Abstract Historically, phenol/croton oil deep chemical peeling has been very effective and has generated excellent results compared to other formulas used in dermatological clinics. However, it can cause serious side effects in patients sensitive to phenol. Therefore, this study aimed to develop a liquid crystalline structure containing croton oil (without phenol) as well as to evaluate the physical characteristics and cytotoxicity of this new system. Rational proportions of the croton oil, purified water, and polyethylene glycol hexadecyl ether were designed through a partial phase diagram to obtain 26 formulations. After macroscopic analysis and polarized light microscopy evaluation, formulations with lamellar liquid crystalline phase (4 samples) were identified and chosen to determine pH, size, polydispersion index (PDI), zeta potential, and rheological behavior. After 48 hours, three samples presented phase separation. Formulation 8 remained stable, but hydroxyethyl cellulose (HEC, 0.5%, w/w) was added to the aqueous phase, to prevent coalescence. Sample 8A exhibited a pH compatible with the skin, nanometric size, narrow PDI, negative zeta potential, and stability throughout the study period. The addition of HEC improved the organization of the system, making the formulation more stable. The oil, fractions of the oil, and the sample exhibited increasing cytotoxicity, respectively. This result could be attributed to the fractionation process of the vegetal matrix, and the surfactant present in the formulation increased the cell membrane permeability. The proposed approach successfully achieved a physically stable liquid crystal system containing croton oil.

Abstract Lemongrass (Cymbopogon citratus) is an aromatic plant of great significance in industries due to its essential oil characteristic aroma. Essential oils are concentrated plant extracts that evaporate when in contact with air and have low chemical stability, which can improve encapsulation techniques. This study aimed to evaluate the seasonal influence in the concentration of the predominant component citral of the essential oil of C. citratus and develop microparticles by spray drying containing this vegetal matrix. The lemongrass leaves were collected in the four seasons, and the essential oil was extracted by hydrodistillation. The chemical composition was determined by gas chromatography coupled with the mass spectrometry technique (GC-MS). Different proportions of arabic and guar gums were evaluated as encapsulating agents. Physicochemical analyses characterized the microparticle powder. GC-MS showed higher citral in the spring and summer (84.89% and 79.39%, respectively), and it was possible to identify a high amount of citral in the microparticles. Field-emission scanning electron microscopy showed agglomerate and collapsed microparticles. Fourier transform infrared spectroscopy suggested the essential oil encapsulation due to a band at 1675 cm-1 used as a reference, related to the acyclic monoterpenes of citral. X-ray diffraction showed the amorphous structure of the microparticles. Thermogravimetric curves of microparticles showed higher Tonset in microparticles than those observed for pure lemongrass essential oil, inferring that microencapsulation improved the thermal stability. This result confirms the lemongrass essential oil microencapsulation and its potential application in food products, drugs, or cosmetics.

Abstract Gastroretentive floating microparticles were developed and evaluated for the controlled metronidazole delivery for treatment of gastric disease. Floating microparticles, varying in proportions of chitosan and hydroxypropyl methylcellulose or ethylcellulose, were obtained by spray drying. Floating microparticles were characterized by physicochemical and in vitro studies, according to their floating ability and drug delivery. Microparticles presented mean diameter from 1.05 to 2.20 µm. The infrared spectroscopy confirmed the drug encapsulation and showed no chemical linkage between microparticles components. X-ray diffraction showed changes in the drug`s solid state, from crystalline to amorphous, indicating partial drug encapsulation, due to the presence of some crystalline peaks of metronidazole in microparticles. All microparticles floated immediately in contact of simulated gastric fluid and both floating and drug release profiles were dependent of microparticles composition. Microparticles samples constituted by chitosan and hydroxypropyl methylcellulose revealed the best relationship between floating duration and drug release, remaining floating during the occurrence of the drug release, ideal condition for the floating gastroretentive systems.

ABSTRACT Halcinonide is a high-potency topical glucocorticoid used for skin inflammation treatments that presents toxic systemic effects. A simple and quick analytical method to quantify the amount of halcinonide encapsulated into lipid nanoparticles, such as polymeric lipid-core nanoparticles and solid lipid nanoparticles, was developed and validated regarding the drug's encapsulation efficiency and in vitro permeation. The development and validation of the analytical method were carried out using the high performance liquid chromatography with the UV detection at 239 nm. The validation parameters were specificity, linearity, precision and accuracy, limits of detection and quantitation, and robustness. The method presented an isocratic flow rate of 1.0 mL.min-1, a mobile phase methanol:water (85:15 v/v), and a retention time of 4.21 min. The method was validated according to international and national regulations. The halcinonide encapsulation efficiency in nanoparticles was greater than 99% and the in vitro drug permeation study showed that less than 9% of the drug permeated through the membrane, indicating a nanoparticle reservoir effect, which can reduce the halcinonide's toxic systemic effects. These studies demonstrated the applicability of the developed and validated analytical method to quantify halcinonide in lipid nanoparticles.