Helena Cabral Marques

A Comparative Study of Naproxen – Beta Cyclodextrin Complexes Prepared by Conventional Methods and Using Supercritical Carbon Dioxide

Naproxen is a poorly soluble anti-inflammatorydrug, the solubility of which canbe enhanced by complexation withbeta-cyclodextrin. Besides that, the inclusioncomplex reduces the incidence of gastrointestinal side effects of the drug. The aim of this work was to compare the physicochemical characteristics of the solid complexes prepared by traditional methods (kneading, freeze-drying and spray-drying) and using a supercritical fluid technology. The unusual solvent properties of carbon dioxide above their critical temperature and pressure were exploited in order to prepare inclusion compounds. Complexes prepared using supercritical fluid technology showed similar properties to those of freeze-drying andspray-drying complexes as proved by DSC, FT-IRand UV.

Advanced Technologies for Oral Controlled Release: Cyclodextrins for Oral Controlled Release

Cyclodextrins (CDs) are used in oral pharmaceutical formulations, by means of inclusion complexes formation, with the following advantages for the drugs: (1) solubility, dissolution rate, stability, and bioavailability enhancement; (2) to modify the drug release site and/or time profile; and (3) to reduce or prevent gastrointestinal side effects and unpleasant smell or taste, to prevent drug–drug or drug–additive interactions, or even to convert oil and liquid drugs into microcrystalline or amorphous powders. A more recent trend focuses on the use of CDs as nanocarriers, a strategy that aims to design versatile delivery systems that can encapsulate drugs with better physicochemical properties for oral delivery. Thus, the aim of this work was to review the applications of the CDs and their hydrophilic derivatives on the solubility enhancement of poorly water-soluble drugs in order to increase their dissolution rate and get immediate release, as well as their ability to control (to prolong or to delay) the release of drugs from solid dosage forms, either as complexes with the hydrophilic (e.g., as osmotic pumps) and/or hydrophobic CDs. New controlled delivery systems based on nanotechnology carriers (nanoparticles and conjugates) have also been reviewed.

An isocratic LC method for the simultaneous determination of vitamins A, C, E and β-carotene

An isocratic liquid chromatographic method for the separation and simultaneous determination of retinyl acetate, propionate or palmitate (esters of vitamin A), beta-carotene (pro-vitamin A), ascorbic acid (vitamin C) and DL-alpha-tocopherol (vitamin E) is described. Samples are analysed by means of a reversed-phase column (LiChrospher 100 RP-18), using methanol as mobile phase. The UV Vis detector used was set at a wavelength of 300 nm and switched to 450 nm at 17 min, allowing the determination of beta-carotene. These vitamins were separated within 25 min and the detection limits ranged from 7 (beta-carotene) to 65 ng ml(-1) (ascorbic acid).

Novel tretinoin formulations: a drug-in-cyclodextrin-in-liposome approach

Abstract Purpose: The aims of this experimental work were the incorporation and full characterization of the system Tretinoin-in-dimethyl-beta-cyclodextrin-in-ultradeformable vesicles (Tretinoin-CyD-UDV) and Tretinoin-in-ultradeformable vesicles (Tretinoin-UDV). Methods: The Tretinoin-CyD complex was prepared by kneading and the UDV by adding soybean phosphatidylcholine (SPC) to Tween® 80 followed by an appropriate volume of sodium phosphate buffer solution to make a 10%–20% lipid suspension. The resulting suspension was brought to the final mean vesicles size, of approximately 150 nm, by sequential filtration. The physicochemical characterization was based on: the evaluation of mean particle size and polydispersity index (PI) measured by photon correlation spectroscopy (PCS) and atomic force microscopy (AFM) topographic imaging; zeta potential (ζ-potential) and the SPC concentration determined by Laser–Doppler anemometry and an enzymatic-colorimetric test, respectively. The quantification of the incorporated Tretinoin and its chemical stability (during preparation and storage) was assayed by a HPLC at 342 nm. Results: It was possible to obtain the system Tretinoin-CyD-UDV. The mean vesicle size was the most stable parameter during experiments time course. AFM showed that Tretinoin-CyD-UDV samples were very heterogeneous in size, having three distinct subpopulations, while Tretinoin-UDV samples had only one homogeneous size population. The results of the ζ-potential measurements have shown that vesicle surface charge was low, as expected, presenting negative values. The incorporation efficiency was high, and no significant differences between Tretinoin-CyD-UDV and Tretinoin-UDV were observed. However, only Tretinoin-UDV with 20% lipid concentration formulation remained chemically stable during the evaluation period. Conclusion: According to our results, Tretinoin-UDV with 20% lipid concentration seems to be a better approach than Tretinoin-CyD-UDV, attending to the higher chemical stability.

In vitro and in vivo topical delivery studies of tretinoin-loaded ultradeformable vesicles

INTRODUCTION Ultradeformable vesicles are highly promising tools to enhance the percutaneous transport of different drugs such as tretinoin across the skin barrier and also to increase the formulation stability at absorption site and reduce the drug induced irritation. METHODS Topical delivery of tretinoin-loaded ultradeformable vesicles (tretinoin-UDV) was evaluated concerning different studies, such as: the release and permeation profiles (tape stripping); skin penetration (fluorescence analysis); induced electrical changes in skin barrier properties; cytotoxicity (Trypan Blue assay) and skin irritation in in vivo conditions (Draize test). The novel formulation performance was also compared to a commercial tretinoin formulation regarding in vivo studies. RESULTS It was obtained a sustained and controlled drug release, as expected for UDV formulation. In addition, a dermal delivery was observed regarding the permeation study since it was not detected any drug amount in the receptor phase after 24h. Nile Red-UDV stained intensively mostly in the stratum corneum, corroborating the tape stripping results. Tretinoin-UDV decreased skin resistance, suggesting its ability to induce skin barrier disruption. Finally, the formulation vehicle (empty UDV) and tretinoin-UDV were not toxic under in vitro and in vivo conditions, at least, at 5×10(-3)mg/mL and 0.5mg/mL of tretinoin, respectively. CONCLUSION Tretinoin-UDV is a promising delivery system for tretinoin dermal delivery without promoting skin irritation (unlike other commercial formulations), which is quite advantageous for therapeutic purpose.

Topical Delivery of Antioxidants

Reactive oxygen species (ROS) and free radicals have been implicated in a number of diseases and disorders, and the skin, for its localization, is exposed to a large number of environmental threats. Free radical scavengers and antioxidants have thus been proposed as protective or therapeutic agents against ROS-mediated injuries. Oral treatment with several antioxidants has been reported to provide skin protection against deleterious effects of ultraviolet radiation. Topical delivery of antioxidants has increasingly gained interest and development, especially by offering better targeting to the upper skin layer. However, the topical delivery of antioxidants for dermal action is a challenging research field since the molecules are, in general, susceptible to degradation. The search for a new delivery system that, simultaneously, preserves the antioxidant stability and enhances its deposition on the skin, opened a new chapter in drug delivery design. Nanocarriers have been successful in enhancing the clinical efficiency of several drugs. More recent approaches in modulating through the skin delivery led to the development of specialized nanoparticulated systems. The first part of this article presents a review of the potential of antioxidants as pharmacological agents in ROS related diseases, with a special focus on oxidative stress implicated skin pathologies: ROS formation and natural protection against ROS toxicity, ROS-mediated skin damage and skin protection by antioxidants. In the second part of this work, we present reported formulation strategies for dermal delivery of antioxidants focusing on the nanoparticulated systems developed in recent years.

Optimisation of Supercritical Carbon Dioxide Systems for Complexation of Naproxen : Beta-Cyclodextrin

Supercritical carbon dioxide (scCO2)offers several attractive scenarios for thepharmaceutical processing as an alternativeto aqueous and organic solvents. In thiswork naproxen, a widely used non steroidalanti-inflammatory drug with analgesic andanti-inflammatory properties, was chosenas a model drug. Its complexation with cyclodextrinsimproves the rate and extent of dissolutionof the drug, increase its rate of absorption and mayreduce the unpleasant side-effects of the drug.The interest in using this supercritical technologyled us to develop an experimental unit for the useof supercritical CO2 as a processing medium forthe complexation of naproxen with beta cyclodextrin (CD).

Complexation of Budesonide in Cyclodextrins and Particle Aerodynamic Characterization of the Complex Solid Form for Dry Powder Inhalation

The purpose of this study is to evaluate the effect ofbudesonide-cyclodextrins (CDs) complex formation in thein-vitro aerodynamic properties of the dry powder producedfor pulmonary delivery. Phase-solubility studies were performedusing budesonide and β-CD, DM-β-CD and HP-β-CD.The complex budesonide:DM-β-CD revealed the highest stabilityconstant (K_s = 3339.7 ± 4.76%; n = 3) and the solid powder was prepared by spray-drying.Complexation was evidenced by Differential Scanning Calorimetry (DSC). A physical mixture of budesonide and DM-β-CD was prepared for use as reference. The fine particle fraction and particle size distribution of both powders were assessed using Twin Stage Liquid Impinger (TSLI) and Aerosizer®LD, respectively. The content uniformity of the capsules filled (sd); (n) was 191.8 (± 2.74) μg; (10) for the budesonide:DM-β-CD solid complex and 204.9 (± 9.35) μg; (10) for the physical mixture. The emitted dose (rsd); (n) was 68.0% (± 26.1%); (5) of the nominal dose (solid complex) and 70.6% (± 12.6%); (5) (physical mixture). The fine particle fraction was 67.7% (± 18.9%); (5) of the emitted dose (solid complex) and 39.8% (± 16.9%); (5) (physical mixture). While no statistically significant difference was observed between the emitted dose means of both the solid complex and physical mixture, a statistically significant higher fine particle fraction mean was obtained for the solid complex. The results suggest that using a spray-dried CD complex powder for pulmonary drug delivery may increase the drugs respirable fraction and consequently its therapeutic efficacy.

The Effect of Lycopene Preexposure on UV-B-Irradiated Human Keratinocytes

Lycopene has been reported as the antioxidant most quickly depleted in skin upon UV irradiation, and thus it might play a protective role. Our goal was to investigate the effects of preexposure to lycopene on UV-B-irradiated skin cells. Cells were exposed for 24 h to 10 M lycopene, and subsequently irradiated and left to recover for another 24 h period. Thereafter, several parameters were analyzed by FCM and RT-PCR: genotoxicity/clastogenicity by assessing the cell cycle distribution; apoptosis by performing the Annexin-V assay and analyzing gene expression of apoptosis biomarkers; and oxidative stress by ROS quantification. Lycopene did not significantly affect the profile of apoptotic, necrotic and viable cells in nonirradiated cells neither showed cytostatic effects. However, irradiated cells previously treated with lycopene showed an increase in both dead and viable subpopulations compared to nonexposed irradiated cells. In irradiated cells, lycopene preexposure resulted in overexpression of BAX gene compared to nonexposed irradiated cells. This was accompanied by a cell cycle delay at S-phase transition and consequent decrease of cells in G0/G1 phase. Thus, lycopene seems to play a corrective role in irradiated cells depending on the level of photodamage. Thus, our findings may have implications for the management of skin cancer.

Chemoprevention of photocarcinogenesis by lycopene.

This review focuses on the photoprotection conferred by lycopene, one of the most potent anti‐oxidants. Lycopene has been recently proposed to play a critical role on anticarcinogenic action at different levels. The photoprotective properties of lycopene remain contradictory. Some studies point out a positive and others a negative effect in both in vitro and in vivo models. Currently, researchers recognise that crucial gaps exist in understanding the role of carotenoids as effective modulators of apoptosis, cell cycle dynamics and/or of their in vivo behaviour as cellular anti‐oxidants. The development of novel therapeutic strategies for skin disorders depends on our understanding of the molecular mechanism of UV damage on skin cells. The use of several effective phytocompounds, including lycopene, working through preventive and/or corrective pathways in the cell, may be an approach for reducing UV‐B‐generated damage.