Capsaicin-Cyclodextrin Complex Enhances Mepivacaine Targeting and Improves Local Anesthesia in Inflamed Tissues.

Acidic environments, such as in inflamed tissues, favor the charged form of local anesthetics (LA). Hence, these drugs show less cell permeation and diminished potency. Since the analgesic capsaicin (CAP) triggers opening of the TRPV1 receptor pore, its combination with LAs could result in better uptake and improved anesthesia. We tested the above hypothesis and report here for the first time the analgesia effect of a two-drug combination (LA and CAP) on an inflamed tissue. First, CAP solubility increased up to 20 times with hydroxypropyl-beta-cyclodextrin (HP-ß-CD), as shown by the phase solubility study. The resulting complex (HP-ß-CD-CAP) showed 1:1 stoichiometry and high association constant, according to phase-solubility diagrams and isothermal titration calorimetry data. The inclusion complex formation was also confirmed and characterized by differential scanning calorimetry (DSC), X-ray diffraction, and 1H-NMR. The freeze-dried complex showed physicochemical stability for at least 12 months. To test in vivo performance, we used a pain model based on mouse paw edema. Results showed that 2% mepivacaine injection failed to anesthetize mice inflamed paw, but its combination with complexed CAP resulted in pain control up to 45 min. These promising results encourages deeper research of CAP as an adjuvant for anesthesia in inflamed tissues and cyclodextrin as a solubilizing agent for targeting molecules in drug delivery.

Extracellular vesicles in infectious diseases caused by protozoan parasites in buffaloes

Extracellular vesicles (EVs) are small membrane-bound vesicles of growing interest in vetetinary parasitology. The aim of the present report was to provide the first isolation, quantification and protein characterization of EVs from buffalo (Bubalus bubalis) sera infected with Theileria spp. Methods: Infected animals were identified through optical microscopy and PCR. EVs were isolated from buffalo sera by size-exclusion chromatography and characterized using western blotting analysis, nanoparticle tracking analysis and transmission electron microscopy. Subsequently, the proteins from isolated vesicles were characterized by mass spectrometry. Results: EVs from buffalo sera have shown sizes in the 124-140 nm range and 306 proteins were characterized. The protein-protein interaction analysis has evidenced biological processes and molecular function associated with signal transduction, binding, regulation of metabolic processes, transport, catalytic activity and response to acute stress. Five proteins have been shown to be differentially expressed between the control group and that infected with Theileria spp., all acting in the oxidative stress pathway. Conclusions: EVs from buffaloes infected with Theileria spp. were successfully isolated and characterized. This is an advance in the knowledge of host-parasite relationship that contributes to the understanding of host immune response and theileriosis evasion mechanisms. These findings may pave the way for searching new EVs candidate-markers for a better production of safe biological products derived from buffaloes.(AU)

Excipient-excipient interactions in the development of nanocarriers: an innovative statistical approach for formulation decisions.

Excipient interaction has become essential knowledge for rational formulation design of nanoparticles. Nanostructured lipid carriers (NLCs) include at least three types of excipient, which enhance excipient interaction possibilities and relevance. The present article introduces an alternative approach for evaluating a great number of excipients with few samples, using NLC as a model delivery system. This approach is based on two sequential experiments using Hall-2 experimental design and analysis of excipient interactions in respect to their physicochemical properties by multilevel statistics. NLCs were prepared using a hot emulsification-ultrasonication method with lidocaine and nine excipients (solid lipids, oils and surfactants). The evaluated parameters were z-average size (DLS), dispersity (DLS), zeta potential (electrophoretic mobility) and entrapment efficiency (HPLC). Cetyl palmitate, beeswax, castor oil, capric/caprylic acid and polysorbate 80 all presented larger effects amongst the studied factors as well as a clear pattern of synergistic interactions. Following the verified trends, we produced an optimized NLC that exhibited all desirable physicochemical characteristics and a modified drug release profile. Our results demonstrate the methodology's robustness, which can be applied to other nanoparticles and establish a cost-effective excipient evaluation.

Exosomes in the serum of Acute Myeloid Leukemia patients induce dendritic cell tolerance: Implications for immunotherapy.

Exosomes may represent an interesting antigenic pulse for new forms of anti-tumor immunotherapy. We evaluated exosomes from serum of patients with acute myeloid leukemia (AML) as an antigenic source for dendritic cells (DC) and the effects upon antitumor cytotoxicity, assessed by the percentage of specific lysis of K562 leukemic cells in co-cultures. Surprisingly, incubation of exosomes with DCs decreased lysis of K562, which may correspond to a mechanism of tumor evasion in vivo. However, when immature DCs were pulsed with exosomes purified from K562 culture supernatants, the lysis of target cells was notably enhanced, associated with a substantial increase in the expression of the maturation marker CD83. Thus, the development of vaccines using patients' exosomes would probably add no benefits to the treatment of AML; alternately, exosomes from cultured cells may represent an effective way for maturing DCs into a cytotoxic phenotype, without the immunosuppression observed with patients' exosomes.

Characterization of Articaine-Loaded Poly(ε-caprolactone) Nanocapsules and Solid Lipid Nanoparticles in Hydrogels for Topical Formulations.

This work describes the development of poly-ε-caprolactone nanocapsules (PCL-NC) and solid lipid nanoparticles (SLN) aiming delivery for articaine (ATC), in order to improve its chemical stability in semi-solid preparations looking forward their use for skin delivery. The nanoparticles were characterized by size, polydispersity index, and pH. Cellular viability was evaluated using the MTT test and the in vitro release kinetics was determined using a two-compartment model. The hydrogels with nanoparticle suspensions were characterized considering their rheological aspects and in vitro permeation across artificial membranes. Colloidal stability was satisfactory, since the formulations did not present major alterations during 120 days. High ATC encapsulation was achieved (78% for PCL-NC and 65% for SLN). The release profile of PCL-NC-ATC was slower, compared to the free molecule and SLN-ATC. MTT experiments showed the nanosystems were capable to increase cellular viability compared with free ATC. The hydrogels showed good consistency, homogeneity, and stability and presented pseudoplastic behavior with thixotropy, improving drug efficacy in clinical applications. The gel based on PCL-NC showed faster onset of activity and flux of 35.68 ± 1.98 µg/cm2/h, which then continued for up to 8 h. This study opens up prospects for employment of nanoparticulate systems for modified release of ATC.

Anaesthetic efficacy of unilamellar and multilamellar liposomal formulations of articaine in inflamed and uninflamed tissue.

We compared the efficacy of articaine encapsulated in multilamellar and unilamellar liposomes with that of articaine with epinephrine, after infiltration into inflamed and uninflamed tissue in rats. We encapsulated 4% articaine in multilamellar (articaine:multi) and unilamellar (articaine:uni) liposomes and compared them with 4% articaine with 1:100 000 epinephrine (articaine:epinephrine), in inflamed (plantar incision into the hind paw) and uninflamed (infraorbital nerve block) tissue in rats. Anaesthetic formulations (0.1ml) were injected near the right infraorbital foramen in uninflamed tissue, where success and duration of anaesthesia were assessed by pinching the upper lip every 5 minutes. For inflamed tissue the anaesthetic formulations (0.1ml) were injected laterally into a surgical wound made 24 hours earlier in the plantar region of the rat's right hind paw. The degree of anaesthesia was assessed by application of forces laterally to the wound with electronic von Frey filaments. Articaine:uni resulted in less successful anaesthesia than both articaine:multi (p=1.1x10(-5)) and articaine:epinephrine (p=4.3x10(-8)) in uninflamed tissue, but there were no differences in duration or success of anaesthesia between articaine:epinephrine and articaine:multi. In inflamed tissue articaine:epinephrine gave significantly more effective anaesthesia for longer than articaine:uni (p=2.3x10(-6)), and articaine:epinephrine (p=1.8x10(-6)) formulations, which did not differ from each other. Multilamellar liposomal articaine could be an option for local anaesthesia in uninflamed tissues. However, articaine with epinephrine gave better results than liposomal formulations in inflamed tissue.

Liposomal encapsulation improves the duration of soft tissue anesthesia but does not induce pulpal anesthesia.

STUDY OBJECTIVE: To compare the topical and the pulpal anesthesia efficacy of liposomal and plain benzocaine formulations. DESIGN: Double-blinded, randomized crossover study. SETTING: University ambulatory dental center. PATIENTS: 30 ASA physical status I volunteers. INTERVENTIONS: Volunteers received, in three different sessions, topical application of liposome-encapsulated 10% benzocaine (LB10), 10% benzocaine gel (B10), and 20% benzocaine gel (B20) in the right maxillary canine mucobuccal fold. MEASUREMENTS: Pain associated with the needle insertion was rated by visual analog scale (VAS) and the duration of topical anesthesia was recorded. Pulpal anesthesia was evaluated using an electric pulp tester. MAIN RESULTS: VAS values (median, 1st - 3rd quartiles) were 17 cm (11 - 25), 14 cm (3 - 22), and 21 cm (9 - 21) for B10, LB10, and B20, respectively. No differences were noted among the groups (Friedman test; P = 0.58). Soft tissue anesthesia was also not different. The LB10 [10 (8 - 12) min] showed longer soft tissue anesthesia (Friedman test; P < 0.01) than the other agents [B10 = 8 (5 - 10) min, and B20 = 7 (6 - 9) min]. None of the topical benzocaine formulations tested induced pulpal anesthesia. CONCLUSIONS: The encapsulation of benzocaine into liposome increased the duration of soft tissue anesthesia. However, it did not induce pulpal anesthesia.

Mistura com excesso enantiomérico de 50 por cento (S75-R25) de bupivacaína complexada com ciclodextrinas e anestesia por via subaracnóidea em ratos / Complexation of 50 percent enantiomeric excess (S75-R25) bupivacaine with cyclodextrins and spinal block anesthesia in rats

JUSTIFICATIVA E OBJETIVOS: Com a finalidade de prolongar a duração de ação e reduzir a toxicidade sistêmica, têm-se desenvolvido formulações de anestésicos locais (AL) complexados com ciclodextrinas (CD). Este estudo realizou a caracterização físico-química e avaliou, em ratos, os efeitos dos complexos de inclusão de bupivacaína racêmica (S50-R50) e da mistura com excesso enantiomérico de 50 por cento (S75-R25) de bupivacaína com hidroxipropil-betaciclodextrina (HP-beta-CD), comparando-os com as soluções atualmente utilizadas na clínica. MÉTODO: Os complexos de inclusão de S75-R25 em HP-beta-CD (razão molar 1:1) foram caracterizados por estudos de solubilidade de fases variando-se as concentrações de HP-beta-CD e a temperatura. Determinaram-se as constantes de afinidade (K) pela HP-beta-CD e os parâmetros termodinâmicos para a complexação. Os bloqueios motor e sensitivo foram avaliados, por meio da administração subaracnóidea das formulações na concentração clínica de 0,5 por cento. RESULTADOS: A formação de complexos de inclusão foi observada pelo aumento da solubilidade aquosa do AL sob diferentes temperaturas e concentrações de HP-beta-CD. Os testes in vivo mostraram que S50-R50HP-beta-CD e S75-R25HP-beta-CD reduziram a latência (p < 0,001) sem alterar o tempo de recuperação do bloqueio motor, tempo para efeito máximo e efeito total dos fármacos. Além disso, ambas as formulações aumentaram a intensidade (1,5 vez, p < 0,001) e prolongaram a duração da analgesia, com relação aos fármacos livres. CONCLUSÕES: Os complexos S50-R50HP-beta-CD e S75-R25HP-beta-CD potencializaram o bloqueio nervoso diferencial, podendo ser utilizados para reduzir a freqüência de administrações ou a dose de AL para indução de um mesmo efeito. A formulação contendo a mistura com excesso enantiomérico de 50 por cento (S75-R25) de bupivacaína mostrou-se interessante no desenvolvimento de formulações seguras e úteis para o tratamento da dor aguda no período pós-operatório.

BACKGROUND AND OBJECTIVES: In order to prolong the action and reduce systemic toxicity, formulations of local anesthetic (LA) complexed with cyclodextrins (CD) have been developed. This study determined the physical-chemical characterization and evaluated the effects of inclusion complexes of racemic bupivacaine (S50-R50) and 50 percent enantiomeric excess (S75-R25) bupivacaine with hydroxypropil-beta-cyclodextrin (HP-beta-CD) in rats, and comparing them with the solutions currently used in the clinical practice. METHODS: Inclusion complexation of S75-R25 with HP-beta-CD (equimolar ratio 1:1) was characterized by phase-solubility studies varying the concentrations of HP-beta-CD and the temperature. Affinity constants (K) for HP-beta-CD and the thermodynamic parameters for complexation were determined. Motor and sensitive anesthesias were evaluated through the subarachnoid administration of the formulations in the concentration of 0.5 percent. RESULTS: Inclusion complexation was observed through the increase in aqueous solubility of LA in different temperatures and concentrations of HP-beta-CD. The in vivo tests demonstrated that S50-R50HP-beta-CD and S75-R25HP-beta-CD reduced latency (p < 0.001) without changing the recovery time of the motor block, time for maximal effect, and total effect of the drugs. Besides, both formulations increased the intensity (1.5 times, p < 0.001) and prolonged the duration of analgesia compared to the free drugs. CONCLUSIONS: The complexes S50-R50HP-beta-CD and S75-R25HP-beta-CD potentiated the differential nervous block, and can be used to reduce the frequency of administration or the dose of the LA to induce the same effect. The formulation containing enantiomeric excess (S75-R25) bupivacaine showed to be interesting in the development of safer formulations, and useful for the treatment of acute pain in the postoperative period.

JUSTIFICATIVA Y OBJETIVOS: Con la finalidad de prolongar la duración de la acción y reducir la toxicidad sistémica, se han desarrollado formulaciones de AL con complejo de ciclodextrinas (CD). Ese estudio realizó la caracterización físico-química y evaluó en ratones, los efectos de los complejos de inclusión de bupivacaína racémica (S50-R50) y de la mezcla con exceso enantiomérico de 50 por ciento (S75-R25) de bupivacaína con hidroxipropil-betaciclodextrina (HP-beta-CD), comparándolos con las soluciones actualmente utilizadas en la clínica. MÉTODO: Los complejos de inclusión de S75-R25 en HP-beta-CD (razón molar 1:1) fueron caracterizados por estudios de solubilidad de fases variando las concentraciones de HP-beta-CD y la temperatura. Fueron determinadas las constantes de afinidad (K) por la HP-beta-CD y los parámetros termodinámicos para los complejos. Los bloqueos motor y sensitivo fueron evaluados en ratones, a través de la administración subaracnoidea de las formulaciones en la concentración clínica de 0,5 por ciento. RESULTADOS: La formación de complejos de inclusión se observó a través del aumento de la solubilidad acuosa del AL bajo diferentes temperaturas y concentraciones de HP-beta-CD. Las pruebas in vivo mostraron que S50-R50HP-beta-CD y S75-R25HP-beta-CD redujeron la latencia (p < 0,001) sin alterar el tiempo de recuperación del bloqueo motor, tiempo para efecto máximo y efecto total de los fármacos. Además, ambas formulaciones aumentaron la intensidad (1,5 veces, p < 0,001) y prolongaron la duración de la analgesia, con relación a los fármacos libres. CONCLUSIONES: Los complejos, S50-R50HP-beta-CD y S75-R25HP-beta-CD, potenciaron el bloqueo nervioso diferencial, pudiendo ser utilizados para reducir la frecuencia de administraciones o la dosis de AL para inducción de un mismo efecto. La formulación conteniendo la mezcla con exceso enantiomérico de 50 por ciento (S75-R25) de bupivacaina fue interesante en el desarrollo de formulaciones...

[Complexation of 50% enantiomeric excess (S75-R25) bupivacaine with cyclodextrins and spinal block anesthesia in rats.]. / Mistura com excesso enantiomérico de 50% (S75-R25) de bupivacaína complexada com ciclodextrinas e anestesia por via subaracnóidea em ratos.

BACKGROUND AND OBJECTIVES: In order to prolong the action and reduce systemic toxicity, formulations of local anesthetic (LA) complexed with cyclodextrins (CD) have been developed. This study determined the physical-chemical characterization and evaluated the effects of inclusion complexes of racemic bupivacaine (S50-R50) and 50% enantiomeric excess (S75-R25) bupivacaine with hydroxypropil-beta-cyclodextrin (HP-beta-CD) in rats, and comparing them with the solutions currently used in the clinical practice. METHODS: Inclusion complexation of S75-R25 with HP-beta-CD (equimolar ratio 1:1) was characterized by phase-solubility studies varying the concentrations of HP-beta-CD and the temperature. Affinity constants (K) for HP-beta-CD and the thermodynamic parameters for complexation were determined. Motor and sensitive anesthesias were evaluated through the subarachnoid administration of the formulations in the concentration of 0.5%. RESULTS: Inclusion complexation was observed through the increase in aqueous solubility of LA in different temperatures and concentrations of HP-beta-CD. The in vivo tests demonstrated that S50-R50HP-beta-CD and S75-R25HP-beta-CD reduced latency (p < 0.001) without changing the recovery time of the motor block, time for maximal effect, and total effect of the drugs. Besides, both formulations increased the intensity (1.5 times, p < 0.001) and prolonged the duration of analgesia compared to the free drugs. CONCLUSIONS: The complexes S50-R50HP-beta-CD and S75-R25HP-beta-CD potentiated the differential nervous block, and can be used to reduce the frequency of administration or the dose of the LA to induce the same effect. The formulation containing enantiomeric excess (S75-R25) bupivacaine showed to be interesting in the development of safer formulations, and useful for the treatment of acute pain in the postoperative period.

Sistemas de liberação controlada com bupivacaína racêmica (S50-R50) e mistura enantiomérica de bupivacaína (S75-R25): efeitos da complexação com ciclodextrinas no bloqueio do nervo ciático em camundongos / Drug-delivery systems for racemic bupivacaine (S50-R50) and bupivacaine enantiomeric mixture (S75-R25): cyclodextrins complexation effects on sciatic nerve blockade in mice

JUSTIFICATIVA E OBJETIVOS: Os efeitos adversos associados ao uso de bupivacaína levaram à procura por novos anestésicos locais (AL) com perfil de bloqueio semelhante e menos tóxicos, surgindo novas preparações como a mistura enantiomérica de bupivacaína (S75-R25). Os sistemas de liberação controlada, contendo AL em carreadores como ciclodextrinas (CD), têm como objetivo melhorar a eficácia anestésica e o índice terapêutico dessas drogas. Este estudo visou a preparação, a caracterização e a avaliação da eficácia anestésica dos complexos de inclusão da mistura enantiomérica da bupivacaína (S75-R25) e da bupivacaína racêmica (S50-R50) com hidroxipropilb-ciclodextrina (HPb-CD) comparando-os com as preparações atualmente utilizadas na clínica. MÉTODO: Os complexos de inclusão foram preparados misturando-se quantidades apropriadas de HPb-CD e S50-R50 ou S75-R25 nas razões molares (1:1 e 1:2) e caracterizados por estudos de solubilidade de fases. Determinaram-se as constantes de afinidade (K) de cada AL pela HPb-CD. Os bloqueios motor e sensorial induzidos pelas drogas livres e complexadas foram avaliados, em camundongos, através do bloqueio do nervo ciático. Para a realização dos experimentos, utilizaram-se três concentrações de AL: 0,125 por cento; 0,25 por cento e 0,5 por cento. RESULTADOS: Os estudos de solubilidade indicaram a formação de complexos de inclusão de S50-R50 e S75-R25 com HPb-CD, com valores de constante de afinidade (K) similares para os dois anestésicos: 14,7 M-1 (S50-R50:HP-bCD) e 14,3 M-1 (S75-R25:HP-bCD). Os testes em animais mostraram que a complexação potencializou o bloqueio nervoso diferencial induzido pelos AL: i) a duração do bloqueio motor induzido por S75-R25 foi similar à do S50-R50, mas menos intenso (p < 0,001). Já os complexos, S50-R50HPb-CD e S75-R25HPb-CD reduziram a latência (p < 0,01 e p < 0,05, respectivamente) sem modificar a intensidade do bloqueio motor (Emáx), em relação às drogas livres; ii) a avaliação do bloqueio sensorial mostrou aumento na intensidade da analgesia com os sistemas S50-R50HPb-CD (2 vezes, p < 0,001) e S75-R25HPb-CD (1,5-1,8 vezes; p < 0,01 e p < 0,001, respectivamente), nas duas proporções molares (1:1 e 1:2, AL:CD), além do prolongamento da duração do efeito analgésico, quando comparados às formulações S50-R50 e S75-R25...

[Drug-delivery systems for racemic bupivacaine (S50-R50) and bupivacaine enantiomeric mixture (S75-R25): cyclodextrins complexation effects on sciatic nerve blockade in mice]. / Sistemas de liberação controlada com bupivacaína racêmica (S50-R50) e mistura enantiomérica de bupivacaína (S75-R25): efeitos da complexação com ciclodextrinas no bloqueio do nervo ciático em camundongos.

BACKGROUND AND OBJECTIVES: Bupivacaine-induced side effects have led to the search for new local anesthetics (LA) with similar potency and lower toxicity, such as bupivacaine enantiomeric mixture (S75-R25). Drug-delivery systems for LA in carriers, such as cyclodextrins (CD), have been developed to improve anesthetic potency and therapeutic index of those drugs. This study aimed at preparing, characterizing and evaluating the anesthetic efficacy of inclusion complexes of bupivacaine enantiomeric mixture (S75-R25) and racemic bupivacaine (S50-R50) with hydroxypropylb- cyclodextrin (HPb-CD) comparing them to clinically available preparations. METHODS: Inclusion complexes were obtained by mixing appropriate volumes of HPb-CD and S50-R50 or S75-R25 to final 1:1 or 1:2 molar ratios and were characterized by phase solubility experiments. Affinity constants (K) were determined between HPb-CD and each LA. Motor and sensory blocks induced by plain or complexed LA formulations were evaluated in mice by sciatic nerve block. Three LA concentrations were used during the experiment: 0.125, 0.25 and 0.5%. RESULTS: Solubility experiments results were indicative of S50-R50:HPb-CD and S75-R25:HPb-CD complexation, with similar affinity constant (K) values: 14.7 M-1 and 14,3 M-1, respectively. In vivo experiments have shown that complexation has enhanced differential nerve blockade induced by LA: i) motor blockade duration induced by S75-R25 was similar, to the induced by but less intense S50-R50 ( p < 0.001). S50-R50HPb-CD and S75-R25HPb-CD complexes have decreased onset (p < 0.01 and p < 0.05, respectively), without changing motor block intensity (Emax) as compared to plain drugs; ii) sensory block evaluation has revealed higher analgesic intensity with S50-R50HPb-CD (2-fold, p < 0.001) and S75-R25HPb-CD (1.5-1.8-fold, p < 0.01 and p < 0.001, respectively) with both molar ratios (1:1 and 1:2, LA:CD), in addition to prolonging analgesic effect as compared to S50-R50 and S75-R25. CONCLUSIONS: More pronounced analgesic effects obtained by complexation with HPb-CD have shown that both formulations, S50-R50HPb-CD and S75-R25HPb-CD, are very useful for postoperative pain relief, requiring lower LA concentrations. Nevertheless, it is worth noticing that S75-R25 - being less toxic than racemic bupivacaine - is an interesting alternative for the development of more effective and safe drug-delivery systems as compared to racemic bupivacaine (S50-R50).

Formulações de anestésicos locais de liberação controlada: aplicações terapêuticas / Drug-delivery systems for local anesthetics: therapeutic applications

JUSTIFICATIVA E OBJETIVOS: O desenvolvimento de sistemas de liberação controlada tem sido alvo de pesquisas há pelo menos quatro décadas. Desde que foi sugerida sua aplicação na indústria farmacêutica, muitos resultados foram obtidos, especialmente na manipulação molecular de carreadores e no estudo de suas interações com as drogas encapsuladas. Esses novos carreadores têm a vantagem de contornar propriedades físico-químicas limitantes (como a solubilidade aquosa ou em membranas) das drogas encapsuladas, melhorando assim a farmacodinâmica (potencialização do efeito terapêutico), farmacocinética (controle da absorção e distribuição tecidual) e os efeitos toxicológicos (redução da toxicidade local e sistêmica) das mesmas. Entre os principais carreadores, destacam-se os lipossomas e as ciclodextrinas, que vêm trazendo inúmeras vantagens no desenvolvimento de formulações para liberação controlada de anestésicos locais. Este trabalho de revisão objetiva descrever a interação de anestésicos locais com lipossomas ou ciclodextrinas, o desenvolvimento das pesquisas básica e clínica nessa área, além da aplicabilidade terapêutica dessas formulações. CONTEUDO: Lipossomas têm a capacidade de veicular drogas em órgãos-alvo, disponibilizando apenas uma fração - liberação controlada - para o sítio de ação. Já as ciclodextrinas alteram a intensidade e a duração do efeitos das drogas através da baixa absorção sistêmica do complexo...

BACKGROUND AND OBJECTIVES: Many researchers in the last four decades have been devoted to the development of drug-delivery systems. Since its first application in the pharmaceutical industry, many results have been obtained especially in the molecular manipulation of carriers and their interaction with encapsulated drugs. These new carriers have the advantage of bypassing encapsulated drugs restraining physicochemical properties (such as water or membrane solubility), thus improving pharmacodynamics (therapeutic effect potentiation), pharmacokinetics (control of tissue absorption and distribution) and toxic effects (lower local and systemic toxicity). Liposomes and cyclodextrins are among the most important carriers which have shown to be quite advantageous in the development of drug-delivery systems for local anesthetics. This study aimed at reviewing the interaction of local anesthetics with liposomes and cyclodextrins, the development of basic and applied research on the field, in addition to therapeutic applicability of these formulations. CONTENTS: Liposomes have the ability to control drug delivery to target tissues, fractionating drug release in its site of action. Cyclodextrins, on the other hand, change intensity and duration of effects due to low systemic drug absorption...

JUSTIFICATIVA Y OBJETIVOS: El desenvolvimiento de sistemas de liberación controlada ha sido motivo de pesquisas desde cuatro décadas por lo menos. Desde que fue sugerida su aplicación en la industria farmacéutica, fueron obtenidos muchos resultados, especialmente en la manipulación molecular de carreadores y en el estudio de sus interacciones con las drogas encapsuladas. Esos nuevos carreadores tienen la ventaja de contornar propiedades físico-químicas limitantes (como la solubilidad acuosa o en membranas) de las drogas encapsuladas, mejorando asi la farmacodinámica (potencialización del efecto terapéutico), farmacocinética (control de la absorción y distribución de tejidos) y los efectos toxicológicos (reducción de la toxicidad local y sistémica) de las mismas. Entre los principales carreadores, se destacan los liposomas y las ciclodextrinas, que están trayendo innúmeras ventajas en el desarrollo de formulaciones para liberación controlada de anestésicos locales. Este trabajo de revisión, objetiva describir la interacción de anestésicos locales con liposomas o ciclodextrinas, el desarrollo de las pesquisas básica y clínica en esa área, además de la aplicabilidad terapéutica de esas formulaciones. CONTENIDO: Liposomas tienen la capacidad de transportar drogas en órganos-clave, disponibilizando apenas una fracción - liberación controlada - para el sitio de acción. Ya las ciclodextrinas alteran la intensidad y la duración de efectos de las drogas a través de la baja absorción sistémica del complejo...

Estudos espectroscopicos dos efeitos de anestesicos locais sobre propriedades estruturais e dinamicas de membranas lipidicas / Spectroscopics studies of the effects of local anesthetics upon structural and dinamic properties of phospholipid membranes

Anestesicos locais (AL) bloqueiam a conducao do impulso nervoso por agir sobre o canal de NA+(inativando-o) e sobre lipidios de membrana. Nesse trabalho mostramos (por ressonancia paramagnetica eletronica) que a forma neutra de AL esteres (procaina, tetracaina e clorprocaina) e amidas (lidocaina, prilocaina, etidocaina, mepivacaina, bupivacaina e dibucaina) diminuem a organizacao de membranas fosfolipidicas. A contribuicao de diferencas na estrutura e propriedades fisico-quimicas dos AL nesse efeito, foi estudada por medidas de ressonancia magnetica nuclear (RMN) em membranas contendo 1:3 AL:lipidio, Mol:mol. Medidas de RMN de deuterio mostram que os AL diminuem a ordem e aumentam a mobilidade de cadeia acila do fosfolipidio, principalmente na regiao do carbono 8. Medidas de RMN de fosforo nao detectaram alteracoes a nivel de cabeca polar dos lipidios por acao dos AL. Medidas de RMN proton evidenciaram uma regiao de membrana (esqueleto do glicerol) comum a insercao dos aneis aromaticos dos nove AL. O perfil da alteracao da membrana pelos AL foi: lidocaina>tetracaina>clorprocaina>prilocaina>procaina>mepivacaina>bupivacaina. Etidocaina e dibucaina nao puderam ser incorporadas na mesma proporcao AL:lipidio que os demais AL. Os resultados indicam que tanto a localizacao como a estrutura quimica dos AL sao responsaveis pelo diferente efeito dos mesmos sobre a membrana