Registration Dossier

Administrative data

Endpoint:
biochemical or cellular interactions
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable well-documented publication which meets basic scientific principles.

Data source

Reference
Reference Type:
publication
Title:
Topical Treatment of Experimental Hydrofluoric Acid Skin Burns by 2.5% Calcium Gluconate
Author:
Roblin, I., Urban, M., Flicoteau, D., Martin, C. Pradeau, D.
Year:
2006
Bibliographic source:
J Burn Care Res 2006; 27: 889–894

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
The efficacy of three different gel formulations (containing 2.5 % calcium gluconate) varying in the amount and/or nature of their gelling and moisturizing agents was experimentally evaluated in rats.
GLP compliance:
no
Type of method:
in vivo
Endpoint addressed:
skin irritation / corrosion
skin sensitisation

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Calcium gluconate

Test animals

Species:
rat
Strain:
Wistar
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Laboratoires Charles River (L’Abresles, France)
- Age at study initiation: not reported
- Weight at study initiation: 250 g
- Fasting period before study: no
- Housing: 10 per cage
- Diet (e.g. ad libitum): ad libitum, standard laboratory chow (Dietex France, Saint-Gratien, France)
- Water (e.g. ad libitum): ad libitum, tap water
- Acclimation period: 4 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
dermal
Vehicle:
unchanged (no vehicle)
Details on exposure:
One day before the experiment, animals were carefully shaved on their right flank with an electric shaver; two square spots of 4 cm2 were clearly demarcated. On day 0, rats were sedated by an intraperitoneal injection of 0.2 ml of 6% pentobarbital (48 mg/kg; Ceva Sante´ animale, Libourne, France). A volume of 60 µL of 40% HF (VWR, Fontenay-sous-bois, France) was applied on each spot with a calibrated pipette and immediately spread over the delimited surface using a polypropylene stick. After a 2-minute contact with HF, the skin was carefully blotted dry for 1-minute with a surgical towel.
Three different 2.5% calcium gluconate gels were prepared Three minutes after burn injury, one lesion was treated with 1 g of calcium gluconate 2.5% gel A, B, or C (25 mg of calcium gluconate, one operator per gel). The gel was massaged for 1 minute to improve penetration, and the treatment was repeated 30 minutes; 1 hour; 1 hour, 30 minutes; 2 hours; 3 hours; and 4 hours after burn. At 2:00 PM on days 1, 2, and 3 after burn, the lesions were treated with 1g of gel by a single operator in a blind fashion (without knowledge of the type of gel). If present, the remaining excess of gel was removed before each new application. The other lesion for each animal received no treatment; in this experimental design, each rat is its own control for assessment of treatment efficacy.
Analytical verification of doses or concentrations:
yes
Duration of treatment / exposure:
single treatment
Frequency of treatment:
The gel was massaged for 1 minute to improve penetration, and the treatment was repeated 30 minutes; 1 hour; 1 hour, 30 minutes; 2 hours; 3 hours; and 4 hours after burn. At 2:00 PM on days 1, 2, and 3 after burn, the lesions were treated with 1g of gel.
Doses / concentrations
Remarks:
Doses / Concentrations:
2.5 % (= 25 mg calcium gluconate)
Basis:
nominal conc.
No. of animals per sex per dose:
10
Control animals:
yes, concurrent no treatment

Results and discussion

Details on results:
Calcium gluconate gel therapy significantly reduced the severity score of burn injury at all time intervals. There was a significant effect (P < .0001) of treatment on the total number of score 1, 2, 3, and 4 lesions; 31 scores of 0 were obtained by therapy. The median effect was 1 for score 1, 2, and 4 lesions and 2 for score 3 lesions. All three gels significantly reduced the severity scores of burns, except gel C on score 1 lesions (P =.210, NS). In 40 of 156 observations (gel A: 19%, B: 24%, C: 30%; NS between gels), no difference was noted between the scores of treated and untreated lesions; there was 4 cases of worsening with gel C. Gel therapy significantly reduced the calculated AUCs of burn injury. There was no difference between gels for total AUCday 0–17 (gel A, 38%; B, 56%; and C, 21%;P= .316).Two treatment failures were noted with gel C (AUCday 0–17 of untreated/treated: 15/21 and 53.5/58.5) and one with gel B (51.5/50.5). Fourteen full wound recoveries were obtained on day 17 after burn (with gel A and C, n=5; gel B, n=4; compared with six in the absence of therapy.

Applicant's summary and conclusion

Conclusions:
Calcium gluconate gel therapy significantly reduced the severity score of burn injury at all time intervals.
Executive summary:

Topical therapy with 2.5% calcium gluconate gel is considered as the “first-aid” treatment of accidental hydrofluoric acid skin burns. The efficacy of three different gel formulations varying in the amount and/or nature of their gelling and moisturizing agents was experimentally evaluated. Thirty male Wistar-Han rats (250 g) were exposed to 60 µL of 40% hydrofluoric acid for 2 minutes on two spots (4 cm2) of skin under pentobarbital anesthesia.

One lesion was massaged with 1 g of gel (10 rats/type of gel) at 3 minutes; 30 minutes; 1 hour; 1 hour, 30 minutes; 2 hours; 3 hours; and 4 hours after injury. During the next 3 days, rats received a single daily application of gel. The other lesion for each rat remained untreated (control). From day 1 after injury to the end of the study (day 17), gel therapy reduced the number of extensive (- 66%), severe (-44%), and moderate (-34%) lesions (P < .0001). It reduced (P < .001) the median Area Under the Curve day 0–17 of burn injury from 34.0 (25th to 75th percentile: 18.2– 44.5; untreated lesions) to 17.7 (7.0 –26.7); overall, there was three cases of treatment failure. At day 17, full wound recovery was obtained in 14 cases by gel therapy compared with 6 in the absence of treatment. The efficacy of the three gel formulations was comparable for all evaluated parameters. Repeated applications of a 2.5% calcium gluconate gel is an efficient treatment of experimental 40% hydrofluoric acid skin burn; few differences were observed between evaluated gel formulations.