Parenteral nanoemulsions with poorly water-soluble psychopharmacological drugs:: formulation, optimization and in vivo disposition evaluation

Da bi se obezbedila brza/kontrolisana isporuka lekovite supstance u mozak i poboljšala njena biološka raspoloživost na ciljnom mestu dejstva, i posledično terapijski efekat, neophodno je savladati brojne ključne izazove, pre svega restriktivna svojstva krvno-moždane barijere, kao i kritične karakteristike same lekovite supstance (slaba rastvorljivost, značajan metabolizam prvog prolaza, nespecifična biodistribucija, efluks od strane P-glikoproteina). Među nanotehnološkim strategijama koje se koriste za poboljšanje ciljne isporuke lekova u mozak, poslednjih godina povećana pažnja fokusirana je na nanoemulzije kao obećavajuće nosače za parenteralnu isporuku slabo rastvorljivih centralno-aktivnih lekovitih supstanci, zahvaljujući njihovim brojnim privlačnim prednostima, uključujući biokompatibilnost, biodegradabilnost, fizičku stabilnost, jednostavan scale up, visok solubilizacioni kapacitet za lipofilne lekovite supstance, moguće povećanje biološke raspoloživosti, kontrolisano oslobađanje i ciljnu isporuku u različite organe. Iako se lipidne nanoemulzije tradicionalno primenjuju u parenteralnoj ishrani, kao i za solubilizaciju i intravensku isporuku nekoliko lipofilnih lekovitih supstanci, neophodno je ulaganje dodatnih napora u cilju optimizacije formulacije, stabilnosti, isporuke lekova, i uopšte in vivo ponašanja ovih sistema, što ovoj temi daje obnovljen i sve veći značaj. Na osnovu navedenog, cilj istraživanja ove doktorske disertacije bio je razvoj i optimizacija ulje-u-vodi nanoemulzija za parenteralnu primenu slabo rastvorljivih psihofarmakoloških lekovitih supstanci, kao i procena sposobnosti razvijenih nanoemulzija da poboljšaju preuzimanje u mozak inkorporirane model lekovite supstance. U tu svrhu, primenom koncepta eksperimentalnog dizajna formulisane su placebo i nanoemulzije sa lekovitom supstancom, izrađene metodom homogenizacije pod visokim pritiskom i detaljno okarakterisane u pogledu veličine i raspodele veličina kapi, površinskog naelektrisanja, viskoziteta, morfologije, lek–nosač interakcija, dugoročne stabilnosti i stabilnosti na autoklaviranje...In order to provide rapid/controlled drug delivery to the brain and improve its bioavailability at the target site, and consequently its therapeutic effect, a number of key challenges must be overcome, primarily the restrictive properties of the blood–brain barrier as well as the critical properties of the drug itself (poor water-solubility, significant first-pass metabolism, nonspecific biodistribution, and P-glycoprotein efflux). Among the reported nanotechnological strategies for enhancing drug delivery and targeting to the brain, an increasing attention has been focused more recently on nanoemulsions as promising carriers for parenteral delivery of poorly water-soluble centrally-acting drugs, having in mind their numerous appealing features, including biocompatibility, biodegradability, physical stability, ease to scale up, high solubilization capacity for lipophilic drugs, possibly enhanced bioavailability, controlled drug release, and organ targeting. Although lipid nanoemulsions have been traditionally employed for parenteral nutrition and to solubilize and intravenously deliver several lipophilic drugs, additional efforts are required in order to optimize nanoemulsion formulation, stability, drug delivery and overall in vivo behavior, giving this topic a renewed and growing interest. Based on this, the aim of the present work was to develop and optimize oil-in-water nanoemulsions for parenteral delivery of poorly water-soluble psychopharmacological drugs, and to evaluate their ability to improve the brain uptake of the incorporated drug. For this purpose, placebo and drug-loaded nanoemulsions were designed with the aid of experimental design, prepared by high pressure homogenization and thoroughly characterized for their droplet size, size distribution, surface charge, viscosity, morphology, drug–vehicle interactions, long-term stability, and stability to autoclaving..

Low-energy nanoemulsions as carriers for red raspberry seed oil: Formulation approach based on Raman spectroscopy and textural analysis, physicochemical properties, stability and in vitro antioxidant/ biological activity

Considering a growing demand for medicinal/cosmetic products with natural actives, this study focuses on the low-energy nanoemulsions (LE-NEs) prepared via the Phase inversion composition (PIC) method at room temperature as potential carriers for natural oil. Four different red raspberry seed oils (ROs) were tested, as follows: cold-pressed vs. CO2- extracted, organic vs. non-organic, refined vs. unrefined. The oil phase was optimized with Tocopheryl acetate and Isostearyl isostearate, while water phase was adjusted with either glycerol or an antioxidant hydro-glycolic extract. This study has used a combined approach to formulation development, employing both conventional methods (pseudo-ternary phase diagram - PTPD, electrical conductivity, particle size measurements, microscopical analysis, and rheological measurements) and the methods novel to this area, such as textural analysis and Raman spectroscopy. Raman spectroscopy has detected fine differences in chemical composition among ROs, and it detected the interactions within nanoemulsions. It was shown that the cold-pressed, unrefined, organic grade oil (RO2) with 6.62% saturated fatty acids and 92.25% unsaturated fatty acids, was optimal for the LE-NEs. Textural analysis confirmed the existence of cubic gel-like phase as a crucial step in the formation of stable RO2-loaded LE-NEs, with droplets in the narrow nano-range (125 to 135 nm; PDI ≤ 0.1). The DPPH test in methanol and ABTS in aqueous medium have revealed a synergistic free radical scavenging effect between lipophilic and hydrophilic antioxidants in LE-NEs. The nanoemulsion carrier has improved the biological effect of raw materials on HeLa cervical adenocarcinoma cells, while exhibiting good safety profile, as confirmed on MRC-5 normal human lung fibroblasts. Overall, this study has shown that low-energy nanoemulsions present very promising carriers for topical delivery of natural bioactives. Raman spectroscopy and textural analysis have proven to be a useful addition to the arsenal of methods used in the formulation and characterization of nanoemulsion systems

Curcumin loaded pegylated nanoemulsions designed for maintained antioxidant effects and improved bioavailability: A pilot study on rats

The current study describes the experimental design guided development of PEGylated nanoemulsions as parenteral delivery systems for curcumin, a powerful antioxidant, as well as the evaluation of their physicochemical characteristics and antioxidant activity during the two years of storage. Experimental design setup helped development of nanoemulsion templates with critical quality attributes in line with parenteral application route. Curcumin-loaded nanoemulsions showed mean droplet size about 105 nm, polydispersity index <0.15, zeta potential of −40 mV, and acceptable osmolality of about 550 mOsm/kg. After two years of storage at room temperature, all formulations remained stable. Moreover, antioxidant activity remained intact, as demonstrated by DPPH (IC50 values 0.078–0.075 mg/mL after two years) and FRAPS assays. In vitro release testing proved that PEGylated phospholipids slowed down the curcumin release from nanoemulsions. The nanoemulsion carrier has been proven safe by the MTT test conducted with MRC-5 cell line, and effective on LS cell line. Results from the pharmacokinetic pilot study implied the PEGylated nanoemulsions improved plasma residence of curcumin 20 min after intravenous administration, compared to the non-PEGylated nanoemulsion (two-fold higher) or curcumin solution (three-fold higher). Overall, conclusion suggests that developed PEGylated nanoemulsions present an acceptable delivery system for parenteral administration of curcumin, being effective in preserving its stability and antioxidant capacity at the level highly comparable to the initial findings

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 0.1M 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 195-220nm with polydispersity index below 0.15 and zeta potential between -30 and -60mV. 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

Evaluation of PEGylation efficacy of curcumin-loaded nanoemulsions using complementary methods to assess protein interactions and physicochemical properties

Nanoemulsions (NEs) are frequently used in the food, cosmetics and pharmaceutical industries to deliver nutraceuticals, pharmaceutical or cosmetic active ingredients. When administering NEs parenterally, various stabilisers are added to prevent rapid plasma clearance and to successfully deliver the active ingredient to the target site. For this purpose, PEGylation is often used to prolong the circulation time of the droplets. However, the problem is to determine the optimal concentration of the PEGylating agent – the PEGylation efficacy – that ensures adequate surface protection. This is a particular challenge when the active ingredient is incorporated into the stabilising layer, where any changes could disrupt the stability of the droplet. For this reason, we aimed to determine the optimal concentration of PEG2000-DSPE for surface protection of curcumin-loaded NEs for parenteral administration using electron paramagnetic resonance (EPR) spectroscopy. NEs were prepared using the high pressure homogenisation technique with 0.1 %, 0.3 % or 0.6 % of the PEGylated phospholipid. A droplet size of approximately 100 nm and polydispersity index below 0.25 indicated suitability for parenteral application. EPR analysis showed that PEG2000-DSPE had a stabilising effect on selected NEs, which was most pronounced in the part of the stabilising layer closest to the aqueous phase. To confirm these results, protein interaction studies were carried out using dynamic light scattering, UV–Vis spectroscopy, atomic force microscopy and release studies from protein-enriched media – bovine serum albumin (BSA) or foetal bovine serum (FBS) in phosphate-buffered saline. These analyses confirmed that the addition of PEG2000-DSPE reduced protein binding to the droplets as a function of concentration, with 0.3 % providing the best protection for the droplets. Our conclusions from the EPR spectroscopy study demonstrate the usefulness of EPR in determining the optimal concentrations of PEGylating agents for surface coverage and its usefulness in the formulation development phase

Nanoemulsions produced with varied type of emulsifier and oil content: An influence of formulation and process parameters on the characteristics and physical stability

The aim of the present study was to prepare oil-in-water nanoemulsions stabilized with a novel natural alkyl polyglucoside surfactant and to compare them with corresponding lecithin/polysorbate 80 - based nanoemulsions in terms of physicochemical properties and physical stability. Nanoemulsions were prepared by high pressure homogenization, using 20, 30 and 40% (w/w) medium chain triglyceride as oil phase, and 4, 6 and 8% (w/w) lecithin/polysorbate 80 mixture (1/1) or caprylyl/capryl glucoside as emulsifiers. The influence of emulsifier type, emulsifier concentration and oil content was investigated with respect to changes in particle size, particle size distribution, surface charge and physical stability. The influence of production parameters (number of homogenization cycles, type of homogenization process, homogenization pressure) on particle size was also investigated. Analysis was performed by photon correlation spectroscopy, laser diffraction, zeta potential, pH and electrical conductivity measurements. All formulations produced revealed a small droplet size ranging from 147 to 228 nm and a very narrow size distribution (polydispersity index range 0,072-0,124). Zeta potentials were about -20 mV and -50 mV for nanoemulsions stabilized with lecithin/polysorbate 80 and caprylyl/capryl glucoside, respectively. The results obtained during the stability studies (6 months at 25°C and 1 month at 40°C) indicated that nanoemulsion stability was influenced by their composition. Acquired results also suggested the most appropriate production parameters: 9 homogenization cycles, homogenization pressure of 500 bar and discontinuous process of homogenization