Sistemi sa kontrolisanim otpuštanjem lekova zasnovani na mezoporoznoj silici i eritrocitnim membranama.

The main aim of this study is the development of two controlled drug delivery systems based on ordered mesoporous silica and erythrocyte membranes (in further text - ghosts) for two widely used drugs: fenofibrate and sodium diclofenac. In the first part of the study, in vitro and in vivo performance of ordered mesoporous silica (OMS) as a carrier for the poorly water soluble compound fenofibrate was evaluated. Fenofibrate was loaded into OMS via incipient wetness impregnation to obtain a 29% drug load and formulated into capsules. Two capsule dosage forms (containing 33.5 mg and 16.75 mg fenofibrate) were compared to the commercially available forms - Lipanthyl® (fenofibrate microcrystals) and Tricor® (fenofibrate nanocrystals). In vitro dissolution tests showed that the amount of fenofibrate released from Lipanthyl® and Tricor® was approximately 30%, whereas ca. 66 and 60% of the drug was released from OMS capsules containing 33.5 and 16.75 mg of fenofibrate, respectively. The in vivo study in dogs confirmed satisfying level of safety and tolerability of fenofibrate-OMS formulation (eq. 33.5 mg) with the potential to improve the absorption of fenofibrate. Though some variability in the data, this formulation was promising to be further investigated in a clinical trial setting. Subsequent clinical trial was conducted to assess the bioavailability-enhancing potential of ordered mesoporous silica in man. In this open-label, randomized, two-way cross-over study, 12 overnight fasted healthy volunteers received a single dose of fenofibrate formulated with ordered mesoporous silica or a marketed product based on micronized fenofibrate. Plasma concentrations of fenofibric acid, the pharmacologically active metabolite of fenofibrate, were monitored up to 96 hours post-dose. The rate (Cmax/dose increased by 77%; tmax reduced by 0.75 h) and extent of absorption (AUC0-24h/dose increased by 54%) of fenofibrate were significantly enhanced following administration of the ordered mesoporous silica based formulation. In the second part of the study controlled drug delivery system based on erythrocyte ghosts for amphiphilic compound sodium diclofenac was developed considering the differences between erythrocytes derived from two readily available materials - porcine slaughterhouse and outdated transfusion human blood. Starting erythrocytes, empty erythrocyte ghosts and diclofenac loaded ghosts were compared in terms of the encapsulation efficiency, drug releasing profiles, size distribution, surface charge, conductivity, surface roughness and morphology. The encapsulation of sodium diclofenac was performed by an osmosis based process - gradual hemolysis. During this process sodium diclofenac exerted mild and delayed antihemolytic effect and increased potassium efflux in porcine but not in outdated human erythrocytes. FTIR spectra revealed lack of any membrane lipid disorder and chemical reaction with sodium diclofenac in encapsulated ghosts. Localization in the suspension and spatial distribution (i. e. mapping) of residual hemoglobin in erythrocyte ghosts has been resolved by two photon excitation fluorescence microscopy. Outdated human erythrocyte ghosts with detected nanoscale damages and reduced ability to shrink had encapsulation efficiency of only 8%. On the other hand, porcine erythrocyte ghosts had encapsulation efficiency of 37% and relatively slow drug release rate. More preserved structure and functional properties of porcine erythrocytes related to their superior encapsulation and release performances, define them as more appropriate for the usage in sodium diclofenac encapsulation process.Glavni cilj ovog rada je razvoj dva sistema sa kontrolisanim otpuštanjem lekova zasnovanih na uređenoj mezoporoznoj silici i eritrocitnim membranama (u daljem tekstu duhovima) za dva leka u širokoj upotrebi: fenofibrat i natrijum diklofenak. U prvom delu ove studije ispitivane su in vitro i in vivo performase uređene mezoporozne silike kao nosača za slabo rastvorni lek fenofibrat. Mezoporozna silika je punjena fenofibratom metodom vlažne impregnacije incipijenta dok sadržaj leka ne dostigne 29%, a potom finalno formulisana kao kapusla. Dve vrste kapsula (koje sadrže 33.5 mg i 16.75 mg fenofibrata) poređene su sa komercijalno dostupnim oblicima - Lipantil® (fenofibrat mikrokristali) i Trikor® (fenofibrat nanokristali). In vitro testovi rastvorljivosti pokazali su da je količina fenofibrata oslobođenog iz Lipantila® i Trikora® aproksimativno iznosila 30% dok je oko 66 i 60% leka oslobođeno iz kapsula sa mezoporoznom silikom koje su sadržale 33.5 i 16.75 mg fenofibrata, respektivno. In vivo studija na psima potvrdila je zadovoljavajući nivo bezbednosti i tolerantnosti formulacija sa mezoporoznom silikom i fenofibratom (33.5 mg) kao i potencijal za poboljšanje apsorpcije fenofibrata. Uprkos variabilnosti dobijenih podataka, ova formulacija je bila obećavajuća za buduća klinička ispitivanja. Sledstvena klinička studija izvedena je sa ciljem da se proceni potencijal uređene mezoporozne silike da poboljša bioraspoloživost fenofibrata kod čoveka. U ovoj otvorenoj, randomizovanoj, dvostruko ukrštenoj studiji, 12 zdravih volontera je primilo pojedinačnu dozu fenofibrata formulisanog sa uređenom mezoporoznom silikom kao i komercijalni proizvod baziran na mikroniziranom fenofibratu. Plazma koncentracije fenofibrinske kiseline, farmakološki aktivnog metabolita fenofibrata bile su praćene 96 sati nakon uzete doze. Stepen (odnos Cmax/doza bio je povećan 77%, a tmax redukovano za 0,75 h) i obim apsorpcije (PIK0-24 h je bila uvećana za 54%) fenofibrata su bili značajno povećani nakon administracije formulacije zasnovane na uređenoj mezoporoznoj silici. U drugom delu studije razvijen je sistem sa kontrolisanim otpuštanjem za amfifilni lek natrijum diklofenak uz razmatranje razlika između eritrocita izolovanih iz dva lako dostupna materijala – svinjske otpadne klanične i prestarele humane krvi. Polazni eritrociti, prazni eritrocitni duhovi kao i inkapsulirani duhovi bili su poređeni u smislu efikasnosti inkapsulacije, profila oslobađanja leka, raspodele veličine, površinskog naelektrisanja, provodljivosti, hrapavosti površine i morfologije. Inkapsulacija natrijum diklofena izvedena je procesom zasnovanim na osmozi – gradualnom hemolizom. Tokom ovog procesa natrijum diklofenak ispoljio je blag i odložen antihemolitički efekat kao i povećan efluks kalijuma kod svinjskih ali ne i kod prestarelih humanih eritrocita. FTIR spektri su otkrili odsustvo narušavanja strukture membranskih lipida kao i hemijske reakcije između natrijum diklofena i inkapsuliranih duhova. Lokalizacija rezidualnog hemoglobina u suspenziji eritrocitinih duhova i njegova prostorna distribucija određeni su primenom dvofotonske fluorescentne mikroskopije. Prestareli humani eritrocitni duhovi sa detektovanim oštećenjma na površini i smanjenom sposobnošću da se skupljaju imali su efikasnost inkapsulacije od samo 8%. Sa druge strane, svinjski eritrocitni duhovi su imali efikasnost inkapsulacije od 37% i relativno nisku brzinu oslobađanja leka. Viši stepen očuvanosti strukture i funkcije svinjskih eritrocita posmatran kroz superiornije performanse inkapsulacije i oslobađanja leka, definiše ih kao pogodniji materijal za inkapsulaciju natrijum diklofena

Comparative studies on osmosis based encapsulation of sodium diclofenac in porcine and outdated human erythrocyte ghosts

The objective of our study was to develop controlled drug delivery system based on erythrocyte ghosts for amphiphilic compound sodium diclofenac considering the differences between erythrocytes derived from two readily available materials - porcine slaughterhouse and outdated transfusion human blood. Starting erythrocytes, empty erythrocyte ghosts and diclofenac loaded ghosts were compared in terms of the encapsulation efficiency, drug releasing profiles, size distribution, surface charge, conductivity, surface roughness and morphology. The encapsulation of sodium diclofenac was performed by an osmosis based process - gradual hemolysis. During this process sodium diclofenac exerted mild and delayed antihemolytic effect and increased potassium efflux in porcine but not in outdated human erythrocytes. FTIR spectra revealed lack of any membrane lipid disorder and chemical reaction with sodium diclofenac in encapsulated ghosts. Outdated human erythrocyte ghosts with detected nanoscale damages and reduced ability to shrink had encapsulation efficiency of only 8%. On the other hand, porcine erythrocyte ghosts had encapsulation efficiency of 37% and relatively slow drug release rate. More preserved structure and functional properties of porcine erythrocytes related to their superior encapsulation and release performances, define them as more appropriate for the usage in sodium diclofenac encapsulation process

Sistemi sa kontrolisanim otpuštanjem lekova zasnovani na mezoporoznoj silici i eritrocitnim membranama.

The main aim of this study is the development of two controlled drug delivery systems based on ordered mesoporous silica and erythrocyte membranes (in further text - ghosts) for two widely used drugs: fenofibrate and sodium diclofenac. In the first part of the study, in vitro and in vivo performance of ordered mesoporous silica (OMS) as a carrier for the poorly water soluble compound fenofibrate was evaluated. Fenofibrate was loaded into OMS via incipient wetness impregnation to obtain a 29% drug load and formulated into capsules. Two capsule dosage forms (containing 33.5 mg and 16.75 mg fenofibrate) were compared to the commercially available forms - Lipanthyl® (fenofibrate microcrystals) and Tricor® (fenofibrate nanocrystals). In vitro dissolution tests showed that the amount of fenofibrate released from Lipanthyl® and Tricor® was approximately 30%, whereas ca. 66 and 60% of the drug was released from OMS capsules containing 33.5 and 16.75 mg of fenofibrate, respectively. The in vivo study in dogs confirmed satisfying level of safety and tolerability of fenofibrate-OMS formulation (eq. 33.5 mg) with the potential to improve the absorption of fenofibrate. Though some variability in the data, this formulation was promising to be further investigated in a clinical trial setting. Subsequent clinical trial was conducted to assess the bioavailability-enhancing potential of ordered mesoporous silica in man. In this open-label, randomized, two-way cross-over study, 12 overnight fasted healthy volunteers received a single dose of fenofibrate formulated with ordered mesoporous silica or a marketed product based on micronized fenofibrate. Plasma concentrations of fenofibric acid, the pharmacologically active metabolite of fenofibrate, were monitored up to 96 hours post-dose. The rate (Cmax/dose increased by 77%; tmax reduced by 0.75 h) and extent of absorption (AUC0-24h/dose increased by 54%) of fenofibrate were significantly enhanced following administration of the ordered mesoporous silica based formulation. In the second part of the study controlled drug delivery system based on erythrocyte ghosts for amphiphilic compound sodium diclofenac was developed considering the differences between erythrocytes derived from two readily available materials - porcine slaughterhouse and outdated transfusion human blood. Starting erythrocytes, empty erythrocyte ghosts and diclofenac loaded ghosts were compared in terms of the encapsulation efficiency, drug releasing profiles, size distribution, surface charge, conductivity, surface roughness and morphology. The encapsulation of sodium diclofenac was performed by an osmosis based process - gradual hemolysis. During this process sodium diclofenac exerted mild and delayed antihemolytic effect and increased potassium efflux in porcine but not in outdated human erythrocytes. FTIR spectra revealed lack of any membrane lipid disorder and chemical reaction with sodium diclofenac in encapsulated ghosts. Localization in the suspension and spatial distribution (i. e. mapping) of residual hemoglobin in erythrocyte ghosts has been resolved by two photon excitation fluorescence microscopy. Outdated human erythrocyte ghosts with detected nanoscale damages and reduced ability to shrink had encapsulation efficiency of only 8%. On the other hand, porcine erythrocyte ghosts had encapsulation efficiency of 37% and relatively slow drug release rate. More preserved structure and functional properties of porcine erythrocytes related to their superior encapsulation and release performances, define them as more appropriate for the usage in sodium diclofenac encapsulation process.Glavni cilj ovog rada je razvoj dva sistema sa kontrolisanim otpuštanjem lekova zasnovanih na uređenoj mezoporoznoj silici i eritrocitnim membranama (u daljem tekstu duhovima) za dva leka u širokoj upotrebi: fenofibrat i natrijum diklofenak. U prvom delu ove studije ispitivane su in vitro i in vivo performase uređene mezoporozne silike kao nosača za slabo rastvorni lek fenofibrat. Mezoporozna silika je punjena fenofibratom metodom vlažne impregnacije incipijenta dok sadržaj leka ne dostigne 29%, a potom finalno formulisana kao kapusla. Dve vrste kapsula (koje sadrže 33.5 mg i 16.75 mg fenofibrata) poređene su sa komercijalno dostupnim oblicima - Lipantil® (fenofibrat mikrokristali) i Trikor® (fenofibrat nanokristali). In vitro testovi rastvorljivosti pokazali su da je količina fenofibrata oslobođenog iz Lipantila® i Trikora® aproksimativno iznosila 30% dok je oko 66 i 60% leka oslobođeno iz kapsula sa mezoporoznom silikom koje su sadržale 33.5 i 16.75 mg fenofibrata, respektivno. In vivo studija na psima potvrdila je zadovoljavajući nivo bezbednosti i tolerantnosti formulacija sa mezoporoznom silikom i fenofibratom (33.5 mg) kao i potencijal za poboljšanje apsorpcije fenofibrata. Uprkos variabilnosti dobijenih podataka, ova formulacija je bila obećavajuća za buduća klinička ispitivanja. Sledstvena klinička studija izvedena je sa ciljem da se proceni potencijal uređene mezoporozne silike da poboljša bioraspoloživost fenofibrata kod čoveka. U ovoj otvorenoj, randomizovanoj, dvostruko ukrštenoj studiji, 12 zdravih volontera je primilo pojedinačnu dozu fenofibrata formulisanog sa uređenom mezoporoznom silikom kao i komercijalni proizvod baziran na mikroniziranom fenofibratu. Plazma koncentracije fenofibrinske kiseline, farmakološki aktivnog metabolita fenofibrata bile su praćene 96 sati nakon uzete doze. Stepen (odnos Cmax/doza bio je povećan 77%, a tmax redukovano za 0,75 h) i obim apsorpcije (PIK0-24 h je bila uvećana za 54%) fenofibrata su bili značajno povećani nakon administracije formulacije zasnovane na uređenoj mezoporoznoj silici. U drugom delu studije razvijen je sistem sa kontrolisanim otpuštanjem za amfifilni lek natrijum diklofenak uz razmatranje razlika između eritrocita izolovanih iz dva lako dostupna materijala – svinjske otpadne klanične i prestarele humane krvi. Polazni eritrociti, prazni eritrocitni duhovi kao i inkapsulirani duhovi bili su poređeni u smislu efikasnosti inkapsulacije, profila oslobađanja leka, raspodele veličine, površinskog naelektrisanja, provodljivosti, hrapavosti površine i morfologije. Inkapsulacija natrijum diklofena izvedena je procesom zasnovanim na osmozi – gradualnom hemolizom. Tokom ovog procesa natrijum diklofenak ispoljio je blag i odložen antihemolitički efekat kao i povećan efluks kalijuma kod svinjskih ali ne i kod prestarelih humanih eritrocita. FTIR spektri su otkrili odsustvo narušavanja strukture membranskih lipida kao i hemijske reakcije između natrijum diklofena i inkapsuliranih duhova. Lokalizacija rezidualnog hemoglobina u suspenziji eritrocitinih duhova i njegova prostorna distribucija određeni su primenom dvofotonske fluorescentne mikroskopije. Prestareli humani eritrocitni duhovi sa detektovanim oštećenjma na površini i smanjenom sposobnošću da se skupljaju imali su efikasnost inkapsulacije od samo 8%. Sa druge strane, svinjski eritrocitni duhovi su imali efikasnost inkapsulacije od 37% i relativno nisku brzinu oslobađanja leka. Viši stepen očuvanosti strukture i funkcije svinjskih eritrocita posmatran kroz superiornije performanse inkapsulacije i oslobađanja leka, definiše ih kao pogodniji materijal za inkapsulaciju natrijum diklofena

Antioksidativna aktivnost etanolnih ekstrakata Thymus serpyllum

Wild Thyme (Thymus serpyllum, Lamiaceae) is a subshrub from the Lamiaceae family, with plants that are rich in essential oils and antioxidative polyphenolic substances. Reducing potential of phenolic compounds gives them a special role in the adsorption and neutralization of free radicals. In the present study, we used a method of maceration, lasting 15, 30, 60 and 90 minutes, degree of fragmentation 0.7, two types of solvent (50% and 96% ethanol) and ratio drugs:solvent 1:20. In Folin-Ciocalteu method, the higest total polyphenols content was obtained in 50% ethanolic extract after 90 minutes of extraction, while the lowest total polyphenols content was recorded in 96% ethanolic extract after 15 minutes (1173,21 mg GA/g DW and 102,56 mg GA/g DW, respectively). Ethanolic extracts were analized for antioxidant activity by using spectrophotometric methods, DPPH method and ABTS method. There is signifficant difference between antioxidant activity in 50% and in 96% ethanolic extracts. The worse result was obtained with 96% ethanol as extractant after 15 minutes of maceration (IC50 31,323 mg/ml and 0,116 mM Trolox/g DW). This study found that both total polyphenols and antioxidant activities determined were significantly affected by the type of solvent and time of extraction. Also, the levels of total soluble phenolic compounds were positively correlated with free radical scavenging activities against DPPH and ABTS radicals.Majčina dušica (Thymus serpyllum, Lamiaceae) je višegodišnji busen iz familije Lamiaceae, koju čine biljke bogate etarskim uljima i antioksidativnim polifenolnim supstancama. Antioksidativnu aktivnost fenolne komponente duguju svom redukujućem potencijalu, koji im daje posebnu ulogu u adsorpciji i neutralizaciji slobodnih radikala. U ovoj studiji ekstrakti T. serpyllum su dobijeni metodom maceracije, u trajanju od 15, 30, 60 i 90 minuta, korišćenjem droge stepena usitnjenosti 0,7, dva rastvarača (50% i 96% etanola) i odnosa droga:rastvarač 1:20. FolinCiocalteu metodom je određen sadržaj ukupnih polifenola, gde je 50% etanolni ekstrakt, nakon 90 minuta ekstrakcije sadržao najveću količinu ukupnih polifenola, dok su najniže vrednosti zabeležene kod 96% etanolnog ekstrakta, nakon 15 minuta (1173,21 mg GA/g suve droge, odnosno 102,56 mg GA/g suve droge). Primenom spektrofotometrijskih metoda, DPPH metode i ABTS metode, određena je antioksidativna aktivnost 50% i 96% etanolnih ekstrakata T. serpyllum. Statistika je pokazala da postoji značajna razlika između antioksidativnog kapaciteta 50% i 96% etanolnih ekstrakata. Najlošiju antioksidativnu aktivnost poseduje 96% etanolni ekstrakt, nakon 15 minuta ekstrakcije (IC50 31,323 mg/ml i 116 mM Troloxa/g suve droge). Sadržaj ukupnih fenola i antioksidativna aktivnost ekstrakata zavise od tipa rastvarača korišćenog za ekstrakciju i vremena ekstrakcije. Ovaj rad pokazuje da postoji pozitivna korelacija između sadržaja ukupnih polifenola i kapaciteta neutralizacije DPPH i ABTS radikala

Određivanje osmotskih osobina životinjskih eritrocita protočnom citometrijom u cilju njihovog inženjeringa kao nosača lekova

Despite the fact that the methods based on the osmotic properties of the cells are the most widely used for loading of drugs in human and animal erythrocytes, data related to the osmotic properties of erythrocytes derived from animal blood are scarce. This work was performed with an aim to investigate the possibility of use the flow cytometry as a tool for determination the osmotic behaviour of porcine and bovine erythrocytes, and thus facilitates the engineering of erythrocytes from animal blood to be drug carriers. The method of flow cytometry successfully provided the information about bovine and porcine erythrocyte osmotic fragility, and made the initial steps in assessment of erythrocyte shape in a large number of erythrocytes. Although this method is not able to confirm the swelling of porcine erythrocytes, it indicated the differences in porcine erythrocytes that had basic hematological parameters inside and outside the reference values. In order to apply/use the porcine and bovine erythrocytes as drug carriers, the method of flow cytometry, confirming the presence of osmotically different fractions of red blood cells, indicated that various amounts of the encapsulated drug in porcine and bovine erythrocytes can be expected.Uprkos činjenici da su metode koje se baziraju na osmotskim osobinama ćelija najčešće korišćene metode za inkapsulaciju lekova u humane i životinjske eritrocite, podaci o osmotskim osobinama eritrocita životinjskog porekla su vrlo oskudni. Cilj ovog rada bio je ispitivanje mogućnosti korišćenja metode protočne citometrije za određivanje osmotskih osobina svinjskih i goveđih eritrocita, čime bi se olakšao inženjering pomenutih životinjskih eritrocita za otpuštanje lekova. Metodom protočne citometrije uspešno su dobijene informacije o osmotskoj fragilnosti svinjskih i goveđih eritrocita i načinjeni su početni koraci u proceni oblika velikog broja eritrocita. Iako ova metoda nije uspela da potvrdi bubrenje svinjskih eritrocita, ukazala je na razliku u uzorcima svinjskih eritrocita koji su imali osnovne hematološke parametre izvan i unutar referentnih vrednosti. U cilju primene svinjskih i goveđih eritrocita kao nosača lekova, metoda protočne citometrije je, potvrdivši prisustvo osmotski različitih frakcija eritrocita, ukazala na to da se različite količine inkapsuliranog leka u pojedinačnim, kako svinjskim, tako i goveđim eritrocitima mogu očekivati

Mapping of hemoglobin in erythrocytes and erythrocyte ghosts using two photon excitation fluorescence microscopy

The present study describes utilization of two photon excitation fluorescence (2PE) microscopy for visualization of the hemoglobin in human and porcine erythrocytes and their empty membranes (i.e., ghosts). High-quality, label-and fixation-free visualization of hemoglobin was achieved at excitation wavelength 730 nm by detecting visible autofluorescence. Localization in the suspension and spatial distribution (i.e., mapping) of residual hemoglobin in erythrocyte ghosts has been resolved by 2PE. Prior to the 2PE mapping, the presence of residual hemoglobin in the bulk suspension of erythrocyte ghosts was confirmed by cyanmethemoglobin assay. 2PE analysis revealed that the distribution of hemoglobin in intact erythrocytes follows the cells' shape. Two types of erythrocytes, human and porcine, characterized with discocyte and echinocyte morphology, respectively, showed significant differences in hemoglobin distribution. The 2PE images have revealed that despite an extensive washing out procedure after gradual hypotonic hemolysis, a certain amount of hemoglobin localized on the intracellular side always remains bound to the membrane and cannot be eliminated. The obtained results open the possibility to use 2PE microscopy to examine hemoglobin distribution in erythrocytes and estimate the purity level of erythrocyte ghosts in biotechnological processes

In Vivo Performance of Fenofibrate Formulated With Ordered Mesoporous Silica Versus 2-Marketed Formulations: A Comparative Bioavailability Study in Beagle Dogs

The present study aims to evaluate the in vitro and in vivo performance of ordered mesoporous silica (OMS) as a carrier for the poorly water-soluble compound fenofibrate. Fenofibrate was loaded into OMS via incipient wetness impregnation to obtain a 29% drug load and formulated into capsules. Two capsule dosage forms (containing 33.5 and 16.75 mg fenofibrate, respectively) were compared with the commercially available forms-Lipanthyl (R) (fenofibrate microcrystals) and Tricor (R) (fenofibrate nanocrystals). In vitro dissolution tests showed that the amount of fenofibrate released from Lipanthyl (R) and Tricor (R) was approximately 30%, whereas approximately 66% and 60% of the drug was released from OMS capsules containing 33.5 and 16.75 mg of fenofibrate, respectively. Storage of OMS capsules loaded with 33.5 mg of fenofibrate at 25 degrees C/60% relative humidity (RH) or 40 degrees C/75% RH did not alter the release kinetics, nor the physical state of the compound, pointing the stability of the present formulation. The in vivo study in dogs confirmed satisfying level of safety and tolerability of fenofibrate-OMS formulation (eq. 33.5 mg) with the potential to improve the absorption of fenofibrate. Though some variability in the data, this formulation is promising to be further investigated in a clinical trial setting

Ordered mesoporous silica to enhance the bioavailability of poorly water-soluble drugs: Proof of concept in man

Formulating poorly water soluble drugs using ordered mesoporous silica materials is an emerging approach to tackle solubility-related bioavailability problems. The current study was conducted to assess the bioavailability-enhancing potential of ordered mesoporous silica in man. In this open-label, randomized, two-way cross-over study, 12 overnight fasted healthy volunteers received a single dose of fenofibrate formulated with ordered mesoporous silica-or a marketed product based on micronized fenofibrate. Plasma concentrations of fenofibric acid, the pharmacologically active metabolite of fenofibrate, were monitored up to 96 h post-dose. The rate (C-max/dose increased by 77%; t(max) reduced by 0.75 h) and extent of absorption (AUC(0-24h)/dose increased by 54%) of fenofibrate were significantly enhanced following administration of the ordered mesoporous silica based formulation. The results of this study serve as a proof of concept in man for this novel formulation approach

Erythrocyte membranes from slaughterhouse blood as potential drug vehicles: Isolation by gradual hypotonic hemolysis and biochemical and morphological characterization

The present study was aimed at investigating the effect of isolation process-gradual hypotonic hemolysis on chosen parameters of the erythrocyte membranes (ghosts) originating from bovine and porcine slaughterhouse blood. The estimation of the gradual hypotonic hemolysis as a drug loading procedure for the erythrocyte ghosts was performed as well. Based on the results derived from analysis of the osmotic properties of the erythrocytes, the gradual hemolysis was performed with high volume of erythrocytes and 35 mM hypotonic sodium-phosphate/NaCl, enabling >90% of hemolysis for both types of erythrocytes. Detailed insight into ghosts' morphology by field emission-scanning electron microscopy revealed a distortion from erythrocyte shape and an altered surface texture with increased bilayer curvature for both samples. Compared to erythrocytes, an average diameter of ghosts from both type of erythrocytes decreased for only about 10%. The reported unidispersity of the isolated ghosts is of great importance for their potential application as vehicles of active compounds. Gradual hemolysis did not lead to substantial loss of cholesterol and membrane/cytoskeleton proteins. This result indicated the ghosts' possibility to mimic the chemical and structural anisotropic environment of in vivo cell membranes, which is of significance for drug diffusion and partition coefficients. Induced shift of phosphatidylserine to external surface of the ghosts demonstrated their potential application as vehicles for targeted drug delivery to cells of reticuloendothelial system. Ultra high-performance liquid chromatography and Fourier transform infrared spectroscopy revealed the presence of a drug model - dexamethasone-sodium phosphate, and its interaction with structural components in both types of erythrocyte ghosts