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EC number: 800-172-4
CAS number: 398141-87-2
Integrity of the Skin
The integrity of the skin was demonstrated prior to application
and after the last sampling. The conductivity prior to the experiment
was in the acceptable range of < 900 µS/cm for all skin samples used.
Table 2. Compartmental Distribution of the Test Material
Test Material in
Expressed as µg/cm² of skin surface mean ± SD (n=4)
Expressed as % of applied dose mean ± SD (n=4)
Wash Solution + SN
Cumulative as µg/cm²
0 - 24
Only valid results were used, i.e. those yielding a recovery > 85%.
SN = the supernatant of impedance measurement after 24 hours.
n.d = not determined
Table 3. Summary of Results
Amount of test material applied (µg/cm²)A
Total amount of test material measured (µg)
Total absorption of the test material (µg/cm²)B
Total absorption (%)C
* Invalid results where the recovery was ≤ 85%
A = amount of test material present in 10 µL without the pipetting
washing solution (PWL).
B = the value is the sum of the amount of the test material
measured in the receptor solution and in the skin extract (epidermis and
dermis) of each diffusion cell.
C = percent total absorption = (total amount of the test material
*100)/ amount of applied test material(µg).
The dermal absorption of the test material was assessed for its
potential to permeate human skin in an in vitro dermal delivery
study using human skin. In total 3 different skin donors were exposed to
10 µL of the test material in duplicate for 24 hours under non-occluded
conditions. Aliquots of the test material were applied directly to the
skin of the 6 replicate test chambers and then removed by washing each
skin sample nine times with 1 mL extraction solution at termination.
PBS/20% EtOH (v/v) was used as the receptor fluid.The
samples were analysed by LC-MS/MS for the presence of the
test material. The conductivity across the skin samples of each chamber
was measured before treatment and after the sampling. No abrupt change
in conductivity, indicating a loss of barrier properties of the skin,
occurred in any chamber up to termination of the experiment at 24 hours.
Four out of the six chambers meet the acceptance criteria,
chambers of 3 and 6 were excluded because of their low recovery rates.
Therefore 4 chambers were used for the analysis. The stratum corneum was
stripped from each of the skin pieces and afterwards
the epidermis and dermis were separated. The amount of the
test material present in each compartment was determined.
Under the conditions of the test, the test material was detected
in all samples relevant for dermal delivery, e.g. in the skin extracts
as well as in all receptor solution samples showing constant penetration
over the sampling time of 24 hours. A higher penetration rate was
observed at the beginning (0.5
hours) of the experiment, after which a relatively constant penetration
rate was observed until termination. The quantity of the
test material that was absorbed was determined to be 111 ± 29.5µg/cm2
and the quantity not absorbed was 13231 ± 1512µg/cm2.
Thus the dermal delivery was determined to be 111 ± 29.5
µg/cm2 (0.844 ± 0.228% of the
applied dose), where the dermal delivery is the sum of the applied dose
found in the treated skin and the receptor fluid at termination.
Accordingly the test material was considered to penetrate into viable
skin at a very low rate.
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