D-gluconic acid, compound with N,N''-bis(4-chlorophenyl)-3,12-diimino-2,4,11,13-tetraazatetradecanediamidine (2:1)

Dermal absorption

Administrative data

Endpoint:

dermal absorption in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1998

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

No data are provided regarding the nature of the radiochemical impurities in the 14C-labelled chlorhexidine. Therefore, it must be considered that impurities such as breakdown products of lower molecular weight may have penetrated through the skin at a higher amount than chlorhexidine itself and contributed to the 14C-activity which was found in urine and faeces. This would have led to an overestimation of the percutaneous absorption of chlorhexidine. After the 24 h application of the test substance, excess material was wiped off but the animals were not washed. Since the animals were housed in the metabolism cages in pairs, it must also be considered that some remaining radioactivity at the site of application could have been licked up by the other animal leading to oral uptake and contributing to the excretion of radioactivity with the faeces. This would also contribute to an overestimation of the percutaneous absorption of chlorhexidine. Furthermore, the distribution of 14C-labelled chlorhexidine in blood and organs was not measured. However, the data on excretion and residual 14C-contents at the application site and in the skin patch clearly indicate that the overall amount of chlorhexidine in the body will be very small. Furthermore, in the same study, the structurally related OPB which was percutaneously absorbed similar to chlorhexidine could hardly be detected in most tissues including blood. The lack of distribution data for chlorhexidine is not considered a major drawback and the data of the study are considered relevant for the evaluation of the toxicokinetics of chlorhexidine digluconate.

Data source

Reference

Reference Type:

publication

Title:

Percutaneous absorption and tissue distribution of 1-(3,4-dichlorobenzyl)-5-octylbiguanide (OPB-2045) in rats

Author:

Kudo S, Furukawa M, Okumura H, Umehara K, Odomi M & Miyamoto G

Year:

1998

Bibliographic source:

Xenobiotic Metabolism and Disposition 13, 13-20

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD Guideline 427 (13th April 2004)

Deviations:

not applicable

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

D-gluconic acid, compound with N,N''-bis(4-chlorophenyl)-3,12-diimino-2,4,11,13-tetraazatetradecanediamidine (2:1)

EC Number:

242-354-0

EC Name:

D-gluconic acid, compound with N,N''-bis(4-chlorophenyl)-3,12-diimino-2,4,11,13-tetraazatetradecanediamidine (2:1)

Cas Number:

18472-51-0

Molecular formula:

C22H30Cl2N10.2C6H12O7

IUPAC Name:

N',N'''''-hexane-1,6-diylbis[N-(4-chlorophenyl)(imidodicarbonimidic diamide)] - D-gluconic acid (1:2)

Details on test material:

Test material: Chlorhexidine from Sigma Aldrich, Tokyo, Japan; 14C-(biguanide)-labelled chlorhexidine from Amersham, Tokyo, Japan; Gluconic acid from Wako Pure Chemical Industries, Osaka, Japan
Lot/Batch number: not given
Specification: Non-radioactive chlorhexidine was mixed with 14C-(biguanide)-labelled chlorhexidine base and with gluconic acid
Description: Non-radioactive chlorhexidine digluconate: 20 % aqueous solution
Purity: Non-radioactive chlorhexidine: no data; 14C-(biguanide)-labelled chlorhexidine base: radiochemical purity >= 97.2 %, specific activity 655 kBq/mg
Impurities: no data about the chemical nature
Stability: no data

Radiolabelling:

yes

Remarks:

14C-(biguanide)-labelled

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
-Source: Charles River, Kanagawa, Japan
-Age at study initiation: 5-6 w
-Weight at study initiation: 188-245 g
-Individual metabolism cages: no (in pairs)
-Diet: ad libitum
-Water: ad libitum
-Acclimation period: ca. 1 w

ENVIRONMENTAL CONDITIONS
-Temperature (°C): 23 +/- 2
-Humidity (%): 60 +/- 10
-Photoperiod (hrs dark / hrs light): 12 / 12

Administration / exposure

Type of coverage:

occlusive

Vehicle:

water

Duration of exposure:

24 h

Doses:

The test solution was prepared by mixing of gluconic acid with a 14C-labelled chlorhexidine solution at a 2:1 molar ratio and diluting to a final concentration of 0.04 (w/v) % a 14C-chlorhexidine (pH 4.74). 0.3 ml of the test solution was applied to a 2.5 cm2 patch, placed on the shaved back skin of the animals, covered with cloth tape, and held by elastic adhesive bandage.

No. of animals per group:

3 m

Control animals:

no

Details on study design:

After an application time of 24 h the excess unabsorbed test material was removed by sanitary cotton.
Two groups of animals: group 1: shaved, intact skin; group 2: shaved, abraded skin (Stratum corneum removed by tape-stripping) with light erythema.
Animals were housed in pairs in metabolism cages. Urine and faeces were collected for 7 days. Cages were washed each day and washings were retained for analysis. Animals were sacrificed at the end of the study and carcasses were retained for analysis of radioactivity.
In the same study, the percutaneous absorption, distribution, and excretion of 14C-labelled 1-(3,4-dichlorobenzyl)-5-octylbiguanide (OPB), a related biguanide biocide, was also studied.

Results and discussion

Signs and symptoms of toxicity:

not specified

Dermal irritation:

not specified

Absorption in different matrices:

see below

Total recovery:

see below

Any other information on results incl. tables

No differences in percutaneous absorption were observed between animals with intact or damaged skin.

Results of percutaneous absorption study in rats following single dermal application of^14C‑(biguanide labelled)-chlorhexidine digluconate   Percentage of total^14C-dose*   Intact skin Damaged skin Urinary excretion (0-168 h) 0.1+.0.1 0.3±.0.1 Faecal excretion (0-168 h) 4.2±1.8 3.5±1.7 Urine + faeces (0-168 h) 4.2±2.0 3.8±1.8 Application site (after 168 h) 1.5±0.5 2.7±1.6 Skin patch (after 24 h) 97.7±5.5 97.2±7.7 Total recovery 103.4 103.7 *: Mean ± SE of 3 animals.

Applicant's summary and conclusion

Conclusions:

Under the conditions of the assay, the percutaneous absorption of chlorhexidine from topically applied liquid solutions of chlorhexidine digluconate is low.

Executive summary:

In this study the percutaneous absorption of 14C-labelled chlorhexidine as chlorhexidine digluconate solution with an application to undamaged and damaged skin of rats under occlusive conditions for 24 h was studied. The recovery of chlorhexidine in skin patch, skin area, urine, and faeces was measured.

Under the conditions of the assay, the percutaneous absorption of chlorhexidine from topically applied liquid solutions of chlorhexidine digluconate is low. More than 97 % of the applied radioactivity was removed with the skin patch and only trace amounts (<= 0.3 %) could be detected in urine. No significant differences in toxicokinetics were observed between undamaged and damaged skin.