Effects of polyethylene glycol 400 (PEG 400) following 13 weeks of gavage treatment in Fischer-344 rats

A Green and Effective Polyethylene Glycols-Based Microwave-Assisted Extraction of Carnosic and Rosmarinic Acids from Rosmarinus officinalis Leaves

Rosmarinus officinalis leaves (ROLs) are widely used as a popular culinary spice for flavoring food, in which carnosic acid (CA) and rosmarinic acid (RA) are the main active components. The extraction of CA and RA is limited by lowextraction efficiency and extraction rate. In this work, a microwave-assisted extraction (MAE) method using biodegradable, low-toxic and nonflammable solvents polyethylene glycols (PEGs) as extraction solvents was developed for theextraction of CA and RA from ROLs. Experimental results suggest that PEG-400 was a better choice compared with PEG-200, and the optimal extraction conditions were as follows: 45% of PEG-400, 4.3% of phosphoric acid, 20 s of microwave irradiation time at 280 W of microwave irradiation power, and a 10 mg mL^-1 solid-liquid ratio, respectively. The tissue structures of ROLs could be effectively disrupted by PEG-based MAE, leading to high CA and RA extraction efficiencies. The PEG-400 extract exhibited stronger 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability compared with butylated hydroxytoluene (BHT). Finally, compared with heating reflux extraction, ultrasound-assisted extraction, maceration, and MAE using ionic liquid and ethanol as extraction solvents, the developed PEG-400 based MAE exhibited the highest extraction ability and fastest extraction rate for CA and RA. These findings suggest that MAE using PEGs as extraction solvents is a promising method for the separation of bioactive compounds from natural plants.

Sex-Specific Response of the Brain Free Oxylipin Profile to Soluble Epoxide Hydrolase Inhibition

Oxylipins are the oxidation products of polyunsaturated fatty acids and have been implicated in neurodegenerative disorders, including dementia. Soluble epoxide hydrolase (sEH) converts epoxy-fatty acids to their corresponding diols, is found in the brain, and its inhibition is a treatment target for dementia. In this study, male and female C57Bl/6J mice were treated with an sEH inhibitor (sEHI), trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid (t-AUCB), for 12 weeks to comprehensively study the effect of sEH inhibition on the brain oxylipin profile, and modulation by sex. Ultra-high-performance liquid chromatography-tandem mass spectrometry was used to measure the profile of 53 free oxylipins in the brain. More oxylipins were modified by the inhibitor in males than in females (19 versus 3, respectively) and favored a more neuroprotective profile. Most were downstream of lipoxygenase and cytochrome p450 in males, and cyclooxygenase and lipoxygenase in females. The inhibitor-associated oxylipin changes were unrelated to serum insulin, glucose, cholesterol, or female estrous cycle. The inhibitor affected behavior and cognitive function as measured by open field and Y-maze tests in males, but not females. These findings are novel and important to our understanding of sexual dimorphism in the brain's response to sEHI and may help inform sex-specific treatment targets.

Multiscale Spectral Analysis on Lysozyme Aqueous Solutions in the Presence of PolyEthyleneGlycol

Infrared spectroscopy measurements were performed on Lysozyme aqueous solutions also in the presence of PolyEthylene Glycol (PEG 400) as a function of an increasing temperature from T = 27 °C to 90 °C, and, successively in sequence, by decreasing temperatures from T = 90 °C to 27 °C. Data were analyzed by evaluating the spectral difference with respect to the initial spectrum collected at 27 °C. This procedure allows to quantitatively evaluate the thermal restraint related to the thermal scan from T = 27 °C to 90 °C, as well as to introduce a spectral resilience concerning the entire increasing and decreasing thermal paths which allow to highlight the bioprotectant effectiveness of low molecular weight PEG. In particular, the main purpose of the present work is to highlight the effects of a thermal treatment on a mixture of Lysozyme/water and of Lysozyme/water/PEG 400 during an increasing temperature scan, and then after a successive decreasing temperature scan, in order to highlight the bioprotectant role of PEG 400. On that score, an evaluation of the spectral distances of the registered spectra as a function of increasing and decreasing temperatures has been performed and analyzed.

High Glycemia and Soluble Epoxide Hydrolase in Females: Differential Multiomics in Murine Brain Microvasculature

The effect of a high glycemic diet (HGD) on brain microvasculature is a crucial, yet understudied research topic, especially in females. This study aimed to determine the transcriptomic changes in female brain hippocampal microvasculature induced by a HGD and characterize the response to a soluble epoxide hydrolase inhibitor (sEHI) as a mechanism for increased epoxyeicosatrienoic acids (EETs) levels shown to be protective in prior models of brain injury. We fed mice a HGD or a low glycemic diet (LGD), with/without the sEHI (t-AUCB), for 12 weeks. Using microarray, we assessed differentially expressed protein-coding and noncoding genes, functional pathways, and transcription factors from laser-captured hippocampal microvessels. We demonstrated for the first time in females that the HGD had an opposite gene expression profile compared to the LGD and differentially expressed 506 genes, primarily downregulated, with functions related to cell signaling, cell adhesion, cellular metabolism, and neurodegenerative diseases. The sEHI modified the transcriptome of female mice consuming the LGD more than the HGD by modulating genes involved in metabolic pathways that synthesize neuroprotective EETs and associated with a higher EETs/dihydroxyeicosatrienoic acids (DHETs) ratio. Our findings have implications for sEHIs as promising therapeutic targets for the microvascular dysfunction that accompanies vascular dementia.

Acute Oral Toxicity Evaluation of Andrographolide Self-Nanoemulsifying Drug Delivery System (SNEDDS) Formulation

Context:

Andrographolide (AND) is an active compound of well-known medicinal plant Andrographis paniculata. It has been widely published for various activities. AND is difficult to develop into dosage form due to its poor solubility and bioavailability. This problem could be solved by using self-nanoemulsifying drug delivery system (SNEDDS) for its formulation. However, the increase of bioavailability might result in potential toxicity as a large amount of drug is absorbed.

Aims:

The aim of this study is to evaluate the acute potential toxicity using Organization for Economic Cooperation and Development (OECD) test: 401 methods.

Subjects and Methods:

The OECD 401 method employs groups of animals treated by a single dose or repeated dose (<24 h) of the drug with three variances of doses. In this study, thirty male Wistar rats were divided into five groups which consisted two groups of control and three groups of AND SNEDDS formulation (500, 700, and 900 mg/kg body weight [BW], respectively). Intensive observation of toxicity symptom was performed during the first 30 minutes followed by periodic observation for 14 days. Posttermination, histopathological examination of the liver and kidney was conducted to confirm the toxicity symptoms. To determine the level of toxicity, the lethal dose 50 (LD₅₀) value was calculated at the end of the study.

Results:

The result showed that all groups presented similar toxicological symptoms such as salivation, lethargy, and cornea reflex. However, based on histopathological examination, there were abnormalities, but still in an early stage. The toxicological symptom that emerged seems related to the SNEDDS formulation with lipophilic properties. Furthermore, the value of LD₅₀ was 832.6 mg/kg BW (po).

Conclusions:

The AND SNEDDS formulation was slightly toxic in male Wistar rats po.

A novel glucokinase activator TMG-123 causes long-lasting hypoglycemia and impairs spermatogenesis irreversibly in rats

The importance of glucose is well known as an energy source in testes. In order to evaluate the effects of long-lasting hypoglycemia on testes, a novel glucokinase activator, TMG-123, was dosed to rats at 5, 20 and 100 mg/kg for 13 weeks. As a result, plasma glucose levels decreased for several hours with increasing doses over the dose range of 5 to 100 mg/kg. No toxicological findings attributable to the test article were observed in clinical observation, measurements of body weight and food consumption, necropsy, and organ weight measurement. Histopathology showed scattered degeneration of seminiferous tubules in testes, and exfoliation of germ cells related to the degeneration of seminiferous tubules was observed in the lumen of both epididymides in the same animals at the end of the dosing period. Similar histopathological findings were noted at the end of the recovery period. In addition, a fertility study was conducted at the same doses for 13 weeks for males and 5 weeks for females. Sperm analysis showed decreases in the sperm concentration and the motility index and an increase in the incidences of sperm malformations. However, there were no abnormalities in the copulation or fertility rate. These results suggest that long-lasting hypoglycemia in rats is harmful to spermatogenesis and the testicular damage does not recover.

Xanthone-enriched fraction of Garcinia mangostana and α-mangostin improve the spatial learning and memory of chronic cerebral hypoperfusion rats

Objectives

Xanthones isolated from the pericarp of Garcinia mangostana has been reported to exhibit neuroprotective effect.

Methods

In this study, the effect of xanthone-enriched fraction of Garcinia mangostana (XEFGM) and α-mangostin (α-MG) were investigated on cognitive functions of the chronic cerebral hypoperfusion (CCH) rats.

Key findings

HPLC analysis revealed that XEFGM contained 55.84% of α-MG. Acute oral administration of XEFGM (25, 50 and 100 mg/kg) and α-MG (25 and 50 mg/kg) before locomotor activity and Morris water maze (MWM) tests showed no significant difference between the groups for locomotor activity.

Conclusions

However, α-MG (50 mg/kg) and XEFGM (100 mg/kg) reversed the cognitive impairment induced by CCH in MWM test. α-MG (50 mg/kg) was further tested upon sub-acute 14-day treatment in CCH rats. Cognitive improvement was shown in MWM test but not in long-term potentiation (LTP). BDNF but not CaMKII was found to be down-regulated in CCH rats; however, both parameters were not affected by α-MG. In conclusion, α-MG ameliorated learning and memory deficits in both acute and sub-acute treatments in CCH rats by improving the spatial learning but not hippocampal LTP. Hence, α-MG may be a promising lead compound for CCH-associated neurodegenerative diseases, including vascular dementia and Alzheimer's disease.

Evaluation of anti-infective potencies of formulated aloin A ointment and aloin A isolated from Aloe barbadensis Miller

Introduction

Isolated bioactive components of plants or their raw extract are utilized as complementary or alternate remedy in copious illnesses. The current research was aimed at assessing the activity of aloin A isolated from Aloe barbadensis Miller and its formulated ointment against six (6) selected clinical isolates.

Methods

The column chromatography was utilized in isolating aloin A from chloroform/methanol solvent polarity. The characterization of the isolated compound was performed by spectroscopy techniques corresponding to UV, IR, ¹H- and ¹³C-NMR spectroscopy. It was formulated as ointment using polyethylene glycol (PEG) and both the ointment and the isolated compound were probed for in vitro antimicrobial activity.

Results

Aloin A has been isolated from chloroform/methanol solvent mixture. The structure has been explicated as (10S)-10-β-d-glucopyranosyl-1,8-dihydroxy-3-(hydroxymethyl)-9(10H)-anthracenone(1S)-1,5-anhydro-1-[(9S)-4,5-dihydroxy-2-(hydroxymethyl)-10-oxo-9,10-dihydro-9-anthracenyl]-d-glucitol. The minimum inhibitory concentration (MIC) of the isolated aloin A on the pathogens ranged from 2.5 to 5.0 mg/ml and 0.32 to 5.0 mg/ml for both aloin A and the formulated ointment respectively. It was further revealed that the activity of aloin A showed dose dependence against all the test microorganisms. There was no significant difference in the activity of the drug against K. pneumoniae, S. aureus, E. coli, C. albicans and T. flavus (P > 0.05) when the concentration was raised from 2.5 to 5 mg/ml, however, there was significant difference (P ˂ 0.05) in activity against P. aeruginosa. The formulated ointment exhibited dose dependent activity against all test microorganisms. At low concentrations, the ointment showed no significant difference in diameter zone of inhibition against all test microorganisms (P > 0.05) except P. aeruginosa which exhibited a highly significant difference (P < 0.05).

Conclusion

Both the isolated aloin A and its formulated ointment demonstrated substantial inhibition of growth of the pathogenic strains. These findings sturdily suggest that aloin A is a nascent drug that could be explored as skin and wound transmittable agent.

Polyethlyene Glycol 200 can Protect Rats against Drug-Induced Kidney Toxicity through Inhibition of the Renal Organic Anion Transporter 3

MK-7680, a cyclic nucleotide prodrug, caused significant kidney tubule injury in female rats when administered orally at 1000 mg/kg/day for 2 weeks using 10% Polysorbate 80 as vehicle. However, kidney injury was absent when MK-7680 was administered at the same dose regimen using 100% Polyethylene Glycol 200 (PEG 200) as the vehicle. Subsequent investigations revealed that MK-7680 triphosphate concentrations in kidney were much lower in rats treated with MK-7680 using PEG 200 compared to 10% Polysorbate 80 vehicle while plasma exposures of MK-7680 prodrug were similar. In vitro studies demonstrated that PEG 200 is an inhibitor of human renal uptake transporter organic anion transporter 3 (OAT3), of which MK-7680 is a substrate. Furthermore, PEG 200 and PEG 400 were found to interfere in vitro with human renal transporters OAT3, organic cation transporter (OCT) 2, multidrug resistance-associated protein (MRP) 2 and 4, and multidrug and toxin extrusion protein (MATE) 1 and 2K, but not OAT1. These results support a conclusion that PEG 200 may prevent MK-7680-induced kidney injury by inhibiting its active uptake into proximal tubular cells by OAT3. Caution should be exercised therefore when using PEGs as vehicles for toxicity assessment for compounds that are substrates of renal transporters.

LP533401 restores bone health in 5/6 nephrectomized rats by a decrease of gut-derived serotonin and regulation of serum phosphate through the inhibition of phosphate co-transporters expression in the kidneys

LP533401 is an orally bioavailable small molecule that inhibits tryptophan hydroxylase-1, an enzyme responsible for the synthesis of gut-derived serotonin (GDS). Recently, we showed that increased GDS in rats with chronic kidney disease (CKD) affected bone strength and metabolism. We tested the hypothesis that treatment with LP533401 could reverse CKD-induced bone loss in uremia. Sixteen weeks after 5/6 nephrectomy, rats were randomized into untreated (CKD), treated with vehicle (VEH) and LP533401 at a dose of 30 or 100 mg/kg daily for 8 weeks. Treatment with LP533401 decreased serotonin turnover and restored bone mineral status, microarchitecture, and strength in CKD rats to the values observed in the controls. In parallel with the reduction of serotonin, serum phosphate levels also decreased, particularly in the LP533401, 100 mg/kg group. The mechanism underlying this phenomenon resulted from decreased expression of the renal VDR/FGF1R/Klotho/Npt2a/Npt2c axis, leading to elevated phosphate excretion in the kidneys. The elevated urinary phosphate excretion resulted in improved bone mineral status and strength in LP533401-treated rats. Unexpectedly, the standard VEH used in this model was able to reduce renal VDR/FGF1R/Klotho/Npt2a expression, leading to a compensatory increase in Npt2c mRNA levels, secondary disturbances in phosphate-regulated hormones and partial improvement in the mineral status of the trabecular bone. The decrease of serotonin synthesis together with the simultaneous reduction of renal Npt2a and Npt2c expression in rats treated with LP533401, 100 mg/kg led to an increase in 1,25(OH)₂D₃ levels; this mechanism seems to be particularly beneficial in relation to the mineral status of cortical bone.

A 90-day toxicity and genotoxicity study with high-purity phenylcapsaicin

To evaluate the safety of the synthetic capsaicin analogue phenylcapsaicin (PheCap; 7-phenylhept-6-yne-acid-hydroxy-3-mathoxylbenzylamide, CAS no 848127-67-3), a 90-day repeated dose oral gavage of 0, 30, 100 or 250 mg/kg body weight (bw)/day toxicity study with a 28-day recovery period was conducted using Wistar rats. Examinations of clinical signs, body and organ weight, haematology, urinalysis, clinical chemistry, food consumption and macroscopic, as well as histopathological tissue examinations were carried out for signs of toxicity. Degenerative, but reversible changes in the liver at 250 mg/kg bw/day, and local irritating effects in the stomach at 100 and 250 mg/kg bw/day were found. These findings were associated with test item-related clinical symptoms, that is, diarrhoea, salivation and moving of bedding material. PheCap did neither cause gene mutations by base pair changes or frame shifts in the genome of the tester stains Salmonella typhimurium TA 98, TA 100, TA 1535, TA 1537 or TA 102 nor induce structural and/or numerical chromosomal damage in human lymphocytes. Therefore, it can be concluded that PheCap is not genotoxic. The No Observed Adverse Effect Level (NOAEL) of PheCap for systemic toxicity is considered to be at 100 mg/kg bw/day which is based on degenerative changes in the liver. Due to irritating effects in the stomach, the NOAEL for local effects was established at 30 mg/kg bw/day.

Toxicological characterisation of two novel selective aryl hydrocarbon receptor modulators in Sprague-Dawley rats

The aryl hydrocarbon receptor (AHR) mediates the toxicity of dioxins, but also plays important physiological roles. Selective AHR modulators, which elicit some effects imparted by this receptor without causing the marked toxicity of dioxins, are presently under intense scrutiny. Two novel such compounds are IMA-08401 (N-acetyl-N-phenyl-4-acetoxy-5-chloro-1,2-dihydro-1-methyl-2-oxo-quinoline-3-carboxamide) and IMA-07101 (N-acetyl-N-(4-trifluoromethylphenyl)-4-acetoxy-1,2-dihydro-5-methoxy-1-methyl-2-oxo-quinoline-3-carboxamide). They represent, as diacetyl prodrugs, AHR-active metabolites of the drug compounds laquinimod and tasquinimod, respectively, which are intended for the treatment of autoimmune diseases and cancer. Here, we toxicologically assessed the novel compounds in Sprague-Dawley rats, after a single dose (8.75-92.5mg/kg) and 5-day repeated dosing at the highest doses achievable (IMA-08401: 100mg/kg/day; and IMA-07101: 75mg/kg/day). There were no overt clinical signs of toxicity, but body weight gain was marginally retarded, and the treatments induced minimal hepatic extramedullary haematopoiesis. Further, both the absolute and relative weights of the thymus were significantly decreased. Cyp1a1 gene expression was substantially increased in all tissues examined. The hepatic induction profile of other AHR battery genes was distinct from that caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The only marked alterations in serum clinical chemistry variables were a reduction in triglycerides and an increase in 3-hydroxybutyrate. Liver and kidney retinol and retinyl palmitate concentrations were affected largely in the same manner as reported for TCDD. In vitro, the novel compounds activated CYP1A1 effectively in H4IIE cells. Altogether, these novel compounds appear to act as potent activators of the AHR, but lack some major characteristic toxicities of dioxins. They therefore represent promising new selective AHR modulators.

Peroral Subchronic, Chronic Toxicity, and Pharmacokinetic Studies of a 100-KiIodaIton Polymer of Ethylene Oxide (Polyox N-10) in the Fischer 344 Rat

Polyox Water Soluble Resins (CAS No. 25322–68–3) are high-molecular-weight polymers of ethylene oxide in a variety of viscosity grades. They are widely used in cosmetic formulations, as pharmaceutical excipients, and food contact applications. The potential for absorption and long-term toxicity (including oncogenicity) from peroral dosing was investigated using an N-10 grade with an average molecular weight of about 100,000 daltons. A subchronic (13-week) toxicity study with up to 3% Polyox N-10 in the diet of Fischer 344 rats showed slight increases in food consumption, body weight, and body weight gain. A dose-related increase in liver weight was observed, but this was not associated with any histopathology, and morphometric analysis showed no alteration in the number or size of the hepatocytes. Because of the lack of correlative pathology findings, the liver weight increase was considered not to be deleterious, but a secondary response to increased food consumption. A chronic (2-year) toxicity/oncogenicity study with up to 2% Polyox N-10 in the diet of Fischer 344 rats showed no effect with respect to clinical signs, body and organ weights, clinical pathology, urinalysis, and neoplastic and non-neoplastic pathology. Pharmacokinetic and material balance studies showed essentially complete recoveries (99% in males, 104% in females) from the excreta, with nearly all the radiolabel being eliminated in the feces (98% in males, 101% in females) in Fischer 344 rats given an oral dose of 14C-labelled Polyox N-10. Recoveries from the urine, expired air, blood, and other tissues were negligible (<1%). In conclusion, Polyox N-10 given orally is not absorbed from the gastrointestinal tract, and does not produce long-term and chronic toxicity, including oncogenicity.

Tolerable Levels of Nonclinical Vehicles and Formulations Used in Studies by Multiple Routes in Multiple Species With Notes on Methods to Improve Utility

Formulation of nonclinical evaluations is a challenge, with the fundamental need to achieve multiples of the clinical exposure complicated by differences in species and routes of administration-specific tolerances, depending on concentrations, volumes, dosing regimen, duration of each administration, and study duration. Current practice to approach these differences is based on individual experience and scattered literature with no comprehensive data source (the most notable exception being our 2006 publication on this same subject). Lack of formulation tolerance data results in excessive animal use, unplanned delays in the evaluation and development of drugs, and vehicle-dependent results. A consulting firm, a chemical company, and 4 contract research organizations conducted a rigorous data mining operation of vehicle data from studies dating from 1991 to 2015, enhancing the data from this author's 2006 publication (3 of the six 2015 contributors were also 2006 contributors). Additional data were found in the published literature. The results identified 108 single-component vehicles (and 305 combination formulations) used in more than 1,040 studies across multiple species (dog, primate, rat, mouse, rabbit, guinea pig, minipig, pig, chick embryo, and cat) by multiple routes for a wide range of study durations. The tabulated data include maximum tolerated use levels by species, route, duration of study, dose-limiting toxicity where reported, review of the available literature on each vehicle, guidance on syringe selection, volume and pH limits by route with basic guidance on nonclinical formulation development, and guidance on factors to be considered in nonclinical route selection.

Macromolecular crowding and hydrophobic effects on Fmoc-diphenylalanine hydrogel formation in PEG : water mixtures

Addition of water triggers gelation in (poly)ethylene glycol (PEG) solutions of peptide gelators, with or without drugs added. The gels are formed by a combination of macromolecular crowding and hydrophobic effects as evident by significant secondary structure changes when compared to gel formed from pure water.

Aldosterone induces fibrosis, oxidative stress and DNA damage in livers of male rats independent of blood pressure changes

Mineralocorticoid receptor blockers show antifibrotic potential in hepatic fibrosis. The mechanism of this protective effect is not known yet, although reactive oxygen species seem to play an important role. Here, we investigated the effects of elevated levels of aldosterone (Ald), the primary ligand of the mineralocorticoid receptor, on livers of rats in a hyperaldosteronism model: aldosterone-induced hypertension. Male Sprague-Dawley rats were treated for 4 weeks with aldosterone. To distinguish if damage caused in the liver depended on increased blood pressure or on increased Ald levels, the mineralocorticoid receptor antagonist spironolactone was given in a subtherapeutic dose, not normalizing blood pressure. To investigate the impact of oxidative stress, the antioxidant tempol was administered. Aldosterone induced fibrosis, detected histopathologically, and by expression analysis of the fibrosis marker, α-smooth muscle actin. Further, the mRNA amount of the profibrotic cytokine TGF-β was increased significantly. Fibrosis could be reduced by scavenging reactive oxygen species, and also by blocking the mineralocorticoid receptor. Furthermore, aldosterone treatment caused oxidative stress and DNA double strand breaks in livers, as well as the elevation of DNA repair activity. An increase of the transcription factor Nrf2, the main regulator of the antioxidative response could be observed, and of its target genes heme oxygenase-1 and γ-glutamylcysteine synthetase. All these effects of aldosterone were prevented by spironolactone and tempol. Already after 4 weeks of treatment, aldosteroneinfusion induced fibrosis in the liver. This effect was independent of elevated blood pressure. DNA damage caused by aldosterone might contribute to fibrosis progression when aldosterone is chronically increased.

Poly(ethylene glycol)-mediated conformational alteration of α-chymotrypsin prevents inactivation of insulin by stabilizing active intermediates

Proteolytic enzymes in the gut represent one of the biggest barriers against oral delivery of therapeutic proteins and peptides. In the current study, we explored the effect of poly(ethylene glycol) 400 (PEG 400), a commonly used crowding agent, on insulin degradation mediated by α-chymotrypsin (α-CT). Without PEG 400, insulin was quickly cleaved by α-CT to generate inactive degradation products. In comparison, incorporation of PEG 400 resulted in reaction mixtures with retained biological activity. The analysis on the conformation of α-CT and the local environment of the enzyme's active site unraveled that PEG 400 altered the conformation of α-CT to prevent the inactivation of insulin via stabilization of active intermediates. These findings indicated that PEG 400 may provide a promising addition toward oral delivery of insulin.

Vehicle selection for nonclinical oral safety studies

INTRODUCTION

The development of poorly soluble or permeable new chemical entities within the pharmaceutical industry often requires the use of nonstandard enabling nonclinical oral formulations. Despite this, the toxicity profile of many commonly used nonclinical vehicles is poorly understood. This lack of data can lead to unexpected formulation-related effects being observed in critical oral safety studies.

AREAS COVERED

This article summarizes the key considerations for formulation selection for oral nonclinical safety studies, and provides a strategy for appropriate development-phase formulation selection. The industry's use of oral nonclinical vehicles is reviewed, based on data from the FDA's Orange Book. Finally, a summary of the repeat dose oral toxicity of commonly used vehicles is presented.

EXPERT OPINION

The rapid identification of a suitable nonclinical oral formulation is a critical step in small-molecule drug development. In order to maintain flexibility and address the needs of a diverse set of new chemical entities (NCEs) with widely varying physiochemical properties, a "tool belt" of multiple oral formulations is recommended. The appropriate formulation is identified based on the goals of the study, as well as exposure required, species, duration and therapeutic indication of the NCE.

Effects of Solutol (Kolliphor) and Cremophor in Polyethylene Glycol 400 Vehicle Formulations in Sprague-Dawley Rats and Beagle Dogs

When conventional vehicles (eg, methylcellulose and water) impart inadequate physical, chemical, and/or biological properties for proper toxicological assessment of test article formulations, nonconventional vehicles may be considered. Often toxicity data for nonconventional vehicle formulations are limited. Studies were conducted to collect toxicity data from a rodent and a non-rodent species given 2 nonconventional vehicles, Solutol HS15/polyethylene glycol (PEG) 400 and Cremophor RH40/PEG 400, with differing formulations and dose volumes (10 mL/kg for rats; 2 or 5 mL/kg for dogs). In rats, both vehicles caused increase in kidney weights (males only) and decrease in thymic weights (males only) without concurrent microscopic findings; altered urine electrolytes, minimally decreased serum electrolytes (males only), and increased serum total cholesterol (females only) were also present. The Cremophor formulation was also associated with increased serum urea (males only) and urine phosphorus: creatinine. For rats given the Solutol formulation, both genders had decreased urine glucose parameters and males had increased urine volume. In dogs, loose/watery feces and emesis were present given either vehicle, and mucus-cell hyperplasia of the ileum was present given the Solutol formulation. Increased red blood cell mass and decreased urine volume in dogs given 30% Solutol/70% PEG 400 (5 mL/kg/d) were likely due to subclinical dehydration and hemoconcentration. For the Cremophor formulations, dose volume-dependent increased incidence of minimal subepithelial gastric hemorrhage was noted in dogs, and dogs given 5 mL/kg/d showed increased serum urea nitrogen. Overall, regardless of the formulation or dose volume, neither vehicle produced overt toxicity in either species, but the Solutol formulation produced fewer effects in rats. Generally, lower dose volumes minimized the severity and/or incidence of findings.

Preclinical pharmacokinetic analysis of armillarisin succinate ester in mouse plasma and tissues by LC-MS/MS

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed and validated to determine the concentration of armillarisin succinate ester in mouse plasma and tissues, used for preclinical evaluation. Bavachin was employed as the internal standard. Separation was performed on a 3.5 µm Zorbax SB-C(18) column (30 × 2.1 mm), with a mobile phase consisting of methanol and aqueous 20 mm ammonium acetate. Both analyte and internal standard were determined using electrospray ionization and the MS data acquisition was via selected ion monitoring in negative scanning mode. Quantification was performed using the transitions m/z 333 → 233 and 323 → 221 for armillarisin succinate ester and internal standard, respectively. The method was validated with respect to linearity, accuracy, precision, recovery and stability. This assay has been successfully applied to a pharmacokinetic and tissue distribution study after intravenous injection of ASE in mouse in a dose of 10 mg/kg.

Systemic toxicity and toxicokinetics of a high dose of polyethylene glycol 400 in dogs following intravenous injection

Polyethylene glycol 400 (PEG-400) has been used in injections. However, limited data are available concerning the toxicity of a high dose of PEG-400 following intravenous (i.v.) injection. The aim of the present study was to estimate the systemic toxicity and toxicokinetics of a high dose of PEG-400 in dogs following i.v. injection. Twenty-four dogs were divided into four groups: a control group receiving normal saline and three test groups receiving 4.23, 6.34, and 8.45 g/kg of PEG-400, respectively, by i.v. injection once a day for 30 days. The repeated-dose toxicity of PEG-400 was assessed. Toxicokinetic parameters of PEG-400 in dogs were estimated on days 1 and 30. Dry mouth and dry nasal mucus membrane were observed in dogs treated with 6.34 and 8.45 g/kg of PEG-400. Cloudy swelling of kidney cell and increased glomerular volume were observed in dogs treated with 8.45 g/kg of PEG-400 when the animals were sacrificed 24 hours after the last injection. No significant histological changes were found 21 days later. Repeated dosing did not affect the toxicokinetic profile of PEG-400 in dogs. This study has shown that the toxicity of a high dose of PEG-400 following repeated intravenous injections is low, and alterations produced are reversible.

Effects of polysorbate 80 on the in-vitro precipitation and oral bioavailability of halofantrine from polyethylene glycol 400 formulations in rats

Objectives

The aim of this study was to examine the effects of formulations of polysorbate 80 (PS 80) and polyethylene glycol 400 (PEG 400) on the precipitation and oral bioavailability of the hydrophobic drug halofantrine.

Methods

The in-vitro dilution profile of the formulations was evaluated in phosphate buffer and in simulated intestinal fluids using a standard dissolution apparatus. The pharmacokinetic profile of the formulations was investigated in fasted rats at two dose levels, 5 and 17.5 mg/kg, with blood sampling by vein puncture in the tail.

Key findings

The solubility of halofantrine was found to be highest in PS 80, and in co-mixtures there was a correlation with the content of PS 80. The in-vitro dilution profile revealed precipitation of halofantrine when dissolved in pure PEG 400, although the precipitation was smaller in the simulated intestinal fluid. Addition of 25% PS 80 to the PEG 400 significantly decreased precipitation. The animals dosed with the PEG 400 formulation had significant lower bioavailability than the PS 80–PEG 400 co-mixtures, possibly due to halofantrine precipitation in the gastrointestinal tract.

Conclusions

Addition of PS80 to the formulation increased the bioavailability of halofantrine and the more compound, the more PS80 was needed to prevent precipitation.

Nonclinical vehicle use in studies by multiple routes in multiple species

The laboratory toxicologist is frequently faced with the challenge of selecting appropriate vehicles or developing utilitarian formulations for use in in vivo nonclinical safety assessment studies. Although there are many vehicles available that may meet physical and chemical requirements for chemical or pharmaceutical formulation, there are wide differences in species and route of administration specific to tolerances to these vehicles. In current practice, these differences are largely approached on a basis of individual experience as there is only scattered literature on individual vehicles and no comprehensive treatment or information source. This approach leads to excessive animal use and unplanned delays in testing and development. To address this need, a consulting firm and three contract research organizations conducted a rigorous data mining operation of control (vehicle) data from studies dating from 1991 to present. The results identified 65 single component vehicles used in 368 studies across multiple species (dog, primate, rat, mouse, rabbit, guinea pig, minipig, chick embryo, and cat) by multiple routes. Reported here are the results of this effort, including maximum tolerated use levels by species, route, and duration of study, with accompanying dose limiting toxicity. Also included are basic chemical information and a review of available literature on each vehicle, as well as guidance on volume limits and pH by route and some basic guidance on nonclinical formulation development.

Effect of commonly used vehicles on gastrointestinal, renal, and liver function in rats

INTRODUCTION

Solubility is often a limiting factor when testing new compounds in animal experiments. Various solubilizing agents may be used, but each have their own pharmacological effects. We investigated the effects of selected vehicles having different chemical characteristics on gastrointestinal, renal, and liver function.

METHODS

Rats were treated orally, intravenously or intraperitoneally and gastric emptying, intestinal transit, renal, and liver function were investigated.

RESULTS

Gastrointestinal motility was influenced by hydroxyethylcellulose, hydroxypropyl-beta-cyclodextrin (HPbetaCD), HPgammaCD, DMSO, polyethylene glycol 400 (PEG 400), fat emulsion, and the corresponding emulsifier. Liver function was affected by HPbetaCD, HPgammaCD, DMSO, PEG 400, Polysorbate 80, Cremophor RH 40, and fat emulsion. An increase in liver enzymes was observed after PEG 400 and Polysorbate 80. DMSO interfered with clinical chemistry measurements in serum. Urinary function was modified by HPgammaCD, DMSO, PEG 400, and Polysorbate 80, while enhanced urine enzyme excretion was observed after HPbetaCD, HPgammaCD, DMSO, PEG 400, and Polysorbate 80.

DISCUSSION

Most of the investigated vehicles changed gastrointestinal, renal, and/or liver parameters after application of a certain threshold dose for each assay. No "best" vehicle could be identified that may be used in each test system. Thus, vehicles must be selected not only on their chemical characteristics but also on their potential pharmacological activity in a given test system.

Safety assessment on polyethylene glycols (PEGs) and their derivatives as used in cosmetic products

This assessment focusses on polyethylene glycols (PEGs) and on anionic or nonionic PEG derivatives, which are currently used in cosmetics in Europe. These compounds are used in a great variety of cosmetic applications because of their solubility and viscosity properties, and because of their low toxicity. The PEGs, their ethers, and their fatty acid esters produce little or no ocular or dermal irritation and have extremely low acute and chronic toxicities. They do not readily penetrate intact skin, and in view of the wide use of preparations containing PEG and PEG derivatives, only few case reports on sensitisation reactions have been published, mainly involving patients with exposure to PEGs in medicines or following exposure to injured or chronically inflamed skin. On healthy skin, the sensitising potential of these compounds appears to be negligible. For some representative substances of this class, information was available on reproductive and developmental toxicity, on genotoxicty and carcinogenic properties. Taking into consideration all available information from related compounds, as well as the mode and mechanism of action, no safety concern with regard to these endpoints could be identified. Based on the available data it is therefore concluded that PEGs of a wide molecular weight range (200 to over 10,000), their ethers (laureths. ceteths, ceteareths, steareths, and oleths), and fatty acid esters (laurates, dilaurates, stearates, distearates) are safe for use in cosmetics. Limited data were available for PEG sorbitan/sorbitol fatty acid esters, PEG sorbitan beeswax and PEG soy sterols. Taking into account all the information available for closely related compounds, it can be assumed that these compounds as presently used in cosmetic preparations will not present a risk for human health. PEG castor oils and PEG hydrogenated castor oils have caused anaphylactic reactions when used in intravenous medicinal products. Their topical use in cosmetics is, however, considered safe as they are not expected to be systemically available. As all PEGs and PEG derivatives, they must not be applied to damaged skin. Manufacturers of PEGs and PEG derivatives must continue their efforts to remove impurities and by-products such as ethylene oxide and 1,4-dioxane. Overall, it is concluded, that the PEGs covered in this review are safe for use in cosmetics under the present conditions of intended use.

Synthesis and Evaluation of PEG414, a Novel Formulating Agent that Avoids Analytical Problems Associated with Polydisperse Vehicles such as PEG400

Polyethylene glycol (PEG) 400 is widely used as a formulating agent for both intravenous and oral studies during drug discovery. It is a polydisperse material containing more than 16 oligomers, which can cause significant problems for high-performance liquid chromatography-mass spectrometry analysis due to ion suppression and isobaric interference. To overcome these difficulties, we have synthesized the single oligomer PEG414. The material has been characterized with a range of diverse drug compounds and shown to be comparable to PEG400 and superior to propylene glycol in terms of its solubilization power. The toxicological and metabolic properties of PEG414 should be similar to PEG400. It suffers none of the analytical problems associated with polydisperse agents and we expect it to be a useful alternative for the formulation of test compounds for intravenous and oral dosing during drug discovery.

Novel vectors for gene delivery formed by self-assembly of DNA with poly(L-lysine) grafted with hydrophilic polymers

Complexes formed between DNA and cationic polymers are attracting increasing attention as novel synthetic vectors for delivery of genes. We are trying to improve biological properties of such complexes by oriented self-assembly of DNA with cationic-hydrophilic block copolymers, designed to enshroud the complex within a protective hydrophilic polymer corona. Poly(L-lysine) (pLL) grafted with range of hydrophilic polymer blocks, including poly(ethylene glycol) (pEG), dextran and poly[N-(2-hydroxypropyl)methacrylamide] (pHPMA), shows efficient binding to DNA and mediates particle self-assembly and inhibition of ethidium bromide/DNA fluorescence. The complexes formed are discrete and typically about 100 nm diameter, viewed by atomic force microscopy. Surface charges are slightly shielded by the presence of the hydrophilic polymer, and complexes generally show decreased cytotoxicity compared with simple pLL/DNA complexes. pEG-containing complexes show increased transfection activity against cells in vitro. Complexes formed with all polymer conjugates showed greater aqueous solubility than simple pLL/DNA complexes, particularly at charge neutrality. These materials appear to have the ability to regulate the physicochemical and biological properties of polycation/DNA complexes, and should find important applications in packaging of nucleic acids for specific biological applications.

Cutaneous toxicity studies with methoxy polyethylene glycol-350 (MPEG-350) in rats and rabbits

The methoxy polyethylene glycols (MPEGs), also referred to as polyethylene glycol methyl ethers, are high molecular weight polymers similar in structure and nomenclature to the polyethylene glycols. Because of the potential for repeated cutaneous exposure of humans to MPEG-350 and the known toxicity of lower alkylene glycol ethers such as ethylene glycol monomethyl ether (EGME), studies were conducted to evaluate the potential toxicity and irritation of MPEG-350 following repeated, cutaneous treatment. New Zealand White rabbits were cutaneously treated with 1.0 ml of either undiluted MPEG-350 or a 50% solution of MPEG-350 in 0.1% methyl cellulose in distilled water for 9 or 90 days. CD(SD)BR rats were cutaneously treated with up to 5 g/kg/day of undiluted MPEG-350 for 14 or 28 days. The treatment area was not occluded but animals were fitted with Elizabethan collars during treatment. Rabbits were treated 6 hr/day 5 days/wk. Rats were treated for at least 19 hr/day (at weekends, the exposure time was approximately 70 hr). None of the animals died. Slight decreases in mean absolute body weight of all dose groups of male rats as compared with the concurrent control group may have been related to minimal toxicity of the test substance but was probably secondary to the dosing procedures. Signs of slight cutaneous irritation were observed in many treated animals of both species but only a few rabbits had confirmatory microscopic diagnoses while none of the rats had microscopic changes in the skin. Slight decreases in the mean absolute weight of the testes, spleen and thymus were observed in rats treated with 5 g undiluted MPEG-350/kg/day for 14 days. Similar changes were not observed in rats following 28 days of treatment. There were no microscopic changes in any of these organs except for one rat that had moderate to high aspermatogenesis and multinucleated spermatids. There were no microscopic changes observed in the testes of any other animals (including rats treated for 28 days with 5 g undiluted MPEG-350/kg/day). Therefore, a relationship of the testicular changes observed in this one animal to treatment with MPEG-350 was considered to be improbable. While a mechanism for the production of toxic metabolites from systemically absorbed MPEG-350 was considered to be possible, there was no indication from these and other cutaneous studies of significant cutaneous absorption of the compound. Therefore, repeated cutaneous exposure to MPEG-350 was not expected to result in significant toxicological effects.