Tacrolimus-loaded lecithin-based nanostructured lipid carrier and nanoemulsion with propylene glycol monocaprylate as a liquid lipid: Formulation characterization and assessment of dermal delivery compared to referent ointment.

Nanostructured lipid carriers (NLC) and nanoemulsions (NE) are colloid carriers which could improve dermal delivery of tacrolimus. The aims of this study were to evaluate effects of different formulation and process parameters on physicochemical characteristics and stability of lecithin-based NLC with glyceryl palmitostearate as solid and propylene glycol monocaprylate as liquid lipid and to compare the influence of different inner structure of tacrolimus-loaded NLC and corresponding NE on physicochemical characteristics, stability, entrapment efficiency, in vitro drug release and overall skin performance. Solid/liquid lipid ratio, total amount of lipids, homogenization pressure and cooling after the preparation were identified as critical variables in NLC development. Moreover, tacrolimus-loaded NLC emerged as more stabile carrier than NE. Differential stripping performed on porcine ear skin revealed significantly higher tacrolimus amount in stratum corneum from nanocarriers compared to referent ointment (Protopic®). Similarly the highest amount of tacrolimus in hair follicles was obtained using NLC (268.54 ±â€¯92.38 ng/cm2), followed by NE (128.17 ±â€¯48.87 ng/cm2) and Protopic® (77.61 ±â€¯43.25 ng/cm2). Contrary, the highest permeation rate through full-thickness porcine ear skin was observed for Protopic®, implying that the selection of experimental setup is critical for reliable skin performance assessment. Overall, developed NLC could be suggested as promising carrier in a form of lotion for tacrolimus dermal delivery.

Can sustained exposure to PFAS trigger a genotoxic response? A comprehensive genotoxicity assessment in mice after subacute oral administration of PFOA and PFBA.

PFAS (perfluoroalkyl substances) are considered non-genotoxic. However, PFAS exposure has been associated with the induction of oxidative stress in vitro and in vivo, and the possible induction of indirect genotoxic effects under sustained PFAS exposure has not been investigated. In order to shed light on this aspect, in this study a comprehensive assessment of genotoxicity was carried out in mice administered with perfluorooctanoic acid (PFOA, 0.1, 1 and 5 mg/kg body weight) and its C4 analogue perfluorobutyric acid (PFBA, 5 mg/kg body weight) for five weeks through drinking water. Markers of cell toxicity, oxidative stress and DNA strand breaks were measured in liver, the main target of toxicity of PFOA in rodents; systemic genotoxicity was also assessed by the analysis of micronuclei in reticulocytes and spleen lymphocytes, and germ cell effects by the Comet assay on testis cells. PFOA administration at the highest dose (5 mg/kg body weight) induced marked liver hypertrophy with signs of cell injury (elevated ALT and AST), with no concurrent evidence of lipid peroxidation and oxidative stress (decreased antioxidant capacity). Only mild liver hypertrophy, with no other signs of toxicity, was determined by PFBA administration. No evidence of treatment related genotoxicity was observed in any experimental group. Overall, data indicate that under the experimental conditions of this study, severe liver toxicity induced by PFOA administration is not associated with oxidative stress. Accordingly, no genotoxic effect is observed in liver and in the other tissues examined. Milder evidence of liver toxicity, with no genotoxicity, and a lower tendency to bioaccumulation were observed in PFBA treated mice.

Perfluorohexanoic acid toxicity, part I: Development of a chronic human health toxicity value for use in risk assessment.

Perfluorohexanoic acid (PFHxA) is a short-chain, six-carbon perfluoroalkyl acid (PFAA) and is a primary impurity, degradant, and metabolite associated with the short-chain fluorotelomer-based chemistry used globally today. The transition to short-chain fluorotelomer-based products as a cornerstone in replacement fluorochemistry has raised questions regarding potential human health risks associated with exposure to fluorotelomer-based substances and therefore, PFHxA. Here, we present a critical review of data relevant to such a risk assessment, including epidemiological studies and in vivo and in vitro toxicity studies that examined PFHxA acute, subchronic, and chronic toxicity. Key findings from toxicokinetic and mode-of-action studies are also evaluated. Sufficient data exist to conclude that PFHxA is not carcinogenic, is not a selective reproductive or developmental toxicant, and does not disrupt endocrine activity. Collectively, effects caused by PFHxA exposure are largely limited to potential kidney effects, are mild and/or reversible, and occur at much higher doses than observed for perfluorooctanoic acid (PFOA). A chronic human-health-based oral reference dose (RfD) for PFHxA of 0.25 mg/kg-day was calculated using benchmark dose modeling of renal papillary necrosis from a chronic rat bioassay. This RfD is four orders of magnitude greater than the chronic oral RfD calculated by the U.S. Environmental Protection Agency for PFOA. The PFHxA RfD can be used to inform public health decisions related to PFHxA and fluorotelomer precursors for which PFHxA is a terminal degradant. These findings clearly demonstrate that PFHxA is less hazardous to human health than PFOA. The analyses presented support site-specific risk assessments as well as product stewardship initiatives for current and future short-chain fluorotelomer-based products.

Assessment of gastric emptying in non-obese diabetic mice using a [13C]-octanoic acid breath test.

Gastric emptying studies in mice have been limited by the inability to follow gastric emptying changes in the same animal since the most commonly used techniques require killing of the animals and postmortem recovery of the meal(1,2). This approach prevents longitudinal studies to determine changes in gastric emptying with age and progression of disease. The commonly used [(13)C]-octanoic acid breath test for humans(3) has been modified for use in mice(4-6) and rats(7) and we previously showed that this test is reliable and responsive to changes in gastric emptying in response to drugs and during diabetic disease progression(8). In this video presentation the principle and practical implementation of this modified test is explained. As in the previous study, NOD LtJ mice are used, a model of type 1 diabetes(9). A proportion of these mice develop the symptoms of gastroparesis, a complication of diabetes characterized by delayed gastric emptying without mechanical obstruction of the stomach(10). This paper demonstrates how to train the mice for testing, how to prepare the test meal and obtain 4 hr gastric emptying data and how to analyze the obtained data. The carbon isotope analyzer used in the present study is suitable for the automatic sampling of the air samples from up to 12 mice at the same time. This technique allows the longitudinal follow-up of gastric emptying from larger groups of mice with diabetes or other long-standing diseases.

Comparing models for perfluorooctanoic acid pharmacokinetics using Bayesian analysis.

Selecting the appropriate pharmacokinetic (PK) model given the available data is investigated for perfluorooctanoic acid (PFOA), which has been widely analyzed with an empirical, one-compartment model. This research examined the results of experiments [Kemper R. A., DuPont Haskell Laboratories, USEPA Administrative Record AR-226.1499 (2003)] that administered single oral or iv doses of PFOA to adult male and female rats. PFOA concentration was observed over time; in plasma for some animals and in fecal and urinary excretion for others. There were four rats per dose group, for a total of 36 males and 36 females. Assuming that the PK parameters for each individual within a gender were drawn from the same, biologically varying population, plasma and excretion data were jointly analyzed using a hierarchical framework to separate uncertainty due to measurement error from actual biological variability. Bayesian analysis using Markov Chain Monte Carlo (MCMC) provides tools to perform such an analysis as well as quantitative diagnostics to evaluate and discriminate between models. Starting from a one-compartment PK model with separate clearances to urine and feces, the model was incrementally expanded using Bayesian measures to assess if the expansion was supported by the data. PFOA excretion is sexually dimorphic in rats; male rats have bi-phasic elimination that is roughly 40 times slower than that of the females, which appear to have a single elimination phase. The male and female data were analyzed separately, keeping only the parameters describing the measurement process in common. For male rats, including excretion data initially decreased certainty in the one-compartment parameter estimates compared to an analysis using plasma data only. Allowing a third, unspecified clearance improved agreement and increased certainty when all the data was used, however a significant amount of eliminated PFOA was estimated to be missing from the excretion data. Adding an additional PK compartment reduced the unaccounted-for elimination to amounts comparable to the cage wash. For both sexes, an MCMC estimate of the appropriateness of a model for a given data type, the Deviance Information Criterion, indicated that this two-compartment model was better suited to describing PFOA PK. The median estimate was 142.1 +/- 37.6 ml/kg for the volume of the primary compartment and 1.24 +/- 1.1 ml/kg/h for the clearances of male rats and 166.4 +/- 46.8 ml/kg and 30.3 +/- 13.2 ml/kg/h, respectively for female rats. The estimates for the second compartment differed greatly with gender-volume 311.8 +/- 453.9 ml/kg with clearance 3.2 +/- 6.2 for males and 1400 +/- 2507.5 ml/kg and 4.3 +/- 2.2 ml/kg/h for females. The median estimated clearance was 12 +/- 6% to feces and 85 +/- 7% to urine for male rats and 8 +/- 6% and 77 +/- 9% for female rats. We conclude that the available data may support more models for PFOA PK beyond two-compartments and that the methods employed here will be generally useful for more complicated, including PBPK, models.