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Basic toxicokinetics

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basic toxicokinetics in vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference Type:
study report

Materials and methods

Objective of study:
Test guideline
no guideline followed
Principles of method if other than guideline:
Three male rats were intravenously administered MADAME at a targeted dose level of 5.66 mg/kg (36 µmol/kg) using sterile saline as the dose vehicle. After dose administration, blood samples (~200 μL) were collected at 5, 10, 30, 60, and 180 minutes into individual pre-weighed glass vials containing ethyl acetate (600 μL) acidified with 10% trifluoroacetic acid (TFA). After vortexing and subsequent centrifugation, the blood extracts underwent quantitative analysis for MADAME by gas chromatography with tandem mass spectrometry (GC/MS-MS).
GLP compliance:

Test material

Test material form:

Test animals

Fischer 344/DuCrj
Details on test animals and environmental conditions:
- Source: Charles River (Kingston, New York)
- Age at study initiation: 9-12 weeks
- Weight at study initiation: 194-197 g
- Housing: singly in glass Roth-type metabolism cages
- Diet (e.g. ad libitum): LabDiet Certified Rodent Diet #5002 (PMI Nutrition International, St. Louis, Missouri) in pelleted form, ad libitum
- Water (e.g. ad libitum): Municipal water, ad libitum
- Acclimation period: 7d

- Temperature (°C): 22°C with a range of 20°C-26°C
- Humidity (%): 50% with a range of 30-70%
- Photoperiod (hrs dark / hrs light): 12-hour light/dark (on at 6:00 a.m. and off at 6:00 p.m.)

Administration / exposure

Route of administration:
other: Intralipid 20%
Details on exposure:
An appropriate amount of MADAME was added to sterile physiological saline to obtain the appropriate dose concentration using aseptic technique. The amount of dose solution administered was targeted at ~2.5 mL/kg bw and injected over ~1 minute for a corresponding injection rate of ~0.5 mL/minute. The dose solution was administered at room temperature (19-25 °C) and used within 24 hours of preparation.
Duration and frequency of treatment / exposure:
single iv treatment
Doses / concentrations
Dose / conc.:
5.66 mg/kg bw/day (nominal)
corresponds to 36 µmol/kg
No. of animals per sex per dose:
3 males
Control animals:
yes, concurrent vehicle
Positive control:
Details on study design:
- Dose selection rationale: previous studies of this type have used similar equimolar ratios
Details on dosing and sampling:
- Tissues and body fluids sampled: blood
- Time and frequency of sampling: 5, 10, 15, 30, 60 and 180 minutes post-dosing
Descriptive statistics were used, i.e., mean ± standard deviation, where applicable. All descriptive statistic calculations were conducted using Microsoft Excel (Microsoft Corporation, Redmond, Washington) spreadsheets in full precision mode (15 digits of accuracy). Pharmacokinetic parameters that were calculated for blood used the pharmacokinetic computer modeling program PK Plus (v. 9.6, Simulation Plus, Inc., Lancaster, California, United States of America).

Results and discussion

Preliminary studies:
The solubility of MADAME was tested at up to 10 mg/mL in Intralipid 20% and sterile saline. The test material was soluble in both vehicles at this concentration and saline was chosen as the vehicle.

Toxicokinetic / pharmacokinetic studies

Toxicokinetic parametersopen allclose all
Key result
Test no.:
Toxicokinetic parameters:
half-life 1st: < 2 min-1
Test no.:
Toxicokinetic parameters:
AUC: 208 µg-min/g
Test no.:
Toxicokinetic parameters:
other: <1% of the dose remaining in the blood 5 minutes post-intravenous administration

Metabolite characterisation studies

Metabolites identified:
not measured

Any other information on results incl. tables

The resulting blood time course showed that MADAME was quickly hydrolyzed with  < 1% of the dose remaining in the blood 5 minutes post-intravenous administration. Further pharmacokinetic analysis of the blood concentrations of MADAME showed that the compound exhibited single-phase elimination (i.e. half-life; t½). The average calculated t½value was < 2 min-1and the average area under the curve (AUC0-t) value was approx. 208 µg-min/g. 

Applicant's summary and conclusion

Overall, the analysis of the blood pharmacokinetics indicated that the parent test material is rapidly removed from blood circulation (i.e. blood compartment)in vivo. This finding is in line with the observations for similar and well-analysed methacrylates. Hence, these data support a pharmacokinetics-based Read-Across for MADAME to the metabolites methacylic acid (CAS No. 79 -41 -4) and 2- dimethyl aminoethanol (CAS No. 108 -01 -0) respectively. For more details please refer to the "Read-across justification based on RAAF 2019" as attached to this IUCLID Chapter 7.8.1 and 7.8.2.
Executive summary:

This study was performed to determine the applicability of a pharmacokinetics-based Read-Across approach for 2-(dimethylamino)ethyl methacrylate (MADAME) to other well-studied methacrylates by evaluating the hydrolysis and pharmacokinetic characteristics of the test materialin vivo. Under thesein vivoconditions less than 1% of the administered dose (on average) remained in the blood 5 minutes post-dosing which indicates that MADAME was rapidly removed from circulating blood. Pharmacokinetic analysis of the blood concentrations of MADAME showed that the compound exhibited a single-phase elimination in which the average t½value was below 2 min. The average AUC0-tvalue for MADAME was approx. 208 µg-min/g. Based on the properties of the quick hydrolysis and pharmacokinetics of MADAME in vivo, these data support a pharmacokinetics-based Read-Across for MADAME with other similar and well-studied methacrylates.