Dissolution test for oral suspension: an overview about use and importance

Abstract This work aims to ascertain the comprehensiveness of dissolution tests for oral suspensions registered in Brazil and the USA. After consulting literature since 1994, a paucity of information about dissolution methods for suspensions was detected. It makes it difficult to establish the most appropriate test parameters. In January, 2019, there were 46 drugs registered in Anvisa (Brazil) as oral suspension, being 47 reference, 173 generic and 114 interchangeable similar (IS) medicines; while in the USA, 90 drugs were registered as oral suspension by FDA, 235 Abreviatted New Drug Application and 111 New Drug Application medicines. Out of 46 and 90, only six and 15 drugs as oral suspension had a pharmacopeial dissolution test, corresponding to 70 (20.9%) and 82 (23.7%) products in Brazil and the USA, respectively. Dissolution studies were found for 17 drugs as oral suspension in the non-compendial literature. Dissolution test conditions were established to few marketable oral suspension drugs, most of which are BCS class II or IV. Thus, investing in dissolution studies could subsidize the registration of these products by regulators, especially for generic and IS drugs, by comparing dissolution profiles, and predicting their in vivo behavior to avoid exposure of healthy individuals to clinical research.

Preparation of high concentration protein powder suspensions by milling of lyophilizates.

Pharmaceutical formulations utilizing protein drugs as powders can be used as drug delivery systems in various ways. Besides powders for inhalation, another promising approach is their use as suspensions in non-aqueous liquids for subcutaneous administration providing high protein stability and good injectability. In this study protein powder suspensions were prepared using a swing-mill. Milling of lyophilizates containing a model monoclonal antibody in presence of the suspension vehicle was compared to cryogenic dry milling. Wet media milling led to injectable suspensions, but resulted in monomer loss and increase in protein aggregation. When the lyophilizates were cryogenic dry ball milled less aggregation and monomer loss were detected. Differences related to protein integrity were found for different process parameters, which were successfully optimized. If not cooled with liquid nitrogen, dry milling resulted in increased damage to the mAb. The type of polyol stabilizer, as well as the protein to stabilizer ratio, did not affect the preservation of protein integrity. As finding the right milling duration is time and resource intensive, a correlation between lyophilizate cake hardness and milling duration was established. Based on this approach high concentration lyophilizates were successfully micronized. Suspensions of cryogenic milled powders lead to clogging of 25G needles, which could be prevented by an additional sieving step. Depending on the suspension vehicle, low viscosity formulations (<10 mPa·s) even at high concentrations (≥100 mg/ml protein concentration) were obtained featuring good injectability.

Transplantation of autologous cells and porous gelatin microcarriers to promote wound healing.

Definitive treatment to achieve wound healing in major burns frequently include skin transplantation, where split-thickness skin grafts is considered gold standard. This method is associated with several drawbacks. To overcome these hurdles, efforts have been made to develop tissue engineered skin substitutes, often comprised of a combination of cells and biomaterials. In the present study, we aimed to investigate transplantation of autologous keratinocytes and fibroblasts seeded on porous gelatin microcarriers using a porcine wound model. Pre-seeded microcarriers were transplanted to a total of 168 surgical full-thickness wounds (2cm diameter) on eight adult female pigs and covered with occlusive dressings. The experimental groups included wounds transplanted with microcarriers seeded with the combination of keratinocytes and fibroblasts, microcarriers seeded with each cell type individually, microcarriers without cells, each cell type in suspension, and NaCl control. Wounds were allowed to heal for one, two, four or eight weeks before being excised and fixated for subsequent histological and immunohistochemical analysis. In vitro, we confirmed that viable cells populate the surface and the pores of the microcarriers. In vivo, the microcarriers were to a large extent degraded after two weeks. After one week, all treatment groups, with the exception of microcarriers alone, displayed significantly thicker neo-epidermis compared to controls. After two weeks, wounds transplanted with microcarriers seeded with cells displayed significantly thicker neo-epidermis compared to controls. After four weeks there was no difference in the thickness of neo-epidermis. In conclusion, the experiments performed illustrate that autologous cells seeded on porous gelatin microcarriers stimulates the re-epithelialization of wounds. This method could be a promising candidate for skin transplantation. Future studies will focus on additional outcome parameters to evaluate long-term quality of healing following transplantation.

Ultra-deformable liposomes containing terpenes (terpesomes) loaded fenticonazole nitrate for treatment of vaginal candidiasis: Box-Behnken design optimization, comparative ex vivo and in vivo studies.

Fenticonazole nitrate (FTN) is a potent antifungal drug adopted in the treatment of vaginal candidiasis. It has inadequate aqueous solubility hence, novel ultra-deformable liposomes 'Terpesomes' (TPs) were developed that might prevail over FTN poor solubility besides TPs might abstain the obstacles of mucus invasion. TPs were assembled by thin-film hydration then optimized by Box Behnken design utilizing terpenes ratio (X1), sodium deoxycholate amount (X2), and ethanol concentration (X3) as independent variable, whereas their impact was inspected for entrapment efficiency (Y1), particle size (Y2), and polydispersity index (Y3). Design Expert® was bestowed to select the optimal TP for more studies. The optimal TP had entrapment efficiency of 62.18 ± 1.39%, particle size of 310.00 ± 8.16 nm, polydispersity index of 0.20 ± 0.10, and zeta potential of -10.19 ± 0.2.00 mV. Elasticity results were greater in the optimal TP related to classical bilosomes. Further, ex vivo permeation illustrated tremendous permeability from the optimal TP correlated to classical bilosomes, and FTN suspension. Besides, in vivo assessment displayed significant inhibition effect in rats from FTN-TPs gel compared to FTN gel. The antifungal potency with undermost histopathological variation was detected in rats treated with FTN-TPs gel. Overall, the acquired findings verified the potency of utilizing FTN-TPs gel for treatment of vaginal candidiasis.

Acceleration of Skin Wound-Healing Reactions by Autologous Micrograft Tissue Suspension.

Background and objectives: Skin grafting is a method usually used in reconstructive surgery to accelerate skin regeneration. This method results frequently in unexpected scar formations. We previously showed that cutaneous wound-healing in normal mice is accelerated by a micrograft (MG) technique. Presently, clinical trials have been performed utilizing this technology; however, the driving mechanisms behind the beneficial effects of this approach remain unclear. In the present study, we focused on five major tissue reactions in wound-healing, namely, regeneration, migration, granulation, neovascularization and contraction. Methods: Morphometrical analysis was performed using tissue samples from the dorsal wounds of mice. Granulation tissue formation, neovascularization and epithelial healing were examined. Results: The wound area correlated well with granulation sizes and neovascularization densities in the granulation tissue. Vascular distribution analysis in the granulation tissue indicated that neovessels extended and reached the subepidermal area in the MG group but was only halfway developed in the control group. Moreover, epithelialization with regeneration and migration was augmented by MG. Myofibroblast is a known machinery for wound contraction that uses α-smooth muscle actin filaments. Their distribution in the granulation tissue was primarily found beneath the regenerated epithelium and was significantly progressed in the MG group. Conclusions: These findings indicated that MG accelerated a series of wound-healing reactions and could be useful for treating intractable wounds in clinical situations.

Preparation of hydroxy genkwanin nanosuspensions and their enhanced antitumor efficacy against breast cancer.

Hydroxy genkwanin (HGK), a flavonoid compound from natural resources, showed good inhibition against the growth of breast tumor cells. However, the poor solubility restricted the further study and the in vivo drug delivery of HGK. We prepared HGK nanosuspensions by antisolvent precipitation method and investigated their characterization, stability, hemolysis probability, release behavior in vitro, antitumor activity in vitro and in vivo, and preliminary safety through acute toxicity experiments. The resultant HGK nanosuspensions (HGK-NSps) showed an average diameter of (261.1 ± 4.8 nm), a narrow particle size distribution (PDI of 0.12 ± 0.01), spherical morphology, high drug-loading content (39.9 ± 2.3%, w/w), and good stability in various physiological media. HGK-NSps was safe for intravenous injection at low concentration and HGK was slowly released from the obtained nanosuspensions. HGK-NSps showed stronger cytotoxicity than free HGK against many tumor cells in vitro. Especially against MCF-7 cells, the IC50 value was decreased to 1.0 µg/mL, 5-fold lower than the HGK solution. In the in vivo antitumor activity study HGK-NSps (40 mg/kg) displayed a similar therapeutic effect to that of the paclitaxel injection (8 mg/kg). The preliminary acute toxicity test showed that even at the highest dose of 360 mg/kg (iv), HGK-NSps had 100% of mice survival and all the mice were in a good state, suggesting a maximum tolerated dose more than 360 mg/kg. The effective antitumor effect and good tolerance showed HGK-NSps were likely to become a safe and effective antitumor drug for the treatment of breast cancer in the future.

Rutin nanosuspension for potential management of osteoporosis: effect of particle size reduction on oral bioavailability, in vitro and in vivo activity.

Clinical significance of Rutin (RUT) is limited by poor dissolution rate and low oral bioavailability. The study was designed to improve the physicochemical and therapeutic potential of the drug by formulating nanosuspension (NS) for osteoporosis. Rutin nanosuspension (RUT-NS) was prepared after screening a range of stabilizers and their combinations at a different concentration by antisolvent precipitation technique. Effect of precipitation on crystallinity (differential scanning calorimetry DSC, X-ray diffraction studies XRD), morphology (scanning electron microscopy, SEM) and chemical interaction (attenuated total reflectance fourier-transform infrared spectroscopy ATR-FTIR) were studied through biophysical techniques. An optimized nanosuspension exhibited a minimum particle size of 122.85 ± 5.02 nm with higher dissolution of RUT-NS (87. 63 ± 2.29%) as compared to pure drug (39.77 ± 2.8 6%). The enhanced intestine absorption and apparent permeability were achieved due to the improved particle size, surface area and dissolution. RUT-NS displayed greater (3 folds) AUC0-24 h than pure drug. In vitro assays with RUT-NS depicted an increased cell proliferation, antioxidant (ROS) activity and osteocalcin production in MG-63 osteoblast cells. The augmented biochemical in vivo biomarkers and bone quality proved the protective effect of RUT-NS. The results supported RUT-NS as a potential therapy for maintaining bone health.

Washed microbiota transplantation vs. manual fecal microbiota transplantation: clinical findings, animal studies and in vitro screening.

Fecal microbiota transplantation (FMT) by manual preparation has been applied to treat diseases for thousands of years. However, this method still endures safety risks and challenges the psychological endurance and acceptance of doctors, patients and donors. Population evidence showed the washed microbiota preparation with microfiltration based on an automatic purification system followed by repeated centrifugation plus suspension for three times significantly reduced FMT-related adverse events. This washing preparation makes delivering a precise dose of the enriched microbiota feasible, instead of using the weight of stool. Intraperitoneal injection in mice with the fecal microbiota supernatant obtained after repeated centrifugation plus suspension for three times induced less toxic reaction than that by the first centrifugation following the microfiltration. The toxic reactions that include death, the change in the level of peripheral white blood cells, and the proliferation of germinal center in secondary lymphoid follicles in spleen were noted. The metagenomic next-generation sequencing (NGS) indicated the increasing types and amount of viruses could be washed out during the washing process. Metabolomics analysis indicated metabolites with pro-inflammatory effects in the fecal microbiota supernatant such as leukotriene B4, corticosterone, and prostaglandin G2 could be removed by repeated washing. Near-infrared absorption spectroscopy could be served as a rapid detection method to control the quality of the washing-process. In conclusion, this study for the first time provides evidence linking clinical findings and animal experiments to support that washed microbiota transplantation (WMT) is safer, more precise and more quality-controllable than the crude FMT by manual.

Enhancement of chitin suspension hydrolysis by a combination of ultrasound and chitinase.

This study evaluated the degradation kinetics and structural characteristics of chitin suspension (CS) with a combination of ultrasound and chitinase. Compared with the enzymolysis, the degradation degree of sonoenzymolysis was enhanced to the maximum by 27.93 % at an intensity of 25 W/mL for 20 min. According to degradation kinetics, ultrasound intensified molecular collision rate between chitinase and substrate, thereby increasing the degradation degree. What's more, combined with chitinase, ultrasound intensified the rate of the breakage of glycosidic bond and viscosity-average molecular weight (Mv) decrease, but no obvious change in acetylation degree (DA). Additionally, the intra- or inter-hydrogen bindings were weakened by ultrasound during sonoenzymolysis, leading to a slight decrease in crystalline index and a more ordered structure, which increased the accessibility of the substrate to enzyme. In conclusion, combination of chitinase and ultrasound could enhance the hydrolysis of CS while without changing its primary structure.

Antifungal prophylaxis with posaconazole tablet and oral suspension in patients with haematologic malignancy: Therapeutic drug monitoring, efficacy and risk factors for the suboptimal level.

BACKGROUND: Posaconazole is used to prevent invasive fungal infections (IFIs) in patients with haematologic malignancy. In this study, we compared plasma posaconazole concentrations (PPCs) and the incidence of breakthrough IFIs between patients with haematologic malignancy receiving posaconazole oral suspension vs tablet. METHODS: We retrospectively collected data on adult patients with haematologic malignancies who received posaconazole prophylaxis during chemotherapy from April 2014 through May 2018. A total of 242 cases with PPCs, 88 in the oral suspension group and 154 in the tablet group, were included in this study. RESULTS: Patients receiving tablets achieved a significantly higher mean PPC than did those on oral suspension (1.631 ± 0.878 µg/mL in the tablet group vs. 0.879 ± 0.585 µg/mL in the oral suspension group). One hundred and thirty-seven of 154 patients (89.0%) receiving tablets had PPCs of 0.7 µg/mL or more, while only 41 of 88 patients (46.6%) receiving oral suspension attained an optimal level (P < .001). The incidence of breakthrough IFIs was significantly higher in the oral suspension group compared with in the tablet group (14.8% of oral suspension vs. 4.5% of tablet; P = .005). In the analysis including patients receiving posaconazole tablets, hypoalbuminemia (< 3.5 g/dL) was found to be a risk factor associated with suboptimal levels (odds ratio: 8.872; 95% confidence interval: 3.011 - 26.141; P < .001). CONCLUSIONS: Suboptimal PPCs in the tablet group were less common than those in the oral suspension group. Therapeutic drug monitoring may be still necessary even in patients receiving posaconazole tablets, especially in those with hypoalbuminemia.

Equilibrium solubility study to determine fexofenadine hydrochloride BCS class and challenges in establishing conditions for dissolution profiles applied to suspension

The aim of this work was to perform solubility studies for fexofenadine hydrochloride and establish dissolution conditions for this drug in oral suspension dosage form. The solubility study was executed through the shake-flask method, below 37 ºC±1 ºC, at 100 rpm stirring for 12 h in three buffer solutions: hydrochloric acid pH 2.0, acetate pH 4.5 and phosphate pH 6.8. The dissolution test was developed in vessels containing 900 mL of the same buffer, employing the paddle apparatus in speed of 25 and 50 rpm, below 37 ºC±0.5 ºC. The drug was classified as low solubility according to the Biopharmaceutics Classification System, since the dose/solubility ratio was higher than 250 mL in all media tested (326.55 mL in buffer pH 2.0; 2,456.33 mL in buffer pH 4.5 and 1,021.16 mL in buffer pH 6.8). The dissolution test showed that a release of 85% in 30 min could be established. The rotation speed of 25 rpm, media volume of 900 mL and insertion of the samples through weighted syringes are adequate. The buffered media pH 2.0 could be chosen as dissolution media.

Effectiveness of Dettol Antiseptic Liquid for Inactivation of Ebola Virus in Suspension.

The efficacy of Dettol Antiseptic Liquid (DAL) for inactivating Ebola virus (Makona C07 variant) (EBOV/Mak) within an organic load in suspension was evaluated per ASTM E1052-11. Three DAL lots were evaluated at dilutions of 1:10, 1:20, and 1:40, with contact times of 0.5, 1, 5, and 10 min. Approximately 7 log10 tissue culture infectious dose50 (TCID50) of EBOV/Mak was exposed to DAL at ambient temperature. Each dilution tested reduced the infectious EBOV/Mak titer by ~5 log10 within one min. Detectable virus was still present after an 0.5-min exposure, but each DAL dilution caused >4 log10 reduction within this time. Detection of virus below the limit of detection of the TCID50 assay was assessed by inoculating flasks of Vero E6 cells with undiluted neutralized sample and evaluating the cultures for cytopathic effect after 14 days incubation. No infectious virus was detected with this non-quantitative method in samples subjected to DAL for 5 or 10 min, regardless of the dilution evaluated. The rapid and substantial inactivation of EBOV/Mak by DAL suggests that use of this hygiene product could help prevent the spread of Ebola virus disease during outbreaks.

Folate-modified Annonaceous acetogenins nanosuspensions and their improved antitumor efficacy.

Annonaceous acetogenins (ACGs) are a large family of fatty acid derived natural products that are exclusively isolated from the Annonaceae species. Many members of this diverse family have a broad spectrum of biological activities, the most impressive of which is anticancer activity. However, their poor solubility and severe toxicity restrict their clinical application, and their complicated composition hinders their formulation and drug delivery. In this study, ß-cyclodextrin was modified with folic acid (FA) and then combined with soybean lecithin to prepare FA-modified ACGs nanosuspensions (FA-ACGs-NSps). The obtained FA-ACGs-NSps had a high drug payload of 57.59% and average particle size of 199.5 nm, and they exhibited sustained drug release within 142 hours. In comparison with ACGs-NSps, FA-ACGs-NSps showed significantly enhanced cytotoxicity and higher cell uptake toward folate receptor-positive 4T1 cell lines. An in vivo study demonstrated that FA-ACGs-NSps more effectively accumulated in tumors and enhanced the antitumor therapeutic efficacy with less toxicity in 4T1 tumor bearing mice. Therefore, FA-ACGs-NSps may be a promising drug delivery system for ACGs to improve their therapeutic window and may be suitable for clinical application to treat folate-positive tumors.

Growth arrest of vascular smooth muscle cells in suspension culture using low-acyl gellan gum.

The proliferation of vascular smooth muscle cells (SMCs) causes restenosis in biomaterial vascular grafts. The purposes of this study were to establish a suspension culture system for SMCs by using a novel substrate, low-acyl gellan gum (GG) and to maintain SMCs in a state of growth inhibition. When SMCs were cultured in suspension with GG, their proliferation was inhibited. Their viability was 70% at day 2, which was maintained at more than 50% until day 5. In contrast, the viability of cells cultured in suspension without GG was 5.6% at day 2. By cell cycle analysis, the ratio of SMCs in the S phase when cultured in suspension with GG was lower than when cultured on plastic plates. In SMCs cultured in suspension with GG, the ratio of phosphorylated retinoblastoma (Rb) protein to Rb protein was decreased and p27Kip1 expression was unchanged in comparison with SMCs cultured on plastic plates. In addition, SMCs could be induced to proliferate again by changing the culture condition from suspension with GG to plastic plates. These results suggest that our established culturing method for SMCs is useful to maintain SMCs in a state of growth inhibition with high viability.

Cardiovascular safety pharmacology studies in dogs enabled for a poorly soluble molecule using spray-dried dispersion: Impact on lead selection.

The aim of this study was to identify an adequate formulation for a poorly soluble lead molecule (BI-A) that would achieve sufficiently high plasma concentrations after oral administration in dogs to enable a robust cardiovascular safety pharmacology assessment in telemetry-instrumented conscious dogs during lead optimization in drug discovery. A spray-dried dispersion of BI-A (BI-A-SDD) containing a 1:2 ratio of BI-A and hydroxypropyl methylcellulose acetate succinate-LF was prepared using a Büchi spray dryer B-90 (B-90). Physical form characterization, an in vitro dissolution test and a preliminary pharmacokinetic (PK) study following oral administration of BI-A-SDD were performed. Thereafter, effects on cardiovascular parameters in conscious, chronically-instrumented dogs were investigated for 24h after a single oral dose (5, 10, and 50mg/kg) using a modified Latin square cross-over study design. The BI-A-SDD powder was confirmed to be amorphous and was stable as an aqueous suspension for at least 4h. The BI-A-SDD suspension provided a greater rate and extent of dissolution than the crystalline BI-A suspension and the supersaturation was maintained for at least 4h. In PK studies the Cmax of the BI-A-SDD formulation (25.4µM; 77-fold the projected efficacious Cmax of 0.33µM) was 7.5-fold higher than the Cmax observed using oral administration of a 10% hydroxypropyl-ß-cyclodextrin formulation at 100mg/kg in dogs (3.4µM). In conscious, chronically-instrumented dogs, the doses tested and plasma concentrations achieved were sufficient to enable a robust safety pharmacology evaluation. Multiple off-target hemodynamic effects were detected including acute elevations in aortic blood pressure (up to 22% elevation in systolic and diastolic blood pressure) and tachycardia (68% elevation in heart rate), results that were confirmed in other in vivo models. These results led to a deprioritization of BI-A. The study demonstrated that a spray-dried dispersion, prepared using the B-90 in drug discovery, enhanced the oral exposure of a poorly water-soluble molecule, BI-A, and thereby enabled its evaluation in safety pharmacology studies that ultimately resulted in deprioritization of BI-A from a pool of lead compounds.

Comparative pharmaceutical study on colon targeted micro-particles of celecoxib: in-vitro-in-vivo evaluation.

In order to target celecoxib which is a COX2 inhibitor, with potentials in the prevention and treatment of colitis and colon cancer, it was formulated as microparticles using the solvent/evaporation method and various pH-dependent Eudragit polymers. The in-vitro evaluation of the prepared microparticles showed spherical and smooth morphology. The encapsulation efficiency and yield were high, indicating that the method used is simple and efficient at this scale. The in-vitro release study showed no release in the acidic medium for 2 h followed by the release of the drug in pH 6.8 in case of Eudragit L100-55 and L100 and pH 7.4 in case of Eudragit S100. The pharmacokinetic parameters were calculated and method validation was performed to insure that it is suitable and reliable. Pharmacokinetic parameters were investigated by determining the Cmax, Tmax, AUC0-t, Kel, and t1/2 of the drug as a suspension and as microparticles. There was a significant difference (p < 0.05) in Tmax between the drug as a suspension and as microparticles. The effect of celecoxib on the degree of inflammation was examined on acetic acid induced colitis rat model and the drug was given as a suspension and as microparticles. The evaluation was done using macroscopical, microscopical and biochemical examination. There was a significant difference between the acetic acid control group and the treatment groups regarding all examination criteria in the order microparticles formulated using Eudragit S100 followed by Eudragit L100-55 while microparticles using Eudragit L100 and drug suspension showed almost the same results.

Preclinical evaluation of a nanoformulated antihelminthic, niclosamide, in ovarian cancer.

Ovarian cancer treatment remains a challenge and targeting cancer stem cells presents a promising strategy. Niclosamide is an "old" antihelminthic drug that uncouples mitochondria of intestinal parasites. Although recent studies demonstrated that niclosamide could be a potential anticancer agent, its poor water solubility needs to be overcome before further preclinical and clinical investigations can be conducted. Therefore, we evaluated a novel nanosuspension of niclosamide (nano-NI) for its effect against ovarian cancer. Nano-NI effectively inhibited the growth of ovarian cancer cells in which it induced a metabolic shift to glycolysis at a concentration of less than 3 µM in vitro and suppressed tumor growth without obvious toxicity at an oral dose of 100 mg/kg in vivo. In a pharmacokinetic study after oral administration, nano-NI showed rapid absorption (reaching the maximum plasma concentration within 5 min) and improved the bioavailability (the estimated bioavailability for oral nano-NI was 25%). In conclusion, nano-NI has the potential to be a new treatment modality for ovarian cancer and, therefore, further clinical trials are warranted.

Nanosizing of valsartan by high pressure homogenization to produce dissolution enhanced nanosuspension: pharmacokinetics and pharmacodyanamic study.

PURPOSE: The purpose of the present study was to formulate and evaluate nanosuspension of Valsartan (VAL), a poorly water soluble and low bioavailable drug (solubility of 0.18 mg mL(-1); 23% of oral bioavailability) with the aim of improving the aqueous solubility thus the bioavailability and consequently better anti-hypertensive activity. METHODS: Valsartan nanosuspension (VAL-NS) was prepared using high-pressure homogenization followed by lyophilisation. The screening of homogenization factors influencing nanosuspension was done by 3-factorial, 3-level Box-Behnken statistical design. Model suggested the influential role of homogenization pressure and cycles on drug nanosizing. The optimized formulation containing Poloxamer(-1)88 (PXM 188) was homogenized for 2 cycles at 500 and 1000 bar, followed by 5 cycles at 1500 bars. RESULTS: The size analysis and transmission electron microscopy showed nanometric size range and uniform shape of the nanosuspension. The in vitro dissolution showed an enhanced release of VAL from nanosuspension (VAL-NS) compared to physical mixture with PXM 188. Pharmacodynamic results showed that, oral administration of VAL-NS significantly lowered (p ≤ 0.001) blood pressure in comparison to non-homogenized VAL (VAL-Susp) in Wistar rat. The level of VAL in rat plasma treated with VAL-NS showed significant difference (p ≤ 0.005) in Cmax (1627.47 ± 112.05 ng mL(-1)), Tmax (2.00 h) and AUC0→24 (13279.2 ± 589.426 ng h mL(-1)) compared to VAL-Susp that was found to be 1384.73 ± 98.76 ng mL(-1), 3.00 h and 9416.24 ± 218.48 ng h mL(-1) respectively. The lower Tmax value, proved the enhanced dissolution rate of VAL. CONCLUSION: The overall results proved that newly developed VAL-NS increased the plasma bioavailability and pharmacodyanamic potential over the reference formulation containing crude VAL.

Formulation and antifungal performance of natamycin-loaded liposomal suspensions: the benefits of sterol-enrichment.

The aim of this study is to develop and evaluate food-grade liposomal delivery systems for the antifungal compound natamycin. Liposomes made of various soybean lecithins are prepared by solvent injection, leading to small unilamellar vesicles (<130 nm) with controlled polydispersity, able to encapsulate natamycin without significant modification of their size characteristics. Presence of charged phospholipids and reduced content of phosphatidylcholine in the lecithin mixture are found to be beneficial for natamycin encapsulation, indicating electrostatic interactions of the preservative with the polar head of the phospholipids. The chemical instability of natamycin upon storage in these formulations is however significant and proves that uncontrolled leakage out of the liposomes occurs. Efficient prevention of natamycin degradation is obtained by incorporation of sterols (cholesterol, ergosterol) in the lipid mixture and is linked to higher entrapment levels and reduced permeability of the phospholipid membrane provided by the ordering effect of sterols. Comparable action of ergosterol is observed at concentrations 2.5-fold lower than cholesterol and attributed to a preferential interaction of natamycin-ergosterol as well as a higher control of membrane permeability. Fine-tuning of sterol concentration allows preparation of liposomal suspensions presenting modulated in vitro release kinetics rates and enhanced antifungal activity against the model yeast Saccharomyces cerevisiae.

Suspension-based differentiation of adult mesenchymal stem cells toward chondrogenic lineage.

Human mesenchymal stem cells (hMSCs) are derived from bone marrow and have the ability to differentiate into cartilage and other mesenchymal cell types found throughout the body. Traditionally, the differentiation of hMSCs toward chondrocytes occurs through a combination of pelleted static cell culture and chemical stimuli. As an alternative to these protocols, we developed an in vitro flow through microfluidic method to induce the differentiation of hMSCs into chondrocytes. Suspensions of unattached hMSCs were exposed to a constant shear flow over a period of 20 minutes, which promoted phenotypic and gene expression changes toward the chondrogenic lineage. These internal and external changes of chondrogenic differentiation were then observed over 3 weeks later in culture, as confirmed through fluorescent immunocytochemical staining and real-time quantitative reverse transcriptase polymerase chain reaction. The increased concentration of Type II collagen on the surface of shear stimulated hMSCs with the upregulation of MAPK1 and SOX9 demonstrated the capabilities of our approach to induce sustained differentiation. In conclusion, our shear stimulation method, in combination with chemical stimuli, illustrates enhanced differentiation of hMSCs toward the chondrogenic lineage.