Development and characterization of parenteral nanoemulsions containing thalidomide

Ultrasonic emulsification of parenteral valproic acid-loaded nanoemulsion with response surface methodology and evaluation of its stability

Response surface methodology (RSM) was used to optimize the formulation of a nanoemulsion for central delivery following parenteral administration. A mixture of medium-chain triglyceride (MCT) and safflower seed oil (SSO) was determined as a sole phase from the emulsification properties. Similarly, a natural surfactant (lecithin) and non-ionic surfactant (Tween 80) (ratio 1:2) were used in the formulation. A central composite design (CCD) with three-factor at five-levels was used to optimize the processing method of high energy ultrasonicator. Effects of pre-sonication ultrasonic intensity (A), sonication time (B), and temperature (C) were studied on the preparation of nanoemulsion loaded with valproic acid. Influence of the aforementioned specifically the effects of the ultrasonic processing parameters on droplet size and polydispersity index were investigated. From the analysis, it was found that the interaction between ultrasonic intensity and sonication time was the most influential factor on the droplet size of nanoemulsion formulated. Ultrasonic intensity (A) significantly affects the polydispersity index value. With this optimization method, a favorable droplet size of a nanoemulsion with reasonable polydispersity index was able to be formulated within a short sonication time. A valproic acid loaded nanoemulsion can be obtained with 60% power intensity for 15 min at 60 °C. Droplet size of 43.21±0.11 nm with polydispersity index of 0.211 were produced. The drug content was then increased to 1.5%. Stability study of nanoemulsion containing 1.5% of valproic acid had a good stability as there are no significant changes in physicochemical aspects such as droplet size and polydispersity index. With the characteristisation study of pH, viscosity, transmission electron microscope (TEM) and stability assessment study the formulated nanoemulsion has the potential to penetrate blood-brain barrier in the treatment of epilepsy.

Prolonged Suppression of Neuropathic Pain by Sequential Delivery of Lidocaine and Thalidomide Drugs Using PEGylated Graphene Oxide

The management of patients with neuropathic pain is challenging. Monotherapy with a single pain relief drug may encounter different difficulties, such as short duration of efficacy and hence too many times of drug administration, and inadequate drug delivery. Recently, nanocarrier-based drug delivery systems have been proved to provide promising strategies for efficient drug loading, delivery, and release. In the present study, we developed poly(ethylene glycol) methyl ether functionalized graphene oxide (GO) bearing two commonly used drugs of lidocaine (LDC) and thalidomide (THD) as an agent for the treatment of neuropathic pain. The sequential drug release of LDC and THD from the developed LDC-THD-GO nanosheets exhibited a synergistic effect on neuropathic pain in vitro and in vivo, as evidenced by the increased pain threshold in mechanical allodynia and hyperalgesic response tests, and the improved inhibition of proinflammatory cytokines TNF-α, IL-1β, IL-6, and nitric oxide. We believed that the present study herein would hold promise for future development of a new generation of potent agents for neuropathic pain relief.

Development of an insecticidal nanoemulsion with Manilkara subsericea (Sapotaceae) extract

BACKGROUND

Plants have been recognized as a good source of insecticidal agents, since they are able to produce their own defensives to insect attack. Moreover, there is a growing concern worldwide to develop pesticides with low impact to environment and non-target organisms. Hexane-soluble fraction from ethanolic crude extract from fruits of Manilkara subsericea and its triterpenes were considered active against a cotton pest (Dysdercus peruvianus). Several natural products with insecticidal activity have poor water solubility, including triterpenes, and nanotechnology has emerged as a good alternative to solve this main problem. On this context, the aim of the present study was to develop an insecticidal nanoemulsion containing apolar fraction from fruits of Manilkara subsericea.

RESULTS

It was obtained a formulation constituted by 5% of oil (octyldodecyl myristate), 5% of surfactants (sorbitan monooleate/polysorbate 80), 5% of apolar fraction from M. subsericea and 85% of water. Analysis of mean droplet diameter (155.2 ± 3.8 nm) confirmed this formulation as a nanoemulsion. It was able to induce mortality in D. peruvianus. It was observed no effect against acetylcholinesterase or mortality in mice induced by the formulation, suggesting the safety of this nanoemulsion for non-target organisms.

CONCLUSIONS

The present study suggests that the obtained O/A nanoemulsion may be useful to enhance water solubility of poor water soluble natural products with insecticidal activity, including the hexane-soluble fraction from ethanolic crude extract from fruits of Manilkara subsericea.

Modulation of drug resistance in ovarian adenocarcinoma using chemotherapy entrapped in hyaluronan-grafted nanoparticle clusters

Resistance to anticancer drugs is considered a major cause of chemotherapy failure. One of the major mediators of resistance is the multidrug extrusion pump protein, P-glycoprotein (P-gp), an ATP-binding cassette (ABC) transporter with broad substrate specificity. In order to bypass this drug resistance mechanism, we have devised phospholipid-based nanoparticle clusters coated with the glycosaminoglycan hyaluronan, the major ligand of CD44, which is upregulated and undergoes different splice variations in many types of cancer cells. These particles, termed glycosaminoglycan particle nanoclusters or gagomers (GAGs), were self-assembled into ∼500 nm diameter clusters, with zeta-potential values of ∼-70 mV. Flow cytometry analysis provided evidence that, unlike free doxorubicin (DOX), a model chemotherapy, DOX entrapped in the GAGs (DOX-GAGs) accumulated in P-gp-overexpressing human ovarian adenocarcinoma cell line and dramatically decreased cell viability, while drug-free GAGs and the commercially available drug DOXIL (PEGylated liposomal DOX) did not produce therapeutic benefit. Furthermore, by using RNA interference strategy, we showed that DOX-GAGs were able to overcome the P-gp-mediated resistant mechanism of these cells. Most importantly, DOX-GAGs showed a superior therapeutic effect over free DOX in a resistant human ovarian adenocarcinoma mouse xenograft model. Taken together, these results demonstrated that GAGs might serve as an efficient platform for delivery of therapeutic payloads by bypassing P-gp-mediated multidrug resistance.

Experimental design in formulation of diazepam nanoemulsions: physicochemical and pharmacokinetic performances

With the aid of experimental design, we developed and characterized nanoemulsions for parenteral drug delivery. Formulations containing a mixture of medium-chain triglycerides and soybean oil as oil phase, lecithin (soybean/egg) and polysorbate 80 as emulsifiers, and 0.1 M phosphate buffer solution (pH 8) as aqueous phase were prepared by cold high-pressure homogenization. To study the effects of the oil content, lecithin type, and the presence of diazepam as a model drug and their interactions on physicochemical characteristics of nanoemulsions, a three factor two-level full factorial design was applied. The nanoemulsions were evaluated concerning droplet size and size distribution, surface charge, viscosity, morphology, drug-excipient interactions, and physical stability. The characterization revealed the small spherical droplets in the range 195 -220 nm with polydispersity index below 0.15 and zeta potential between -30 and - 60 mV. Interactions among the investigated factors, rather than factors alone, were shown to more profoundly affect nanoemulsion characteristics. In vivo pharmacokinetic study of selected diazepam nanoemulsions with different oil content (20%, 30%, and 40%, w/w) demonstrated fast and intense initial distribution into rat brain of diazepam from nanoemulsions with 20% and 30% (w/w) oil content, suggesting their applicability in urgent situations.

Development of intravenous lipid emulsion of α-asarone with significantly improved safety and enhanced efficacy

Severe adverse events have been frequently associated with taking the commercially available formulation of α-asarone injection (α-asarone-I). Hence, we sought to develop an intravenous lipid emulsion of α-asarone (α-asarone-LE), where we hypothesized that these adverse events could be prevented. Using a central composite design-response surface methodology, we developed and optimized an emulsion formulation of α-asarone-LE that composed of 10.0% (w/v) soybean oil, 0.4% (w/v) α-asarone, 1.2% (w/v) soybean lecithin, 0.3% (w/v) F68, and 2.2% (w/v) glycerol. The mean particle size of α-asarone-LE was 226±11 nm, the ζ-potential was -25.6±1.2 mV, the encapsulation efficiency was 99.2±0.1% and the drug loading efficiency was 3.45%. Stability, safety, and efficacy studies of α-asarone-LE were systematically investigated and compared to those of α-asarone-I. The α-asarone-LE not only showed a desired stability, but also exhibited excellent safety and improved efficacy in vivo, indicating its great potential for clinical application in the future.

Nanoemulsions and nanoparticles for non-melanoma skin cancer: effects of lipid materials

Basal cell carcinomas and squamous cell carcinomas are non-melanoma skin cancers reported to be among the most common malignancies, being responsible for high human morbidity. Conventional chemotherapy applied to these conditions shows non-specific targeting, thus severe adverse side effects are also commonly reported. New therapeutic strategies based on nanoparticulates technology have emerged as alternatives for site specific chemotherapy. Among the different types of nanoparticulates, lipid nanoemulsions and nanoparticles have several advantages for topical delivery of poorly soluble chemotherapeutics. These particles show sustained drug release and protection of loaded drugs from chemical degradation. This technology is promising to enhance the intracellular concentration of drugs and consequently reduce the cytotoxicity of skin chemotherapy.

Impact of process parameters in the generation of novel aspirin nanoemulsions--comparative studies between ultrasound cavitation and microfluidizer

In the present investigation, the operating efficiency of a bench-top air-driven microfluidizer has been compared to that of a bench-top high power ultrasound horn in the production of pharmaceutical grade nanoemulsions using aspirin as a model drug. The influence of important process variables as well as the pre-homogenization and drug loading on the resultant mean droplet diameter and size distribution of emulsion droplets was studied in an oil-in-water nanoemulsion incorporated with a model drug aspirin. Results obtained show that both the emulsification methods were capable of producing very fine nanoemulsions containing aspirin with the minimum droplet size ranging from 150 to 170 nm. In case of using the microfluidizer, it has been observed that the size of the emulsion droplets obtained was almost independent of the applied microfluidization pressure (200-600 bar) and the number of passes (up to 10 passes) while the pre-homogenization and drug loading had a marginal effect in increasing the droplet size. Whereas, in the case of ultrasound emulsification, the droplet size was generally decreased with an increase in sonication amplitude (50-70%) and period of sonication but the resultant emulsion was found to be dependent on the pre-homogenization and drug loading. The STEM microscopic observations illustrated that the optimized formulations obtained using ultrasound cavitation technique are comparable to microfluidized emulsions. These comparative results demonstrated that ultrasound cavitation is a relatively energy-efficient yet promising method of pharmaceutical nanoemulsions as compared to microfluidizer although the means used to generate the nanoemulsions are different.

Modification of palm kernel oil esters nanoemulsions with hydrocolloid gum for enhanced topical delivery of ibuprofen

INTRODUCTION

During recent years, there has been growing interest in the use of nanoemulsion as a drug-carrier system for topical delivery. A nanoemulsion is a transparent mixture of oil, surfactant and water with a very low viscosity, usually the product of its high water content. The present study investigated the modification of nanoemulsions with different hydrocolloid gums, to enhanced drug delivery of ibuprofen. The in vitro characterization of the initial and modified nanoemulsions was also studied.

METHODS

A palm kernel oil esters nanoemulsion was modified with different hydrocolloid gums for the topical delivery of ibuprofen. Three different hydrocolloids (gellan gum, xanthan gum, and carrageenan) were selected for use. Ternary phase diagrams were constructed using palm kernel oil esters as the oil, Tween 80 as the surfactant, and water. Nanoemulsions were prepared by phase inversion composition, and were gradually mixed with the freshly prepared hydrocolloids. The initial nanoemulsion and modified nanoemulsions were characterized. The abilities of the nanoemulsions to deliver ibuprofen were assessed in vitro, using a Franz diffusion cell fitted with rat skin.

RESULTS

No significant changes were observed in droplet size (~16-20 nm) but a significant difference in polydispersity indexes were observed before and after the modification of nanoemulsions using gellan gum, carrageenan, and xanthan gum. The zeta potentials of the initial nanoemulsions (-11.0 mV) increased to -19.6 mV, -13.9 mV, and -41.9 mV, respectively. The abilities of both the initial nanoemulsion (T802) and the modified nanoemulsion to deliver ibuprofen through the skin were evaluated in vitro, using Franz diffusion cells fitted with rat skin. The in vitro permeation data showed that the modified nanoemulsion (Kp value of 55.4 × 10(-3) cm · h(-1)) increased the permeability of ibuprofen 4.40 times over T802 (Kp value of 12.6 × 10(-3) cm · h(-1)) (P < 0.05).

CONCLUSION

The modified nanoemulsion may be a promising vehicle to enhance the permeation of ibuprofen for topical delivery.

Preparation, characterization, and in vitro intestinal permeability evaluation of thalidomide-hydroxypropyl-β-cyclodextrin complexes

Thalidomide is emerging as a therapeutic agent with renewed clinical importance, presenting anti-inflammatory, immunomodulatory, and antineoplasic properties. In this work, we studied the complexation of thalidomide with cyclodextrins as a strategy to circumvent the poor aqueous solubility of the drug. Thalidomide-hydroxypropyl-β-cyclodextrin complexes were obtained by kneading method and were characterized by differential scanning calorimetry, powder X-ray diffractometry, and scanning electronic microscopy. The aqueous solubility and in vitro dissolution of thalidomide were significantly improved through the complexation. Physicochemical analysis of the complexes in solid state revealed a decreased crystallinity of the complexed drug in comparison with free thalidomide. Thalidomide was able to dissociate from the complexes and permeates across intestinal epithelial Caco-2 cells with a favorable high permeability profile equivalent to that of the free drug. In summary, the present results suggest that thalidomide-hydroxypropyl-β-cyclodextrin complexes could be regarded as a promising strategy for improving the gastrointestinal absorption of thalidomide.