Loading Effect on Particle Size Measurements by Inertial Sampling of Albuterol Metered Dose Inhalers

Purpose. The purpose of this study is to investigate the albuterol loading effect on particle size measurements by studying the effect of the amount of albuterol delivered, the number of puffs used, and the sampling techniques used in particle size measurement. Methods. Particle size distribution profiles for different albuterol loadings were evaluated using an 8-stage cascade impactor and a sensitive HPLC electrochemical assay method. A commercial albuterol MDI (Proventil^R) and other specially prepared albuterol MDIs were used in the study. Results. As the amount of albuterol was increased, either by increasing the number of puffs or the amount delivered per puff, the measured MMAD increased. This increase was more prominent in some formulations (Proventil^R) than others. Further, albuterol particles previously deposited on the valve and/or actuator didn't play a role in the observed multi-puff/loading effect. Conclusions. The collection of the least amount of aerosol in a cascade impactor provides a better estimate of MMAD, as it minimizes modifications of the collection surfaces.     

Properties of bioadhesive ketoprofen liquid suppositories: preparation,determination of gelation temperature,viscosity studies and evaluation of mechanical properties using texture analyzer by 4 × 4 factorial design

Abstract

Context: Development and evaluation of thermosensitive and bioadhesive liquid suppositories containing ketoprofen (KP).

Objective: This study was conducted to develope thermosensitive and bioadhesive liquid suppositories containing KP using poloxamer and different bioadhesive polymers and to investigate their gelation temperature, viscosity and mechanical properties.

Materials and methods: Bioadhesive liquid suppositories were prepared by the cold method using poloxamer 407 (P 407), Poloxamer 188 (P 188) and various amounts of different bioadhesive polymers. Their gelation temperatures, viscosity values and mechanical properties were determined using texture analyzer by 4?×?4 factorial design.

Results: It was seen that in presence of KP, gelation temperature of formulation P 407/P 188 (4/20%) significantly decreased from 64 to 37.1?°C. It is to be noted that addition of increasing concentrations of bioadhesive polymers lowered gelation temperature and its decrease was highest with addition of Carbopol 934 P (C). Results of texture profile analysis (TPA) showed that formulations containing C have significantly higher hardness and adhesiveness values than other bioadhesive formulations. According to TPA, gel structure of liquid suppository formulation F5, containing P 407/P 188/KP/C (4/20/2.5/0.8%), exhibited the greatest hardness, compressibilty, adhesiveness and besides greatest viscosity.

Discussion and conclusion: According to mechanical properties and viscosity values, it was concluded that F5 could be a promising formulation.     

The safety of ethambutol dihydrochloride dry powder formulations containing chitosan for the possibility of treating lung tuberculosis

Abstract

Objective: The aim of this study was to conduct in vitro studies of a dry powder formulation of ethambutol dihydrochloride (EDH) to determine if it was an acceptable candidate for further in vivo studies to target alveolar macrophages for the treatment of lung tuberculosis.

Materials and methods: Nanosized drug particles were prepared by optimizing the spray drying conditions. The cell toxicities were determined by interacting the formulations with respiratory cell lines (A549, calu-3 and NR8383 cell lines), and phagocytosis of the formulations was tested on a macrophage cell line. Permeations of the EDH formulations across a lipid bilayer were studied using the Ussing chamber and HPLC. Bioactivity tests of the formulations were carried out by using the resazurin method on M. bovis cells.

Result and discussion: Spray rate and inlet temperature were the two most important factors that affected the size and % yield of the product. The % cell viability of A549 cells with all EDH formulations, pure EDH and chitosan carrier was higher than 80%, the calu-3 cell line had % viabilities of between 85 and 99%, and the % viability of NR8383 cells was between 81 and 100%. The pure EDH had a minimum inhibitory concentration (MIC) of 2?µg/mL while the EDH formulations had MIC values of less than 1?µg/mL when tested against M. bovis. The formulation was completely phagocytized by the macrophage cells after 30?min. The permeability of pure EDH across lipid bilayer was 48.7% after 2?h while in the EDH formulations it was enhanced to 71%.

Conclusion: The EDH formulations showed a lower toxicity, higher potency and better permeation than the pure EDH. Thus, EDH DPI formulations could help to minimize the duration of treatment and the risk of developing multidrug resistance tuberculosis compared to the non-formulated EDH.     

Poloxamer-based in situ hydrogels for controlled delivery of hydrophilic macromolecules after intramuscular injection in rats

Abstract

This study is aimed to investigate the applicability of poloxamer 407 (P407) and 188 (P188)-based temperature-sensitive in situ hydrogel (TSHG) in sustained delivery of hydrophilic macromolecules following intramuscular administration. Polyethylene glycols (PEGs) with molecular weight of 5-, 20-, and 40-kDa were used as model drugs, which can represent the common size range of hydrophilic macromolecular drugs using TSHG. The correlation between the level of poloxamers and thermogelling transition temperatures (T_sol–gel) was established and two formulations “20% P407/10% P188” and “24% P407/10% P188” were chosen for further study. The results showed that the release kinetics of PEGs was close to zero order. Sustained in vivo behaviors were achieved by both of the two formulations for all the PEGs though variations were seen. Lower molecular weight PEG showed more remarkable pharmacokinetic improvements. No significant differences in pharmacokinetics were observed between the two formulations for the same PEG. This suggested that 20–24% P407/10% P188 formulations, with accordingly T_sol–gel in the range of 24.6?°C–31.7?°C, might be freely chosen to achieve comparable pharmacokinetics for hydrophilic macromolecular drugs after intramuscular injection.     

Plasma stable,pH-sensitive non-ionic surfactant vesicles simultaneously enhance antiproliferative effect and selectivity of Sirolimus

Abstract

Objective: The purpose of the present investigation was to prepare a plasma stable, pH-sensitive niosomal formulation to enhance Sirolimus efficacy and selectivity.

Materials and methods: pH-sensitive niosomal formulations bearing PEG-Poly (monomethyl itaconate)-CholC6 (PEG-PMMI-CholC6) copolymers and cholesteryl hemisuccinate (CHEMS) were prepared by a modified ethanol injection method and characterized with regard to pH-responsiveness and stability in human serum. The ability of pH-sensitive niosomes to enhance the Sirolimus cytotoxicity was evaluated in vitro using human erythromyeloblastoid leukemia cell line (K562) and compared with cytotoxicity effect on human umbilical vein endothelial cells (HUVEC).

Results and discussion: This study showed that both formulations can be rendered pH-sensitive property and were found to rapidly release their contents under mildly acidic conditions. However, the CHEMS-based niosomes lost their pH-sensitivity after incubation in plasma, whereas, PEG-PMMI-CholC6 niosomes preserved their ability to respond to pH change. Sirolimus encapsulated in pH-sensitive niosomes exhibited a higher cytotoxicity than the control conventional formulation on K562 cell line. On the other hand, both pH-sensitive niosomes showed lower antiproliferative effect on HUVEC cells.

Conclusion: Plasma stable, pH-sensitive PEG-PMMI-CholC6-based niosomes can improve the in vitro efficiency and also reduce the side effects of Sirolimus.     

Ability of Doxorubicin-Loaded Nanoparticles to Overcome Multidrug Resistance of Tumor Cells After Their Capture by Macrophages

Purpose. Investigation of the ability of doxorubicin-loaded nanoparticles (NP/Dox) to overcome multidrug resistance (MDR) when they have first been taken up by macrophages. Methods. The growth inhibition of P388 sensitive (P388) and resistant (P388/ADR) tumor cells was evaluated in a coculture system consisting of wells with two compartments. The tumor cells were seeded into the lower compartment, the macrophages were introduced into the upper part in which the drug preparations were also added. Results. Doxorubicin exerted lower cytotoxicity on tumor cells in coculture compared with direct contact. In P388/ADR, NP/Dox cytotoxicity was far higher than that of free doxorubicin (Dox). Three different formulations of cyclosporin A (either free (CyA), loaded to nanoparticles (NP/CyA) or in a combined formulation with doxorubicin (NP/Dox-CyA)), were added to modulate doxorubicin efficacy. The addition of cyclosporin A to Dox increased drug cytotoxicity. Both CyA added to NP/Dox and NP/Dox-CyA were able to bypass drug resistance. Conclusions. Despite the barrier role of macrophages, NP/Dox remained far more cytotoxic than Dox against P388/ADR. Both NP/ Dox + CyA and NP/Dox-CyA allowed to overcome MDR, but the last one should present greater advantagein vivo by confining both drugs in the same compartment, hence reducing the adverse effects.     

Safety of calcipotriene and betamethasone dipropionate foam for the treatment of psoriasis

ABSTRACT

Introduction: Psoriasis vulgaris is a chronic inflammatory skin disease characterized by well-demarcated red and scaly plaques. Most patients have mild disease that is usually controlled with topical treatment. Calcipotriene 0.05% and betamethasone dipropionate 0.064% (Cal/BD) in aerosol foam (Enstilar®) is a novel formulation, which has shown promising results in terms of efficacy and safety.

Areas covered: This review evaluates the safety profile of Cal/BD aerosol foam and also the key points regarding its efficacy. A literature search was performed in PubMed in November 2019 from the start of records. Additional references were searched and retrieved manually.

Expert opnion: Cal/BD aerosol foam has proven its efficacy, safety, and tolerability in several clinical trials and real clinical practice. It has also demonstrated higher efficacy than the ointment and gel formulations of the fixed combination. It has a low incidence of adverse events; nasopharyngitis and site application pain were the most frequently reported. Moreover, it is devoid of changes in calcium homeostasis and hypothalamic-pituitary-adrenal axis. As a result of its unique formulation, it is easily spread, is rapidly absorbed, and has a rapid onset of action. These features upgrade patient’s satisfaction and they may increase adherence to topical therapy.     

Aerosol particle generation from solution-based pressurized metered dose inhalers: a technical overview of parameters that influence respiratory deposition

Abstract

There are a multitude of formulation factors to consider when developing a solution-based pressurized metered dose inhaler (pMDI). Evaluation of these variables and their underpinning driving force has been performed over the years. Key components, including formulation composition and device design, play significant roles in determining the aerosol performance of these solution-based formulations. This review outlines research efforts that have focused on these essential governing factors, how the aerosol performance changes when these variables are modified and fundamental mechanisms affecting the delivery efficiency of such formulations.     

Preservative-free versus preserved brimonidine %0.15 preparations in the treatment of glaucoma and ocular hypertension: short term evaluation of efficacy,safety, and potential advantages

Abstract

Purpose: To compare the efficacy, safety, and potential advantages of the preservative-free versus preserved brimonidine %0.15 preparations in patients with primer open-angle glaucoma (POAG) or ocular hypertension (OHT).

Methods: Forty-two eyes of the 21 treatment-naive patients with POAG or OHT were enrolled in this study. Eyes were randomly assigned to receive brimonidine-purite 0.15% or preservative-free brimonidine 0.15% two times daily. Efficacy of the two eye drops was assessed by measuring the intraocular pressure (IOP) at 9–10 am at baseline and week 4. Safety and potential advantages of the drops were evaluated at weeks 4 in terms of ocular symptoms and tear parameters. Ocular symptom values of the patients were evaluated with a scale of 0–4 (0?=?no discomfort and 4?=?severe discomfort).

Results: Both of the brimonidine tartrate formulations resulted in statistically similar IOP reduction (preserved formulation; ?5.2?mmHg [22.9% reduction] preservative-free formulation; ?5.7?mmHg [24.1% reduction], p?=?0.37). It was found that brimonidine tartrate formulations with and without topical preservatives did not produce a statistically significant difference in pain, stinging, and blurred vision at the upon instillation (p?>?0.05). However, the burning sensation was significantly higher in the preservative-free formulation at the first instillation compared to the preserved formulation (p?=?0.01). Also, there was no statistically significant difference between the two formulations in terms of symptoms (itching, burning, tearing, stinging, and photophobia) and tear parameters during the day (p?>?0.05).

Conclusions: Although topical preservative-free brimonidine tartrate treated eyes had a more burning sensation at the first drop, the two formulations were similar in terms of ocular tolerability in the short term period. Also, both formulations were found to reduce IOP at a similar rate.     

Organ burden and pulmonary toxicity of nano-sized copper (II) oxide particles after short-term inhalation exposure

Introduction: Increased use of nanomaterials has raised concerns about the potential for undesirable human health and environmental effects. Releases into the air may occur and, therefore, the inhalation route is of specific interest. Here we tested copper oxide nanoparticles (CuO NPs) after repeated inhalation as hazard data for this material and exposure route is currently lacking for risk assessment.

Methods: Rats were exposed nose-only to a single exposure concentration and by varying the exposure time, different dose levels were obtained (C?×?T protocol). The dose is expressed as 6?h-concentration equivalents of 0, 0.6, 2.4, 3.3, 6.3, and 13.2?mg/m³ CuO NPs, with a primary particle size of 10 9.2–14?nm and an MMAD of 1.5?μm.

Results: Twenty-four hours after a 5-d exposure, dose-dependent lung inflammation and cytotoxicity were observed. Histopathological examinations indicated alveolitis, bronchiolitis, vacuolation of the respiratory epithelium, and emphysema in the lung starting at 2.4?mg/m³. After a recovery period of 22 d, limited inflammation was still observed, but only at the highest dose of 13.2?mg/m³. The olfactory epithelium in the nose degenerated 24?h after exposure to 6.3 and 13.2?mg/m³, but this was restored after 22 d. No histopathological changes were detected in the brain, olfactory bulb, spleen, kidney and liver.

Conclusion: A 5-d, 6-h/day exposure equivalent to an aerosol of agglomerated CuO NPs resulted in a dose-dependent toxicity in rats, which almost completely resolved during a 3-week post-exposure period.     

Montelukast nasal spray: formulation development and in vitro evaluation

Objectives: The aim of this study was to evaluate potential development of montelukast sodium (MTS) as a nasal spray.

Materials and methods: The formulations were prepared using hydroxypropyl cellulose (HPC) and carbomer 940 (C940). The prepared formulations were evaluated for clarity, pH, hydrodynamic size, zeta potential, viscosity, contact angle, surface tension, droplet size distribution, muco-adhesiveness, drug release, and stability. The suitable formulations were also assessed for their effects on nasal epithelial cells.

Results and discussion: At room temperature (25?°C), the formulation containing 0.01% w/v C940 exhibited suitable viscosity and rheological properties. Spray droplets were in ranges of 10–40?µm, which are suitable for nasal administration. The works of adhesion of the formulations containing HPC or C940 were in the range of 0.8–4.0 and 0.2–27 µJ, respectively. In addition, the formulation containing 0.01% w/v C940 and the 0.5–15?µg/50?µL concentrations of MTS showed no signs of cytotoxicity and did not open the tight junction of nasal epithelial cells.

Conclusion: The formulated MTS nasal spray is ideal for nasal administration for the treatment of allergic rhinitis. The formulation containing 0.01% w/v C940 had no toxicity nor alteration on the tight junction of nasal epithelial cells.     

Lung burdens and kinetics of multi-walled carbon nanotubes (Baytubes) are highly dependent on the disaggregation of aerosolized MWCNT

Abstract

Previous repeated inhalation exposure studies on rats with multi-walled carbon nanotubes (MWCNT, Baytubes®) suggested that their pulmonary toxicity was predominated by the morphology and density of the aggregated structure. Evidence of any disintegration of these structures in the lung did not exist. The objective of this study was to study as to which extent the formulation of pristine MWCNT as wet-dispersion changes the morphology of assemblage structures in the presence of disintegrated sub-structures. The focus was on the comparative inhalation dosimetry and kinetics of dry- and wet-dispersed Baytubes to better understand the cause of putative differences in pulmonary toxicity originating from pristine and rigorously formulated MWCNT. Rats were nose-only exposed to dry-dispersed and wet-dispersed Baytubes for 6-h at 25–30?mg/m³. Aerodynamic particle size measurements demonstrate substantial differences in the particle size of dry- (MMAD 2.6?µm) and wet-dispersed (MMAD 0.8?µm) MWCNT. Time-course changes of MWCNT retained in the lung were examined during a post-exposure period of 3 months. Lung burdens were analytically determined in digested lungs using the EC/OC total carbon method. Dosimetry was complemented by light and transmission electron microscopy (TEM) of MWCNT retained in alveolar macrophages (AM). As a result, the initially deposited pulmonary dose of MWCNT was three times higher following wet-dispersed MWCNT at essentially similar inhalation chamber concentrations. The elimination half-time of dry- and wet-dispersed MWCNT was 87 and 46?d, respectively. TEM provided evidence that wet-dispersed MWCNT were inhaled as disintegrated structures with distribution-patterns within the cytoplasm of AMs that differed appreciably from those of dry-dust exposed animals. In summary, this study shows that specialized technical processes to formulate MWCNT may have dramatic consequences on their pulmonary fate and associated toxicity. Such properties can only be revealed by the comparison of pulmonary toxicity with pulmonary (micro-)dosimetry and kinetics.     

Nasal in-situ gels for delivery of rasagiline mesylate: improvement in bioavailability and brain localization

Abstract

Intranasal thermosensitive gel for rasagiline mesylate (RM) was developed for effective treatment of Parkinson’s disease. Intranasal gels were prepared by combination of poloxamer 407 and poloxamer 188 (1:1) with mucoadhesive polymers (carbopol 934?P and chitosan). The formulations were evaluated for sol–gel transition temperature, in-vitro drug release and in-vivo mucociliary transit time. Further, optimal intranasal gel formulations were tested for in-vivo pharmacokinetic behavior, nasal toxicity studies and brain uptake studies. It was found that optimal formulations had acceptable gelation temperature (28–33?°C) and adequate in-vitro drug release profile. Pharmacokinetic study in rabbits showed significant (p?<?0.05) improvement in bioavailability (four- to six-folds) of the drug from intranasal gels than oral solution. Chronic exposure studies in Wistar rats showed that these intranasal gels were non-irritant and non-toxic to rat nasal mucosa. Estimation of RM in rat brain tissue showed significant (p?<?0.01) improvement in uptake of RM form intranasal gel formulations than nasal solution.     

In vitro and ex vivo toxicological testing of sildenafil-loaded solid lipid nanoparticles

Abstract

The aim of this study was to investigate the potential cytotoxicity of solid lipid nanoparticles (SLN) loaded with sildenafil. The SLNs were tested as a new drug delivery system (DDS) for the inhalable treatment of pulmonary hypertension in human lungs. Solubility of sildenafil in SLN lipid matrix (30:70 phospholipid:triglyceride) was determined to 1% sildenafil base and 0.1% sildenafil citrate, respectively. Sildenafil-loaded SLN with particle size of approximately 180?nm and monomodal particle size distribution were successfully manufactured using a novel microchannel homogenization method and were stable up to three months. Sildenafil-loaded SLN were then used in in vitro and ex vivo models representing lung and heart tissue. For in vitro models, human alveolar epithelial cell line (A459) and mouse heart endothelium cell line (MHEC5-T) were used. For ex vivo models, rat precision cut lung slices (PCLS) and rat heart slices (PCHS) were used. All the models were treated with plain SLN and sildenafil-loaded SLN in a concentration range of 0–5000?µg/ml of lipid matrix. The toxicity was evaluated in vitro and ex vivo by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Median lethal dose 50% (LD₅₀) values for A549 cells and PCLS were found to be in the range of 1200–1900?µg/ml while for MHEC5-T cells and precision cut heart slices values were found between 1500 and 2800?µg/ml. PCHS showed slightly higher LD₅₀ values in comparison to PCLS. Considering the toxicological aspects, sildenafil-loaded SLN could have potential in the treatment of pulmonary hypertension via inhalation route.     

Aerosol-based efficient delivery of azithromycin to alveolar macrophages for treatment of respiratory infections

The efficacy of aerosol-based delivery of azithromycin (AZM) for the treatment of respiratory infections caused by pathogenic microorganisms infected in alveolar macrophages (AMs) was evaluated by comparison with oral administration. The aerosol formulation of AZM (0.2?mg/kg) was administered to rat lungs using a Liquid MicroSprayer^®. The oral formulation of AZM (50?mg/kg) was used for comparison. Time-courses of concentrations of AZM in AMs following administration were obtained, and then the therapeutic availability (TA) was calculated. In addition, the area under the concentrations of AZM in AMs – time curve/minimum inhibitory concentration at which 90% of isolates ratio (AUC/MIC₉₀) were calculated to estimate the antibacterial effects in AMs. The TA of AZM in AMs following administration of aerosol formulation was markedly greater than that following administration of oral formulation. In addition, the AUC/MIC₉₀ of AZM in AMs was markedly higher than the effective values. This indicates that the aerosol formulation could be useful for the treatment of respiratory infections caused by pathogenic microorganisms infected in AMs. This study suggests that aerosolized AZM is an effective pulmonary drug delivery system for the treatment of respiratory infections.     

Formulation,characterization, in vitro and in vivo evaluation of castor oil based self-nano emulsifying levosulpiride delivery systems

Context: Levosulpiride (LSP) is a hydrophobic benzamide derivative used in the treatment of schizophrenia. SNEDDS were extensively practiced for systemic delivery of poorly aqueous soluble drugs to achieve maximum bioavailability.

Objective: The present study was focussed on the formulation, optimisation and evaluation of LSP SNEDDS using castor oil, for enhancement of drug absorption and bioavailability.

Materials and methods: Pseudo-ternary phase diagram was plotted to identify the range of SNEDDS components. Twenty formulations were designed, prepared and characterised by its particle size, zeta potential, viscosity, and stability. In vitro dissolution data modelling was performed. Microscopy, FTIR and in vivo bioavailability studies were conducted for optimum formulation.

Results, discussion and conclusion: F18 containing castor oil, 0.9?mL; PEG 600, 1.36?mL and Tween 80, 2.74?mL was found to be optimum. The optimised formulation had shown uniform globule size, no interactions of LSP with SNEDDS components and higher pharmacokinetic parameters than that of commercial preparation.     

Design and evaluation of oral nanoemulsion drug delivery system of mebudipine

Abstract

A nanoemulsion drug delivery system was developed to increase the oral bioavailability of mebudipine as a calcium channel blocker with very low bioavailability profile. The impact of nano-formulation on the pharmacokinetic parameters of mebudipine in rats was investigated. Nanoemulsion formulations containing ethyl oleate, Tween 80, Span 80, polyethylene glycol 400, ethanol and deionized water were prepared using probe sonicator. The optimum formulation was evaluated for physicochemical properties, such as particle size, morphology and stability. The particle size of optimum formulation was 22.8?±?4.0?nm. Based on the results of this study, the relative bioavailability of mebudipine nanoemulsion was enhanced by about 2.6-, 2.0- and 1.9-fold, respectively, compared with suspension, ethyl oleate solution and micellar solution. In conclusion, nanoemulsion is an interesting option for the delivery of poorly water soluble molecules, such as mebudipine.     

Development of a High Efficiency Dry Powder Inhaler: Effects of Capsule Chamber Design and Inhaler Surface Modifications

Purpose

The objective of this study was to explore the performance of a high efficiency dry powder inhaler (DPI) intended for excipient enhanced growth (EEG) aerosol delivery based on changes to the capsule orientation and surface modifications of the capsule and device.

Methods

DPIs were constructed by combining newly designed capsule chambers (CC) with a previously developed three-dimensional (3D) rod array for particle deagglomeration and a previously optimized EEG formulation. The new CCs oriented the capsule perpendicular to the incoming airflow and were analyzed for different air inlets at a constant pressure drop across the device. Modifications to the inhaler and capsule surfaces included use of metal dispersion rods and surface coatings. Aerosolization performance of the new DPIs was evaluated and compared with commercial devices.

Results

The proposed capsule orientation and motion pattern increased capsule vibrational frequency and reduced the aerosol MMAD compared with commercial/modified DPIs. The use of metal rods in the 3D array further improved inhaler performance. Coating the inhaler and capsule with PTFE significantly increased emitted dose (ED) from the optimized DPI.

Conclusions

High efficiency performance is achieved for EEG delivery with the optimized DPI device and formulation combination producing an aerosol with MMAD?<?1.5 μm, FPF_<5μm/ED?>?90%, and ED?>?80%.     

Development and in vitro evaluation of an oral SEDDS for desmopressin

Abstract

Context: Self-emulsifying drug delivery systems (SEDDS) are among most promising tools for improving oral peptide bioavailability.

Objective: In this study, in vitro protective effect of SEDDS containing desmopressin against presystemic inactivation by glutathione and α-chymotrypsin was evaluated.

Materials and methods: The partitioning coefficient (log P) of desmopressin was increased via hydrophobic ion pairing using anionic surfactants. Solubility studies were performed to select the appropriate solvents for SEDDS preparation. Subsequently, droplet size and emulsification properties of 22 SEDDS formulations were evaluated. Moreover, the peptide-surfactant complex was dissolved in two chosen SEDDS formulations. Finally, SEDDS containing desmopressin were characterized regarding lipase stability, toxicity, and in vitro protective effect toward glutathione and α-chymotrypsin.

Results: Desmopressin log P was increased from initial ?6.13 to 0.33 using sodium docusate. The resulting desmopressin docusate complex (DES/AOT) was incorporated in two different SEDDS formulations, containing Capmul 907 P as main solvent. DES/AOT-SEDDS-F4 (containing 0.07% w/w DES/AOT) was composed of 50% Capmul 907P, 40% Cremophor RH40, and 10% Transcutol. The comparatively more hydrophilic formulation DES/AOT-SEDDS-F15 (containing 0.25% w/w DES/AOT) consisted of 20% Capmul 907P, 40% Acconon MC8-2, and 40% Tween 20. Both formulations were stable toward digestion by lipase and protected desmopressin toward α-chymotrypsin degradation. Moreover, DES/AOT-SEDDS-F4 also protected the peptide from thiol/disulfide exchange reactions with glutathione and was not cytotoxic at a concentration of 0.375% (w/w).

Conclusion: DES/AOT-SEDDS-F4 protected desmopressin from in vitro glutathione and α-chymotrypsin degradation. DES/AOT-SEDDS-F4 was metabolically stable and nontoxic. Therefore, it could be considered as a potential delivery system for oral desmopressin administration.     

Importance of the HIF pathway in cobalt nanoparticle-induced cytotoxicity and inflammation in human macrophages

Abstract

Recent, unexpected high failure rates of metal-on-metal hip implants have reintroduced the issue of cobalt toxicity. An adverse reaction to cobalt ions and cobalt-induced lung injury occurs during environmental exposure and is now strictly controlled. Currently adverse reaction occurs to cobalt nanoparticles during wear and tear of metal-on-metal hip implants of which the underlying mechanism is not fully understood. The putative role of the hypoxia-inducible factor (HIF) pathway in the mechanism of cobalt nanoparticle (Co-NPs) toxicity was examined using the U937 cell line, human alveolar macrophages and monocyte-derived macrophages. Co-NPs (5–20?μg/ml)-induced cytotoxicity (viability ranged from 75% to <20% of control, respectively) and reactive oxygen species (ROS), whereas a comparable concentration of cobalt ions (Co(II); up to 350?μM) did not. Co-NPs induced HIF-1α stabilization. Addition of ascorbic acid (100?µM) and glutathione (1?mM) both prevented the increased ROS. However, only treatment with ascorbic acid reduced HIF-1α levels and prevented cell death, indicating that a ROS-independent pathway is involved in Co-NPs-induced cytotoxicity. Replenishing intracellular ascorbate, which is crucial in preventing HIF pathway activation, modified Co-induced HIF target gene expression and the inflammatory response, by decreasing interleukin-1 beta (IL-1β) mRNA and protein expression. Addition of glutathione had no effect on Co-NPs-induced HIF target gene expression or inflammatory response. Thus, Co-NPs induce the HIF pathway by depleting intracellular ascorbate, leading to HIF stabilization and pathway activation. This suggests a strong, ROS-independent role for HIF activation in Co-NPs-induced cytotoxicity and a possible role for HIF in metal-on-metal hip implant pathology.