Dexpanthenol

Endpoint summary

Description of key information

A read across approach was performed with the supporting substance DL-Ethyl Panthenol. In a 90 day subchronic GLP and guideline study in rats, the test item showed a NOAEL of 1000 mg/kg bw/day, which was the highest dose tested. In addition oral exposure of rats for 28 days resulted in a NOAEL of 1000 mg/kg bw/day (highest dose tested). In a supporting subchronic oral toxicity study with DL- Panthenol the voluntary consumption of the test item by male and female rats in drinking water in the concentrations of 200, 50 and 20 mg/kg bw/day for a 90 day period showed essentially negative results. The no observed adverse effect level (NOAEL) under the conditions of this study was considered to be 200 mg/kg bw/day. In conclusion no adverse effects releated on D- Panthenol could be observed after oral exposure for 90 days.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: oral

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

22 August 2011 to 24 April 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

For justification of read across please refer to the attachment in IUCLID section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Version / remarks:

1998

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

- ANIMAL HOUSING
Upon arrival, all animals were housed individually in clean, stainless steel, wire-mesh cages suspended above cage-board. Animals were maintained in accordance with the Guide for the Care and Use of Laboratory Animals (National Research Council, 1996). The animal facilities at WIL Research are accredited by AAALAC International. Enrichment devices were provided to all animals as appropriate throughout the study for environmental enrichment and to aid in maintaining the animals’ oral health, and were sanitized weekly.
- DIET, DRINKING WATER, AND MAINTENANCE
The basal diet used in this study, PMI Nutrition International, LLC, Certified Rodent LabDiet® 5002 (meal), is a certified feed with appropriate analyses performed by the manufacturer and provided to WIL Research. Reverse osmosis-treated (on-site) drinking water, delivered by an automatic watering system, and the basal diet were provided ad libitum throughout the study, except during the period of fasting prior to clinical pathology blood collection when food, but not water, was withheld. Municipal water supplying the facility was analyzed for contaminants according to SOPs. The results of the diet and water analyses are maintained at WIL Research. No contaminants were present in animal feed or water at concentrations sufficient to interfere with the objectives of this study.
- ENVIRONMENTAL CONDITIONS
All animals were housed throughout the acclimation period and during the study in an environmentally controlled room. The room temperature and humidity controls were set to maintain environmental conditions of 71 ± 5°F (22 ± 3°C) and 50 ± 20%, respectively. Room temperature and relative humidity data were monitored continuously and were scheduled for automatic collection on an hourly basis. Actual mean daily temperature ranged from 69.9°F to 70.7°F (21.1°C to 21.5°C) and mean daily relative humidity ranged from 38.4% to 54.1% during the study. Fluorescent lighting provided illumination for a 12-hour light (0600 hours to 1800 hours)/12-hour dark photoperiod. The light status (on or off) was recorded once every 15 minutes. The 12-hour light/12-hour dark photoperiod was interrupted as necessary to allow for the performance of protocol-specified activities. Air handling units were set to provide a minimum of 10 fresh air changes per hour.

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

The vehicle and test article formulations were administered orally by gavage via an appropriately sized flexible Teflon®-shafted, stainless steel ball-tipped dosing cannula once daily for 91 or 92 consecutive days, through the day prior to the primary necropsy. The dose volume for all groups was 10 mL/kg. Individual doses were based on the most recently recorded body weights to provide the correct mg/kg/day dosage. Adjusted doses became effective the day of collection of the weekly body weights. The first day of dosing was study day 0; the first week of dosing was study week 0.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Stability of Ethyl Panthenol at concentrations of 50 to 100 mg/mL was previously confirmed following 10 days of refrigerated storage (approximately 2°C to 8°C). Prior to the initiation of dose administration, samples for homogeneity determination were collected from the top, middle, and bottom strata of the 25, 50, and 100 mg/mL dosing formulations. Aliquots approximately equivalent in volume to a daily dispensation aliquot were then transferred from the pre-initiation batch into the same type of storage container that was used for the daily aliquots for dosing and stored refrigerated (approximately 2°C to 8°C) for 10 days. Following the storage period, each aliquot was resuspended for a minimum of 30 minutes, and samples were collected from the top and bottom strata of each aliquot for assessment of 10-day refrigerated stability and aliquot resuspension homogeneity. Samples for concentration analysis were collected during study weeks 0, 3, 7, and 12 from the middle stratum of each dosing formulation (including the control group).
One duplicate set of samples was analyzed and the remaining duplicate set was refrigerated (approximately 2°C to 8°C) and retained as backup samples until the results were verified as acceptable. All analyses were conducted by the WIL Research Analytical Chemistry Department utilizing a validated gas chromatography method using flame ionization detection.

Duration of treatment / exposure:

91 or 92 days of tretment
28 day recovery period

Frequency of treatment:

1 per day

Remarks:

Doses / Concentrations:
0 mg/ kg bw/ day
Basis:
other: gavage

Remarks:

Doses / Concentrations:
250 mg/kg bw/ day
Basis:
other: gavage

Remarks:

Doses / Concentrations:
500 mg/kg bw/ day
Basis:
other: gavage

Remarks:

Doses / Concentrations:
1000 mg/kg bw/ day
Basis:
other: gavage

No. of animals per sex per dose:

Control group: 15 males, 15 females
250 mg/kg bw/d: 10 males, 10 females
500 mg/kg bw/d: 10 males, 10 females
1000 mg/kg bw/d: 15 males, 15 females

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: The highest dose of 1000 mg/kg body weight (bw)/day was selected on the basis of a 4-week oral toxicity study in rats, conducted according to OECD Test Guideline 407 (Strobel, 1995). In the referenced study, a no-observed-effect level (NOEL) of 1000 mg/kg bw/day was established. For studies performed according to OECD Guideline 408, 1000 mg/kg/day is a common limit dosage level. The lower doses of 500 and 250 mg/kg bw/day were chosen due to the recommendation on OECD Test Guideline 408 that spacing factors of 2-4 should be used for dose selection. The selected route of administration for this study was oral (gavage) because this is a potential route of exposure for humans and the requirement for the study was for chemical registration purposes and not specifically with regard to cosmetic use.

- Rationale for animal assignment: Randomization procedure based on body weight

- Post-exposure recovery period in satellite groups: 28 d

Positive control:

none

Observations and examinations performed and frequency:

SURVIVAL: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Clinical examinations were performed twice daily during the dosing period, at the time of dose administration and approximately 1 to 2 hours following dose administration. During the recovery period, the animals were observed once daily.

BODY WEIGHT: Yes
- Time schedule for examinations: Individual body weights were recorded approximately weekly beginning during acclimation and at the time of randomization. Body weights were also recorded on the day prior to the first day of the scheduled necropsies. During study weeks 12 to 13, body weights were recorded twice weekly.

FOOD CONSUMPTION:
- Individual food consumption was recorded approximately weekly beginning during acclimation and throughout the study. During study weeks 12 and 13, food consumption was recorded twice weekly.

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Ocular examinations were conducted on all animals prior to randomization (study week -2), near the end of the treatment period (study week 12), and near the end of the recovery period (study week 16).
- Dose groups that were examined: all dose groups.

HAEMATOLOGY: Yes
- Time schedule for collection of blood: time of the primary and recovery necropsies for those animals scheduled for necropsy
- Anaesthetic used for blood collection: Yes, isoflurane
- Animals fasted: Yes, overnight prior to blood collection
- How many animals: all animals
- Parameters checked in table [No.1] were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: time of the primary and recovery necropsies for those animals scheduled for necropsy
- Animals fasted: Yes, overnight prior to blood collection
- How many animals: all animals
- Parameters checked in table [No.2] were examined.

URINALYSIS: Yes
- Time schedule for collection of urine: time of the primary and recovery necropsies for those animals scheduled for necropsy
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes
- Parameters checked in table [No.3] were examined.

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: study week 12
- Dose groups that were examined: 10 animals/sex/group
- Battery of functions tested: home cage observations/ handling observations/ open field observations/ sensory activity /neuromuscular observations/physiological observations/ locomotor activity

DETERMINATION OF ESTROUS CYCLES: Yes
- Time schedule for examinations: Daily vaginal lavages were performed on all females to determine the stage of estrus beginning 2 weeks prior to and on the day of the scheduled primary necropsy. Vaginal lavage samples were microscopically evaluated to determine the stage of estrus.
- Dose groups that were examined: all females.

PLASMA BIOANALYSIS: Yes
- Time schedule for examinations: 6 hours following dosing administration on study days 7, 28, and 84.
- Dose groups that were examined: 4 animals/sex/group

Sacrifice and pathology:

ANATOMIC PATHOLOGY
- A complete necropsy was conducted on all animals. Animals were euthanized by carbon dioxide inhalation followed by exsanguination. The necropsies included, but were not limited to, examination of the external surface, all orifices, and the cranial, thoracic, abdominal, and pelvic cavities, including viscera.
- Organ weight
- Slide preparation and microscopic examination

SPERMATOGENIC EVALUATIONS
- Dose group: all males (10/group) at the primary necropsy
- Motility/ Viability assessment
- Morphology assessment
- Enumeration of epididymal and testicular sperm, numbers and sperm production rate

Statistics:

All statistical tests were performed using WTDMS™ unless otherwise noted. Analyses were conducted using two-tailed tests (except as noted otherwise) for minimum significance levels of 1% and 5%, comparing each test article-treated group with the control group by sex.
Body weight, body weight change, food consumption, continuous FOB, clinical pathology (except gamma glutamyltransferase [GGT]), estrous length, sperm production rate, epididymal and testicular sperm numbers, and organ weight data were subjected to a parametric one-way ANOVA (Snedecor and Cochran, 1980) to determine intergroup differences. If the ANOVA revealed statistically significant (p<0.05) intergroup variance, Dunnett's test (Dunnett, 1964) was used to compare the test article-treated groups with the control group. Functional observational battery parameters that yielded scalar or descriptive data were analyzed using Fisher’s Exact Test (Steel and Torrie, 1980). The percentage of motile spermatozoa and the percentage of sperm with normal
morphology were subjected to the Kruskal-Wallis nonparametric ANOVA test (Kruskal and Wallis, 1952) to determine intergroup differences. If the ANOVA revealed significance (p<0.05), Dunn’s test (Dunn, 1964) was used to compare the test article-treated groups with the control group. GGT values under range were assigned a value of 0.1 (half the lower limit of quantitation) for statistical analysis and reporting. GGT data were subjected to the Kruskal-Wallis nonparametric ANOVA test (Kruskal and Wallis, 1952) to determine intergroup differences. If the ANOVA revealed significance (p< 0.05), Dunn’s test (Dunn, 1964) was used to compare the test article-treated groups with the control group.

Clinical signs:

no effects observed

Description (incidence and severity):

One female rat in the control group was found dead on study day 84 subsequent to mechanical trauma. All other animals survived to the scheduled necropsies.

Mortality:

no mortality observed

Description (incidence):

One female rat in the control group was found dead on study day 84 subsequent to mechanical trauma. All other animals survived to the scheduled necropsies.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Body weights were unaffected by test article administration. There were no statistically significant differences when the control and test article-treated groups were compared.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

not applicable

Food efficiency:

no effects observed

Description (incidence and severity):

Food consumption was unaffected by test article administration. Any statistically significant differences in food consumption were not test article-related.

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

no effects observed

Description (incidence and severity):

No ophthalmic lesions indicative of toxicity were observed in any of the test article-treated groups.

Haematological findings:

no effects observed

Description (incidence and severity):

There were no test article-related alterations in hematology and coagulation parameters at the primary or recovery necropsy.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

There were no test article-related effects on serum chemistry parameters.

Urinalysis findings:

no effects observed

Description (incidence and severity):

There were no test article-related effects on urinalysis parameters.

Behaviour (functional findings):

no effects observed

Description (incidence and severity):

Neurobehaviour patterns were unaffected by the test article administration. There were no statistically significant differences when the test article-treated males and females were compared with the control group at the study week 12 evaluation.

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Test article-related higher liver and kidney weights were noted in the 1000 mg/kg/day group but considered non adverse.

Gross pathological findings:

no effects observed

Description (incidence and severity):

No test article-related gross observations were noted at the primary or recovery necropsy.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Test article-related microscopic findings were noted at the primary necropsy in the livers of the 250, 500, and 1000 mg/kg/day group females but considered non adverse.

Histopathological findings: neoplastic:

not examined

Details on results:

CLINICAL CHEMISTRY:
Slightly higher test article-related mean calcium values were noted in the 500 and 1000 mg/kg/day group males at the primary necropsy. The relatively small difference in the mean values between the test article-treated groups and the control group at the primary necropsy was therefore not considered an adverse finding.
The mean alanine aminotransferase (ALT) value for the 1000 mg/kg/day group males was higher than the mean ALT value for the control group at the recovery necropsy, but was within the range of means (35 to 59 U/L) recorded in the historical control database. Because the observed mean value was within the range of means in the WIL Research historical control database and no other serum chemistry values associated with liver disease were elevated, this finding was considered due to biological variation. The mean serum alkaline phosphatase (ALP) value for the 1000 mg/kg/day group females was lower than the mean ALP value for the control group at the recovery necropsy but was not considered test article-related. Higher ALP values may be associated with liver disease, but lower values may be indicative of primary or secondary malnutrition (Lum, 1995). In this study, however, all mean serum ALP values of control and test article-treated animals were within the mean values (37 to 69 U/L) recorded in the WIL Research historical control database suggesting that the low values were due to biological variation and were not test article-related.

URINALYSIS:
A statistically significantly higher mean specific gravity value was noted in the 1000 mg/kg/day group males at the primary necropsy and a lower mean pH value was noted in the 1000 mg/kg/day group males at the primary necropsy. These differences were not considered to be test article-related as both findings were within the range of means (5.9 to 8.6 for pH; 1.0206 to 1.0633 for specific gravity) recorded in the WIL Research historical control database, there was not a statistically significant difference between control and test article-treated groups at the recovery necropsy, and no correlating histological changes were noted in the kidneys.

ORGAN WEIGHTS:
Higher mean liver and kidney weights (absolute and relative to body and brain weights) were noted in the 1000 mg/kg/day group females at the primary necropsy and higher mean liver weight relative to final body weight was noted in the 1000 mg/kg/day group males at the primary and recovery necropsies. These differences were relatively small, i.e., not more than 18% as compared with the control group, and were not detected at the recovery necropsy indicating that the organ weight effects were nonadverse.

GROSS PATHOLOGY:
Dilated renal pelvis was observed in the 250 and 500 mg/kg/day group males at the primary necropsy, and in the 1000 mg/kg/day group males at the recovery necropsy, but this finding was unilateral and occurred only in males, and was therefore not considered to be test article-related. A renal mass was noted in one 1000 mg/kg/day group female at the recovery necropsy.

HISTOPATHOLOGY:
Mild vacuolation of hepatocytes was noted in one 1000 mg/kg/day group male and in 1 control group male, indicating that this finding can be a normal background lesion and was therefore not test article-related in the males. However in the females at the primary necropsy, minimal to mild microvesicular vacuolation of hepatocytes was noted in the females in the 250 and 500 mg/kg/day groups (3 and 4 animals, respectively) and 3 of 10 animals in the 1000 mg/kg/day group had mild vacuolation of hepatocytes which for 2 of these animals was further specified as microvesicular hepatocellular vacuolation, suggesting a relationship with the test article. No instances of hepatocellular vacuolation were noted in the control or 1000 mg/kg/day group females examined at the recovery necropsy. Taking into account the mild nature of the vacuolation at the primary necropsy, the lack of associated liver enzyme alterations, the lack of persistence of the vacuolation at the recovery necropsy, and historical data, the hepatocellular vacuolation, mainly evident as microvesicular hepatocellular vacuolation, was considered to be an adaptive change and nonadverse.
One female in the 1000 mg/kg/day group at the recovery necropsy had a renal carcinoma, but it was not considered test article-related as there were no other lesions associated with renal tumor progression and no evidence of renal toxicity in any other animal. Spontaneous renal tubule carcinomas in rats have been previously described and were considered most likely attributable to genetic predisposition.

ESTROUS CYCLE:
Estrous cycles were unaffected by test article administration. There were no statistically significant differences when the test article-treated females were compared to the control group.

SPERMATOGENIC EVALUATIONS:
There were no test article-related effects on spermatogenic endpoints (testicular and epididymal sperm numbers, sperm production rate, motility, and the percentage of morphologically normal sperm) observed at any dosage level.

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No adverse effects observed.

Critical effects observed:

not specified

Conclusions:

Based on the results of this study, oral administration of the test item to Crl:CD(SD) rats over a period of 91 or 92 days resulted in a no-observed-adverse-effect level (NOAEL) of 1000 mg/kg/day, the highest dosage level investigated.

Executive summary:

Objective:

The objective of the study was to evaluate the potential toxicity and toxicokinetic profile of the test item when administered orally, by gavage, to Sprague Dawley rats for a minimum of 91 days. In addition, a 28-day recovery period assessed the reversibility, persistence, or delayed occurrence of potential test article-related effects. The protocol was designed to be in general accordance with the OECD Guidelines for the Testing of Chemicals (Guideline 408). The study was conducted in accordance with appropriate GLP guidelines except for the bioanalytical analyses, which were conducted in compliance with the Swiss Ordinance relating to GLPs and the evaluation report of the

bioanalytical plasma data that was written by the Sponsor.

Study design:

The test item in the vehicle (deionized water) was administered orally by gavage once daily for a minimum of 91 consecutive days to 3 groups (Groups 2-4) of Crl:CD(SD) rats. Dosage levels were 250, 500, and 1000 mg/kg/day for Groups 2, 3, and 4, respectively. A concurrent control group (Group 1) received the vehicle (deionized water) on a comparable regimen. The dose volume was 10 mL/kg for all groups. Groups 1 and 4 each consisted of 15 animals/sex and Groups 2 and 3 each consisted of 10 animals/sex. Following approximately 13 weeks of dose administration, 10 rats/sex/group were

euthanized; the remaining ≤ 5 rats/sex in the control and high-dose groups were euthanized following a 28-day nondosing (recovery) period.

All animals were observed twice daily for mortality and moribundity. Clinical examinations were performed daily, and detailed physical examinations were performed approximately weekly. Individual body weights and food consumption were recorded approximately weekly. Functional observational battery (FOB) and locomotor activity data were recorded for all animals prior to the initiation of dose administration, and for 10 animals/sex/group during study week 12. Ophthalmic examinations were performed during study weeks -2, 12, and 16. Clinical pathology parameters (hematology, coagulation, serum chemistry, and urinalysis) were analyzed for animals at the primary (study week 13) and recovery (study week 17) necropsies. Daily vaginal lavages for estrous cycle determination were performed on all females beginning 2 weeks prior to the primary necropsy. Complete necropsies were conducted on all animals, and selected organs were weighed at the scheduled necropsies. Selected tissues were examined microscopically. Microscopic examination was performed on a wide range of listed tissues from the animal found dead and all animals in the control and 1000 mg/kg/day groups at the scheduled primary necropsy. The liver was examined from all females in the 250 and 500 mg/kg/day groups at the primary necropsy and from all females in the control and 1000 mg/kg/day groups at the recovery necropsy. Gross lesions were examined from all animals at the primary and recovery necropsies. Spermatogenic endpoints were evaluated for all males at the primary necropsy.

For plasma bioanalysis, blood samples were collected from 4 animals/sex/group at approximately 6 hours after dose administration on study days 7, 28, and 84.

Results:

There were no test article-related effects on survival, body weight, food consumption, FOB or locomotor activity assessment, hematology, coagulation, urinalysis, ophthalmic examinations, estrous cycle, macroscopic examinations, or spermatogenic endpoints. Yellow staining on the ventral trunk and/or around the anogenital and/or urogenital areas was noted in the 1000 mg/kg/day group females beginning on study day 11 and sporadically throughout the dosing period.

Nonadverse test article-related higher calcium values were noted in the 500 and 1000 mg/kg/day group males at the primary necropsy. Nonadverse test article-related higher mean liver and kidney weights (absolute and relative to body and brain weights) were noted in the 1000 mg/kg/day group females at the primary necropsy and higher mean liver weight relative to final body weight was noted in the 1000 mg/kg/day group males at the primary and recovery necropsies. In the females from the 1000 mg/kg/day group at the primary necropsy, 3 of 10 animals had mild vacuolation of hepatocytes, which for 2 of these animals was further specified as microvesicular hepatocellular vacuolation. From the extension of histological evaluations, minimal to mild microvesicular hepatocellular vacuolation was also noted at the primary necropsy in 3 of 10 females in the 250 mg/kg/day group and in 4 of 10 females in the 500 mg/kg/day group. No instances of vacuolation were noted in the control or 1000 mg/kg/day group females examined at the recovery necropsy. Taking into account the mild nature of the vacuolation at the primary necropsy, the lack of associated liver enzyme alterations, the lack of persistence of the vacuolation at the recovery necropsy, and historical data, the hepatocellular vacuolation, mainly evident as microvesicular hepatocellular vacuolation, was considered to be an adaptive change and nonadverse.

Plasma concentrations of the test article and the two metabolites Panthenol and Pantothenic Acid ranged from the lower limit of quantitation (LLQ) to 41,700 ng/mL (178.7 μM) for the test item, from the LLQ to 16,600 ng/mL (80.9 μM) for Panthenol, and from 198 ng/mL to 21,600 ng/mL (98.5 μM) for Pantothenic Acid. The mean plasma concentrations for all 3 analytes increased with dosage on all 3 sampling days in both genders. In females the mean test item plasma concentrations were generally higher than the mean male value of the corresponding group and day of sampling. In contrast, the mean values for the 2 metabolites were lower in females than the corresponding male values. Regarding the sum of the 3 analytes (read-across substance, Panthenol, and Pantothenic Acid) a dose-dependent increase in analyte concentrations was visible. For both genders a plasma level of the combined analytes of approximately 50, 100, and 200 μM was observed respectively at a daily dosage of 250, 500, and 1000 mg/kg body weight, both on days 7 and 28. These data underline the linear dose dependence of plasma levels which are not evident from looking at the test item data alone due to its rapid metabolism to Panthenol. There was a slight decline of combined plasma levels on study day 84, which was more apparent in males than in females; this may indicate some sort of adaptation of the animals to the prolonged substance administration. In summary, plasma data showed dose dependence of test item absorption, metabolism to Panthenol and Pantothenic Acid, and no indication of bioaccumulation over time.

Conclusion:

Based on the results of this study, oral administration of the test item to Crl:CD(SD) rats over a period of 91 or 92 days resulted in a no-observed-adverse-effect level (NOAEL) of 1000 mg/kg/day, the highest dosage level investigated.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

GLP and guideline study

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Additional information

Repeated dose toxicity: oral

-90d repeated dose toxicity study with DL- Ethyl Panthenol (read across):

The potential toxicity and toxicokinetic profile of DL- Ethyl Panthenol was evaluated in a repeated dose 90- day oral toxicity study in Sprague Dawley rats. In addition, a 28-day recovery period assessed the reversibility, persistence, or delayed occurrence of potential test article-related effects. The protocol was designed to be in general accordance with the OECD Guidelines for the Testing of Chemicals (Guideline 408) and the study was performed under GLP.

Ethyl Panthenol in the vehicle (deionized water) was administered orally by gavage once daily for a minimum of 91 consecutive days to 3 groups (Groups 2-4) of Crl:CD(SD) rats. Dosage levels were 250, 500, and 1000 mg/kg/day for Groups 2, 3, and 4, respectively. A concurrent control group (Group 1) received the vehicle (deionized water) on a comparable regimen. The dose volume was 10 mL/kg for all groups. Groups 1 and 4 each consisted of 15 animals/sex and Groups 2 and 3 each consisted of 10 animals/sex. Following approximately 13 weeks of dose administration, 10 rats/sex/group were euthanized; the remaining ≤ 5 rats/sex in the control and high-dose groups were euthanized following a 28-day nondosing (recovery) period.

All animals were observed twice daily for mortality and moribundity. Clinical examinations were performed daily, and detailed physical examinations were performed approximately weekly. Individual body weights and food consumption were recorded approximately weekly. Functional observational battery (FOB) and locomotor activity data were recorded for all animals prior to the initiation of dose administration, and for 10 animals/sex/group during study week 12. Ophthalmic examinations were performed during study weeks -2, 12, and 16. Clinical pathology parameters (hematology, coagulation, serum chemistry, and urinalysis) were analyzed for animals at the primary (study week 13) and recovery (study week 17) necropsies. Daily vaginal lavages for estrous cycle determination were performed on all females beginning 2 weeks prior to the primary necropsy. Complete necropsies were conducted on all animals, and selected organs were weighed at the scheduled necropsies. Selected tissues were examined microscopically. Microscopic examination was performed on a wide range of listed tissues from the animal found dead and all animals in the control and 1000 mg/kg/day groups at the scheduled primary necropsy. The liver was examined from all females in the 250 and 500 mg/kg/day groups at the primary necropsy and from all females in the control and 1000 mg/kg/day groups at the recovery necropsy. Gross lesions were examined from all animals at the primary and recovery necropsies. Spermatogenic endpoints were evaluated for all males at the primary necropsy.

For plasma bioanalysis, blood samples were collected from 4 animals/sex/group at approximately 6 hours after dose administration on study days 7, 28, and 84.

There were no test article-related effects on survival, body weight, food consumption, FOB or locomotor activity assessment, hematology, coagulation, urinalysis, ophthalmic examinations, estrous cycle, macroscopic examinations, or spermatogenic endpoints. Yellow staining on the ventral trunk and/or around the anogenital and/or urogenital areas was noted in the 1000 mg/kg/day group females beginning on study day 11 and sporadically throughout the dosing period.

Nonadverse test article-related higher calcium values were noted in the 500 and 1000 mg/kg/day group males at the primary necropsy. Nonadverse test article-related higher mean liver and kidney weights (absolute and relative to body and brain weights) were noted in the 1000 mg/kg/day group females at the primary necropsy and higher mean liver weight relative to final body weight was noted in the 1000 mg/kg/day group males at the primary and recovery necropsies. In the females from the 1000 mg/kg/day group at the primary necropsy, 3 of 10 animals had mild vacuolation of hepatocytes, which for 2 of these animals was further specified as microvesicular hepatocellular vacuolation. From the extension of histological evaluations, minimal to mild microvesicular hepatocellular vacuolation was also noted at the primary necropsy in 3 of 10 females in the 250 mg/kg/day group and in 4 of 10 females in the 500 mg/kg/day group. No instances of vacuolation were noted in the control or 1000 mg/kg/day group females examined at the recovery necropsy. Taking into account the mild nature of the vacuolation at the primary necropsy, the lack of associated liver enzyme alterations, the lack of persistence of the vacuolation at the recovery necropsy, and historical data, the hepatocellular vacuolation, mainly evident as microvesicular hepatocellular vacuolation, was considered to be an adaptive change and nonadverse.

Plasma concentrations of the test article and the two metabolites Panthenol and Pantothenic Acid ranged from the lower limit of quantitation (LLQ) to 41,700 ng/mL (178.7 μM) for Ethyl Panthenol, from the LLQ to 16,600 ng/mL (80.9 μM) for Panthenol, and from 198 ng/mL to 21,600 ng/mL (98.5 μM) for Pantothenic Acid. The mean plasma concentrations for all 3 analytes increased with dosage on all 3 sampling days in both genders. In females the mean Ethyl Panthenol plasma concentrations were generally higher than the mean male value of the corresponding group and day of sampling. In contrast, the mean values for the 2 metabolites were lower in females than the corresponding male values. Regarding the sum of the 3 analytes (Ethyl Panthenol, Panthenol, and Pantothenic Acid) a dose-dependent increase in analyte concentrations was visible. For both genders a plasma level of the combined analytes of approximately 50, 100, and 200 μM was observed respectively at a daily dosage of 250, 500, and 1000 mg/kg body weight, both on days 7 and 28. These data underline the linear dose dependence of plasma levels which are not evident from looking at the Ethyl Panthenol data alone due to its rapid metabolism to Panthenol. There was a slight decline of combined plasma levels on study day 84, which was more apparent in males than in females; this may indicate some sort of adaptation of the animals to the prolonged Ethyl Panthenol administration. In summary, plasma data showed dose dependence of Ethyl Panthenol absorption, metabolism to Panthenol and Pantothenic Acid, and no indication of bioaccumulation over time.

 

- 28d repeated dose toxicity study with DL-Ethyl Panthenol (read across):

A read across approach was performed with the supporting substance DL-Ethylpanthenol. For justification of read across please refer to the attachment in IUCLID5 section 13. The repeated dose toxicity of DL-Ethylpanthenol was investigated in a subacute 28-day GLP and guideline oral toxicity study by daily gavage in the rat. Based on the results of a 5-day range finding study, the dose levels for the 28-day toxicity study were selected to be 0, 50, 200 and 1000 mg/kg bw/day. The test substance was administered daily for 28 days by oral gavage to SPF-bred Wistar rats. One control group and three treated groups were tested, each consisting of 5 males and 5 females. The following parameters were evaluated: clinical signs daily, body weight and food consumption weekly; ophthalmoscopy at week 4; clinical pathology and macroscopy at termination; organ weights and histopathology on a selection of tissues.

Results:

Formulations: Homogeneity was assumed, based on visually clear solutions obtained after preparation. Accuracy of test substance formulations were demonstrated by analyses.

50 mg/kg bw/day: No treatment-related findings noted.

200 mg/kg bw/day: No treatment-related findings noted.

1000 mg/kg bw/day: No treatment-related findings noted.

Conclusion:

From the results presented in this report a definitive No Observed Effect Level (NOEL) of 1000 mg/kg bw/day was established.

Based on the strong structural similarity between DL-Ethyl Panthenol and D- Panthenol, it can be assumed that also for D-Panthenol the NOAEL in a sub-chronic 90d study would be 1,000 mg/kg bw/d.

 

- 90d repeated dose toxicity study with D-Panthenol:

The test item was administered to male and female Charles River rats in drinking water for 13 weeks at nominal doses of 0 (vehicle control), 20, 50 and 200 mg/kg body weight/day (Pharmacology Research Inc., 1953). The test material was administered at nominal concentrations in slightly acidified drinking water. Six male and six female rats per dose group received the test solution as the only drinking supply ad libitum; the control group received drinking water only.

Data and dose calculation:

The fluid volumes consumed by each group of animals were averaged on a weekly basis and divided by the number of animals composing the group and were stated as cc/rat. These values were converted to cc/kg and further to mg/kg bw/day uptake of the test item. The intended doses had been approximated in every instance with a maximum deviation not greater than 12 %.

Body weights were recorded twice weekly during the initial two-week period and then weekly until termination of the study. Hematological studies were conducted immediately preceding start of the study, again at the mid-point of the study, and finally at termination. After ninety experimental days, all surviving animals were sacrified and individual weights of the vital organs were recorded. Gross examinations of the viscera were made at this time to note any deviations from normal appearance or structure and representative sections of various organs and tissues were removed for histological examination.

The following substance-related findings were obtained:

The growth pattern of all experimental groups did not differ significantly. Mortalities were observed only among the males during the course of the experiment; these were one male at the high dose, two males at the median dose, and one male at the low dose. This was not considered to be significant and was not appeared to be related to drug consumption in any instance.

No significant alterations in the hemogram were observed with the possible exception of a mild eosinophilia which was present among the females at each of the three dosage levels and among the males at the high dosage level only. However, this mild eosinophilia was not considered significant. Of the organs weighed at termimation of the experiment, the only marked deviations observed were in reference to the livers of the treated animals: The average weight of this organ was less than the controls among the rats at the high dosage level and also at the low dosage level. The difference does not appear to be of sufficient magnitude to be significant.

Gross examination of the various organs at autopsy did not reveal any deviations from normal appearance or structure.

Conclusions:  

The subchronic toxicity following voluntary consumption of the test item by male and female rats in drinking water in the concentrations of 200, 50 and 20 mg/kg bw/day for a 90 day period showed essentially negative results. The test item was concluded to be relatively innocuous under the conditions of the experiment. Signs of a mild eosinophilia appeared to be present among the experimental animals, but this has been seriously questioned. The no observed adverse effect level (NOAEL) under the conditions of this study was considered to be 200 mg/kg bw/day.

 

CONCLUSION: No adverse effects after repeated exposure of DL-/ D- Panthenol in rats could be observed.

 

Repeated dose toxicity: dermal

In accordance with REACH Annex IX, column 2, a sub-chronic inhalation repeated dose toxicity study (section 8.6.2) is not required, as information on sub-chronic oral toxicity is available which was considered as most appropriate route of exposure. Thus, further testing is not required.

 

Repeated dose toxicity: inhalation

In accordance with REACH Annex IX, column 2, a sub-chronic dermal repeated dose toxicity study (section 8.6.2) is not required, as available information on short term toxicity (oral and dermal), as well as the available oral repeated dose toxicity studies together with the low logPow (< 0) indicate low dermal toxicity after repeated application. Additionally, the repeated dose toxicity was adequately addressed by the oral route (section 7.5.1), allowing evaluation of systemic toxic effects after dermal exposure.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
The close structural similarity between DL-Ethyl-Panthenol and D-Panthenol strongly suggest that D-Panthenol do also not induce adverse effects after repeated exposure. For justification of read across please refer to the attachment in IUCLID5 section 13.

Justification for selection of repeated dose toxicity inhalation - systemic effects endpoint:
In accordance with REACH Annex IX, column 2, a sub-chronic inhalation repeated dose toxicity study (section 8.6.2) is not required, as information on sub-chronic oral toxicity is available which was considered as most appropriate route of exposure.

Justification for selection of repeated dose toxicity inhalation - local effects endpoint:
In accordance with REACH Annex IX, column 2, a sub-chronic inhalation repeated dose toxicity study (section 8.6.2) is not required, as information on sub-chronic oral toxicity is available which was considered as most appropriate route of exposure.

Justification for selection of repeated dose toxicity dermal - systemic effects endpoint:
In accordance with REACH Annex IX, column 2, a sub-chronic dermal repeated dose toxicity study (section 8.6.2) is not required, as available information on short term toxicity (oral and dermal), as well as the available oral repeated dose toxicity studies together with the low logPow (<0) indicate low dermal toxicity after repeated application. Additionally, the repeated dose toxicity was adequately addressed by the oral route (see section 7.5.1), allowing evaluation of systemic toxic effects after dermal exposure.

Justification for selection of repeated dose toxicity dermal - local effects endpoint:
Based on the results obtained from testing the substance was considered not irritating to skin (see. section 7.3.1).

Justification for classification or non-classification

The test item did not induce adverse effects indicative of serious damage at dose levels relevant for classification and labelling when tested for oral repeated dose toxicity. Thus, D- Panthenol is not subjeced to classification and labelling for repeated dose toxicity according to Directive 67/548/EEC and Regulation (EC) No 1272/2008.