Comparative analysis of docetaxel: physical and chemical characterisation of Taxotère® and generics.

Several cases of fatal enterocolitis have been described in association with the use of docetaxel (DTX), and this increase in adverse events has been concomitant with a change in formulation. Indeed in 2010, a new DTX-based presentation has been introduced in the form of a single ready-to-use vial by Sanofi-Aventis, presentation also used for generics. In this study, different available formulations were compared (Sanofi 2 vials, Sanofi 1 vial, Accord Healthcare, Kabi, Hospira) in terms of composition compliance with control specifications and simulated micelle behaviour to try to determine what could be the potential causes of this problem. This work had permitted to show that all the tested products complied with specifications in terms of dosage and purity. Variations in the composition of polysorbate 80 (PS80) have been observed but are probably too small to be responsible for the toxicity found in patients. However, we identified a difference in micelle size and release kinetics probably because of doubling concentration of ethanol in new formulation. As a result, we emphasised the importance in the case of DTX of conducting bioequivalence studies as expected in European Medicines Agency (EMA) guidance to ensure patient safety, even though these formulation changes might seem minor. Therefore, further studies are needed to explore the potential role of ethanol, PS80 and the unbound fraction of DTX in the development of enterocolitis in patients treated with DTX.

Drug excipients, food additives, and cosmetic ingredients probably not carcinogenic to humans reveal a functional specificity for the 2-year rodent bioassay.

Regarding carcinogenicity testing, the long-term rodent bioassay (RCB) has been the test required by most regulatory agencies across the world. Nonetheless, due to the lack of knowledge about its specificity, it has been argued that the RCB is unspecific or even invalid. Because of the substantial limitations of epidemiology to identify chemicals probably not carcinogenic to humans (PNCH), it has been very difficult to address the specificity of the RCB. Nevertheless, because mechanistic/pharmacological data are currently recognized as a valid stream of evidence for the identification of chemical hazards, the road is now open to gain insight into the specificity of the RCB. Based on sound mechanistic/pharmacological data that support the classification of chemicals as PNCH, 100 PNCH substances were gathered in this investigation. Contrary to what was previously forecast, in this study, the RCB exhibited a functional specificity that ranged from 83% to 91%, depending on the settings of the testing (2-species vs. rats only, and the nominal maximum tolerated dose). Other contributions of this work were: (a) enabling the comparison, in terms of specificity, between the RCB and the alternative methods that could replace it (eg, Tg.AC mouse, rasH2 mouse); (b) disclosing what the specificity is for alternative methods that were developed using the RCB as the reference standard; and (c) expanding the previous narrow (only seven substances) set of chemicals identified as not likely to be carcinogenic to humans by hazard identification programs.

Safety assessment of excipients (SAFE) for orally inhaled drug products.

The development of new orally inhaled drug products requires their demonstration of safety, which must be proven in animal experiments. New in vitro methods may replace, or at least reduce, these animal experiments, provided they are able to correctly predict safety or possible toxicity in humans. However, the challenge is to link in vitro data obtained in human cells to human in vivo data. We here present a new approach to the safety assessment of excipients (SAFE) for pulmonary drug delivery. The SAFE model is based on a dose response curve of 23 excipients tested on the human pulmonary epithelial cell lines A549 and Calu-3. The resulting in vitro IC50 values were correlated with the FDA-approved concentrations in pharmaceutical products for either pulmonary (if available) or parenteral administration. Setting a threshold of 0.1% (1 mg/mL) for either value yielded four safety classes and allowed to link IC50 data as measured in human cell cultures in vitro with the concentrations of the same compounds in FDA-approved drug products. The necessary in vitro data for novel excipients can be easily generated, and the SAFE approach allows putting them into context for eventual use in human pulmonary drug products. Excipients that are most likely not safe for use in humans can be excluded early on from further pharmaceutical development. The SAFE approach thus helps to avoid unnecessary animal experiments.

In vitro toxicity screening of polyglycerol esters of fatty acids as excipients for pulmonary formulations.

One of the main problems for the development of pulmonary formulations is the low availability of approved excipients. Polyglycerol esters of fatty acids (PGFA) are promising molecules for acting as excipient for formulation development and drug delivery to the lung. However, their biocompatibility in the deep lung has not been studied so far. Main exposed cells include alveolar epithelial cells and alveolar macrophages. Due to the poor water-solubility of PGFAs, the exposure of alveolar macrophages is expected to be much higher than that of epithelial cells. In this study, two PGFAs and their mixture were tested regarding cytotoxicity to epithelial cells and cytotoxicity and functional impairment of macrophages. Cytotoxicity was assessed by dehydrogenase activity and lactate dehydrogenase release. Lysosome function, phospholipid accumulation, phagocytosis, nitric oxide production, and cytokine release were used to evaluate macrophage function. Cytotoxicity was increased with the increased polarity of PGFA molecules. At concentrations above 1 mg/ml accumulation in lysosomes, impairment of phagocytosis, secretion of nitric oxide, and increased release of cytokines were noted. The investigated PGFAs in concentrations up to 1 mg/ml can be considered as uncritical and are promising for advanced pulmonary delivery of high powder doses and drug targeting to alveolar macrophages.

Safety assessment of the pharmacological excipient, diethylene glycol monoethyl ether (DEGEE), using in vitro and in vivo systems.

BACKGROUND: Diethylene glycol monoethyl ether (DEGEE) is widely used as a solubilizer in cosmetics as well as in oral, topical, transdermal and injectable pharmaceutical formulations. Due to the unavailability of detailed toxicological studies on DEGEE, the Scientific Committee on Consumer Products (SCCP) found its toxicological reports to be unsatisfactory, comprising only summaries. Also, a few reports have raised concern on the use of DEGEE as it might cause damage to the kidneys. OBJECTIVE: Safety assessment of DEGEE using in vitro and in vivo models. METHODS: In vitro effects of DEGEE (0.5-25 mg/ml) were assessed in the HEK293 human embryonic kidney cells. In vivo effects were evaluated after single acute exposure of DEGEE via intraperitoneal route in Swiss albino mice and further, a 28 days subchronic exposure study was conducted where DEGEE was administered orally, once daily. RESULTS: DEGEE was cytotoxic to HEK293 cells, and an IC50 of 15 mg/ml was established. An increase in the intracellular levels of ROS and alteration in the mitochondrial membrane potential led to nuclear fragmentation and induction of apoptosis in these cells. Survival rate of animals administered intraperitoneally with a single acute dose of 1000 mg/kg DEGEE was 100% with no significant changes in the behavioural and histological parameters. However, the dose of 3000 mg/kg and above led to total mortality within 14 days of acute exposure. Subchronic oral exposure of 500-2000 mg/kg DEGEE showed no significant changes in the hematological, biochemical and histopathological parameters. CONCLUSIONS: The in vitro findings indicate that the nephrotoxic potential of DEGEE cannot be ruled out. The results of the in vivo studies reveal that the degree of toxic effects shown by DEGEE varies, depending on the dose, duration of exposure and routes of administration. Therefore, the present findings are of relevance and thorough studies should be conducted before using this substance in clinical formulations. Graphical abstract Evaluation of the toxic potential of Diethylene glycol monoethyl ether.

Cumulative exposure to phthalates from phthalate-containing drug products: a Danish population-wide study.

AIMS: Up to 50-fold higher levels of urinary phthalate metabolites have been observed in users of phthalate-containing drug products compared with non-users. This is of concern, as phthalates are suspected endocrine disrupters and have been associated with cancer development. This study aims to quantify annual cumulated phthalate exposure from drug products among users of phthalate-containing oral medications in Denmark throughout the period of 2004-2016. METHODS: We conducted a Danish nationwide cohort study using The Danish National Prescription Registry and an internal database held by The Danish Medicines Agency. These databases hold information on drug products; date of dispensing, and the type and quantity of excipients in drugs with Danish marketing permission. We present the number of users over time and their distribution of exposure to enteric phthalate polymers and ortho-phthalates. RESULTS: The annual number of individuals exposed to phthalate-containing products declined during 2004-2016. The total number of individuals exposed to dibutyl phthalate declined from 21 499 in 2004 to 5400 in 2016. However, among those exposed, the median dibutyl phthalate exposure remained above European regulatory limit of exposure ranging between 380-1710 mg/year throughout the study period. Lithium-products constituted the majority of dibutyl phthalate exposure. Diethyl phthalate exposure, mainly caused by erythromycin, theophylline and diclofenac products, did not exceed the EMA regulatory limit. CONCLUSION: While the number of individuals exposed to phthalates from oral medications during 2004-2016 declined, the use of phthalate-containing drugs is still considerable.

Polymer-Lipid Microparticles for Pulmonary Delivery.

Toward engineering approaches that are designed to optimize the particle size, morphology, and mucoadhesion behavior of the particulate component of inhaler formulations, this paper presents the preparation, physicochemical characterization, and preliminary in vitro evaluation of multicomponent polymer-lipid systems that are based on "spray-drying engineered" α-lactose monohydrate microparticles. The formulations combine an active (budesonide) with a lung surfactant (dipalmitoylphosphatidylcholine) and with materials that are known for their desirable effects on morphology (polyvinyl alcohol), aerosolization (l-leucine), and mucoadhesion (chitosan). The effect of the composition of formulations on the morphology, distribution, and in vitro mucoadhesion profiles is presented along with "Calu-3 cell monolayers" data that indicate good cytocompatibility and also with simulated-lung-fluid data that are consistent with the therapeutically useful release of budesonide.

Toxicological assessment of Anionic Methacrylate Copolymer: I. Characterization, bioavailability and genotoxicity.

Anionic Methacrylate Copolymer (AMC) is a fully polymerized copolymer used in the pharmaceutical industry as an enteric/delayed-release coating to permit the pH-dependent release of active ingredients in the gastrointestinal tract from oral dosage forms. This function is of potential use for food supplements. Oral administration of radiolabeled copolymer to rats resulted in the detection of chemically unchanged copolymer in the feces, with negligible absorption (<0.1%). AMC is therefore determined not to be bioavailable. Within a genotoxicity test battery AMC did not show any evidence of genotoxicity in bacteria and mammalian cells. Furthermore, no genotoxic effects occurred in vivo within a micronucleus test. There would therefore appear to be no safety concerns under intended conditions of oral use for the discussed toxicological endpoints.

In vitro study of the cytotoxic and genotoxic effects of indomethacin-loaded Eudragit(®) L 100 nanocapsules.

Indomethacin is a non-steroidal anti-inflammatory agent included in one of the most commonly used drug classes worldwide. The use of this drug results in certain side effects, including gastrointestinal complications. Therefore, there exists a need to develop better methods for the delivery of such drugs into the body, such as those employing nanoparticles. The aim of the present study was to evaluate the cytotoxic and genotoxic effects of indomethacin-loaded Eudragit(®) L 100 nanocapsules (NI; based on methacrylic acid and methyl methacrylate) on cells unable (lymphocytes) and able to metabolize drugs (HepG2 cells), using comet and cytokinesis-block micronucleus (CBMN) assays in vitro. Cells were exposed to NI at concentrations of 5, 10, 50, 125, 250, and 500 µg/mL. The comet assay showed that NI induced no significant DNA damage in either cell type at any of the concentrations tested. The CBMN test confirmed these results; however, the highest concentration of 500 µg/mL resulted in a small but statistically significant clastogenic/aneugenic effect in HepG2 cells. These findings should encourage the development of new investigations of this nanomaterial as a delivery vehicle for anti-inflammatory drugs, such as indomethacin.

S-protected thiolated hydroxyethyl cellulose (HEC): Novel mucoadhesive excipient with improved stability.

The aim of this study was the design of novel S-protected thiolated hydroxyethyl cellulose (HEC) and the assessment of its mucoadhesive properties and biodegradability compared to the corresponding unmodified polymer. Thiolated HEC was S-protected via disulfide bond formation between 6-mercaptonicotinamide (6-MNA) and the thiol substructures of the polymer. In vitro screening of mucoadhesive properties was accomplished using two different methods: rotating cylinder studies and viscosity measurements. Moreover, biodegradability of these polymers by cellulase, xylanase and lysozyme was evaluated. MTT and LDH assays were performed on Caco-2 cells to determine the cytotoxicity of S-protected thiolated HEC. Thiolated HEC displayed 280.09±1.70µmol of free thiol groups per gram polymer. S-protected thiolated HEC exhibiting 270.8±21.11µmol immobilized 6-MNA ligands per gram of polymer was shown being 2.4-fold more mucoadhesive compared to thiolated HEC. No mucoadhesion was observed in case of unmodified HEC. Results were in a good agreement with rheological studies. The presence of free thiol moieties likely caused lower degree of hydrolysis by xylanase, whereas the degradation by both enzymes cellulase and xylanase was more hampered when 6-MNA was introduced as ligand for thiol group's protection. Findings in cell viability revealed that all three conjugates were non-toxic. S-protection of thiolated hydroxyethyl cellulose improved mucoadhesive properties and provided pronounced stability towards enzymatic attack, that makes this excipient superior for non-invasive drug administration over thiolated and unmodified forms.

Design, characterization and in vitro evaluation of a novel thiolated polymer: preactivated carboxymethyl cellulose.

AIM: To design a novel preactived carboxymethyl cellulose derivative. METHODS: First, carboxymethyl cellulose (CMC) was chemically modified by amide bond formation between primary amino group of cysteine (CYS) and carboxylic moiety of CMC mediated by carbodiimide. Second, obtained CMCCYS was preactivated with 2,2'-dithiodinicotinic acid. Designed CMC-S-S-MNA was characterized by FT-IR. Furthermore, cytotoxicity was conducted on Caco-2 cell line. Swelling behavior, erosion and release of novel CMC-S-S-MNA were performed compared with thiolated and unmodified cellulose, respectively. RESULTS: CMC-S-S-MNA showed no harmful effect on cells. CMC-S-S-MNA exhibited 2.13-fold higher stability in comparison to unmodified cellulose. Furthermore, preactivated carboxymethyl cellulose-cysteine revealed 1.9-fold controlled released compared with respective unmodified carboxymethyl cellulose. CONCLUSION: Novel preactivated carboxymethyl cellulose represents a versatile excipient for drug delivery.

Regulatory risk assessments: Is there a need to reduce uncertainty and enhance robustness?

A critical evaluation of several recent regulatory risk assessments has been undertaken. These relate to propyl paraben (as a food additive, cosmetic ingredient or pharmaceutical excipient), cobalt (in terms of a safety-based limit for pharmaceuticals) and the cancer Threshold of Toxicological Concern as applied to food contaminants and pharmaceutical impurities. In all cases, a number of concerns can be raised regarding the reliability of the current assessments, some examples being absence of data audits, use of single-dose and/or non-good laboratory practice studies to determine safety metrics, use of a biased data set and questionable methodology and lack of consistency with precedents and regulatory guidance. Drawing on these findings, a set of recommendations is provided to reduce uncertainty and improve the quality and robustness of future regulatory risk assessments.

Nonclinical evaluation of the potential for mast cell activation by an erythropoietin analog.

The erythropoietin analog peginesatide was withdrawn from marketing due to unexpected severe anaphylactic reactions associated with administration of the multi-use formulation. The adverse events occurred rapidly following the first ever administration of the drug with most affected patients becoming symptomatic in less than 30min. This is most consistent with an anaphylactoid reaction due to direct activation of mast cells. Laboratory evaluation was undertaken using rat peritoneal mast cells as the model system. Initial studies showed that high concentrations of the formulated drug as well as formulated vehicle alone could cause mast cell degranulation as measured by histamine release. The purified active drug was not able to cause histamine release whereas the vehicle filtrate and lab created drug vehicle were equally potent at causing histamine release. Individual formulations of vehicle leaving one component out showed that histamine release was due to phenol. Dose response studies with phenol showed a very sharp dose response curve that was similar in three buffer systems. Cellular analysis by flow cytometry showed that the histamine release was not due to cell death, and that changes in light scatter parameters consistent with degranulation were rapidly observed. Limited testing with primary human mast cells showed a similar dose response of histamine release with exposure to phenol. To provide in vivo confirmation, rats were injected with vehicle formulated with various concentrations of phenol via a jugular vein cannula. Significant release of histamine was detected in blood samples taken 2min after dosing at the highest concentrations tested.

Strategic approaches for enhancement of in vivo transbuccal peptide drug delivery in rabbits using iontophoresis and chemical enhancers.

PURPOSE: To evaluate the feasibility of iontophoresis and the combination effects with chemical enhancers on in vivo hypocalcemic effect of transbuccally delivered salmon calcitonin (sCT). METHODS: N-acetyl-L-cysteine (NAC), sodium deoxyglycocholate (SDGC), and ethanol were used as chemical enhancers; and 0.5 mA/cm(2) fixed electric current was employed as a physical enhancer. sCT hydrogel was applied to rabbit buccal mucosa, and blood samples were obtained via the central auricular artery. Blood calcium level was measured by calcium kit and the conformational changes of buccal mucosa were investigated with FT-IR spectroscopy. Hematoxylin/eosin staining was used for the histological evaluation of buccal mucosa. RESULTS: Iontophoresis groups except iontophoresis-NAC group showed significant hypocalcemic effect compared to negative control, in particular iontophoresis-SDGC combination group showed fast onset of action as well as sustained hypocalcemic effect (p < 0.05). FT-IR result demonstrated the reduction of buccal barrier function, and the histological study showed a decrease in buccal thickness as well as minor damage to the dermal-epidermal junctions in the enhancing method groups; however, the damaged tissues virtually recovered within 24 h after the removal of electrodes. CONCLUSIONS: Iontophoresis and combination with SDGC were found to be safe and potential strategies for transbuccal peptide delivery in vivo.

Surface coating mediates the toxicity of polymeric nanoparticles towards human-like macrophages.

The purpose of this study was to investigate the toxicity of a series of poly(lactide-co-glycolic) (PLGA) nanoparticles on human-like THP-1 macrophages. Positively-, negatively-charged and neutral nanoparticles (200 nm) were prepared using chitosan (CS), poloxamer 188 (PF68) and poly(vinyl alcohol) (PVA) as stabilizer. Stabilizer-free PLGA nanoparticles were obtained as well. When used at therapeutically relevant concentrations (up to 0.1 mg/mL in vitro), all tested nanoparticles showed no or scarce signs of toxicity, as assessed by cell mitochondrial activity, induction of apoptosis and necrosis, production of intracellular reactive oxygen species (ROS) and secretion of pro-inflammatory cytokines. At high concentrations (above 1mg/mL), cytotoxicity was found to be induced by the presence of stabilizers, whatever the toxicological pattern of the stabilizer itself. While stabilizer-free PLGA nanoparticles exerted no cytotoxicity, the slightly cytotoxic CS polymer conferred PLGA nanoparticles significant cytotoxicity when used as nanoparticle stabilizer; more surprisingly, the otherwise innocuous PVA and PF68 polymers also conferred a significant cytotoxicity to PLGA nanoparticles. These results unveiled the critical toxicological contribution played by stabilizers used for the formulation of PLGA nanoparticles when used at high concentrations, which may have implications for local toxicities of PLGA-based nanomedicine, and provided additional insight in cytotoxic effects of internalized nanoparticles.

A review of the nonclinical safety of Transcutol®, a highly purified form of diethylene glycol monoethyl ether (DEGEE) used as a pharmaceutical excipient.

Transcutol® (Diethylene glycol monoethyl ether, DEGEE), CAS # 111-90-0, is commonly used as a vehicle in the formulation or manufacturing process of pharmaceuticals, cosmetics, and food additives. This paper presents unpublished nonclinical safety data using a form of DEGEE which includes a significantly decreased level of impurities, specifically ethylene glycol and diethylene glycol. It also reviews the history of use, regulatory status, and previously published toxicity data for DEGEE. The review supports that DEGEE is well tolerated across animal species and gender with toxicity occurring only at levels well above those intended for human use. At high levels of exposure, the kidney is identified as the critical target organ of DEGEE toxicity. DEGEE is negative for genotoxicity in in vitro and in vivo studies. Subchronic and chronic toxicity studies produced no reports of preneoplastic changes in organs, but the animal data is insufficient to allow a definitive opinion as to carcinogenicity. In silico data suggested that DEGEE is not carcinogenic or genotoxic. Developmental toxicity was seen in rats but only at levels 200 times greater than the estimated oral Permissible Daily Exposure Level of 10 mg/kg/day. The nonclinical data along with the long history of DEGEE use as a vehicle and solvent by multiple routes provide evidence of its safety. Furthermore, the novel data discussed herein provides evidence that toxicity previously associated with high levels of DEGEE in nonclinical studies conducted prior to 1990 could possibly be attributed to the presence of significant amounts of ethylene glycol or other impurities.

Budesonide/cyclodextrin complex-loaded lyophilized microparticles for intranasal application.

OBJECTIVE: Lyophilized microparticles composed of budesonide (BDS), hydroxypropyl-ß-cyclodextrin (HP-ß-CD), and hydroxypropylmethylcellulose (HPMC) or sodium carboxymethylcellulose (CMC-Na) were developed for intranasal delivery and their characteristics were evaluated. MATERIALS AND METHODS: The particle size and morphology were assessed by mean diameter measurement and scanning electron microscopy (SEM) image, respectively. The solid-state of products was tested by X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). In vitro drug release and cytotoxicity to the primary human nasal epithelial (HNE) cells were also evaluated. RESULTS AND DISCUSSION: Lyophilized microparticles exhibited vanishment of crystallinity of drug in XRPD analysis, the enfeeblement of carbonyl (C=O) stretching bands of carboxyl group in BDS in FT-IR spectra and the disappearance of endothermic peak of drug in the results of DSC study. Based on the results of solid-state studies, BDS was existed as an amorphous form in the lyophilized microparticles. CD complexation enhanced drug solubility and release rate, and HPMC or CMC-Na also improved drug dissolution rates. Cytotoxicity of developed microparticles to the HNE cells was measured and their safety to HNE cell was identified. CONCLUSION: Developed microparticles can efficiently deliver insoluble drug, such as BDS, to the nasal epithelium and thus it may improve therapeutic efficacy in the respiratory tract.

Augmented cytotoxicity of hydroxycamptothecin-loaded nanoparticles in lung and colon cancer cells by chemosensitizing pharmaceutical excipients.

The aim of this was to investigate and compare the chemosensitizing effect of some pharmaceutical excipients (TPGS, Pluronic P85 and chitosan) by evaluating the cytotoxicity of the chemotherapeutic drug Hydroxy Camptothecin (HCPT) loaded into PLGA nanoparticles. Different nanoparticles formulations were developed and evaluated for size, zeta potential, morphology, loading and encapsulation efficiency as well as in vitro drug release. The cytotoxicity of the nanoparticles was evaluated by MTT assay in A549 (human lung carcinoma cell line) and HT29 (human colon carcinoma cell line) whereas their cellular uptake was determined by confocal laser scanning microscopy and microfluorimetry assay. The results revealed that nanoparticles possessed a desirable nanometric size (revealed by dynamic light scattering measurements and TEM) with appreciable HCPT encapsulation (>48%) and negative surface charge that was switched to positive upon coating with chitosan. The nanoparticles adopted a sustained release phase preceded by initial burst of HCPT that was reduced by chitosan coating. The cytotoxicity of the nanoparticles in A549 and HT29 cells was significantly augmented compared to simple drug solution and basic nanoparticles without excipients. The excipients could be ranked according to their IC50 lowering effect in the following order [TPGS (sixfold lower IC50) > Pluronic P85 > Chitosan]. The augmented cytotoxicity and chemosensitizing effect might be attributed to overcoming drug efflux (in case of TPGS 1000 or Pluronic P85) and/or maximizing internalization by cancer cells (chitosan coating). Acting as chemopotentiators, the studied excipients could have potential in reducing therapeutic HCPT doses and minimizing adverse effects in lung and colon chemotherapy.

New polyfluorothiopropanoyloxy derivatives of 5ß-cholan-24-oic acid designed as drug absorption modifiers.

A series of final six propanoyloxy derivatives of 5ß-cholan-24-oic acid (tridecafluoroctylsulfanyl- and tridecafluoroctylsulfinylethoxycarbonylpropanoyloxy derivatives) as potential drug absorption promoters (skin penetration enhancers, intestinal absorption promoters) was generated by multistep synthesis. Structure confirmation of all generated compounds was accomplished by (1)H NMR, (13)C NMR, IR and MS spectroscopy methods. All the prepared compounds were analyzed using RP-TLC, and their lipophilicity (RM) was determined. The hydrophobicity (log P), solubility (logS), polar surface area (PSA) and molar volume (MV) of the studied compounds were also calculated. All the target compounds were tested for their in vitro transdermal penetration effect and as potential intestinal absorption enhancers. The cytotoxicity of all the evaluated compounds was evaluated against normal human skin fibroblast cells. Their anti-proliferative activity was also assessed against human cancer cell lines: T-lymphoblastic leukaemia cell line and breast adenocarcinoma cell line. One compound showed high selective cytotoxicity against human skin fibroblast cells and another compound possessed high cytotoxicity against breast adenocarcinoma cell line and skin fibroblast cells. Only one compound expressed anti-proliferative effect on leukaemia and breast adenocarcinoma cells without affecting the growth of normal cells, which should be promising in potential development of new drugs. Most of the target compounds showed minimal anti-proliferative activity (IC50>37µM), indicating they would have moderate cytotoxicity when administered as chemical absorption modifiers. The relationships between the lipophilicity/polarity and the chemical structure of the studied compounds as well as the relationships between their chemical structure and penetration enhancement effect are discussed in this article.

Kinetic analysis of the toxicity of pharmaceutical excipients Cremophor EL and RH40 on endothelial and epithelial cells.

Cremophor EL and RH40 are widely used excipients in oral and intravenous drug formulations such as Taxol infusion to improve drug dissolution and absorption. Studies indicate that Cremophors, especially EL, have toxic side effects, but few data are available on endothelial and epithelial cells, which form biological barriers and are directly exposed to these molecules. Human hCMEC/D3 brain endothelial and Caco-2 epithelial cells were treated with Cremophor EL and RH40 in the 0.1-50 mg/mL concentration range. Cell toxicity was monitored by real-time cell microelectronic sensing and verified by lactate dehydrogenase release and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays, and morphological methods. Cremophors caused dose- and time-dependent damage in both cell types. In endothelial cells, 0.1 mg/mL and higher concentrations, in epithelial cells, concentrations of 5 mg/mL and above were toxic, especially at longer incubations. Cell death was also proven by double fluorescent staining of cell nuclei. Immunostaining for tight junction proteins claudin-4 and -5 showed barrier disruption in cells treated by surfactants at 24 h. In conclusion, Cremophor EL and RH40 in concentrations corresponding to clinical doses caused endothelial and epithelial toxicity. Endothelial cells were more sensitive to surfactant treatment than epithelial cells, and Cremophor EL was more toxic than RH40 in both cell types.