2-methyl-p-phenylenediamine sulfate

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1981

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well-documented study report which meets basic scientific principles.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1981

Materials and methods

Objective of study:

absorption

excretion

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

The absorption and excretion of two formulations containing p-toluenediamine was evaluated in adult healthy humans by dermal route of application.

Test material

Test material information

Constituent 1

Reference substance name:

2-methyl-p-phenylenediamine

EC Number:

202-442-1

EC Name:

2-methyl-p-phenylenediamine

Cas Number:

95-70-5

Molecular formula:

C7H10N2

IUPAC Name:

2-methylbenzene-1,4-diamine

Constituent 2

Reference substance name:

p-toluenediamine

IUPAC Name:

p-toluenediamine

Details on test material:

- Name of test material (as cited in study report): p-toluenediamine
- Specific activity: 7.63 µCi/mg
- Locations of the label: The radiolabelling was located in the methyl group.

Radiolabelling:

yes

Test animals

Species:

human

Sex:

male

Administration / exposure

Route of administration:

dermal

Vehicle:

other: Water (formulation I) and hydrogen peroxide (6%) (formulation II)

Details on exposure:

TEST SITE
- Area of exposure: The subjects were exposed on the hair bearing scalp (250 cm2).
- % coverage: 250 cm2

REMOVAL OF TEST SUBSTANCE
- Washing: The test substance was removed with shampoo washings after 30 min of application. - Time after start of exposure: 30 min

TEST MATERIAL
- Amount(s) applied: 45 g of formulation containing 371 mg of test substance

Duration and frequency of treatment / exposure:

Once for 30 min

Doses / concentrations

Remarks:

Doses / Concentrations:
45 g formulation (containing 0.371 g test substance) was applied

Details on study design:

- Age of human Subjects: Between 20 and 45 years
- Weight of human subjects: 73.2 ± 4.35 kg
- Number of human subjects: 5 subjects per formulation group
- Dose selection rationale: Studies in rats and preliminary studies in human were conducted and dose was selected accordingly.

PREPARATION OF FORMULATION: Formulations contained creamy substance containing resorcinol (88.35 g), cold solution of 2-methyl-p-phenylenediamine sulphate (1.6384 g) and radiolabelled test substance (0.0116 g). The above mixture was added in water (10 g, KOH, pH-9.4) to get 100 g mixture.
To prepare formulation I, 100 g of water was added to 100 g of above mixture.
In case of preparation of formulation II, 100 g of hydrogen peroxide (6%) was added to 100 g of above mixture.
- Each of the two formulations was prepared immediately and each subject received of 45 g formulation (contained 371 mg of test substance and 19.98 µCi total radioactivity).
Further details are provided in the study report.

Details on dosing and sampling:

PHARMACOKINETIC STUDY (Absorption and , excretion)
- Tissues and body fluids sampled: urine, feces, blood
- Time and frequency of sampling: The samples were collected as follows:
- Urine was collected at the following intervals after treatment:
0-12 h, 12-24 h, and 24-48 h.
- Feces were collected at the following intervals after treatment:
0-24 h, 24-48 h, 48-72 h and 0-72 h.
- Blood samples were collected from antecubital vein at the following intervals before and after treatment as follows: 7 d (before treatment as baseline value) and 0.5, 1, 2, 4 and 6 h after treatment (in morning).

Statistics:

T-test

Results and discussion

Main ADME results

Main ADME results 1

Type:

absorption

Results:

71 ± 9.26 μgeq/cm2 (formulation I, non-oxidative conditions)

Main ADME results 2

Type:

absorption

Results:

20 ± 2.02 μgeq/cm2 (formulation II, oxidative conditions)

Main ADME results 3

Type:

excretion

Results:

Total recoverable radioactivity in elimination via urine and feces for Formulation 1 was 4.81% (mean value).

Main ADME results 4

Type:

excretion

Results:

Total recoverable radioactivity in elimination via urine and feces for Formulation 2 was a mean of 1.31% (mean value).

Toxicokinetic / pharmacokinetic studies

Details on absorption:

WHOLE BLOOD RADIOACTIVITY LEVELS: Only in one subject, following application of formulation 2, were no discernible levels of radioactivity encountered in whole blood. Clearly whole blood levels of radioactivity were far greater following application of formulation 1. Following formulation 1 the mean AUC (0-infinity) was 41.61 ng equivalent.ml^-1.h (s.e.m.: 1.738) compared with a mean AUC value of 9.18 ng equaivalent.ml^-1.h (s.e.m: 3.105) after formulation 2. Since the AUC was a measure of the extent of absorption, these data supported the greater absorption of the test substance from formulation 2.
Not too much reliance could be placed upon the values of T1/2 obtained in the study since there were too few sampling times. Nevertheless following formulation 1 blood radioactivity levels declined with half-lives ranging from 1.20 h to 2.70 h.
Absorption of test substance from applied formulation 1 (i.e., mixed with an equal quantity of water) was at least of the order of 5.0 % applied dose compared with an absorption in the region of 1.4 % test substance from formulation 2 (i.e., with equal quantity of 6% hydrogen peroxide). The absorption rates of toluene-2,5-diamine sulfate were 71 ± 9.26 μgeq/cm2 (formulation I, non-oxidative conditions) and 20 ± 2.02 μgeq/cm2 (formulation II, oxidative conditions). In terms of absolute quantities, and by reference to the dose of each formulation containing 371 mg test substance, indicate absorption of around 18 mg with formulation 1 and 5 mg with formulation 2.
Details are provided in the study report.

Details on excretion:

ELIMINATION OF RADIOACTIVITY IN URINE
- Urinary elimination: During the first 24 h following application, the urinary elimination of radioactivity of formulation 1 (mean: 2.12% ± 0.466%) was significantly greater than that of formulation 2 (mean: 0.684% ± 0.096% (t=-3.019; p<0.02). With both formulations, however, maximum elimination of radioactivity in the urine was greatest during the period of 0-12 hours post-application.
- Cumulative urinary elimination: Following application of formulation 1 the total elimination of radioactivity in 48 h ranged from 0.98% to 3.56%, contrasting with the range of urinary elimination of 0.60% to 1.20% during the 48 h period following application of formulation 2.
- Urinary excretion per kg bw: There was little variability between subjects for urinary excretion per kg body weight within each formulation group. After formulation 1 mean urinary excretion/kg body weight was 0.029 % (s.e.m.: 0.004 %) compared with a corresponding mean value of 0.010 % (s.e.m.: 0.001 %) following application of formulation 2.

ELIMINATION OF RADIOACTIVITY IN FEACES
- Statistical analysis for differences in mean fecal elimination during the 72 h post-application period between the two formulations was undertaken employing the t-test for Independent Means. The value for tind derived was 3.245 which was a significant result (p<0.02).
- Moreover, elimination of radioactivity in feces during the first 24 hours and the second 24 hour period (24-48 h) after application was significantly greater after application of formulation 1.Thus, following application of formulation 1 the mean fecal elimination of radioactivity was 2.5% (s.e.m.: 0.574) whereas of Formulation 2 the mean fecal elimination (0-72 h) was 0.57 % (s.e.m.: 0.159).

TOTAL RECOVERABLE RADIOACTIVITY IN URINE AND FAECES
- Following elimination of formulation 1 total recoverable radioactivity in urine and feces ranged from 2.84% to 6.06% (mean: 4.81 %; s.e.m.: 0.624%).Following formulation 2 total recoverable radioactivity in urine and feces ranged from 0.97% to 1.79% (mean: 1.31%; s.e.m.: 0.136%).Analysis of the mean data by the t-test for independent means yielded a significant result (t ind=5.106; p<0.001). Clearly elimination of radioactivity by the combined processes of urinary excretion and fecal elimination was significantly greater following application of formulation 1.
Details are provided in the study report.

Toxicokinetic parameters

Toxicokinetic parameters 1

Toxicokinetic parameters:

AUC: Mean AUC (0-infinity) for formulation 1 was 41.61 ng equiv.h/mL, with a S.D. of 1.738

Toxicokinetic parameters 2

Toxicokinetic parameters:

AUC: Mean AUC (0-infinity) for formulation 2 was 9.18 ng equiv.h/mL, with a S.D. of 3.105

Toxicokinetic parameters 3

Toxicokinetic parameters:

half-life 1st: Half-life 1st: Mean T1/2 for formulation 1 was 1.80 h, with a S.D. of 0.270

Metabolite characterisation studies

Metabolites identified:

not measured

Any other information on results incl. tables

Recovery of Applied Radioactivity Dose in Shampoo Washings, Rinsing, etc.:

Following application of formulation 1, the mean recovery in washings etc., was 86.34 % (s.e.m.: 1.58 %) compared with a mean recovery of only 46.48 % (s.e.m.: 3.49 %) following application of formulation 2. This represented a significant difference (t = 10.416: p<0.001).

Since the data presented thus far indicated that absorption of radioactivity following application of formulation 1 was greater than that following application of formulation 2, the reduced recovery of radioactive in washings etc., following formulation 2 indicated that there was greater retention of radioactivity at the site of application following administration of formulation 2.

Table 1: Distribution of radioactivity after scalp application of two formulations. Results expressed as percentage recovery of applied dose (study # 79249)

Location	Percent recovery of applied radioactive doses (%)
	Formulation 1	Formulation 2	Tind	P
Urine elimination (0-48 h)	2.31±0.501	0.784±0.107	-2.979	<0.05
Faecal Elimination(0-72 h)	2.50 ±0.574	0.57±0.159	-3.245	<0.02
Shampoo washings+Rinses and disposable	86.34± 1.58	46.48 ±3.49	10.416	<0.001
Total	91.20± 1.73	47.64±3.43	11.327	<0.001

Table2: Blood concentration of p-toluenediamine (ng equivalent per mL) (mean ± SD) after topical treatment with formulation (study # 79249)

Groups	Time intervals
	Basal	0.5	1	2	4	6
Formulation I	ND	47.6 ± 20.38	25.8 ± 9.01	15.8 ± 3.56	7.6 ± 3.85	3.0 ± 2.83
Formulation II	ND	4.40 ± 6.39	9.4 ± 5.68	4.6 ± 3.21	4.2 ± 2.49	3.4 ± 3.44

ND = not determined 

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): other: absorption and excretion of p-(Me-14C) p-toluenediamine in formulation I was higher than formulation II
The absorption and excretion of p-(Me-14C) p-toluenediamine in formulation I was higher than formulation II, when applied topically to human subjects for 30 min.

Executive summary:

The purpose of this study was to determine the absorption and excretion of p-toluenediamine, after topical application of two formulations containing (Me-14C) p-toluenediamine.

The healthy adult human (male) were selected and grouped randomly into 2 groups containing 5/ group. The formulation I & II contained 50% of deionized water and hydrogen peroxide (6%), respectively. The 45 g of formulations containing 371 mg test substance were applied to hair bearing scalp for 30 min.

The blood samples (7 d) before treatment (as baseline value) and 0.5, 1, 2, 4 and 6 h after treatment and fecal samples (0-24 h, 24-48 h, 48-72 h and 0-72 h) and urine samples (0-12 h, 12-24 h, and 24-48) were collected.. The analysis of blood, urine and feces was performed by Packard B-306 Oxidizer and the Micro-Processor Controlled LKB Rack Beta B-counter with automatic quench correction and quench curve generation using External Standardization Ratio Techniques. The radioactivity in unit weight equivalents per mL/unit weight for each sample was calculated by computer programs.

The mean AUC (0 to infinity) for formulation I & II was 41.61± 1.738 and 9.18 ± 3.105 (ng ± s.e.m). The half live values for formulation I was from 1.20 h to 2.70 h.

For formulation I, the absorption was 5% of the applied dose while for formulation II the absorption was 1.4% of the applied dose. The absorption rates of toluene-2,5-diamine sulfate were 71 ± 9.26 μgeq/cm2 (formulation I, non-oxidative conditions) and 20 ± 2.02 μgeq/cm2 (formulation II, oxidative conditions).

In terms of absolute quantities, and by reference to the dose of each formulation containing 371 mg test substance, indicate absorption of around 18 mg with formulation I and 5 mg with formulation II.

The total urine excretion (48 h) was 0.98 to 3.56% and 0.6 to 1.2% for formulation I & II, respectively. 

The mean fecal excretion (72 h) of radioactivity was 2.5 ± 0.574 and 0.57 ± 0.159% for formulation I & II, respectively. 

The mean recovery of radioactivity in washing for formulation I & II was 86.34 ± 1.58% (± s.e.m.) and 46.48 ± 3.49% (± s.e.m.), which indicated that the more amount of radioactive substance from formulation II was retained at site of application. The mean total recoverable radioactivity in urine and feces for formulation I & II was 4.81 ± 0.624% and 1.31 ± 0.159%, respectively. The mean values for formulation I was significantly higher than (p<0.001) values of formulation II.

Total elimination via urine and feces for Formulation I was 4.81% (mean value) while Total elimination via urine and feces for Formulation II was 1.31% (mean value).

The absorption and excretion of p-(Me-14C) p-toluenediamine in formulation I was observed to be higher than formulation II.