Methacrylamide

Endpoint summary

Link to relevant study record(s)

Reference

Reference 1

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

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

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

Species:

other: Rabbit, rat and mouse

Strain:

other: Japanese white rabbits, Wistar rats and ddY mice

Sex:

male

Details on test animals or test system 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

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

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 / concentration:

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.

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.

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

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.

Reference 2

Endpoint:

dermal absorption, other

Remarks:

in silico prediction

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Specific details on test material used for the study:

SMILES structure: CC(=C)C(N)=O

Species:

rat

Remarks on result:

other: a moderate relative dermal absorption was calculated

Calculation of dermal absorption of methacrylamide in rats under the conditions of test guideline OECD 402, Acute dermal toxicity in rats:

Heylings at al have established an in silico model to predict dermal absorption of methacrylates and methacrylamides. This model is based onestablished model (Potts and Guy, 1992), using data derived with human epidermal membranes.

QSARs, when applied to estimating dermal permeability coefficients, are sometimes known as quantitative structure-permeability relationships (QSPeRs or QSPRs). Descriptors such as hydrophobicity, molecular size, and possibility of hydrogen bonding (which may describe non-covalent interactions with skin proteins) are important for the development of QSARs.

QSPeRs are statistically-derived linear and non-linear relationships between the steady-state permeability of a compound, usually measured from water, and various physicochemical descriptors and/or structural properties of the molecule. Typically, the main input parameter is the octanol:water partition coefficient. The dermal absorption measurement that has been most commonly used in QSAR modelling is the permeability coefficient Kp,because it characterises the steady-state permeation rate of a chemical from a specific vehicle through a given membrane. Although Kpis not directly suitable for application in risk assessment, it can be used in conjunction with measured (or estimated) solubility in the same vehicle (e.g. water) to predict a maximum flux through the skin.

Potts RO and Guy RH (1992). Predicting Skin Permeability. Pharm. Res. 9(5): 663-669.

 

No.	Chemical Class	Test Chemical / Compound Identity	Acronym	Molecular Weight	Log P	Predicted Flux (μg/cm2/h)	Relative Dermal Absorption
33	Methacrylamides-tier 1	Methacrylamide	MAA	85.1	-0.15	42.625	Moderate

 

Parameters for prediction of dermal absorption in rats:

Surface of the body for application of test substance: not less than 10 % (OECD 402)

Exposure time: 24 hours (OECD 402)

Representative body weight rat: 0.15 kg (Handbook of Toxicology)

Representative surface area rat: 0.025 m² (Handbook of Toxicology)

 

Calculation:

10 % body surface of a rat correspond to 25 cm²

 

Absorption of methacrylamide in 1 rat under the conditions of OECD 402:

42.625 µg/cm²/h x 25 cm² x 24 h = 25.577 mg/150 g

25.277 mg/150 g correspond to 170.5 mg/kg

 

The maximum absorption of methacrylamide in rats under the conditions of OECD 402 is 170.5 mg/kg

 

Conclusions:

The maximum dermal absorption of methacrylamide under the condtions of an acute dermal toxicity test acc. OECD 402 was calculated based on QSAR predictions by Heylings et al. An absorption of 170.5 mg/kg bw in maximum in rats was predicted.

Executive summary:

A predicted dermal flux of 42.625 µg/cm2/h was calculated, indicative for a moderate relative dermal absorption.

Description of key information

Distribution, Metabolism & Excretion

After i.v. administration of radioactive labelled MAAmide, 86% of the radioactivity was excreted via urine within 24 hrs in rabbits. The highest concentrations of the remaining radioactivity were found in the liver.

After dermal administration of radioactive labelled MAAmide, 23 -52% of the radioactivity was excreted via urine within 24 hrs in rabbits.

There is evidence of effective detoxification by phase II metabolism.

Dermal Absorption

As shown in the rabbit study, MAAmide has the potential to be absorbed through the skin.

This is supported by QSAR findings, where a predicted dermal flux of 42.625 µg/cm2/h was calculated, indicative for a moderate relative dermal absorption.

Additional information

An experiment on distribution and excretion of methacrylamide was conducted by Hashimoto (1985a).

Distribution and excretion of 14C-methacrylamide was studied in male rabbits after i.v. administration (15% in water). Most of the radioactivity (86 % of the dose) was excreted with the urine within 24hours. Expired14C-CO2was 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 excreted with urine within 24hours while only 3.7 to 5.7 % of the radioactivity was excreted in the urine of male rats after 24 hours following 15 to 30 minutes dermal exposure.

In vitro Studies

An in vitro study regarding the metabolism of methacrylamide demonstrated that phenobarbital induction increased the reaction rate about 2-fold suggesting a cytochrome P-450 dependent metabolism.(Tanii,1981)

The substance has the potential to be absorbed through the skin. There is evidence of effective detoxification by phase II metabolism (GSH, glucuronides) while phase I enzyme P-450 seems also to be involved in the metabolism.

A predicted dermal flux of 42.625 µg/cm2/h was calculated, indicative for a moderate relative dermal absorption.