Acute exposure and biomarkers assessment in rainbow trout exposed to selected pharmaceuticals.

Pharmaceuticals released from municipal effluents discharges pose a risk to aquatic organisms. The toxicity of 5 pharmaceuticals with distinct therapeutic actions were assessed in rainbow trout: olanzapine (antipsychotic), erythromycin (antibiotic), mycophenoate (immunosuppression), pinaverium (anti-inflammatory) and trazodone (sedative). Juveniles were exposed to these drugs for 96 h at concentrations between 64 µg/L up to 40 mg/L to reach lethality. Survival was determined and a suite of biomarkers was analyzed for drug biotransformation, oxidative stress/damage and metabolic activity at sublethal concentrations. The data revealed the following toxicity: olanzapine >trazodone>mycophenolate>pinaverium∼erythromycin based on mortality. The data also revealed that toxicity was associated to mass, pKa and hydrophobicity and the following sublethal effects: GST, LPO and DNA strand breaks. Pharmaceuticals with lower molecular weight, physiological pKa, moderate hydrophobicity, low biotransformation and DNA strand breaks were generally more toxic to fish. However, this should be considered as a general guide in identifying toxic pharmaceuticals in non-target organisms.

Removal mechanisms of erythromycin by microalgae Chlorella pyrenoidosa and toxicity assessment during the treatment process.

Microalgae-based biotechnology for antibiotic removal has received increasing attention as an economical and green method. This study investigated the removal mechanism of erythromycin by Chlorella pyrenoidosa and its correlation with the ecotoxic responses of microalgae. The degradation products (DPs) were identified, and their toxicity was predicted. The results indicated that only 4.04 %, 6.28 % and 23.53 % of erythromycin were left after 21-day microalgae treatment in 0.1, 1.0 and 10 mg/L treatments, respectively. Biodegradation contributed 48.62-67.01 %, 16.67-52.32 % and 6.42-24.82 %, while abiotic degradation contributed 8.76-29.61 %, 5.19-41.39 %, and 16.55-51.22 % to erythromycin attenuation in 0.1, 1.0, and 10 mg/L treatments, respectively. The growth and physiological-biochemical parameters of microalgae were slightly affected in low concentration treatment, which may be the main reason that biodegradation was the prominent removal mechanism. By contrast, oxidative damage in high concentration treatment inhibited the cell growth and chlorophyll content of microalgae, which hindered erythromycin biodegradation. In addition, eleven erythromycin degradation products (DPs) were identified during microalgae treatment of 21 days. Seven DPs including DP717, DP715, DP701A, DP701B, DP657, DP643, and DP557, represented higher toxicity to aquatic organisms than erythromycin.

Investigation of pharmaceutically active compounds in an urban receiving water: Occurrence, fate and environmental risk assessment.

Pharmaceutically active compounds (PhACs) recently have been recognized to constitute a health risk for aquatic ecosystems. The major pathways of PhACs to enter the aquatic environment are excretion and discharge of effluents through sewage treatment plants (STPs). The occurrence, bioaccumulation and risk assessment of lipophilic PhACs, including erythromycin, ketoconazole, indomethacin, diclofenac, gemfibrozil, bezafibrate, propranolol, carbamazepine, sertraline and 17α-ethinylestradiol were investigated in a river that receives effluents from STP. The results indicate that the PhACs were extensively existed in fish, sediment, suspended particulate matter (SPM), colloidal phase (5 kDa to 1 µm) and truly dissolved phase (< 5 kDa) water, with total concentration of ten PhACs (Σ10PhACs) of ND-19.6 ng/g, 7.3-11.2 ng/g, 25.3-101.5 ng/g, 10.1-27.7 ng/L and 67.0-107.6 ng/L, respectively. The Σ10PhACs for particulate and water samples collected from STP's outfall site were higher than those collected from upstream and downstream, indicating that the STP is an important PhACs source of river. However, the Σ10PhACs in sediment showed no significant statistical differences in the sampling area, and which was 3.5-9.5 times lower than those in SPM samples. The colloidal phase contributed 2.5-28.5% of erythromycin, 5.8-45.6% of ketoconazole, 8.4-32.2% of indomethacin, 7.0-21.4% of diclofenac, 11.6-36.9% of gemfibrozil, 10.2-45.9% of bezafibrate, 5.9-16.8% of propranolol, 1.9-11.1% of carbamazepine and 1.1-23.8% of sertraline in the aquatic environment. This suggests that aquatic particulates (e.g., colloids and SPM) maybe an important carrier for PhACs in the aquatic system. In general, the Σ10PhACs in the tissues of fish were in order as follows: kidney > brain > liver > gill > muscle. Based on truly dissolved concentrations of PhACs in the water, bioaccumulation factors were between 3.7 and 2727.3 in the fish tissues, sertraline exhibited bioaccumulation potential. In all the risk assessments, erythromycin could cause most harmful adverse health effects for the most sensitive algae group based on the acute and chronic data. In addition, the risk quotient values for diclofenac toward fish were higher than 1. These results indicate that the PhACs pose a potential risk to the aquatic organisms, especially for chronic risk.

High-content screening imaging and real-time cellular impedance monitoring for the assessment of chemical's bio-activation with regards hepatotoxicity.

Testing hepatotoxicity is a crucial step in the development and toxicological assessment of drugs and chemicals. Bio-activation can lead to the formation of metabolites which may present toxicity for the organism. Classical cytotoxic tests are not always appropriate and are often insufficient, particularly when non metabolically-competent cells are used as the model system, leading to false-positive or false-negative results. We tested over 24 h the effects of eight reference compounds on two different cell models: primary cultures of rat hepatocytes and FAO hepatoma cells that lack metabolic properties. We performed inter-assay validation between three classical cytotoxicity assays and real-time cell impedance data. We then complemented these experiments with high-content screening (HCS) to determine the cell function disorders responsible for the observed effects. Among the different assays used, the neutral red test seemed to be well suited to our two cell models, coupled with real-time cellular impedance which proved useful in the detection of bio-activation. Indeed, impedance monitoring showed a high sensitivity with interesting curve profiles yet seemed unsuitable for evaluation of viability on primary culture. Finally, HCS in the evaluation of hepatotoxicity is likely to become an essential tool for use in parallel to a classical cytotoxic assay in the assessment of drugs and environmental chemicals.

Toxicity of five antibiotics and their mixtures towards photosynthetic aquatic organisms: implications for environmental risk assessment.

The individual and combined toxicities of amoxicillin, erythromycin, levofloxacin, norfloxacin and tetracycline have been examined in two organisms representative of the aquatic environment, the cyanobacterium Anabaena CPB4337 as a target organism and the green alga Pseudokirchneriella subcapitata as a non-target organism. The cyanobacterium was more sensitive than the green alga to the toxic effect of antibiotics. Erythromycin was highly toxic for both organisms; tetracycline was more toxic to the green algae whereas the quinolones levofloxacin and norfloxacin were more toxic to the cyanobacterium than to the green alga. Amoxicillin also displayed toxicity to the cyanobacterium but showed no toxicity to the green alga. The toxicological interactions of antibiotics in the whole range of effect levels either in binary or multicomponent mixtures were analyzed using the Combination Index (CI) method. In most cases, synergism clearly predominated both for the green alga and the cyanobacterium. The CI method was compared with the classical models of additivity Concentration Addition (CA) and Independent Action (IA) finding that CI could accurately predict deviations from additivity. Risk assessment was performed by calculating the ratio between Measured Environmental Concentration (MEC) and the Predicted No Effect Concentration (PNEC). A MEC/PNEC ratio higher than 1 was found for the binary erythromycin and tetracycline mixture in wastewater effluents, a combination which showed a strong synergism at low effect levels in both organisms. From the tested antibiotic mixtures, it can be concluded that certain specific combinations may pose a potential ecological risk for aquatic ecosystems with the present environmentally measured concentrations.

Assessment of the carcinogenic potential of mitemcinal (GM-611): increased incidence of malignant lymphoma in a rat carcinogenicity study.

Mitemcinal is an erythromycin derivative, which acts as an agonist of the motilin receptor. For assessment of the carcinogenicity of mitemcinal, we conducted a short-term carcinogenicity study in p53 (+/-) C57BL/6 mice and a 104-week carcinogenicity study in CD(SD)IGS rats. There was no evidence of a carcinogenic potential in mouse when administered for 26 consecutive weeks at levels up to 250 mg/kg/day. In the rat study, an increased incidence of lymphoma was noted in 5/60 males and 8/60 females of the high dose group (60 mg/kg/day) compared to 1/60 and 0/60 in control males and females, respectively, with statistical significance in females. Rat lymphomas include different immunomorphologic types (T- or B-cell lineage). Immunohistochemical analysis revealed that lymphomas from mitemcinal-treated rats and spontaneous cases were of T-cell lineage. The overall weight of evidence suggests that the incidence of spontaneous lymphoma was enhanced in the rat study. They also indicate that the increased incidence of lymphomas was based on a non-genotoxic effect with a threshold dose-response and that the tumorigenesis was based on the strain or species specificity of background factors. The high dose in the rat study is approximately 1600-fold higher (AUC) than that of the clinical dose, a sufficient margin of safety for the clinical dose. We conclude that the risk of carcinogenesis due to mitemcinal in humans can be considered to be minimal and is to represent an acceptable risk for the continued administration of mitemcinal to humans.