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 documented publication which meets basic scientific principles
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
publication
Title:
Percutaneous absorption of co-administered N-methyl-2-[' 4C]pyrrolidone and 2-['4C]pyrrolidone in the rat
Author:
Midgley I, et al.
Year:
1991
Bibliographic source:
Fd Chem. Toxic., Vol. 30(1), 57-64

Materials and methods

Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
In-vivo percutaneous absorption test
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): 2-pyrrolidinone and N-methyl-2-pyrrolidinone, mixture (2:3)
- Physical state: liquid
- Specific activity (if radiolabelling): 4.9 (2-P) and 7.4 mCi/mmol (NMP)
- Locations of the label (if radiolabelling): N-methyl-2-[2-14C]pyrrolidinone; 2-[5-14C]pyrrolidinone
Radiolabelling:
yes
Remarks:
14C

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River breeding Laboratories (Portage, MI, USA)
- Age at study initiation:
- Weight at study initiation: 192-239 g
- Fasting period before study:
- Housing: individual
- Individual metabolism cages: yes
- Diet: LAD1 Bioscure Ltd., Manea, UK ad libitum
- Water: ad libitum


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24
- Humidity (%): 30-70
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Type of coverage:
occlusive
Vehicle:
other: isopropanol
Duration of exposure:
single exposure, up to 120 hrs
Doses:
- Nominal doses: Males: ca. 15 mg/ animal (1.67 mg/cm²) Females: ca. 15 mg/ animal (1.67 mg/cm²)
No. of animals per group:
33 males and 33 females in total; 3 per sex and time-point
Control animals:
yes
Remarks:
vehicle
Details on study design:
DOSE PREPARATION
- Method for preparation of dose suspensions: each compound was diluted with the corresponding non-radioactive compound and, where necessary, purified by distillation to provide material of above mentioned purity.
- Method of storage: not reported


APPLICATION OF DOSE: to an area of 9 cm² of carefully-shaved skin on the back of each animal


VEHICLE
- Justification for use and choice of vehicle (if other than water):
- Amount(s) applied (volume or weight with unit): 150 µl
- Concentration (if solution): mixture 22.5 mg/15 mg (see above) in 150 µl isopropanol
- Lot/batch no. (if required): not reported
- Purity: not reported


TEST SITE
- Preparation of test site: shaved
- Area of exposure: back
- % coverage: not reported
- Type of cover / wrap if used: aluminium foil
- Time intervals for shavings or clipplings: not reported


SITE PROTECTION / USE OF RESTRAINERS FOR PREVENTING INGESTION: yes: adhesive tape was used to secure the aluminium foil


REMOVAL OF TEST SUBSTANCE
- Removal of protecting device: after the animals were killed
- Washing procedures and type of cleansing agent: the occlusive dressing from each topically-dosed rat was removed and incubated (40°C, 24h) with 100 ml of the digestion mixture (methanol/aqueous methanol (50%))
- Time after start of exposure: 120 h


SAMPLE COLLECTION
- Collection of blood: by cardiac puncture
- Collection of urine and faeces: at the final killing time. The metabolism cages were washed with water, and the washungs, excreta and carcasses stored
- Collection of expired air: at the final killing time, expired air was trapped in a mixture of ethanolamine-2-ethoxyethanol (1:3, v/v) at 24h intervals
- Terminal procedure: the rats were killed by cervical dislocation
- Analysis of organs: yes. Remaining carcasses from topically-dosed rats were solubilized by digestion (45°C, 48 hr) in a solution of NaOH (80g) and Triton X-405 (p-tert-octylphenoxypolyethoxyethanol; 100 ml) in methanol (300 ml) diluted to 1 litre with distilled water.

SAMPLE PREPARATION
- Storage procedure: at -20°C until analysed
- Preparation details: Replicate aliquots (0.25-1 ml) of plasma, urine, cage washings, contents of expired air traps, occlusive dressing digests and extracts, application-site washings, skin digests and carcass digests were separately mixed with Special Scintillator MI-31 (Canberra Packard, Pangbourne, UK) for measurement of radioactivity. Replicate weighed portions of faeces (after homogenization with distilled water) were combusted in oxygen using an automatic sample oxidizer (Packard Model 306), and the products of combustion dissolved in Optisorb 1 and mixed with Optisorb S scintillator (FSA Laboratory Supplies, Loughborough, UK) for measurement of radioactivity.


ANALYSIS
- Method type(s) for identification ( HPLC-UV for measurement of unchanged test substances in the plasma, Liquid scintillation counting for measurement of radioactivity)
- Liquid scintillation counting results (cpm) converted to dpm as follows: not reported
- Validation of analytical procedure: yes
- Limits of detection and quantification: not reported


OTHER:

Results and discussion

Signs and symptoms of toxicity:
no effects
Dermal irritation:
no effects
Absorption in different matrices:
- Non-occlusive cover + enclosure rinse: done, but results were not reported
- Skin wash: done, but results were not reported
- Skin test site: done, but results were not reported
- Skin, untreated site: done, but results were not reported
- Blood: Following dermal co-administration, plasma radioactivity levels changed little during the first six hours. The greatest mean values were obtained at 2h (0.265% dose/ml) and 6 h (0.204% dose/ml) after dosing.. 12 hours following topical administration little or none of the intact pyrrolidinones were found in plasma
- Carcass: 1% of the total dose remained in the carcass
- Urine: Urinary excretion was predominant (61-70%) mostly during the first 24 h after dosing.
- Cage wash + cage wipe: done, but results were not reported
- Faeces: Faecal excretion represented only 1-2% of the total dose
- Expired air (if applicable): 6-7% was excreted by exhalation
Total recovery:
up to 93%
Percutaneous absorptionopen allclose all
Dose:
6.15 µg/ml
Parameter:
percentage
Absorption:
ca. 0.1 %
Remarks on result:
other: 6 h
Remarks:
Time point is the time taken to attain dose (males)
Dose:
10.93 µg/ml
Parameter:
percentage
Absorption:
0.1 %
Remarks on result:
other: 2 h
Remarks:
Time point is the time taken to attain dose (female)
Conversion factor human vs. animal skin:
not appplicable

Any other information on results incl. tables

Results on pharmakokinetic parameters are attached in "Attached background material".

Table 2: Excretion balance of radioactivity following co-administration of 14C-NMP and 14C-2 -P to rats

 

Oral

Dermal

Sample

Time (hr)

M

F

M

F

Urine

0-6

16.0

21.4

5.5

11.0

6-24

65.2

60.9

45.3

46.7

24-72

2.9

4.2

8.1

8.8

72-120*

1.1

1.3

2.4

3.3

 

Total

85.2

87.8

61.3

69.8

Faeces

0-24

1.2

0.6

0.7

0.5

24-72

0.8

0.5

0.8

0.6

72-120

0.1

0.1

0.1

0.2

 

Total

2.1

1.2

1.6

1.3

Expired air

0-24

6.8

4.8

3.5

4.2

24-72

0.6

0.6

2.0

2.0

72-120

0.1

0.1

0.5

0.5

 

Total

7.5

5.5

6.0

6.7

Total excretion

0-120

94.8

94.5

68.9

77.8

Carcass

120

1.1

1.2

1.0

1.1

Dose dressing

120

10.7

11.3

Dose-site wash

120

1.2

0.3

Treated skin

120

11.2

2.0

Untreated skin

120

ND

<0.1

Total recovery

0-120

95.9

95.7

93.0

92.5

Applicant's summary and conclusion

Conclusions:
2-pyrrolidone administered topical is absorbed through the skin and then mainly excreted through the urine. Percutaneous absorption is greater in femals than in males (Table 2).
Executive summary:

Male and female Sprague-Dawley CD strain (albino) rats were administered topically to the [14C]NMP/[14C]2-P mixture (22.5mg/15mg) to assess percutaneous absorption and excretion rates of this compounds.

The radioactivity was measured in plasma, urine, faeces, expired air and remaining carcasses of killed animals to caculate pharmacokinetic parameters of the applied mixture and excretion balance.

Mean concentrations of 2 -pyrrolidone in plasma reached values after 6 h for males and 2 h for females However, plasma concentration of the unchanged 2 -pyrrolidone altered little during 6 -h post-administration and reflected that of total plasma radioactivity. At the termination, plasma level of the unchanged 2 -pyrrolidone was not measurable anymore.

The balance of the radioactivity applied was recovered in the all samples taken. The excretion of 2 -pyrrolidone take place predominantly through the urine (Table 2 in "Remarks on results").