Registration Dossier

Administrative data

Endpoint:
dermal absorption in vivo
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: well conducted published NTP study

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
2005

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Information concerning the used methods can be found at NTP homepage or under J Robert Buchanan, Leo T. Burka, Ronald L. Melnick. Purpose and Guidelines for Toxicokinetics Studies within the National Toxicology Program. Environmonmental Health Perspectives, Vol. 105, No. 5, pp. 468-471, 1997.
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
Technical-grade unlabeled trimethylolpropane triacrylate was obtained from Aldrich Chemical Company
(Milwaukee, WI) in two lots (03115TV and 03914PV). Identity and purity analyses were conducted by the study
laboratory. Proton- and 13C-nuclear magnetic resonance and mass spectra were consistent with the structure.
Reverse phase high-performance liquid chromatography (HPLC) indicated the presence of several ultravioletabsorbing
impurities that were not identified
[14C]-Trimethylolpropane triacrylate (7.5 mCi, lot 91-350-35-02 and 5 mCi, lot R90-306-69-34) was obtained from
Chemsyn Science Laboratories (Lenexa, KS). The chemical’s identity was confirmed by coelution of
[14C]-trimethylolpropane triacrylate with unlabeled trimethylolpropane triacrylate by reverse phase HPLC. The
radiochemical purity of [14C]-trimethylolpropane triacrylate was determined to be less than 70%. After
development and application of a purification method, the average radiochemical purity of
[14C]-trimethylolpropane triacrylate was determined to be 98.8%.
Radiolabelling:
yes

Test animals

Species:
other: rats and mice
Strain:
other: male F344/N (rats) and B6C3F (mice)
Sex:
not specified
Details on test animals and environmental conditions:
Young adult male F344/N rats (240-306 g) and adult B6C3F1 mice (25-35 g) were obtained from Charles River Laboratories (Raleigh, NC, and Kingston, NY). Animals were coded by ear tags and quarantined for approximately 1 week. Purina Rodent Chow No. 5002 and tap water were available ad libitum. Prior to the experiments, rats and mice were housed up to a maximum of four animals per cage in polycarbonate cages. During the excretion studies, animals were housed individually in glass metabolism chambers that allowed for separate collection of urine, feces, and exhaled CO2 beginning at least 1 day before the studies.

Administration / exposure

Type of coverage:
occlusive
Vehicle:
acetone
Remarks:
for dermal studies
Duration of exposure:
72h
Doses:
intravenous injection:
- Nominal doses (rats) [14C]: 9.4mg/kg bw

dermal:
- Nominal doses (rats) [14C]: 1.7, 15.2 and 130 mg/kg bw
- Nominal doses (mice) [14C]: 1.2 mg/kg bw

dermal strip experiment:
- Nominal doses (rats) [14C]: 124 mg/kg bw

preexposure dermal study:
- Nominal doses (rats) [unlabeled]: 151 mg/kg bw

- Actual doses: stability was confirmed during an dermal carcinogenicity experiment; using GC, recovery rates were (with minor exception) in the range above 85% (mostly near 100).
- Actual doses calculated as follows: Nominal doses were used
- Dose volume: no data
No. of animals per group:
- 5 animals per dose group according to raw data
Control animals:
no
Details on study design:
1. dermal, rats and mice
APPLICATION OF DOSE:

VEHICLE
All dermal doses were prepared by dissolving appropriate quantities of labeled and/or nonlabeled trimethylolpropane triacrylate in acetone.

TEST SITE
Animals in dermal dosing experiments were sedated with an intramuscular dose of 60 mg/kg ketamine:xylazine (7:1) approximately 24 hours beforedermal doses were applied, and the fur on the back of each animal was clipped. The clipped area was wiped with acetone, dried, and examined; animals with broken skin in the clipped area were excluded from the study. The doses were applied to 1 square inch (rats) or 0.5 square inch (mice)
previously outlined with a permanent, felt-tip marker. Before dosing, a self-adhering protective foam appliance Libertyville, IL). Doses were administered with either a ball-tipped gavage needle and glass syringe equipped with a Teflon®-tipped plunger or a silylated glass wiretrol (Drummond Scientific Co., Broomall, PA) to the square inch of skin exposed through the window in the foam appliance. After dosing was complete, a cloth cover was attached to the foam appliance, and a protective metal cover was secured over the appliance with either Elastoplast® or Coban® adhesive bandage (3M Medical-Surgical Division, St. Paul, MN).After dosing the mice, a halved tissue capsule (Fisher HistoPrep; Fisher Scientific Company, Pittsburgh, PA), the latticed top of which was covered with 50/50 polyester/cotton sheeting, was glued over the dosing site with Dura Quick Gel super glue (Loctite Corp., Rocky Hill, CT). Doses were administered to the shaved skin of mice with a 50 μL wiretrol.

SITE PROTECTION / USE OF RESTRAINERS FOR PREVENTING INGESTION: yes: (see above)

REMOVAL OF TEST SUBSTANCE
At 72 hours postdosing the dosing appliances were removed from the anesthetized animals.The dosing site skin was washed and collected for analysis of acetone-extractable and nonextractable radiolabel
- Time after start of exposure: 72h

SAMPLE COLLECTION
To measure cumulative excretion of radiolabel, collection flasks and traps were changed at 8, 24, 48, and 72 hours postdosing
- Collection of blood:Blood was withdrawn from the animals into a heparinized syringe by cardiac puncture
- Collection of urine and faeces:Urine and feces were collected separately into round-bottom flasks cooled with dry ice
- Collection of expired air:Exhaled 14CO2 was collected by passing air from the metabolism cages through two traps containing room temperature 1 N sodium hydroxide
- Terminal procedure:The animals were sacrificed by intracardiac injection of Euthanasia-6® (Sparhawk Veterinary Laboratories, Inc., Lenexa, KS) or by carbon dioxide asphyxiation. Bladder urine was removed from each animal and added to the final urine collection.
- Analysis of organs: yes

SAMPLE PREPARATION
- Storage procedure: Selected tissues were removed from the carcasses and the blood, urine, and tissues were stored at –20° C for subsequent analysis of total radiolabel.
- Preparation details:Aliquots of urine, cage rinse, skin wash, and breath trap contents were mixed with scintillation cocktail and directly assayed for 14C content by liquid scintillation spectrometry (LSS); aliquots of blood, feces, and tissues were digested in Soluene 350® (Packard Instrument Company, Meriden, CT), neutralized, decolorized with perchloric acid and hydrogen peroxide, and assayed for total radiolabel. Skin samples and the residual carcass were digested in 2 N ethanolic sodium hydroxide prior to analysis for radiolabel. The dosing appliances were cut into eight pieces, added to scintillation vials containing 2 mL methanol, and analyzed by LSS. Appropriate background samples containing the same combination of reagents as the corresponding biological samples were prepared for all sample types
For mice urine, feces, breath, cage rinse, skin wash, appliance, and tissue samples were collected, digested,and analyzed as in the definitive dermal studies in rats, except the skin samples were not extracted with acetone prior to digestion.

2. intravenous, rats
APPLICATION OF DOSE :
In the intravenous injection study, a group of five male rats was given a single bolus dose of 9.4 mg [14C]-trimethylolpropane triacrylate/kg.

SAMPLE COLLECTION
- Collection of blood:Serial blood collections were taken at 0.08, 0.5, 1, 3, 6, 24, and 48 hours from the indwelling cannula and at 72 hours by cardiac puncture to analyze for blood concentrations of radiolabel
- Collection of urine and faeces:Urine, feces, cage rinse, and exhaled 14CO2 were collected and analyzed for cumulative excretion of radiolabel as
in the definitive dermal rat studies except that collections were made at 3, 6, 24, 48, and 72 hours postdosing
- Collection of expired air: see above
- Tissue samples were collected at 72 hours postdosing and digested and analyzed for radiolabel as described for the definitive dermal studies in rats.

3. general
ANALYSIS
- Method type(s) for identification: Liquid scintillation counting

please refer to the orginal NTP Protocol (which is published) for more detailed informations

Results and discussion

Signs and symptoms of toxicity:
no effects
Dermal irritation:
yes
Remarks:
erythema and edema at all dermal dose levels with the lowest doses (1.5 mg/kg in rats and 1.2 mg/kg in mice) exhibiting only slight irritation.
Absorption in different matrices:
Absorbed dose (rats, dermal, 1.7mg/kg) percentage
- Urine: 28
- Cage wash:0.9
- Faeces:2.5
- Expired air (CO2):13.1
- Dose site skin:
- Acetone extractable:-
- non extractable: 8.5
- Selected tissue:0.4
- Carcass:1.7
- Total Absorbed Dose: 55.1
- Total unabsorbed Dose (appliance and skin wash): 34.8

Absorbed dose (rats, dermal, 15.2mg/kg) percentage
- Urine: 12.1
- Cage wash:0.9
- Faeces:1.2
- Expired air (CO2):4.9
- Dose site skin:
- Acetone extractable:8.0
- non extractable: 3.3
- Selected tissue:1.0
- Carcass:1.2
- Total Absorbed Dose: 32.7
- Total unabsorbed Dose (appliance and skin wash): 57.0

Absorbed dose (rats, dermal, 130mg/kg) percentage
- Urine: 3.0
- Cage wash:0.1
- Faeces:0.2
- Expired air (CO2):1.4
- Dose site skin:
- Acetone extractable:10.4
- non extractable: 3.2
- Selected tissue:0.2
- Carcass:0.3
- Total Absorbed Dose: 18.7
- Total unabsorbed Dose (appliance and skin wash): 76.1

Absorbed dose (rats, dermal, 151mg/kg) percentage
- Urine: 5.8
- Cage wash:0.4
- Faeces:0.4
- Expired air (CO2):3.4
- Dose site skin:
- Acetone extractable:8.5
- non extractable: 2.6
- Selected tissue:0.7
- Carcass:3.6
- Total Absorbed Dose: 25.4
- Total unabsorbed Dose (appliance and skin wash): 65.3
Total recovery:
Absorbed dose (rats, dermal, 1.7mg) percentage
- Total Dose Recovery: 90
Absorbed dose (rats, dermal, 15.2mg/kg) percentage
- Total Dose Recovery: 89.7
Absorbed dose (rats, dermal, 130mg/kg) percentage
- Total Dose Recovery:94.8
Absorbed dose (rats, dermal, 151mg/kg) percentage
- Total Dose Recovery:90.7
Percutaneous absorptionopen allclose all
Dose:
130 mg/kg
Parameter:
percentage
Absorption:
18.7 %
Remarks on result:
other: 72h
Remarks:
rat
Dose:
15.2 mg/kg
Parameter:
percentage
Absorption:
32.7 %
Remarks on result:
other: 72h
Remarks:
rat
Dose:
1.7 mg/kg
Parameter:
percentage
Absorption:
55.1 %
Remarks on result:
other: 72h
Remarks:
rat
Dose:
1.2 mg/kg
Parameter:
percentage
Absorption:
75 %
Remarks on result:
other: 72h
Remarks:
mouse
Dose:
151 mg/kg
Parameter:
percentage
Absorption:
25 %
Remarks on result:
other: 72h
Remarks:
rat 24h preexposed to TMPTA (skin irritation)

Applicant's summary and conclusion

Conclusions:
Trimethylolpropane triacrylate was absorbed dermally and excreted mainly via urine and exhaltion. Absorption rate increases with decreasing dosage up to 55.1% (rats) and 75% (mice) Trimethylolpropane was instable in whole blood.
Executive summary:

A study to investigated the absorption, distribution and excretion of Trimethtylolpropane triacrylate was performed within the scope of an NTP toxicity profile. The study was conducted with rats and mice according to guidelines for toxicokinetics studies within the National Toxicology Program. Therefore rats and mice received different dosages of TMPTA via dermal application or tail vein injection. Excreta, blood and tissue samples were collected using different techniques.

In male F344/N rats, 18.7% of a single dermal dose of 130 mg/kg [14C]-trimethylolpropane triacrylate was absorbed and an average of 76% of the administered radiolabel was recovered unabsorbed 72 hours after dosing (Appendix L). In rats administered a 24-hour preexposure dose of nonradiolabeled trimethylolpropane triacrylate, 25% of a subsequent 151 mg/kg radiolabeled dose was absorbed and 65% was recovered unabsorbed from the dose site 72 hours after dosing. The absorption of dermally administered trimethylolpropane triacrylate was inversely related to dose; a total of 18.7% of the 130 mg/kg dose was absorbed, while 32.7% of the 15.2 mg/kg and 55.1% of the 1.7 mg/kg dose were absorbed. In mass terms, approximately five times more trimethylolpropane triacrylate was absorbed as the dose concentration increased by one order of magnitude. An average of less than 5% of the dose was recovered in the excreta of rats 72 hours after dermal application of 130 mg/kg, compared to an average of approximately 19% of the 15.2 mg/kg dose and 45% of the 1.7 mg/kg dose (Appendix L). Very little radioactivity was associated with most of the tissues 72 hours after exposure; however, the kidney had elevated tissue:blood ratios at each dose concentration. In male B6C3F1 mice, a total of 75% of dermally applied [14C]-trimethylolpropane triacrylate was absorbed 72 hours after a single 1.2 mg/kg dose. A much larger percentage of the applied radioactivity remained at the site of application in mice than in rats (31% in mice, 9% in rats). The collected tissues and residual carcass contained less than 2% of the administered dose. Approximately 21% of the dose remained unabsorbed, and approximately 42% was excreted in the urine, feces, and exhaled carbon dioxide after 72 hours. Very little radiolabel was associated with most of the tissues 72 hours after dosing; the non-application site skin, however, had an elevated tissue:blood ratio. During the 72 hours following an intravenous bolus dose of 9.4 mg/kg [14C]-trimethylolpropane triacrylate to rats, a total of 77.4% of the radiolabel was excreted in the urine, feces, and exhaled carbon dioxide, with urine and exhaled carbon dioxide accounting for the largest percentages. Total radiolabel (but not parent trimethylolpropane triacrylate) was measured in the blood, and only slight changes in radiolabel concentrations were observed in blood after 1 hour. Among the tissues collected 72 hours after dosing, the highest radiolabel concentration was in the blood, and the average total recovery of radiolabel was 90% during the 72 hours after the intravenous dose.