1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylindeno[5,6-c]pyran

Dermal absorption

Administrative data

Endpoint:

dermal absorption in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

other information

Study period:

September 2001

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: SCCNFP in-vitro assessment of percutaneous absorption guidelines

Version / remarks:

SCCNFP/0167/99

Deviations:

not specified

Principles of method if other than guideline:

For the present human skin penetration study, 12 human epidermal membranes were clamped in dosage chambers. Permeation of HHCB was then measured over a 24 hrs period. The epidermal membranes were then tape stripped 10 times and the radiolabel content of the strips and remaining epidermis determined.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylindeno[5,6-c]pyran

EC Number:

214-946-9

EC Name:

1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylindeno[5,6-c]pyran

Cas Number:

1222-05-5

Molecular formula:

C18H26O

IUPAC Name:

4,6,6,7,8,8-hexamethyl-1H,3H,4H,6H,7H,8H-indeno[5,6-c]pyran

Test material form:

liquid: viscous

Radiolabelling:

yes

Administration / exposure

Duration of exposure:

24 hrs

Doses:

- Nominal doses: 20 uL/cm2 target dose of a 1% solution in ethanol
- Dose volume: 20 uL

Details on study design:

VEHICLE
-Justification for use and choice of vehicle (if other than water): ethanol, because highest concentrations of test material are found in ethanolic products

SAMPLE PREPARATION
-Twelve active dosed chambers were prepared plus two control chambers.

ANALYSIS
-Determination of skin penetration: following application of the vehicles, 200 uL samples were taken from each receptor chamber at 1, 2, 6, 12 and 24 hrs. Each sample was placed into scintillation fluid and analysed for 14C.

Details on in vitro test system (if applicable):

SKIN PREPARATION
- Source of skin: Obtained from cosmetic surgery.
- Type of skin: Female breast and abdominal skin
- Preparative technique: Freshly obtained skin, was thawed for processing. Following removal of subcutaneous fat by blunt dissection, individual portions of skin were immersed in water at 60°C for 50 secs. The skin was then pinned, dermis side down, on a cork board and the epidermis (comprising stratum corneum and epidermis) gently removed from the underlying dermis. The latter was discarded and the epidermal membrane floated onto the surface of water and was taken up onto aluminium foil. The membranes were thoroughly dried and stored flat at -20°C until used. On the day of use, the epidermal membranes were floated onto water from the aluminium foil and taken onto 25 mm diameter filter paper supports, ensuring complete coverage of the filter paper. The membranes were then mounted onto the diffusion chambers. The skin samples were mounted in a exposure chamber with the stratum corneum facing the donor chamber. Controls: Two control chamber were prepared.
- Membrane integrity check: YES

PRINCIPLES OF ASSAY
- Diffusion chamber: Franz-type
- Receptor fluid: Water
- Static system: YES
- Test temperature: 32±1°C

Results and discussion

Signs and symptoms of toxicity:

not examined

Dermal irritation:

not examined

Total recovery:

- Total recovery: Overall recovery of radioactive material was 92.1 +/- 0.8%.
- Recovery of applied dose acceptable: YES

Percutaneous absorption

Key result

Time point:

24 h

Dose:

20 uL/cm2 1% HHCB

Parameter:

percentage

Remarks:

+/-0.59

Absorption:

ca. 5.16 %

Remarks on result:

other: Total HHCB in remaining stratum corneum plus epidermis, filter paper, and receptor fluid

Any other information on results incl. tables

Table 1: Distribution of HHCB in all compartments at 24 hrs (% of applied dose)

	Surface wipe	Strip 1	Strips 2 -3	Strips 4 -6	Strips 7 -10	Remaining s  kin	Receptor phase	Donor chamber	Filter paper	Total recovered
Mean	58.2	2.15	2.04	1.07	0.578	4.52	0.397	22.9	0.245	92.1
SD	6.5	0.86	1.21	0.58	0.315	1.96	0.197	4.8	0.108	2.7

Applicant's summary and conclusion

Conclusions:

The results of the present study indicated that the level of in-vitro percutaneous absorption of HHCB was quite low, with the majority of the applied HHCB remaining at the skin surface.

Executive summary:

The dermal absorption (non-GLP, but with QA statement) of HHCB was determined over a 24-hr period according to the methodology of the SCCNFP. Radiolabeled HHCB (uniformly labelled in the aromatic ring – radiochemical purity 99.3%) was applied in 1% solution in ethanol (96% v/v) to human epidermal membranes (prepared from female breast or abdominal skin and assayed for integrity with tritiated water) supported on a piece of filter paper (for strength) in glass diffusion cells (n=12). The area of the membrane available for absorption was approximately 1 cm² and the average applied dose was 20±0.2 µL/cm². The amount of material absorbed into the receptor phase, 6% Volpo N20 (to enhance solubility) in pH 7.4 phosphate buffered saline, after 24 hr was 0.40±0.06% of the applied dose. The majority of applied HHCB (81±2% of the applied dose) was found in the 24-hr surface wipe and donor chamber wash plus wipe. The stratum corneum tape strips contained 5.8±0.8% of the applied dose and the remaining stratum corneum plus epidermis 4.5±0.6% of the applied dose. Levels of HHCB in the remaining stratum corneum plus epidermis, filter paper (on which the epidermis samples rested) and permeated HHCB were combined to produce a total absorbed dose value of 5.2±0.6% of the applied dose. Overall recovery of radioactivity was 92±0.8%.