1-Hexyl 4,5-diamino pyrazole hemisulfate

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

The calculation of acute toxicity values for 1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATE is based on the current understanding and knowledge of the test substance. Toxicity data were obtained from publically available publications such as the opinion document from the Scientific Committee on Consumer Safety of the European Commission on 1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATE, and study reports provided by Service Germany GmbH. If more (detailed) information becomes available or if updated guidance becomes available, the statement might be subject to review

Data source

Reference

Reference Type:

other company data

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

The calculation of acute toxicity values for 1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATE is based on the current understanding and knowledge of the test substance. Toxicity data were obtained from publically available publications such as the opinion document from the Scientific Committee on Consumer Safety of the European Commission on 1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATE, and study reports provided by Service Germany GmbH. If more (detailed) information becomes available or if updated guidance becomes available, the statement might be subject to review

Test material

Test material information

Constituent 1

Reference substance name:

2-hexylpyrazole-3,4-diamine;sulfuric acid

EC Number:

696-231-5

Cas Number:

1361000-03-4

Molecular formula:

C9H18N4 x 0.5 H2SO4

IUPAC Name:

2-hexylpyrazole-3,4-diamine;sulfuric acid

Constituent 2

Reference substance name:

C6 Pyrazole hemisulfate

IUPAC Name:

C6 Pyrazole hemisulfate

Constituent 3

Reference substance name:

4,5-diamino-1-hexyl-1H-pyrazole hemisulfate

IUPAC Name:

4,5-diamino-1-hexyl-1H-pyrazole hemisulfate

Test material form:

solid: crystalline

Details on test material:

UNLABELLED TEST SUBSTANCE- Name of test material: 4,5-diamino-1-hexyl-1H-pyrazole hemisulfate (Code: A0021277)- TSIN: WR804146 - Substance type: Pure active substance- Physical state: White feathery crystals- Storage condition of test material: Ambient temperature (in dark)LABELLED TEST SUBSTANCE- Name of test material: [14C] n-Hexylpyrazole Hemisulfate ([14C]-C6P)- Substance type: Pure active substance- Specific activity: 59 mCi/mmol (2.18 GBq/mmol) (measured by mass spectroscopy)- Locations of the label: Ring-14C- Storage condition of test material: At - 20°C.

Results and discussion

Effect levels

Key result

Sex:

not specified

Dose descriptor:

LD50

Effect level:

ca. 218 mg/kg bw

Any other information on results incl. tables

Oral LD₅₀value using data from repeated dose toxicity studies and evaluation of applicability of thein vivoMTD data to meet OECD requirements for acute oral toxicity

 

The acute oral toxicity of1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATEwas not investigated.

However, no deaths were observed in the sub-chronic (13-week) oral toxicity study (Ref 2) or in the developmental toxicity study in rats (Ref 3) at dose levels up to 20 mg/kg bw/day. Likewise, in a 28-day repeated dose range finding study in rats (Ref 4), none of the doses up to 240 mg/kg bw /day caused any deaths. This 28-day dose range finding study for the 90-day study was not carried out as a GLP study and was conducted using the dihydrochloride salt.

 

Since no additionalin vivostudies are available, a conservative value for the oral acute toxicity (LD₅₀,oral) of1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATEwas set at 218 mg/kg bw. This was calculated by applying a conversion factor of 0.91 to the LD₅₀value of 240 mg/kg based on the molar mass differences between the hydrochloride and hemisulfate salt of1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE(Ref 1). This derived LD₅₀value is within the required test concentrations and possible LD₅₀estimations, namely between 50 and 300 mg/kg bw for the OECD.

 

 

Table 1: Comparison of study requirements from OECD guidelines for acute oral toxicity study(f = female, m = male).

Test type	Guideline (OECD)	Animal species	Doses (mg/kg bw)	animal number	observation period	determined LD50mg/kg bw
Acute oral toxicity	423 (Ref 5)	Rat	5, 50, 300, 2000 (Guideline recommendation)	3/dose (Total: 3 to 12)	1 to 14 days	Possible values: 5, 25, 50, 200, 300, 500, 2000, 2500, 5000
28-Day repeated dose (Ref 4)	407 (Ref 6)   Not GLP compliant	Rat	Determination of MTD (doses tested: 26, 80, 240)	(required: min. 3) 10 to 15/dose (m & f)	28 days	LD50: >240 (none of the animals died) MTD: >240

 

 

Result:

LD_{50 calc}oral 1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATE= 218 mg/kg bw

 

Conclusion: Based on the above, a conservative value for the LD₅₀of 218 mg/mg/kg bw determined from the 28-day repeated toxicity study was used for the calculations of the acute dermal and inhalation toxicity potential of1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATE. This LD₅₀, oralvalue is in line with the OECD criteria.

 

Data from anin vivoADME studies

 

The oral bioavailability of1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATEbased on the blood AUC was high (93%) compared to the AUC after i.v. administration. When calculated from the urine data from the mass balance groups, the oral bioavailability was also determined to be high and was 84% at 12 mg/kg bw (Table 2).

 

The average dermal absorption of1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATE,when calculated from the urine data from the mass balance groups, was low, and was 9% at 11 mg/kg bw (0.5 hours exposure) and 17% at 11.5 mg/kg bw (24 hours exposure).

 

After i.v. and oral administration, elimination, mainly via the urine, was fast, with 85% of the total amount being excreted within in the first 48 h. The elimination after dermal doses was relatively slow, with 62% and 50% of the absorbed radioactive dose recovered by 48 h after a 0.5 h and 24 h exposure, respectively.

 

 

 

Table 2:   Overview of the mass balance data from the ADME study with1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATEin rats

Group No.	1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATEDose Level / Concentration	Dosing route	Absorption (%)	Excretion via urine/feces (%) (relative to administered dose)
1	11.9 mg/kg bw	i.v.	100	69 / 12
2	12 mg/kg bw	oral	82	69 / 15
3	11 mg/kg bw; 0.186 mg/cm² (0.5 hours exposure)	dermal	9*	3 / 4
4	11.5 mg/kg bw; 0.208 mg/cm² (24 hours exposure)	dermal	17*	8 / 6

*: Percentage of the dose recovered from: excretion + exhaled air + cage-wash + carcass.

 

For appropriate comparability between the different application routes, the mass balance data were used in the calculations of inhalation and dermal acute toxicity according to the applicability to the endpoint to derive the most conservative extrapolation.

 

Applicant's summary and conclusion

Interpretation of results:

Category 3 based on GHS criteria

Conclusions:

The acute oral toxicity of 1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATE was determined from a 28-day repeated dose finding study conducted using the dihydrochloride salt. The determined LD50, oral value of 218 mg/kg bw is considered conservative since none of the animals died at this dose and it was 10-fold lower than that of a structurally related chemical. It was also in accordance with the required test concentrations and possible LD50 estimations (between 50 and 300 mg/kg bw) for the OECD. Based on the calculated LD50 oral. value, 1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATE should be classified as Acute Tox Cat.3; H301: “toxic if swallowed”, according to the Globally Harmonized System of Classification and Labeling (GHS).

Executive summary:

1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATE is a diaminopyrazole and is an ingredient used in oxidative hair coloring products.

Based on the available in vivo repeated dose toxicity study of the dihydrochloride salt (Ref 4), together with a toxicokinetics study of orally and topically applied hemisulfate salt (ADME) (Ref 6), the acute oral toxicity of 1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATE could be determined, as well as its acute dermal and acute inhalation toxic potential.

The pre-clinical toxicity studies were carried out with two forms of 1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE, namely the hemisulfate salt and the dihydrochloride salt. The free base component is considered responsible for the toxic potential of 1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE salts. Therefore, studies carried out with the hemisulfate and dihydrochloride salts are both relevant for the risk assessment of 1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATE upon adjustment for molecular weight and content. Correspondingly, in all studies performed with the dihydrochloride salt, the concentrations used were converted to the concentration of the hemisulfate salt by applying a conversion factor of 0.91 adjusting for the differences in molecular weight and free base content (Ref 1).

The acute oral toxicity of 1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATE was not investigated.

However, no deaths were observed at doses up to 240 mg/kg bw /day in a 28-day repeated dose range finding study in rats using the dihydrochloride salt (Ref 3). This value was adjusted using the conversion factor of 0.91 to result in an oral LD50 value of 218 mg/kg for the hemisulfate salt. Since no additional in vivo studies are available, a conservative value for the oral acute toxicity (LD50, oral) of 1-HEXYL-1H-PYRAZOLE-4,5-DIAMINE HEMISULFATE was set at 218 mg/kg bw. This derived LD50 value is within the required test concentrations and possible LD50 estimations for the OECD. The LD50, calc, oral of 218 mg/kg bw was therefore used for the route extrapolation calculations.