Casearia sylvestris Sw., popularly known in Brazil as 'guaçatonga', has been used as antitumor, antiseptic, antiulcer, local anaesthetic and healer in folk medicine. Snakebite envenomation by Bothrops jararacussu (Bjssu) constitutes a relevant public health hazard capable of inducing serious local damage in victims. This study examined the pharmacological action of apolar and polar C. sylvestris leaf extracts in reverting the neuromuscular blockade and myonecrosis, which is induced by Bjssu venom and its major toxin bothropstoxin-I on the mouse phrenic nerve-diaphragm preparations. The polar methanol extract (ME) was by far the most efficacious. ME not only prevented myonecrosis and abolished the blockade, but also increased ACh release. Such facilitation in neuromuscular transmission was observed with ME alone, but was accentuated in preparations incubated with ME plus venom or toxin. This established synergy opens an interesting point of investigation because the venom or toxin in contact with ME changes from a blocking to a facilitating effect. It is suggested that rutin, known to have potent antioxidant properties, and one of the components present in the ME, could have a role in the observed effects. Since commercial rutin did not reproduce the ME effects, it is likely that a rutin-containing phytocomplex is neutralizing the bothropic envenoming effects.

Numerous plants are used as snakebite antidotes in Brazilian folk medicine, including Casearia sylvestris Swartz, popularly known as guaçatonga. In this study, we examined the action of a hydroalcoholic extract from C. sylvestris on the neuromuscular blockade caused by bothropstoxin-I (BthTX-I), a myotoxin from Bothrops jararacussu venom, in mouse isolated phrenic nerve-diaphragm (PND) preparations. Aqueous (8 and 12 mg/ml, n=4 and 5, respectively) and hydroalcoholic (12 mg/ml, n=12) extracts of the leaves of C. sylvestris caused facilitation in PND preparations followed by partial neuromuscular blockade. BthTX-I (20 µg/ml, n=4) caused 50% paralysis after 65±15 min (mean ± S.E.M). Preincubation (30 min at 37°C) of BthTX-I (20 µg/ml, n=4) with a concentration of the hydroalcoholic extract (4 mg/ml) that had no neuromuscular activity, such as the control (n=5), prevented the neuromuscular blockade caused by the toxin. This protection may be mediated by compounds such as flavonoids and phenols identified by thin-layer chromatography and colorimetric assays.

ObjectiveThe permeation of hydrophilic molecules through the skin is still a challenge due to the barrier posed by stratum corneum, the outermost layer of the skin. Liposomes have frequently been used as carriers for different types of drugs and may also function as permeation enhancers. Propylene glycol has also been used as an edge activator in liposomes to increase the permeation. The aim of this work was to prepare liposomes containing an edge activator and loaded with caffeine to evaluate the potential of caffeine reaching the deeper layers in the skin.MethodsThe formulations were prepared by a top‐down process using high‐pressure homogenization at 200 00 psi for 10 min. They were characterized by size, polydispersity index (PI), zeta potential (ZP), pH, caffeine content and encapsulation efficiency (EE%) on preparation (time zero) and after 30 days. Cytotoxicity of blank and loaded liposomes was assessed by MTT proliferation assay with a normal keratinocyte cell line (HaCaT). In vitro permeation tests were performed with human skin in Franz cells over 24 h, and caffeine concentration was determined in the skin surface, stratum corneum, dermo‐epidermal fraction and receptor medium by HPLC.ResultsThe caffeine liposomes with (DL‐Caf) or without propylene glycol (CL‐Caf) showed, respectively, mean size 94.5 and 95.4 nm, PI 0.48 and 0.42, ZP + 1.3 and + 18.1 mV and caffeine content of 78.57 and 80.13%. IC50 values of caffeine in DL‐Caf (3.59 v/v %) and CL‐Caf (3.65 v/v %) were not significantly different from conventional blank liposome (3.27 v/v %). The DL‐Caf formulation presented the best capability to enhance the caffeine permeation through the skin, resulting 1.94‐folds higher than caffeine solution. Furthermore, the caffeine flux from DL‐Caf was 1.56‐ and 3.05‐folds higher than caffeine solution and CL‐Caf, respectively. On the other hand, CL‐Caf showed the lowest caffeine penetration revealing the importance of edge activator to aid hydrophilic drug penetration to all skin layers.ConclusionThe DL‐Caf formulation tested was able to improve the permeation of caffeine through the stratum corneum and dermo‐epidermal layers, suggesting that this delivery system may be effective for deep skin delivery of hydrophilic drugs.

Cyclodextrins are oligosaccharides, specifically cyclic alpha-1,4-D-glucose oligomers, that possess a cone-like shape resulting in a hydrophobic inner cavity capable of forming complexes with several guest molecules in a hydrophilic matrix. This capability has led to an extensive investigation into cyclodextrin applications in several different substrates with the purpose of overcoming limitations, such as solubility issues, physical degradation and sensitivity to solvents, in guest substances. Researchers have recently described successful interactions between cyclodextrins and proteins, such as enzymes, peptides and amino acids. These complex biomolecules consist of potent active ingredients and are employed in several industrial biocatalyst processes. However, this group in particular tends to have limited usage in pharmaceuticals due to its natural processes of degradation and instability in unusual environments, frequently requiring accurate procedures and stabilization methods in all stages of production. In several cases, the final product still has a short shelf-life and often requires a controlled environment for storage. The formation of a cyclodextrin supramolecular complex could not only prevent such problems, but also enhance the intrinsic characteristics of guest substances, thus allowing for an expansion in their industrial production and application. This work focuses on cyclodextrin interactions with protein-like structures in order to describe their possible applications in the formulation of pharmaceutical proteins.

With the purpose of evaluating the behavior of different polymers employed as binders in small-diameter pellets for oral administration, we prepared formulations containing paracetamol and one of the following polymers: PVP, PEG 1500, hydroxypropylmethylcellulose and methylcellulose, and we evaluated their different binding properties. The pellets were obtained by the extrusion/spheronization process and were subsequently subjected to fluid bed drying. In order to assess drug delivery, the United States Pharmacopeia (USP) apparatus 3 (Bio-Dis) was employed, in conjunction with the method described by the same pharmacopeia for the dissolution of paracetamol tablets (apparatus 1). The pellets were also evaluated for granulometry, friability, true density and drug content. The results indicate that the different binders used are capable of affecting production in different ways, and some of the physicochemical characteristics of the pellets, as well as the dissolution test, revealed that the formulations acted like immediate-release products. The pellets obtained presented favorable release characteristics for orally disintegrating tablets. USP apparatus 3 seems to be more adequate for discriminating among formulations than the basket method.Uniterms: Binders/evaluation. Pellets/dissolution profile. Pellets/physicochemical characteristics. Extrusion/spheronization process. Drug delivery/evaluation. Com a finalidade de se avaliar o comportamento de diferentes polímeros empregados como aglutinantes em pellets de pequeno diâmetro para uso oral foram preparadas formulações contendo paracetamol e um dos seguintes polímeros: PVP, PEG 1500, hidroxipropilmetilcelulose e metilcelulose por apresentarem diferentes propriedades aglutinantes. Os pellets foram obtidos pelo processo de extrusão/esferonização e secagem em leito fluidizado. Para avaliar a liberação do fármaco, empregou-se o método 3 da Farmacopeia Americana, também conhecido como Bio-Dis e o método preconizado pela mesma farmacopeia para comprimidos de paracetamol. Os pellets foram avaliados, ainda, com relação à granulometria, friabilidade, densidade verdadeira e teor. Os resultados indicaram que os diferentes aglutinantes empregados são capazes de afetar a produção e algumas das características físico-químicas dos pellets e o ensaio de dissolução revelou que as formulações comportam-se como produtos de liberação imediata. Os pellets obtidos apresentaram características de liberação favoráveis para a obtenção de comprimidos de liberação instantânea. O aparato 3 da Farmacopeia Americana demonstrou ser um método com melhor capacidade discriminatória entre as formulações, quando comparado com o método da cesta.Unitermos: Aglutinantes/avaliação. Pellets/perfil de dissolução. Pellets/características físico-químicas. Processo de extrusão/esferonização. Liberação do fármaco.

The use of sunscreen products is widely promoted by schools, government agencies, and health-related organizations to minimize sunburn and skin damage. In this study, we developed stable solid lipid nanoparticles (SLNs) containing the chemical UV filter octyl methoxycinnamate (OMC). In parallel, we produced similar stable SLNs in which 20% of the OMC content was replaced by the botanical urucum oil. When these SLNs were applied to the skin of human volunteers, no changes in fluorescence lifetimes or redox ratios of the endogenous skin fluorophores were seen, suggesting that the formulations did not induce toxic responses in the skin. Ex vivo (skin diffusion) tests showed no significant penetration. In vitro studies showed that when 20% of the OMC was replaced by urucum oil, there was no reduction in skin protection factor (SPF), suggesting that a decrease in the amount of chemical filter may be a viable alternative for an effective sunscreen, in combination with an antioxidant-rich vegetable oil, such as urucum. There is a strong trend towards increasing safety of sun protection products through reduction in the use of chemical UV filters. This work supports this approach by producing formulations with lower concentrations of OMC, while maintaining the SPF. Further investigations of SPF in vivo are needed to assess the suitability of these formulations for human use.

In vitro three-dimensional human skin models are an innovative alternative to evaluate cytotoxicity and phototoxicity in the cosmetic industry. The aim of this study was to use a skin model to evaluate the potential toxicity of sunscreen formulations with or without exposure to UV radiation. In addition, the toxicity of these formulations was evaluated after exposure to photodegradation. The results showed toxicity with all formulations/conditions tested, including the control formulation, compared to PBS. Cell viability of photodegraded formulations - prior to the phototoxicity radiation process - was higher, indicating that some formulation components were degraded into products with reduced toxicity. The results also indicated that avobenzone was more unstable/toxic than octyl p-methoxycinnamate under the same test conditions. The sunscreens and their formulations were shown to be toxic to skin model cells to some extent, even when not exposed to UV irradiation; however the biological role of this toxicity is unclear. This result shows the importance of testing sunscreen formulations in real in-use conditions. Finally, since we used an in vitro assay based on a human cell model, this non-invasive technique represents a suitable alternative to animal models for phototoxicity tests in general and could have application in screening new sunscreen products.

Recebido em 9/1/06; aceito em 27/10/06; publicado na web em 28/5/07 PREPARATION AND PHYSICO-CHEMICAL CHARACTERIZATION OF INCLUSION COMPLEXES BETWEEN LOCAL ANESTHETICS AND HYDROXYPROPYL-β-CYCLODEXTRIN. S(-) Bupivacaine (S(-)BVC) and Lidocaine (LDC) are widely used local anesthetics (LA). Hydroxypropyl β-cyclodextrin (HP-β-CD) is used as a drug-carrier system. The aim of this work was to characterize inclusion complexes between LA and HP-β-CD. The affinity constants determined at different pHs show favourable complexation. The release kinetics experiments showed that S(-)BVC and LDC changed the released profiles in the presence of HP-β-CD. Nuclear magnetic resonance experiments gave information about the interaction between LA and the cyclodextrin cavity. This study focused on the physicochemical characterization of drug-delivery formulations that come out as potentially new therapeutic options for pain treatment.Keywords: S(-) Bupivacaine; lidocaine; cyclodextrin. INTRODUÇÃOOs anestésicos locais (AL) são moléculas anfifílicas utilizadas no controle da dor crônica ou aguda e que possuem toxicidade proporcional à potência 1 . Evitam ou aliviam a dor por interromperem a condução nervosa através da ligação específica aos canais de Na + voltagem-dependente dos axônios, bloqueando, assim, o movimento de íons sódio para o interior da célula nervosa 2 , impedindo a propagação do estímulo nervoso.Os anestésicos locais têm efeito direto nos canais de sódio e interagem com diferentes graus de afinidade com esta proteína, dependendo do estado funcional (ativado, inativado, em repouso) da mesma. Até a década de 90, acreditava-se que a forma ionizada dos AL seria a responsável pelo efeito anestésico (ligação direta ao canal de sódio) e que caberia a forma neutra dos AL (mais hidrofóbica) a função de facilitar à penetração dos anestésicos nas membranas 3,4 . No entanto, trabalhos do grupo de Catterall [5][6] , usando mutação sítio-específica, demonstraram que anestésicos locais, em sua forma neutra, interagem e modificam a função de canais de sódio.Em clínica, os anestésicos locais mais amplamente utilizados na terapia da dor aguda e crônica são os do tipo amino-amida 7 , como bupivacaína, BVC e lidocaína, LDC (Figura 1).A bupivacaína é mais cardiotóxica que doses equieficazes da lidocaína. Clinicamente, a cardiotoxicidade da bupivacaína manifesta-se por arritmias ventriculares graves e depressão miocárdica após administração intravascular inadvertida de grandes doses. É provável que este efeito da bupivacaína seja devido a vários fatores: lidocaína e bupivacaína bloqueiam os canais de sódio cardíacos rapidamente durante a sístole, entretanto, a bupivacaína dissocia-se muito mais lentamente que a lidocaína durante a diástole, de forma que uma fração significativa de canais de sódio permanece bloqueada no final da diástole com bupivacaína 8 . Portanto, o bloqueio com bupivacaína é cumulativo e substancialmente maior do que seria previsível por sua potência anestésica local.A bupivacaína, por possuir estereocentro, possui dois is...