Morpholine, 4-[(triethoxysilyl)methyl]-

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2008-05-14 to 2009-02-06

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: followed OECD Guideline under GLP

Cross-reference

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Objective of study:

other: Bioavailability and excretion profile

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 417 (Toxicokinetics)

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

(N-Morpholinomethyl)triethoxysilan

IUPAC Name:

(N-Morpholinomethyl)triethoxysilan

Radiolabelling:

yes

Remarks:

14C

Test animals

Species:

mouse

Strain:

NMRI

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Netherlands 5960 AD Horst / The Netherlands
- Age at Acclimatisation: 8 weeks
- Weight: The mean body weight of the animals on the day of administration was 31 g ± 2.1 in males and 24 g ± 1.4 in females, respectively.
- Fasting period before study:
- Housing: During acclimatisation in groups of 7/8 in macrolon type 3 cages.
- Individual metabolism cages: no, groups a three
- Diet (e.g. ad libitum): Pelleted 3433 Kliba standard diet ad libitum* (PROVIMI KLIBA AG, 4303 Kaiseraugst / Switzerland)
- Water (e.g. ad libitum): Tap water ad libitum
- Acclimation period: 7 days to laboratory environment, including 1 day in metabolism cages.


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3 °C
- Humidity (%): 30.0 - 70.0%
- Air changes (per hr): 10-15 times/hour
- Photoperiod (hrs dark / hrs light): 12 hours fluorescent light / 12 hours dark

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
On the day of administration, the administration solution was prepared. For administration at the target dose level of 2000 mg/kg, an aliquot of 300 mg of the radiolabeled test item, an aliquot of 2700 mg of the non-labeled test item and 12 mL corn oil were mixed to give a target concentration of 2000 mg/kg/10 mL. The exact amount of radioactivity in the application solution was determined by Liquid Scinitillation Counting (LSC) resulting in 21.5 MBq, equivalent to 308 mg of undiluted 14C- N-(Morpholinomethyl)triethoxysilane. The total amount of diluted 14C- N-(Morpholinomethyl)triethoxysilane was 3008 mg, resulting in a new specific activity of 0.0072 MBq/mg. The concentration of N-(Morpholinomethyl)triethoxysilane (= N-(Morpholinomethyl)triethoxysilane & 14C- N-(Morpholinomethyl)triethoxysilane) in the formulation was 200.5 mg/mL.

HOMOGENEITY AND STABILITY OF TEST MATERIAL:
Stability of the test item in the application solution was demonstrated by HPLC. The radio-purity of the test item in the formulation was found to be 99.78% after application.

Duration and frequency of treatment / exposure:

single treatment by oral gavage

Doses / concentrations

Remarks:

Doses / Concentrations:
only one dose: 2000 mg/kg b.w.

No. of animals per sex per dose / concentration:

3 male and 3 female animals per time point 1 h
3 male and 3 female animals per time point 4 h
6 male and 6 female animals per time point 24 h

Control animals:

no

Positive control reference chemical:

no

Details on study design:

- Dose selection rationale: The dose corresponds to the highest dose used in the in vivo micronucleus test (see section 7.6.2).
- Rationale for labelling design: As (N-Morpholinomethyl)tiethoxysilan hydrolyses in water under the formation of the Silanetriol and Ethanol the morpholino ring was labelled to get infromation on the bioavailabilty of the silan moiety.

Details on dosing and sampling:

TOXICOKINETIC STUDY (Absorption, distribution, excretion)
Twelve male and twelve female mice were treated with the test item via the oral route. Three male and three female animals each were sacrificed one and four hours after test item administration, and terminal blood, femur, stomach, combined GI tract contents, small intestine, large intestine, liver and kidney were isolated. 24 h after test item administration terminal blood, femur, stomach, small intestine, large intestine, combined GI tract contents, liver, kidney as well as urine and faeces were isolated.

Statistics:

range, mean, SD

Results and discussion

Preliminary studies:

-

Toxicokinetic / pharmacokinetic studies

Details on absorption:

After an oral dose of 2000 mg/kg, 14C- N-(Morphlinomethyl)triethoxysilane was rapidly absorbed and distributed in blood, plasma and all organs investigated. Peak concentrations were found at t = 1 h in blood, plasma, femur, liver and kidney.

Details on distribution in tissues:

Cmax in blood, plasma, femur, liver and kidney of male mice were 70.0 ± 11.2 μgeq/g, 72.7 ± 12.9 μgeq/g, 49.2 ± 12.7 μgeq/g, 179.2 ± 40.1 μgeq/g, and 481.3 ± 340.4 μgeq/g. The corresponding values in female mice were 74.6 ± 12.3 μgeq/g, 78.2 ± 11.9 μgeq/g, 177 ± 36.3 μgeq/g and 33
Peak concentrations in stomach, small intestine, large intestine, combined GI tract contents were found at t = 1 h or t = 4 h.
Cmax in stomach, small intestine, large intestine and combined GI tract contents were 12986.0 ± 7940.9 μgeq/g, 4543.4 ± 1710.2 μgeq/g, 1524.0 ± 1311.7 μgeq/g and 30171.4 ± 4649.0 μgeq/g. The corresponding values in female mice were 9183.3 ± 3435.5 μgeq/g, 2867.6 ± 503.0 μgeq/g, 3170.4 ± 1792.8 μgeq/g and 28315.7 ± 1552.2 μ
Mean plasma concentrations declined during the 24 h observation period to approximately 6.8% of the peak value in male mice and to 6.0% of the peak value in female mice. A comparable effect was seen in all tissues analysed.

Details on excretion:

After the 24 hours time period, 24.9% and 17.4% of the applied dose was detected in urine, 3.4% and 9.8% of the applied dose in cage wash of male and female mice, respectively. Based on these data the systemic absorption (bioavailability) for N-(Morpholinomethyl)triethoxysilane was at least 28.3% in male mice and 27.2% in female mice. During the same period, a total of 63.8% and 64.2% of the applied dose was excreted via faeces in male and female mice, respectively.

Metabolite characterisation studies

Metabolites identified:

not measured

Details on metabolites:

-

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): other: high bioavailability of the test item after oral exposure
From the results presented here it can be concluded that after a nominal oral dose of 2000 mg/kg 14C- N-(Morpholinomethyl)triethoxysilane to male and female mice, blood, plasma and femur were exposed to test item and/or its metabolites.
At the end of the 24 hours time period, 24.9% and 17.4% of the applied dose was detected in urine, 3.4% and 9.8% of the applied dose in cage wash of male and female mice, respectively.
Based on these data the systemic absorption (bioavailability) for N-(Morpholinomethyl)triethoxysilane was at least 28.3% in male mice and 27.2% in female mice. During the same period, a total of 63.8% and 64.2% of the applied dose was excreted via faeces in male and female mice, respectively.
Overall significant mean levels of the test item were found in blood and plasma as early as 1 hour after application. This indicates that after oral administration the test item was rapidly absorbed in significant amounts.

Executive summary:

To get information on the bioavailabilty of the silan moiety, as needed for the interprtation of the in vivo micronucleus test, an animal experiment with radio-labelled (N-Morpholinomethyl)triethoxysilane (labelled at the morpholino ring) was carried out (OECD Guideline 417). Twelve male and twelve female NMRI mice were treated once orally with 14C- N-(Morpholinomethyl)triethoxysilane at a nominal dose of 2000 mg/kg. The animals were sacrificed after one (three males and three females), after four (three males and three females) and after twentyfour hours (six males and six females). The concentrations of total radioactive residues were determined by Liquid Scintilla-tion Counting (LSC) in blood, plasma, femur, stomach, large intestine, small intestine, GI tract contents, liver and kidney. 24 hours after treatment total radioactivity was additionally deter-mined in faeces and urine.

One hour after application the mean total radioactive residue concentrations in male and female mice were found to be between 70.0 – 74.6μgeq/g in blood, 72.7 – 78.2μgeq/g in plasma, 42.4 – 48.9μgeq/g in femur, 5512.9 – 9183.3.μgeq/g in stomach, 2867.6 – 3180.5μgeq/g in small in-testine, 1221.5 – 1328.9μgeq/g in large intestine, 8480.0 – 23815.0μgeq/g in GI tract contents, 177.0 – 179.2μgeq/g in liver and 332.8 – 481.3μgeq/g in kidney.

Compared to 1 hour after application mean radioactive residue concentrations in male and fe-male mice were similar or higher 4 hours after application in, in small intestine, in large intestine and in combined GI tract contents reflecting the proceeding passage through the GI tract. In con-trast, in blood, in plasma, in kidney and in liver a decrease in mean radioactive residue concen-tration was observed. In femur, similar or slightly lower mean radioactive residue concentrations were observed.

24 hours after application only minor mean radioactive residue concentrations were left in stom-ach, small intestine, large intestine and combined GI tract contents compared to the 1 and 4 hours sampling time points. The same was true for blood, and femur.

At the end of the 24 hours time period, 24.9% and 17.4% of the applied dose was detected in urine, 3.4% and 9.8% of the applied dose in cage wash of male and female mice, respectively. Based on these data the systemic absorption (bioavailability) for N-(Morpholinomethyl)triethoxysilane was at least 28.3% in male mice and 27.2% in female mice. During the same period, a total of 63.8% and 64.2% of the applied dose was excreted via faeces in male and female mice, respectively.

Overall, significant mean levels of the test item were found in blood and plasma as early as 1 hour after application. This indicates that after oral administration the test item was rapidly ab-sorbed in significant amounts.