Enhancement of the Skin Permeation of Clindamycin Phosphate by Aerosol OT/1-Butanol Microemulsions

Evaluation of the Properties of Encapsulated Stavudine Microparticulate Lipid-based Drug Delivery System in Immunocompromised Wistar Rats

BACKGROUND

Lipid-based formulations have been confirmed to lower some side effects of drugs and can be tailor-made to offer sustained drug release of drugs with short half-life like stavudine.

AIM

This study aimed to evaluate the immunomodulatory properties of stavudine-loaded solid lipid microparticles (SLMs) using immunocompromised Wistar rats.

METHODS

The SLMs were formulated by the homogenization method. The optimized batches were used for further in vivo studies. The effect of formulation on the CD4 count and the haematological properties of immunocompromised Wistar rats were studied.

RESULTS

The particle size range was 4 -8 μm, EE range was 85-93 % and maximum drug release was observed at 10 h. The CD4 cells increased from 115 ± 3.17 cell/mm3 at day zero to 495 ± 5.64 cell/mm3 at day 14 of treatment and 538 ± 6.31 cell/mm3 at day 21. The red blood cells increased from 2.64 ± 1.58 (x 106/mm3) at day zero to 6.96 ± 3.47 (x 106/mm3) at day 14 and 7.85 ± 3.64 (x 106/mm3) at day 21. PCV increased significantly (p < 0.05) to about 42-50 % at day 21 in the groups that received the SLMs formulations. White blood cells (WBC) also were 12 x 103/mm3, for SLM formulations, while the rats that received plain stavudine exhibited WBC of 9.6 x 103/mm3 at day 21. The histopathological studies revealed that oral stavudine-loaded SLMs had no significant damage to the kidney, liver, spleen and the brain of Wistar rats.

CONCLUSION

The formulations exhibited significantly higher immunomodulatory properties than plain stavudine (p<0.05) and showed good properties for once daily oral administration and could be a better alternative to plain stavudine tablets for the management of patients living with HIV.

Transdermal transport of collagen and hyaluronic acid using water in oil microemulsion

Collagen and hyaluronic acid (HA) are biopolymers that affect the appearance and condition of the skin. Delivery of these compounds into the skin is highly challenging since have a number of disadvantageous properties, such as high molecular weight and hydrophilicity. Here, we evaluated the transdermal penetration of low and high molecular weight collagen and HA from microemulsions. A number of microemulsion formulations, differing in the content of polymers and surfactants (i.e. penetration promoters), were used for the permeation study. In addition, a correlation was made between the composition of these microemulsions and the polymers transport efficiency. The results indicate that, microemulsions enable transdermal permeation of collagen and HA. The concentration of polymers and the solubilization capacity of microemulsions had the greatest influence on the permeation. Surprisingly, the molecular weight of polymers and the content of other components affected the size of microemulsion particles, and thus these parameters had an indirect influence on the permeation process. This study demonstrated therefore the potential therapeutic use of microemulsion with collagen and HA in improving and regenerating the barrier of aged or diseased skin.

Collagen and hyaluronic acid hydrogel in water-in-oil microemulsion delivery systems

The increase in skin related health issues has promoted interest in research on the efficacy of microemulsion in dermal and transdermal delivery of active ingredients. Here, we assessed the water-in-oil microemulsion capacity to incorporate two natural polymers, i.e. collagen and hyaluronic acid with low and high molecular weight. Systems were extensively characterized in terms of conductivity, phase inversion studies, droplet diameter, polydispersity index and rheological properties. The results of this research indicate that the structure and extent of water phase in microemulsions is governed by ratio and amount of surfactant mixture (sorbitan ester derivatives). However, results have also shown that collagen, depending upon the weight of the molecule and its surface activity, influence the droplet size of the microemulsions. While the hyaluronic acid, especially with high molecular weight, due to the water-binding ability and hydrogel formation alters the rheological properties of the microemulsion, thus providing viscous consistency of the formulation.

Evaluation of nicotinamide microemulsion on the skin penetration enhancement

This study purposed to evaluate a microemulsion containing nicotinamide for its characteristics, stability, and skin penetration and retention comparing with a solution of nicotinamide in 2:1 mixture of water and isopropyl alcohol (IPA). The microemulsion system was composed of 1:1 mixture of Span80 and Tween80 as a surfactant mixture, isopropyl palmitate (IPP) as an oil phase, and 2:1 mixture of water and IPA as an aqueous phase. Nicotinamide microemulsion was prepared by dissolving the active in the aqueous phase before simply mixing with the other components. It was determined for its characteristics and stability under various conditions. The skin penetration and retention studies of nicotinamide microemulsion and solution were performed by modified Franz diffusion cells, using newborn pig skin as the membrane. The results showed that nicotinamide microemulsion could be obtained as clear yellowish liquid, was water-in-oil (w/o) type, possessed Newtonian flow, and exhibited physicochemical stability when kept at 4 °C and room temperature (≈30 ± 2 °C) during 3 months. From the skin penetration data, the microemulsion could enhance the skin penetration of nicotinamide comparing with the solution. Additionally, nicotinamide microemulsion could provide much higher amount of skin retention than that of skin penetration, resulting in suitability for a cosmeceutical product.

Distribution of polyphenols and a surfactant component in skin during Aerosol OT microemulsion-enhanced intradermal delivery

As for most other polyphenols, intradermal delivery of curcumin and resveratrol is limited; however, it was significantly improved by a microemulsion using Aerosol OT (Aerosol OT microemulsion) and Tween 80 (Tween 80 microemulsion) as surfactants. Aerosol OT microemulsion was more effective and the incorporation ratio of these polyphenols into skin by Aerosol OT microemulsion was five-fold or ten-fold that by Tween 80 microemulsion. To clarify the mechanism of the enhancement we examined the distribution of these polyphenols and the surfactant component, Aerosol OT, using excised guinea pig skin and Yucatan micropig (YMP) skin. During permeation, polyphenols distributed deep in the skin. In particular, a small molecule, resveratrol, was mainly present in the dermis in YMP skin. Aerosol OT also distributed deep in the skin. These findings suggest the possible involvement of the interaction of surfactant molecules with skin components in the enhanced delivery process of polyphenols. The distribution ratio between the dermis and epidermis of the polyphenols, including quercetin, in the presence of Aerosol OT microemulsion decreased with the increase of molecular weight in YMP skin, suggesting the possibility that distribution to the dermis is regulated by the molecular size.

Preparation and evaluation of topical microemulsion system containing metronidazole for remission in rosacea

The aim of this study was to prepare a topical water-in-oil type microemulsion containing metronidazole and to compare its effectiveness with a commercial gel product in the treatment of rosacea. A pseudo-ternary phase diagram (K(m)=2:1) was constructed using lecithin/butanol/isopropyl myristate/water. The microemulsion was chosen from the microemulsion region in the phase diagram. The formulation was a water-in-oil type microemulsion (droplet size: 11.6 nm, viscosity: 457.3 mPa·s, conductivity: 1.5 µs/cm, turbidity: 6.89 NTU) and the addition of the metronidazole did not alter the properties of the system. The release experiment showed that the release rate of metronidazole from the commercial gel product was higher than that of the microemulsion. Stability experiments showed that the metronidazole microemulsion remained stable for at least 6 months; none of the characteristic properties of the microemulsion had changed, the system retained its clarity and there was no sign that crystallization of metronidazole has occurred. Microemulsion was compared to a gel product in a randomized, double-blind, baseline-controlled, split-face clinical trial for the treatment of patients. After the 6-week treatment period there was a statistically significant difference in reduction of the main symptoms of rosacea. Of the patients treated with the microemulsion, 17% experienced complete relief from inflammatory lesions, and 50% from erythema. The microemulsion resulted in complete relief in 38% of the patients with telangiectasia while the commercial product did not provide any relief of telangiectasia symptoms. In conclusion, the microemulsion containing metronidazole was found to be more effective in reducing the symptoms of rosacea compared to the commercial gel product.

Probing the microstructure of nonionic microemulsions with ethyl oleate by viscosity, ROESY, DLS, SANS, and cyclic voltammetry

Microemulsions are important formulations in cosmetics and pharmaceutics and one peculiarity lies in the so-called "phase inversion" that takes place at a given water-to-oil concentration ratio and where the average curvature of the surfactant film is zero. In that context, we investigated the structural transitions occurring in Brij 96-based microemulsions with the cosmetic oil ethyl oleate and studied the influence of the short chain alcohol butanol on their structure and properties as a function of water addition. The characterization has been carried out by means of transport properties, spectroscopy, DLS, SANS, and electrochemical methods. The results confirm that the nonionic Brij 96 in combination with butanol as cosurfactant forms a U-type microemulsion that upon addition of water undergoes a continuous transition from swollen reverse micelles to oil-in-water (O/W) microemulsion via a bicontinuous region. After determining the structural transition through viscosity and surface tension, the 2D-ROESY studies give an insight into the microstructure, i.e., the oil component ethyl oleate mainly is located at the hydrophobic tails of surfactant while butanol molecules reside preferentially in the interface. SANS experiments show a continuous increase of the size of the structural units with increasing water content. The DLS results are more complex and show the presence of two relaxation modes in these microemulsions for low water content and a single diffusive mode only for the O/W microemulsion droplets. The fast relaxation reflects the size of the structural units while the slower one is attributed to the formation of a network of percolated microemulsion aggregates. Electrochemical studies using ferrocene have been carried out and successfully elucidated the structural transformations with the help of diffusion coefficients. An unusual behavior of ferrocene has been observed in the present microheterogeneous medium, giving a deeper insight into ferrocene electrochemistry. NMR-ROESY experiments give information regarding the internal organization of the microemulsion droplets. In general, one finds a continuous structural transition from a W/O over a bicontinuous to an O/W microemulsion, however with a peculiar network formation over an extended concentration range, which is attributed to the somewhat amphiphilic oil ethyl oleate. The detailed knowledge of the structural behavior of this type of system might be important for their future applications.

Nanocarrier for the transdermal delivery of an antiparkinsonian drug

The purpose of the present study was to investigate the potential of nanoemulsions as nanodrug carrier systems for the percutaneous delivery of ropinirole. Nanoemulsions comprised Capryol 90 as the oil phase, Tween 20 as the surfactant, Carbitol as the cosurfactant, and water as an external phase. The effects of composition of nanoemulsion, including the ratio of surfactant and cosurfactant (Smix) and their concentration on skin permeation, were evaluated. All the prepared nanoemulsions showed a significant increase in permeation parameters such as steady state flux (Jss) and permeability coefficient (Kp) when compared to the control (p<0.01). Nanoemulsion composition (NEL3) comprising ropinirole (0.5% w/w), Capryol 90 (5% w/w), Smix 2:1 (35% w/w), and water (59.5% w/w) showed the highest flux (51.81+/-5.03 microg/cm2/h) and was selected for formulation into nanoemulsion gel. The gel was further optimized with respect to oil concentration (Capryol 90), polymer concentration (Carbopol), and drug content by employing the Box-Behnken design, which statistically evaluated the effects of these components on ropinirole permeation. Oil and polymer concentrations were found to have a negative influence on permeation, while the drug content had a positive effect. Nanoemulsion gel showed a 7.5-fold increase in skin permeation rate when compared to the conventional hydrogel. In conclusion, the results of the present investigation suggested a promising role of nanoemulsions in enhancing the transdermal permeation of ropinirole.

Permeation studies of indomethacin from different emulsions for nasal delivery and their possible anti-inflammatory effects

The purpose of this research was to develop an emulsion formulation of indomethacin (IND) suitable for nasal delivery. IND was incorporated into the oil phases of oil in water (O/W) and water in oil (W/O) emulsions. For this purpose, different emulsifying agents (Tween 80, Span 80 and Brij 58) were used in two emulsion formulations. When the effects of several synthetic membranes (nylon, cellulose, cellulose nitrate) were compared with the sheep nasal mucosa, the cellulose membrane and sheep nasal mucosa showed similar permeation properties for O/W emulsion (P > 0.05). To examine the absorption characteristics of IND, the anti-inflammatory properties of intravenous solution of IND, intranasal O/W emulsions of IND (with or without enhancers) and intranasal solution of IND (IND-Sol) were investigated in rats with carrageenan-induced paw edema. When citric acid was added to the nasal emulsion, the anti-inflammatory activity was similar to that of intravenous solution (P > 0.05). Finally, it was concluded that, intranasal administration of IND emulsion with citric acid may be considered as an alternative to intravenous and per oral administrations of IND to overcome their adverse effects.