Registration Dossier

Administrative data

Endpoint:
basic toxicokinetics in vivo
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1985

Materials and methods

Objective of study:
toxicokinetics
Principles of method if other than guideline:
The study was undertaken, to measure the percutaneous absorption and distribution of [14C]methacrylamide in the body of rabbit, rat and mouse.
Measurement of its excretion in urine, expiration of 14CO2, and autoradiographic examination of the skin was also performed in rabbits.

Injection study for comparative purposes: Rabbits were given an i.v. injection of 0.1 ml of (15%[14C]methacrylamide in water) to compare the time course and distribution of radioactivity in blood and tissues and recovery of radioactivity in urine with the topical application study. Radioactivity levels were determined in the blood at the time of administration, over the following 7 hours, and after 24 hours. Levels were also measured in the tissues after 24 hours, in the urine after 24 hours and 3 days, and in the expired air over 24 hours.

Topical application of [14C]methacrylamide: (a) application with cloth in rabbit: cotton cloth of 2.5 cm² and 0.35 mm thick was moistened with 100 µl test solution (15%) and applied to the clipped back of the unanesthetized rabbit, covered with waxed paper and held in place for 30 min. (b) direct application of the test solution (15 or 5% aqueous solution, 0.05 ml) was applied directly with a micropipette onto the clipped back of the anesthetized rabbit, on an area of about 2.5 cm², with a duration of application (not further explained, possibly a divided dose spread over this time) of 30 minutes and 15 min for the 15% and 5% solutions, respectively).
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Specific details on test material used for the study:
- Name of test material (as cited in study report): [14C]Methacrylamide
- Supplier: Japan Atomic Research Laboratory
- Radiochemical purity: 98.3%
- Specific activity (if radiolabelling): 263 µCi/mmol
Radiolabelling:
yes
Remarks:
C14

Test animals

Species:
other: Rabbit, rat and mouse
Strain:
other: Japanese white rabbits, Wistar rats and ddY mice
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: no data
- Age at study initiation: no data
- Weight at study initiation: rabbits (2.2 +/- 0.2 kg), rats (250 +/- 17 g), mice (25 +/- 2 g)
- Fasting period before study: no data
- Housing: no data
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: no data


ENVIRONMENTAL CONDITIONS
- Temperature (°C): no data
- Humidity (%): no data
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): no data

Administration / exposure

Route of administration:
dermal
Vehicle:
water
Details on exposure:
TEST SITE (topical application) also see table 1 any other information on materials and methods
- Area of exposure: hair on the right dorsal midlumbar region
- % coverage: 2.5 cm² in rabbit, 2.5 cm² in rat, 0.8 cm² in mouse
- Type of wrap if used: cotton cloth, covered with waxed paper and secured with plaster tape


REMOVAL OF TEST SUBSTANCE
- Washing (if done): the skin surface was washed five times with cotton blocks moistened with water.
- Time after start of exposure:


TEST MATERIAL
- Amount(s) applied (volume or weight with unit): topical application: 100, 50 or 10 µl
- concentration (if solution): 15% or 5% in aqueous solution
Duration and frequency of treatment / exposure:
duration of topical application 30 minutes and 15 minutes also see table 1 any other information on materials and methods
Doses / concentrations
Remarks:
Doses / Concentrations:
topical administration: 5 and 15 % in aqueous solution
i.v. injection: 15% in aqueous solution
also see table 1 any other information on materials and methods
No. of animals per sex per dose:
not specified
Control animals:
no
Details on dosing and sampling:
PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled: urine, blood, serum, lung, heart, liver, kidney, brain, Sciatic nerve, muscle, skin, bile
- Time and frequency of sampling: Rabbit blood was collected at 0, 15, 30, 60, 180, 300, 420 min and 24 hr after injection or topical application.
injection study: Radioactivity levels were determined in the blood at the time of administration, over the
following 7 hours, and after 24 hours. Levels were also measured in the tissues after 24 hours /rabbit, rat and mouse), in the urine after 24 hours
and 3 days, and in the expired air over 24 hours.
Statistics:
All experments were done in triplicate unless otherwise stated, and the results were expressed as mean +/- SD. Differences in the time course of
Blood radioactivity between non-washed and washed groups after direct application studies were compared by a two-way analysis of variance.
Differences in urinary recovery of radioactivity between i.v. and topical applications, and in radioactivity in tissues between the non-wash and wash groups were comparted by Student's t-test.

Results and discussion

Toxicokinetic / pharmacokinetic studies

Details on absorption:
Skin absorption:
Skin absorption of 14C-methacrylamide was studied in male Japanese white rabbits under both occluded and unoccluded conditions (5 and 15 % in
water, for 15 or 30 minutes). After 24 hours the majority of the radioactivity remained at the application site. Autoradiography of the treated skin
showed an accumulation in the hair follicles. Small amounts of radioactivity were also found in the other tissues. The highest levels were observed in
the liver while radioactivity in the other tissues was evenly distributed. Results with occluded administration did not differ significantly from those
obtained without occlusion. Washing of the application site after 15 minutes resulted in decreased serum levels of radioactivity.

Absorption
Dermal absorption of 14C-methacrylamide in male Wistar rats and male ddY mice after direct administration of 5 or 15 % aqueous solution for 30
minutes was lower than in rabbits, when adjusted to the dose per unit body weight. The majority of the radioactivity remained in the skin.
Details on distribution in tissues:
Distribution of radiolabelled 14C-methacrylamide was studied in male Japanese white rabbits after i.v. administration (15 % in water). Radioactivity
was determined in different tissues after 24 hours. The highest concentration of radioactivity were found in the liver, followed by serum, kidney, total
blood and lung. Lower levels were observed in the heart, brain, sciatic nerve and muscle. Most of the radioactivity (86 % of the dose) was excreted
with the urine within 24 hours. Expired 14C-CO2 was very low (1 %).
Details on excretion:
After 24 hours 23 - 52% of the administered radioactivity was excreted with urine suggesting that methacrylamide may be absorbed through rabbit
skin relatively easy. Primary absorption sites seemed to be the hair follicles.

Only 3.7 to 5.7 % of the radioactivity was excreted in the urine of the rats after 24 hours. Urinary excretion was not determined in mice.

Any other information on results incl. tables

Table 2

Radioactivity in tissues 24 hr after i.v. or percutaneous dosing with [14C]methacrylamide

Rabbit

Rat

Mouse

 

A

B

C

D

E

F

G

H

I

Dosing

tissue

i.v.(a)

Cloth(b)

Direct(c)       Direct      Direct       Direct       Direct        Direct       Direct

Concentration of radioactivity (dpm/g wet tissue [x 10E-3]]

Total blood

3.64(d)

±1.10

0.92

±1.10

1.04

±0.49

0.98

±0.37

0.21

±0.075

0.11

±0.031

2.08

±0.27

1.68

±0.11

24.9

±5.78

Serum

5.26

±1.16

0.81

±0.81

1.04

±0.75

0.75

±0.21

0.25

±0.040

0.12*

±0.0041

0.36

±0.11

0.087*

±0.040

26.6

±7.51

Lung

3.24

±4.46

1.40

±2.12

1.79

±0.24

1.73

±0.98

0.32

±0.092

0.20

±0.12

0.87

±0.12

0.49*

±0.14

23.1

±5.78

Heart

2.60

±0.34

0.81

±1.13

0.92

±0.052

0.69

±0.23

0.15

±0.023

0.14

±0.075

0.58

±0.78

0.51

±0.35

No(e)

Liver

6.94

±0.92

0.58

±0.58

3.51

±1.04

3.87

±0.75

0.54

±0.20

0.42

±0.10

0.98

±0.17

0.47*

±0.26

28.3

±13.9

Kidney

3.99

±0.41

1.39

±1.33

1.56

±0.44

1.39

±1.21

0.69

±0.28

0.36

±0.017

1.39

±0.69

0.81

±0.40

37.0

±16.8

Brain

1.39

±0.69

1.16

±0.69

0.98

±0.17

0.92

±0.55

0.30

±0.17

0.15

±0.058

0.64

±0.23

0.18

±0.15

21.4

±3.18

Sciatic nerve

1.39

±0.41

0.98

±0.58

0.87

±0.29

0.56

±0.17

0.43

±0.32

0.11

±0.035

0.36

±0.15

0.13

±0.081

14.5

±6.36

Muscle

1.33

±1.60

0.69

±0.57

0.81

±0.75

0.81

±0.22

0.19

±0.092

0.092

±0.10

0.69

±0.83

0.44

±0.13

No

Skin un-contacted

1.97

±0.92

3.21

±1.50

0.98

±1.26

1.16

±0.51

1.85

±1.04

0.81

±1.09

1.27

±0.30

0.92

±0.49

41.6

±13.9

Skin contacted

No

88.9

±86.1

97.1

±37.6

67.0

±15.0

145.1

±21.4

76.9

±68.8

2390

±1220

805

±1060

206

±49.2

Bile

3.90

±1.13

No

No

No

No

No

No

No

No

(a)      i.v. injection (b)   topical contact with cloth (c)   direct topical contact (d)   mean ±SD of triplicate experiments (e)  no data

*       P0.05 cf. non-wash experiments

Table 3

Radioactivity in urine and expiration in 24 hr after intravenous dosing in rabbits

Cumulative radioactivity in urine

Time (hr)

(dpm [x 10E-6])

(% of dose)

0-24

88.0(a)

86

- 48

90.9

89

- 72

91.8

90

Cumulative radioactivity in expiration

(dpm [x 10E-3])

(% of dose)

0 - 1

112(d)

0.11

   - 2

241

0.24

   - 3

250

0.25

   - 6

269

0.26

   - 24

305(b)

0.29

Rabbits received an i.v. injection of 15% solution (46.4 µCi).

(a) mean of duplicate experiments. (b) Estimation from measurement between 23 and 24 hr.

Table 4

Total recovery of radioactivity in urine in 24 hr after dosing

Rabbit

Rat

A

B

C

D

E

F

G

H

Dosing

i.v.(a)

Cloth (b)

Direct (c)

Direct       Direct        Direct        Direct     Direct

Radioactivity in urine (dpm [x 10E-6])

Total excretion in 24 hr

89.8 (d)

 

±3.1

23.5

 

±11.2

26.5

 

±3.6

23.0

 

±4.1

6.78

 

±2.54

4.95

 

±0.85

0.581

 

±0.224

0.376

 

±0.244

% of dose

88

23**

52*

45**

40**

29**

5.7

3.7

Experimental conditions are shown in Table 1. (a) i.v. injection; (b) contact with cloth; (c) direct contact;

(d) mean ±SD of triplicate experiments; **P<0.01 versus i.v. injection (rabbit)

Table 5

Protein-bound radioactivity in tissues 24 hr after direct contact of [14C]methacrylamide in rabbits

Tissue

Total

Concentration of radioactivity

(dpm/g [x 10E-6])

Protein-bound

Protein/Total ratio

Total blood

1.18 (a)

0.70

0.59

Lung

1.84

1.10

0.60

Liver

3.74

2.06

0.55

Kidney

1.58

0.39

0.25

Brain

1.03

0.36

0.35

Sciatic nerve

1.16

0.44

0.38

Skin contacted

106

41.3

0.39

Experimental conditions are shown in Table 1. (a) mean of duplicate experiments; Protein-bound radioactivity was calculated as (total - TCA soluable count) after deproteinization

Applicant's summary and conclusion

Conclusions:
Distribution and excretion of [14C]methacrylamide was studied in male rabbits after i.v. administration (15% in water). In all experiments (particularly after intravenous injection) there was a rapid increase in radioactivity in the blood, and this began to diminish exponetially within 1 hour. Most of the radioactivity (86% of the dose) was excreted with the urine within 24 hours. Expired 14C-CO2 was very low (1%). After 24 hours i.v. administration to male rabbits, the highest concentration of radioactivity in the body was found in the liver, followed by serum, kidney, total blood and muscle.
Following 15 to 30 minutes dermal exposure to male rabbits, 23 to 52% of the administered radioactivity was excreated with urine within 24 hours. On the other hand, only 3.7 to 5.7 % of the radioactivity was excreted in the urine of male rats after 24 hours following 15 and 30 minutes dermal exposure.
In the rat, radioactivity levels were highest in the blood, kidneys and skin (particularly at the application site). Compared with the rabbit, tissue levels in the rat were low, whilist only 3.7 - 5.7% of the dose was recovered in the urine 24 hours after application. In the mouse, again the kidneys and the skin (particularly the application site) showed the highest levels of radioactivity.
The substance has the potential to be absorbed through the skin. There is evidence of effective detoxification by phase II metabolism (GSH, glucuronides).
Executive summary:

This experiment on distribution and excretion in the rabbit, rat and mouse is classified acceptable and satisfies the requirements for a distribution/excretion study in rabbit, rat and mouse.