6-nonyl-1,3,5-triazine-2,4-diamine

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Data are included to support toxicokinetik assessment

Data source

Reference

Reference Type:

publication

Title:

Metabolism of Hexamethylmelamine-Ring-14C in Rats and Man

Author:

Worzalla JF et al.

Year:

1974

Bibliographic source:

CANCER RESEARCH 34, 2669-2674, October 1974

Materials and methods

Objective of study:

excretion

metabolism

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

The metabolism of hexamethylmelamine (HMM), an antineoplastic drug, was studied in man and rats.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Altretamine

EC Number:

211-428-4

EC Name:

Altretamine

Cas Number:

645-05-6

IUPAC Name:

N,N,N',N',N'',N''-hexamethyl-1,3,5-triazine-2,4,6-triamine

Constituent 2

Reference substance name:

2-N,2-N,4-N,4-N,6-N,6-N-hexamethyl-1,3,5-triazine-2,4,6-triamine

IUPAC Name:

2-N,2-N,4-N,4-N,6-N,6-N-hexamethyl-1,3,5-triazine-2,4,6-triamine

Constituent 3

Reference substance name:

Hexamethylmelamine

IUPAC Name:

Hexamethylmelamine

Details on test material:

- Name of test material (as cited in study report): hexamethylmelamine (HMM)
- Radiochemical purity (if radiolabelling): >98.5% (determined by TLC)
- Specific activity (if radiolabelling): 26.0 µCi/mg
- Locations of the label (if radiolabelling): HMM-ring-14C

Radiolabelling:

yes

Remarks:

14C

Test animals

Species:

other: human / rat (Sprague-Dawley)

Sex:

male

Details on test animals or test system and environmental conditions:

PATIENTS
Patients selected for study were those accepted for Phase II or Phase III clinical cancer chemotherapy trials with HMM utilizing study protocols approved by the University of Wisconsin Center for Health Sciences Committee for Review of Clinical Research and Investigation Involving Human Subjects. Patient A. G. was a 62-year-old male with squamous cell tumor of the tonsil; Patient A. H. was a 51-year-old male with squamous cell lung carcinoma.

TEST ANIMALS
- Source: Sprague-Dawley, Inc., Madison, Wis.
- Weight at study initiation: 180 to 220 g
- Housing: in glass metabolism cages
- Individual metabolism cages: no data

Administration / exposure

Route of administration:

other: human: oral, added to orange juice / rat: i.p.

Vehicle:

other: HCl

Duration and frequency of treatment / exposure:

single dose

Doses / concentrations

Remarks:

Doses / Concentrations:
human: 4 mg/kg HMM (clinical dose) (A. G., 200 mg; A. H., 350 mg) together with HMM-ring-14C, 100 µCi, at 7 a.m. on the day of the experiment, followed by another dose of unlabeled HMM, 4 mg/kg, at 7 p.m.
rat: 5 mg of HMM dissolved in a minimum of HCl containing 19.1 mCi of HMM-ring-14C

No. of animals per sex per dose / concentration:

2 male patients
4 male rats

Control animals:

no

Details on dosing and sampling:

PHARMACOKINETIC STUDY (Metabolism)
HUMAN:
- Tissues and body fluids sampled: expired breath, urine, and feces, whole blood, hemolyzed erythrocytes, plasma proteins
- Time and frequency of sampling:
Plasma: 11 samples up to 24 hours, 1 sample after 48 hours p.a. (recognizably only from a diagram)
CO2, urine, feces: 24 hr, 48 hr, 72 hr p.a.

RAT:
- Tissues and body fluids sampled: CO2 , urine, feces
- Time and frequency of sampling: 24, 48, 72 h p.a.

METABOLITE CHARACTERISATION STUDIES
- Tissues and body fluids sampled: urine
- Method type(s) for identification: gas chromatography and mass spectrometry, thin-layer chromatography, liquid scintillation counting

Results and discussion

Main ADME results

Main ADME results 1

Type:

metabolism

Results:

The s-triazine ring is very stable and does not undergo cleavage. The rat urinary metabolites were the same as those observed in humans.

Main ADME results 2

Type:

excretion

Results:

mainly in urine (human: 86 and 91%, respectively; rat: average 79%)

Toxicokinetic / pharmacokinetic studies

Details on distribution in tissues:

Plasma levels of radioactivity reached a maximum of 4380 and 3270 dpm/mL of plasma 1 hr after administration to Patients A. G. and A. H., respectively. The half-life of radioactivity in these patients was 13 hr. Hemolyzed erythrocytes that had been washed 3 times contained 6 to 9% of the radioactivity in 1 mL of whole blood. Proteins that were precipitated from plasma with sulfosalicylic acid and washed 3 times contained only 1 to 2% of the activity in 1 mL of plasma.

A tissue distribution study of radioactivity after administration of HMM-ring-14C in rats revealed no unusually high localization of radioactivity in any tissues.

Details on excretion:

Recovery of radioactivity in urine after administration of HMM-ring-14C to 2 cancer patients was as follows: in 24 hr each patient excreted 61 % of the total dose of radioactivity; A. G. excreted 25% and A. H. excreted 21 % from 24 to 48 hr; A. G. excreted 5% and A. H. excreted 4% from 48 to 72 hr. Total urinary excretion of radioactivity was 91 % for A. G. and 86% for A. H. (a portion of the urine sample from 0 to 24 hr was accidentally lost by A. H.). The amounts of radioactivity in the feces of Patients A. G. and A. H. within 48 hr after administration were 0.2 and 0.1%, respectively. No radioactivity could be found as expired 14CO2 in the breath of the patients during the 1st 6 hr after the administration of HMM-ring-14C.
The excretion of radioactivity in rats was similar to that of humans, except that rats appeared to excrete the radioactivity more rapidly; also the amount of radioactivity observed in the feces of rats (20%) was higher than that found in human feces (0.1%).

Toxicokinetic parameters

Toxicokinetic parameters 1

Toxicokinetic parameters:

half-life 1st: 13 hrs in plasma (human)

Toxicokinetic parameters 2

Toxicokinetic parameters:

C(time): 1 hr in plasma (human)

Metabolite characterisation studies

Metabolites identified:

yes

Details on metabolites:

The human urinary metabolites observed were pentamethylmelamine; N2, N2, N4, N6-tetramethylmelamine; N2, N2, N4-trimethylmelamine; N2, N2, N6-trimethylmelamine; N2, N2-dimethylmelamine; N2, N4-dimethylmelamine; monomethylmelamine; and melamine. The identities of the metabolites were confirmed by mass spectrometry. The rat urinary metabolites were the same as those observed in humans.

Any other information on results incl. tables

The concentrated urine samples were also used for TLC. Assay of thin-layer chromatograms of urines on a radio-chromatogram scanner revealed the presence of 4 major radioactive metabolites in humans; the RF values of the radioactive metabolites were identical to samples of the authentic compounds indicated . Quantification of metabolites with a Disc integrator tracing of the radioactivity on the TLC plates gave the proportional amounts of the major radioactive metabolites in 24-hr urines. Multiplication of these proportions by the total percentage of radioactivity in the 24 hr urines gave estimates of the percentages of the various metabolites. The activity in the miscellaneous category includes a mixture of the other methylmelamines identified by gas chromatography and also of any possible unidentified metabolites. The percentage values of the metabolites correspond to the molar percentages of the metabolites since the specific activity per mole of melamine is identical to the specific activity of HMM-ring-14C.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): low bioaccumulation potential based on study results
The experiments indicate that the s-triazine ring is very stable and that it does not undergo cleavage. This is suggested by the fact that there is no production of 14CO2 after administration of HMM-ring-14C to either man or rats. The identification of the major urinary metabolites as methylmelamines and melamine also confirms the stability of the s-triazine ring in mammalian systems.
Excretion is mainly via the urine. The rat urinary metabolites were the same as those observed in humans.

Executive summary:

The metabolism of hexamethylmelamine (HMM), an antineoplastic drug, was studied in man and rats. After administration of HMM-ring-14C to 2 patients, peak plasma levels of radioactivity were seen 1 hr after drug administration and the plasma half-life of radioactivity was 13 hr. Patients excreted 61% of the radioactivity in the urine within 24 hr and 89% within 72 hr. No expired 14CO2 was found in the breath of patients within 6 hr of administration, and less than 0.2% of radioactivity was found in the feces in 48 hr.

Rats that were given HMM-ring-14C i.p. excreted 74% radioactivity in urine, 19% in feces, and none as 14CO2 within 24 hr.

Urinary metabolites were isolated by ion exchange methods, identified by gas chromatography-mass spectrometry, and quantitated using thin-layer chromatography with a radiochromatogram scanner. The urinary metabolites of HMM in both rats and man were N-demethylated homologs of HMM. These experiments suggest that in man and rats there is no significant metabolomic cleavage of the s-triazine ring and that methyl-melamines appear to be the only major urinary metabolites of HMM.