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EC number: 237-185-4 | CAS number: 13680-35-8
Oral absorption is estimated to be approximately 50%; inhalation absorption of 100% is assumed.
Data indicate a similar extent of absorption following oral and dermal exposure; correction for differences in the extent of absorption is not required.
From analysis of toxicity data for M-DEA, the following qualitative TK characteristics are proposed. M-DEA is absorbed from the gastrointestinal tract following oral administration. Deposition will favour lipophilic stores such as adipose tissue. M-DEA, or a further active metabolite, likely undergoes conjugation with GSH, prior to elimination. It is not possible to make quantitative estimations from the available data.
Acute oral toxicity
The combined LD50 on Wistar rats was found to be 1901 mg/kg; the LD50 for males 1736 mg/kg and for females 2026 mg/kg.
Acute dermal toxicity
The acute dermal toxicity on rats was found to be > 2000 mg/kg.
Acute inhalation toxicity
Study not performed; dermal route was chosen instead.
M-DEA was found to be non-irritating to skin and non-irritating to eyes.
M-DEA is not a skin sensitiser.
Repeated dose toxicity
Under the conditions of the present study, LZ 596 caused slight reduction in body weight development and food consumption, changes in serum biochemical parameters (elevated gamma glutamyltransferase activity and cholesterol concentration – male and female – liver weight alterations along with cytoplasmic vacuolization in the liver lobes (male and female) following a consecutive 90 days oral administration at 50 mg/kg bw/day to Hsd.Brl.Han:Wistar rats. At 25 mg/kg bw/day, slightly elevated cholesterol concentration (female) and changes in liver weights and cytoplasmic vacuolization in the liver lobes (male and female) were detected. At 10 mg/kg bw/day, slightly elevated cholesterol concentration (female) and changes in liver weights (male and female) were observed. Based on the observations made in this toxicity study the dose levels for the No Observed Adverse Effect Levels (NOAEL) was determined as follows:
- NOAEL for systemic toxicity of male rats: 10 mg/kg bw/day
- NOAEL for systemic toxicity of female rats: 10 mg/kg bw/day
The test item was tested for genetic toxicity in several in-vitro studies, both with and without metabolic activation. A reverse mutation assay (Ames test), a chromosomal aberration test in-vitro and a gene mutation test in-vitro (HPRT) were performed according to the corresponding OECD-guidelines. The Ames test used Salmonella typhimurium and E.coli strains and showed a negative result (non-mutagenic). The HPRT test on CHO cells showed a negative result as well and confirmed the non-mutagenic result of the Ames test. The chromosomal aberration test in-vitro performed with Chinese V79 cells showed no clastogenic effects, too. A micronucleus test in-vitro was not further assessed due to significant deficiencies in quality.
Prenatal developmental toxicity
Groups of twenty four sperm-positive female Hsd. Brl. Han: WIST Rats were treated with the test item by oral administration at three dose levels of 5, 15 and 50 mg/kg bw/day and one control group from day 5 up to and including day 19 post coitum daily. The control animals were given the vehicle (1% methylcellulose) alone. The treatment volume was 5 mL/kg/bw. Formulation analytics (checking of homogeneity and achieved concentrations of the test item in the dosage forms) was performed two times during the treatment period using a validated HPLC/UV method. During the study animals were checked for mortality and clinical signs. Body weight and food consumption of the dams were also recorded. The day of detection of sperm in the vaginal smear of females was regarded as day 0 of gestation. A Caesarean section and gross pathology were performed on gestational day 20. Organs of the dams were examined macroscopically. Organs and tissues with undiagnosed macroscopic findings were fixed in 4 % buffered formalin solution at necropsy for possible histological examination. The number of implantations, early and late resorptions, live and dead fetuses in each uterine horn and the number of corpora lutea were recorded. Each fetus was weighed and examined for sex and external abnormalities. The placentas were weighed and examined externally. The body of about half of each litter was subjected to visceral examination by means of a dissecting microscope after fixation in Sanomiya mixture. The heads were examined by Wilson's free-hand razor blade method. After double staining, the skeletons were examined by means of a dissecting microscope. All abnormalities found during the fetal examinations were recorded. In total, there were 89 dams with live fetuses at termination on gestation day 20, (23, 24, 21 and 21 in the control, 5, 15 and 50 mg/kg bw/day groups respectively. Results The formulations were proved to be homogeneous. Measured concentrations of LZ 596 were in the range of 93-107% of the nominal concentrations at all the three concentration levels for both investigated series.
There was no mortality and were no clinical signs observed during the in-life phase. Enlarged or slightly enlarged liver was found at necropsy in the majority of the dams in the 50 mg/kg bw/day group which was attributed to the treatment of the dams. No treatment related findings were recorded in the 5 and 15 mg/kg bw/day dose groups.
Reduction in the food consumption as well as body weight gain and corrected body weight gain of the dams was observed in the 50 mg/kg bw/day dose group which was considered to be due to the treatment with the test item.
No treatment related changes were indicated in the 5 and 15 mg/kg bw/day groups. There were no significant differences in the mean values of corpora lutea, implantations, early- and late embryonic death, dead fetuses, viable fetuses and and the sex distribution of fetuses in the experimental groups. Intrauterine parameters There was no significant differences in the body weight of the fetuses and placental weight. Fetal- and placental weight The number of litters with malformed fetuses was two in each group during the fetal examinations. Fetal examination No test item effect was indicated. External examination There were no malformations recorded in the 15 and 50 mg/kg bw/day groups. One fetus was found with meningocele and short tail in the control group and one fetus with a malrotated forelimb in the 5 mg/kg bw/day dose group which was not confirmed at skeletal examination. Incidence of body weight retarded fetuses and other variations was not influenced by the treatment. Malformation of the brain was found in one fetus in the 5 and one in the 15 mg/kg bw/day dose group. Considering that no malformation of the brain was recorded for the fetuses in the 50 mg/kg bw/day dose group and that brain malformations occur sporadically with low incidence unrelated to the treatment according to the historical control data and background data another strain of rats, i.e. CrL:CD(R) BR rats (Lang, 1993), this was judged not to be a consequence of the treatment of the dams with LZ 596. Visceral examination Situs inversus totalis in one fetus in the 15 mg/kg bw/day group was considered to be without any test item relationship. Statistically significant increase was indicated in the incidence of fetuses with variations and abnormalities due to the increase of fetuses with bilateral hydroureter in the 50 mg/kg bw/day group which is a common finding in prenatal developmental toxicity studies according to the background data of this laboratory (Appendix XXIV/A, B) and another strain of rats, i.e. CrL:CD(R) BR rats (Lang, 1993).
The percentage of bilateral hydroureter was not higher than 7% in this study and the incidence of associated variation dilated renal pelvis was with a very low incidence and did not increase in the test item treated groups which suggests that this variation was without a toxicological relevance. Misaligned tracheal cartilage rings as another type of variation were found without any dose response. No test item effect was indicated. Skeletal examination None of the variations or malformations increased significantly in the test item treated groups. Conclusion Based upon these data, treatment of pregnant Hsd. Brl. Han: WIST Rats from gestational day 5 to 19 by oral administration of LZ 596, caused maternal toxicity such as reduced food consumption and body weight gain as well as enlargement of the livers at the dose level of 50 mg/kg bw/day. The test item did not result in external and skeletal abnormalities or visceral malformations. The slightly higher incidence of visceral variation hydroureter at 50 mg/kg bw/day was judged to be without a toxicological relevance. The doses of 5 and 15 mg/kg bw/day of LZ 596 did not cause any maternal or fetal effects.
Based on these observations the No Observed Adverse Effect Level (NOAEL) was determined as follows:
- NOAEL maternal toxicity: 15 mg/kg bw/day
- NOAEL developmental toxicity: 50 mg/kg bw/day
DNELs were not calculated. The weight-of-the-evidence from the genotoxicity studies support that the test item is not genotoxic at doses that do not cause excessive toxicity.
- ECHA (2008) Guidance on information requirements and chemical safety assessment, Chapter R.8: Charactersation of dose [concentration]-response for human health, European CHemicals Agency (ECHA), GUIDEANCE FOR THE IMPLEMENTATION OF REACH, pp. 1 -150.
- ECETOC (2003) Derivation of assessment factors for human health risk assessment, European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC), TECHNICAL REPORT NO. 86, pp. 1-86.
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