RESUMO
Breast cancer is the neoplasia of highest incidence in women worldwide. Docetaxel (DTX), a taxoid used to treat breast cancer, is a BCS-class-IV compound (low oral bioavailability, solubility and intestinal permeability). Nanotechnological strategies can improve chemotherapy effectiveness by promoting sustained release and reducing systemic toxicity. Nanostructured lipid carriers (NLC) encapsulate hydrophobic drugs in their blend-of-lipids matrix, and imperfections prevent drug expulsion during storage. This work describes the preparation, by design of experiments (23 factorial design) of a novel NLC formulation containing copaiba oil (CO) as a functional excipient. The optimized formulation (NLCDTX) showed approximately 100% DTX encapsulation efficiency and was characterized by different techniques (DLS, NTA, TEM/FE-SEM, DSC and XRD) and was stable for 12 months of storage, at 25 °C. Incorporation into the NLC prolonged drug release for 54 h, compared to commercial DTX (10 h). In vitro cytotoxicity tests revealed the antiproliferative effect of CO and NLCDTX, by reducing the cell viability of breast cancer (4T1/MCF-7) and healthy (NIH-3T3) cells more than commercial DTX. NLCDTX thus emerges as a promising drug delivery system of remarkable anticancer effect, (strengthened by CO) and sustained release that, in clinics, may decrease systemic toxicity at lower DTX doses.
Assuntos
Antineoplásicos , Neoplasias da Mama , Nanopartículas , Nanoestruturas , Óleos Voláteis , Feminino , Humanos , Docetaxel/farmacologia , Docetaxel/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Antineoplásicos/química , Preparações de Ação Retardada/uso terapêutico , Portadores de Fármacos/química , Nanoestruturas/química , Óleos Voláteis/uso terapêutico , Tamanho da Partícula , Nanopartículas/químicaRESUMO
Tetracaine (TTC) is a local anesthetic broadly used for topical and spinal blockade, despite its systemic toxicity. Encapsulation in nanostructured lipid carriers (NLC) may prolong TTC delivery at the site of injection, reducing such toxicity. This work reports the development of NLC loading 4% TTC. Structural properties and encapsulation efficiency (%EE > 63%) guided the selection of three pre-formulations of different lipid composition, through a 23 factorial design of experiments (DOE). DLS and TEM analyses revealed average sizes (193-220 nm), polydispersity (< 0.2), zeta potential |- 21.8 to - 30.1 mV| and spherical shape of the nanoparticles, while FTIR-ATR, NTA, DSC, XRD and SANS provided details on their structure and physicochemical stability over time. Interestingly, one optimized pre-formulation (CP-TRANS/TTC) showed phase-separation after 4 months, as predicted by Raman imaging that detected lack of miscibility between its solid (cetyl palmitate) and liquid (Transcutol) lipids. SANS analyses identified lamellar arrangements inside such nanoparticles, the thickness of the lamellae been decreased by TTC. As a result of this combined approach (DOE and biophysical techniques) two optimized pre-formulations were rationally selected, both with great potential as drug delivery systems, extending the release of the anesthetic (> 48 h) and reducing TTC cytotoxicity against Balb/c 3T3 cells.
Assuntos
Anestésicos Locais/farmacologia , Proliferação de Células , Portadores de Fármacos/química , Composição de Medicamentos/métodos , Liberação Controlada de Fármacos , Nanoestruturas/administração & dosagem , Tetracaína/farmacologia , Anestésicos Locais/química , Animais , Células 3T3 BALB , Camundongos , Nanoestruturas/química , Tetracaína/químicaRESUMO
Nanostructured lipid carriers (NLC) belong to youngest lipid-based nanocarrier class and they have gained increasing attention over the last ten years. NLCs are composed of a mixture of solid and liquid lipids, which solubilizes the active pharmaceutical ingredient, stabilized by a surfactant. The miscibility of the lipid excipients and structural changes (polymorphism) play an important role in the stability of the formulation and are not easily predicted in the early pharmaceutical development. Even when the excipients are macroscopically miscible, microscopic heterogeneities can result in phase separation during storage, which is only detected after several months of stability studies. In this sense, this work aimed to evaluate the miscibility and the presence of polymorphism in lipid mixtures containing synthetic (cetyl palmitate, Capryol 90®, Dhaykol 6040 LW®, Precirol ATO5® and myristyl myristate) and natural (beeswax, cocoa and shea butters, copaiba, sweet almond, sesame and coconut oils) excipients using Raman mapping and multivariate curve resolution - alternating least squares (MCR-ALS) method. The results were correlated to the macroscopic stability of the formulations. Chemical maps constructed for each excipient allowed the direct comparison among formulations, using standard deviation of the histograms and the Distributional Homogeneity Index (DHI). Lipid mixtures of cetyl palmitate/Capryol®; cetyl palmitate/Dhaykol®; myristyl myristate/Dhaykol® and myristyl myristate/coconut oil presented a single histogram distribution and were stable. The sample with Precirol®/Capryol® was not stable, although the histogram distribution was narrower than the samples with cetyl palmitate, indicating that miscibility was not the factor responsible for the instability. Structural changes before and after melting were identified for cocoa butter and shea butter, but not in the beeswax. Beeswax + copaiba oil sample was very homogenous, without polymorphism and stable over 6â¯months. Shea butter was also homogeneous and, in spite of the polymorphism, was stable. Formulations with cocoa butter presented a wider histogram distribution and were unstable. This paper showed that, besides the miscibility evaluation, Raman imaging could also identify the polymorphism of the lipids, two major issues in lipid-based formulation development that could help guide the developer understand the stability of the NLC formulations.
Assuntos
Portadores de Fármacos/química , Lipídeos/química , Nanopartículas/química , Diglicerídeos/química , Composição de Medicamentos , Estabilidade de Medicamentos , Armazenamento de Medicamentos , Excipientes/química , Análise Multivariada , Miristatos/química , Palmitatos/química , Tamanho da Partícula , Óleos de Plantas/química , Polímeros/química , Propilenoglicóis/química , Solubilidade , Análise Espectral Raman , Tensoativos/química , Ceras/químicaRESUMO
In formulations of nanostructured lipid carriers, lipid solid dispersions and self-emulsifying drug delivery systems, it is common that a solid or semi-solid lipid excipient is mixed with a liquid solvent or liquid lipid. Even when the excipients are visually miscible upon melting, they might have microscopic non-homogeneities which could lead to instability over time and future phase separation. Raman mapping associated with chemometric methods can be useful to evaluate spatial distribution of compounds, however it has not been extensively applied to the formulations mentioned above. The aim of this work was to compare the outcomes of three different chemometric methods - principal components analysis (PCA), multivariate curve resolution with alternating least squares (MCR-ALS) and independent components analysis (ICA) - to study two systems of very different degrees of microscopic miscibility: cetyl palmitateâ¯+â¯Transcutol© (heterogeneous) and polyethylene glycol 6000 (PEG 6000)â¯+â¯Tween 80© (homogeneous). These two samples were chosen due to large differences in spatial distribution of the compounds over the pixels which could require different approaches for data treatment. The three methods were compared regarding recovered concentrations (or scores), signals (or loadings) and the need for matrix augmentation to obtain reliable results. Results showed that PCA loadings were the mathematical differences of the spectra of pure compounds for both samples, and therefore only 'contrast images' could be generated. MCR and ICA provided signals that could be related to the chemical components, however MCR presented rotational ambiguities even for the very heterogeneous sample, a situation in which ICA performed better as a blind search method. For the homogeneous sample, both methods showed rank deficiency and therefore the use of a matrix augmentation was necessary. ICA and PCA allowed identifying physical modifications in the homogeneous semi-solid PEG 6000/Tween 80® sample over the time, probably due to the folding/unfolding of the crystalline chains of PEG 6000. Therefore, this work discusses the ability of the three chemometrics methods to extract information from Raman spectra in order to characterize the chemical, spatial and even physical aspects of semi-solid pharmaceutical formulations, which could be of much use for stability studies of different drug delivery systems.
Assuntos
Excipientes/química , Preparações Farmacêuticas/química , Análise Espectral Raman , Etilenoglicóis/química , Análise dos Mínimos Quadrados , Palmitatos/química , Polietilenoglicóis/química , Polissorbatos/química , Análise de Componente PrincipalRESUMO
The short time of action and systemic toxicity of local anaesthetics limit their clinical application. Bupivacaine is the most frequently used local anaesthetic in surgical procedures worldwide. The discovery that its S(-) enantiomeric form is less toxic than the R(+) form led to the introduction of products with enantiomeric excess (S75:R25 bupivacaine) in the market. Nevertheless, the time of action of bupivacaine is still short; to overcome that, bupivacaine S75:R25 (BVCS75) was encapsulated in nanostructured lipid carriers (NLC). In this work, we present the development of the formulation using chemometric tools of experimental design to study the formulation factors and Raman mapping associated with Classical Least Squares (CLS) to study the miscibility of the solid and the liquid lipids. The selected formulation of the nanostructured lipid carrier containing bupivacaine S75:R25 (NLCBVC) was observed to be stable for 12 months under room conditions regarding particle size, polydispersion, Zeta potential and encapsulation efficiency. The characterisation by DSC, XDR and TEM confirmed the encapsulation of BVCS75 in the lipid matrix, with no changes in the structure of the nanoparticles. The in vivo analgesic effect elicited by NLCBVC was twice that of free BVCS75. Besides improving the time of action, no statistical difference in the blockage of the sciatic nerve of rats was found between 0.125% NLCBVC and 0.5% free BVCS75. Therefore, the formulation allows a reduction in the required anaesthesia dose, decreasing the systemic toxicity of bupivacaine, and opening up new possibilities for different clinical applications.