1,3-dihydro-1,3-dioxo-2H-isoindole-2-hexanoic acid

Dermal absorption

Administrative data

Endpoint:

dermal absorption in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP and OECD guidelline study. No deviations from guideline.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 428 (Skin Absorption: In Vitro Method)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

1,3-dihydro-1,3-dioxo-2H-isoindole-2-hexanoic acid

EC Number:

224-675-8

EC Name:

1,3-dihydro-1,3-dioxo-2H-isoindole-2-hexanoic acid

Cas Number:

4443-26-9

Molecular formula:

C14H15NO4

IUPAC Name:

6-(1,3-dioxo-2,3-dihydro-1H-isoindol-2-yl)hexanoic acid

Details on test material:

Lot/Batch number:
- Non-labelled: BUDDPAC396
- Labelled: CFQ14921 Batch 1
Specification: White solid
Labelled material: Specific activity 58 mCi/mmol
Purity: Non-labelled: > 98% w/w; Labelled: 99.8% w/w

Radiolabelling:

yes

Remarks:

14C carbonyl of phthalimide moiety

Administration / exposure

Duration of exposure:

8 hours

Doses:

High dose: 5% (439 µg.cm-2) PAC in typical liquid formulation
Low dose: 0.1% (10.2 µg.cm-2) PAC 15% aqueous ethanol solution.

Details on study design:

analytics;
The radioactivity in the samples was determined by a scintillation couter.

Details on in vitro test system (if applicable):

SKIN PREPARATION
- Source of skin: both human and rat skin samples were used.
- Preparation:
-- Human: Frozen skin samples from 3 donors (2 samples/donor) directly after abdominal surgery. The frozen samples were thawed and dermatomed to a recorded thickness of approximately 400 μm.
-- Rat: 12 membranes obtained from a male Wistar rat of ca 7 weeks old. After the sacrifice of the rat, skin samples were collected from the dorsal and flank skin of the animal and frozen. After thawing, discs with a diameter of 16 mm were punched out and subcutaneous tissue was removed.
- The exact thickness of human and rat skin membranes was measured with a digimatic micrometer and recorded.
- Integrity of skin membranes: Prior to the determination of the percutaneous absorption, the integrity of human and rat skin membranes was evaluated by measuring the permeability coefficient (Kp) for tritiated water.

PRINCIPLES OF ASSAY
- Diffusion cell: 9 mm flow-through automated diffusion cells
- Flow-through system: yes
- Test temperature: 32°C
- Humidity: ambient
- Volume applied: 6.4 µl
- Size of test site: 0.64 cm2

Results and discussion

Any other information on results incl. tables

Solubility in receptor fluid:

11.18 µg/ml (mean of 3 independent vials, 3 replicates/vial)

Skin membrane integrity:

The selected human membranes had a Kp value ranging from 0.91× 10 ^-3and 2.42× 10 ^-3cm/h. The selected rat membranes had a Kp value ranging from 1.19× 10^-3and 2.43× 10^-3cm/h

Percutaneous cumulative absorption:

	Cumulative absorption (mg/cm^-2)
	Human				Rat
Test group	A		B		C		D
Time (h)	Mean	SD	Mean	SD	Mean	SD	Mean	SD
1	0.17	0.09	0.04	0.03	2.42	4.22	0.06	0.12
2	3.95	1.66	0.44	0.30	8.73	11.59	0.29	0.41
4	16.49	2.25	1.15	0.62	17.80	14.07	0.71	0.57
6	24.80	1.64	1.62	0.81	23.03	14.19	1.05	0.61
8	30.86	2.46	1.96	0.92	26.58	14.14	1.34	0.65
10	35.56	3.24	2.25	1.00	29.79	14.30	1.60	0.68
12	38.68	3.60	2.44	1.03	32.04	14.03	1.77	0.65
14	40.51	3.86	2.56	1.05	33.39	13.86	1.87	0.63
16	41.67	4.03	2.64	1.05	34.33	13.74	1.94	0.62
18	42.49	4.12	2.69	1.05	35.04	13.67	1.98	0.61
20	43.09	4.20	2.74	1.05	35.62	13.61	2.01	0.60
22	43.57	4.27	2.77	1.05	36.11	13.55	2.04	0.59
24	43.95	4.32	2.80	1.05	36.55	13.51	2.06	0.59
	Mean	SD	Mean	SD	Mean	SD	Mean	SD
Maximal flux (µg.cm^-2.h^-1)	6.27	0.35	0.41	0.21	7.13	6.77	0.28	0.26
Lag time (h)	1.4	0.2	1.1	0.3	1.0	0.6	1.2	0.4

Radioactivity recovery:

	Cumulative absorption (mg/cm^-2)
	Human				Rat
Test group	A		B		C		D
	Mean	SD	Mean	SD	Mean	SD	Mean	SD
Receptor fluid	9.99	1.02	27.46	10.29	8.49	3.10	18.18	3.27
Receptor compartment	0.04	0.02	0.11	0.04	0.04	0.00	0.08	0.02
Donor compartment	0.42	0.29	0.12	0.08	0.42	0.22	0.14	0.10
Tape strips	3.17	2.37	5.42	2.57	3.88	0.69	6.95	3.53
Skin wash	78.79	4.05	59.13	5.92	69.72	7.53	35.22	1.76
Digested membranes	0.67	0.17	2.74	0.56	5.51	1.55	36.21	5.21
Total recovery	93.0	2.5	95.0	5.5	88.1	6.5	96.8	2.0
Total absorption^*	10.7	1.2	30.3	10.5	14.0	2.6	54.5	6.6

Applicant's summary and conclusion

Conclusions:

PAC showed a relevant percutaneous absorption both in rat and human skin membranes in vitro.

Executive summary:

The percutaneous absorption of [¹⁴C]-PAC, was evaluated on 12 human skin and 12 rat skin membranes. The exposure time was 8 hours, with a 16-hour post exposure time. PAC was tested as included in a formulation representative of marketed products (Modified EURECO L5A containing 5% w/w PAC, high dose) or as such in a concentration simulating condition of use (0.1% w/w in 15% aqueous ethanol solution, low dose). 6 membranes/species/concentration were used.

Skin integrity was evaluated before the start of the study.

Percutaneous absorption was monitored by means of scintillation counting of the receptor fluid. Total radioactivity recovery was calculated by determining the cumulative absorption and the radioactivity measured in skin and diffusion cell washes, tape stripping of membranes and in digested skin. The mean penetration of PAC through human skin into the receptor fluid after 24 hours was 9.99 % and 27.46 % of the applied dose for high and low dose, respectively. The correspondent mean total absorption, defined as the compound-related radioactivity present in the receptor fluid, the receptor compartment wash and the skin membranes (excluding tape strips), was 10.7 % and 30.3 % for the high and low dose respectively.

The mean maximal flux for the absorption of PAC through human skin was 6.27 µg.cm^-2.h^-1for the high dose and 0.41 µg.cm^-2.h^-1for the low dose. The lag times were 1.4 h and 1.1 h, respectively.

For rat skin, the mean penetration after 24 hours was 8.49 % and 20.22 % for the high and low dose, respectively. The mean total absorption was 14.0 % for the high dose and 54.5 % for the low dose.

The mean maximal flux for the absorption of PAC was 7.13 µg.cm^-2.h^-1for the high dose and 0.28 µg.cm^-2.h^-1for the low dose, and the lag times were 1.0 h and 1.2 h.

The mean recovery of PAC in human skin was 93.0 ± 2.5 % and 95.0 ± 5.5 %. In rat skin the mean recovery was 88.1 ± 6.5 % and 96.8 ± 2.0 %.