceftizoxima/análogos & derivados , Lipossomos , Compostos de Organotecnécio , Osteomielite , Alendronato/química , Alendronato/farmacocinética , Animais , Ceftizoxima/química , Ceftizoxima/farmacocinética , Lipossomos/química , Lipossomos/farmacocinética , Compostos de Organotecnécio/química , Compostos de Organotecnécio/farmacocinética , Osteomielite/diagnóstico , Osteomielite/metabolismo , Osteomielite/patologia , Ratos , Ratos WistarRESUMO
This work reports the preparation of tablets by direct compression of sodium alendronate-loaded microparticles, using pullulan as filler. The tableting properties of pullulan were compared with those of microcrystalline cellulose and lactose. Pullulan tablets showed low variations in average weight, thickness and drug content. Moreover, these tablets exhibited a higher hardness compared to the other excipients. In vitro release studies showed that only pullulan was capable to maintain gastroresistance and release properties of microparticles, due to its ability to protect particles against damage caused by compression force. Thus, pullulan was considered an advantageous excipient to prepare tableted microparticles.
Neste trabalho relata-se a preparação de comprimidos pela compressão direta de micropartículas contendo alendronato de sódio, utilizando o pullulan como diluente. As propriedades dos comprimidos de pullulan foram comparadas com as de comprimidos de celulose microcristalina e de lactose. Os comprimidos de pullulan mostraram baixa variação no peso médio, espessura e teor. Por outro lado, estes apresentaram altos valores de dureza comparados aos preparados com os outros excipientes. Através dos estudos de liberação in vitro pode-se observar que apenas o pullulan foi capaz de manter a gastrorresistência e as propriedades de liberação das micropartículas, o que se deve à sua capacidade de proteger as partículas do dano causado pela força de compressão. Dessa forma, o pullulan foi considerado um excipiente vantajoso para a preparação de comprimidos microparticulados.
Assuntos
Polissacarídeos/classificação , Comprimidos/farmacocinética , Alendronato/farmacocinética , Excipientes/classificação , Trituração de Resíduos SólidosRESUMO
The bioequivalence and upper digestive tract transit time of a drinkable solution of 70 mg/100 mL alendronate was compared to reference tablets. A randomized, single- dose, two-way crossover study of the rate of urinary recovery of alendronate during 36 h (AE((0-36 h))) by HPLC, in 104 healthy young male volunteers, showed that AE((0-36 h)) and the maximum excretion rate (R (max)) were within the accepted range of bioequivalence 81.8-105.7 and 81.7-106.2, respectively. To characterize the oesophageal passage time of the two alendronate formulations, we performed a randomized, controlled study, in 24 healthy men and women (mean 52 years old), who took the formulations standing or lying down, by an X-ray video deglutition system. When taken in the standing position, both formulations had equal mean transit times from mouth to stomach and tablet disintegration but data dispersion was significantly smaller with the liquid form. When taken in lying position, drinkable alendronate had shorter and less variable median transit times compared to the tablets. These results show that the drinkable alendronate formulation is bioequivalent to the tablets and may be advantageous in patients in whom the transit or disintegration of the tablets is impaired.
Assuntos
Alendronato/farmacocinética , Deglutição , Trato Gastrointestinal Superior/metabolismo , Administração Oral , Adulto , Alendronato/administração & dosagem , Disponibilidade Biológica , Química Farmacêutica , Estudos Cross-Over , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Equivalência TerapêuticaRESUMO
Bisphosphonates (BPs) inhibit osteocyte and osteoblast apoptosis via opening of connexin (Cx) 43 hemichannels and activating the extracellular signal regulated kinases ERKs. Previously, we hypothesized that intracellular survival signaling is initiated by interaction of BPs with Cx43. However, using whole cell binding assays with [(3)H]-alendronate, herein we demonstrated the presence of saturable, specific and high affinity binding sites in the Cx43-expressing ROS 17/2.8 osteoblastic cells, authentic osteoblasts and MLO-Y4 cells expressing Cx43 or not, as well as in HeLa cells lacking Cx43 expression and ROS 17/2.8 cells pretreated with agents that disassemble Cx channels. In addition, both BPs and the PTP inhibitor Na(3)VO(4) increased proliferation of cells expressing Cx43 or not. Furthermore, although BPs are internalized and inhibit intracellular enzymes in osteoclasts, whether the drugs penetrate non-resorptive bone cells is not known. To clarify this, we evaluated the osteoblastic uptake of AF-ALN, a fluorescently labeled analog of alendronate. AF-ALN was rapidly internalized in cells expressing Cx43 or not indicating that this process is not mediated via Cx43 hemichannels. Altogether, these findings suggest that although required for triggering intracellular survival signaling by BPs, Cx43 is dispensable for cellular BP binding, its uptake, as well as the proliferative effects of these agents.
Assuntos
Alendronato/farmacocinética , Apoptose/efeitos dos fármacos , Conservadores da Densidade Óssea/farmacocinética , Proliferação de Células/efeitos dos fármacos , Conexina 43/metabolismo , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Osteócitos/metabolismo , Alendronato/farmacologia , Animais , Conservadores da Densidade Óssea/farmacologia , Conexina 43/genética , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Células HeLa , Humanos , Canais Iônicos/metabolismo , Camundongos , Osteócitos/citologia , Vanadatos/farmacologiaRESUMO
Spray-dried powders for lung delivery of sodium alendronate (SA) were prepared from hydroalcoholic solutions. Formulations display geometric particle size below to 12 µm and spherical shape associated to a hollow structure. The addition of leucine and ammonium bicarbonate leads to porous particles with rough surfaces. The tapped density ranges from 0.016 to 0.062 g/cm(3), decreasing with the increase of the leucine concentration. For all formulations, the calculated aerodynamic diameters are lower than 5 µm. The in vitro aerodynamic evaluation shows that all powders present a high emitted fraction of 100%, a fine particle fraction ranging from 34.4% to 62.0% and an alveolar fraction ranging from to 23.7% to 42.6%. An optimized sample was evaluated regarding sodium alendronate acute pulmonary toxicity and lung bioavailability. The bronchoalveolar lavage study shows that the intratracheal administration of sodium alendronate dry powder and sodium alendronate aqueous solution do not induce significant increases of lung toxicity indicators as compared with the positive control. Moreover, the intratracheal administration of sodium alendronate dry powder results in a 6.23 ± 0.83% bioavailability, a 3.5-fold increase as compared to oral bioavailability. Finally, these results suggest that sodium alendronate pulmonary delivery could be a new and promising administration route.
Assuntos
Alendronato/administração & dosagem , Alendronato/farmacocinética , Pulmão/metabolismo , Administração por Inalação , Aerossóis/química , Alendronato/toxicidade , Alendronato/urina , Animais , Bicarbonatos/química , Disponibilidade Biológica , Líquido da Lavagem Broncoalveolar/química , Química Farmacêutica/métodos , Cães , Etanol/química , Instilação de Medicamentos , Insuflação , L-Lactato Desidrogenase/metabolismo , Leucina/química , Pulmão/efeitos dos fármacos , Masculino , Microscopia Eletrônica de Varredura , Tamanho da Partícula , Excipientes Farmacêuticos/química , Pós , Proteínas/análise , Ratos , Ratos Wistar , Gravidade Específica , Propriedades de SuperfícieRESUMO
Sodium alendronate, an antiresorptive drug, primarily used in the treatment of osteoporosis was encapsulated in blended microparticles composed of Eudragit S100 and Methocel K15M. The micropowder obtained by spray-drying technique was characterized in terms of its morphology, particle size, encapsulation efficiency and in vitro drug release. In vivo studies were carried out in order to evaluate the pharmacodynamic effect and the ulcerogenic activity of sodium alendronate-loaded microparticles after oral administration in rats. Drug encapsulation efficiency was close to 80% and particle mean diameter of 13.8 microm. SEM analysis showed spherical collapsed shape particles with smooth surface. At pH 1.2, in vitro experiments showed that <10% of the drug was released from the microparticles. At pH 6.8, the microparticles were able to prolong the sodium alendronate release for 12h. In vivo experiments carried out in ovariectomized rats showed bone mineral density significantly higher for the sodium alendronate-loaded microparticles than for the negative control groups. Furthermore, the microencapsulation of the drug showed a significant reduction in the ulcerative lesion index. In conclusion, the blended microparticles are excellent oral carriers for sodium alendronate since they were able to maintain the drug antiresorptive effect and to reduce the gastrointestinal drug toxicity.
Assuntos
Alendronato/administração & dosagem , Conservadores da Densidade Óssea/administração & dosagem , Reabsorção Óssea/prevenção & controle , Portadores de Fármacos/química , Microesferas , Alendronato/química , Alendronato/farmacocinética , Animais , Disponibilidade Biológica , Densidade Óssea , Conservadores da Densidade Óssea/química , Conservadores da Densidade Óssea/farmacocinética , Osso e Ossos/química , Osso e Ossos/metabolismo , Portadores de Fármacos/síntese química , Ovariectomia , Tamanho da Partícula , Polímeros , Ratos , Ratos Wistar , Úlcera Gástrica/induzido quimicamente , Propriedades de SuperfícieRESUMO
Sodium alendronate is an effective treatment for osteoporosis, but its oral administration is associated with adverse gastrointestinal effects. The aim of this work was to evaluate gastroresistant sodium alendronate-loaded microparticles prepared by spray-drying using Eudragit S100 or a blend of Eudragit S100/Methocel E4M. Both formulations presented high encapsulation efficiencies, mean diameters below 17 microm, and similar collapsed shape. Dissolution experiments showed good gastro-resistance for the microparticles at pH 1.2. At pH 6.8, the blended microparticles retarded the drug release. In vivo studies showed that the formulations were able to protect the rat stomachs against ulcer formation by sodium alendronate. In conclusion, the microparticles seems to be promising oral carriers for sodium alendronate.
Assuntos
Alendronato/efeitos adversos , Mucosa Gástrica/efeitos dos fármacos , Mucosa Intestinal/efeitos dos fármacos , Alendronato/síntese química , Alendronato/farmacocinética , Animais , Composição de Medicamentos , Feminino , Mucosa Gástrica/metabolismo , Mucosa Gástrica/patologia , Mucosa Intestinal/metabolismo , Mucosa Intestinal/patologia , Ratos , Ratos WistarRESUMO
The aim of this study was to evaluate the influence of erbium:yttrium-aluminum-garnet (Er:YAG) laser compared with traditional treatment on dentin permeability to calcitonin and sodium alendronate. Forty bovine roots were sectioned and divided into eight groups. Groups 1 and 2 (G1/G2) were immersed in saline solution; G1T/G2T were immersed in ethylene diamine tetra-acetic acid plus sodium lauryl ether sulfate (EDTA-T) and sodium hypochlorite (NaOCl); G1I/G2I were irradiated with Er:YAG laser (2.94 microm, 6 Hz, 40.4 J/cm(2)); G1TI/G2TI were immersed in EDTA-T, NaOCl and subjected to Er:YAG irradiation. After 4 h the radioactivity of the saline solution was measured. Statistical analysis revealed a significant difference (P < 0.05) when the groups treated with EDTA-T and NaOCl followed by Er:YAG laser irradiation were compared with the groups treated with EDTA-T only and with the groups that received no treatment. Er:YAG laser associated with traditional procedures significantly increased the diffusion of calcitonin and sodium alendronate through dentin. All groups showed calcitonin and sodium alendronate diffusion.