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Diss Factsheets

Administrative data

basic toxicokinetics in vivo
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference Type:
Pharmacokinetics and material balance studies of diethylenetriamine trihydrochloride in the Fischer 344 rat following oral, endotracheal or intravenous dosing
Leung HW, Tyler TR
Bibliographic source:
J Appl Toxicol., 17: 361-7

Materials and methods

Objective of study:
Principles of method if other than guideline:
The metabolism and disposition of diethylenetriamine trihydrochloride (DETA·3HCI) were studied with regard to route of administration and dosage effects. Male Fischer 344 rats were administered 50 or 500 mg kg-1 of [1,2-14C]-DETA·3HCI orally or endotracheally, and the fate of the 14C-radioactivity was followed for 48 h.
GLP compliance:
not specified

Test material

Constituent 1
Reference substance name:
EC Number:
EC Name:
Cas Number:
Details on test material:
High-purity DETA (CAS no. 111-40-0) was obtained from the Union Carbide Corporation, South Charleston, WV. [ 1 ,2- 14C]-Diethylenetriamine trihydrochloride (14C-DETA·3HCl) with a specifie activity of 6 mCi/mmol and a radiochemical purity of >98% was custom synthesized by Midwest Research Institute (Kansas City, MO).

Test animals

Fischer 344
Details on test animals or test system and environmental conditions:
- Source: Charles River Breeding Laboratories, Portage, Michigan
- Age: 36 days of age upon receipt
- Weight at study initiation: no data
- Fasting period before study: no data
- Housing: wire-bottom and -front stainless steel cages, three animals per cage, for 9 to 14 days prior to the start of each study
- Individual metabolism cages: yes
- Diet (ad libitum): ground feed (NIII-07 diet, Zeigler Brothers, Gardner, PA)
- Water (ad libitum): tap water
- Acclimation period: 9 to 14 days

- Temperature (°C): no data
- Humidity (%): no data
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
other: oral gavage, endotracheal and intravenous
physiological saline
Details on exposure:
Dosing solutions were prepared by mixing appropriate amounts of unlabeled DETA with [14C]-DETA-3HCI in physiological saline to provide target dosages of 50 and 500 mg kg-1 at a constant dosing volume of 0.25 ml per animal. The dosing solutions were adjusted to pH 7.4 using hydrochloric acid or ammonium hydroxide, as required.

Animals in the pharmacokinetics study groups had an indwelling cannula implanted in the right jugular vein 1 day prior to dosing. Intravenous dosing was accomplished by injecting via the tail vein. Oral dosing was performed with a stainless-steel feeding needle, and endotracheal instillation was achieved by injecting through a small polyethylene tube into the trachea of rats under light anesthesia with Metofane.
Duration and frequency of treatment / exposure:
Single administration
Doses / concentrations
Doses / Concentrations:
50 and 500 mg per kg body weight.
No. of animals per sex per dose / concentration:
4 (intravenous and endotracheal), 5 (oral)
Control animals:
Positive control reference chemical:
not applicable
Details on dosing and sampling:
Sample collection:
For the material balance study, the animals were placed in all-glass Roth metabolism cages immediately after dosing. Expired 14C02 was trapped using a solution of 2-methoxyethanol-ethanolamine (7:3, v/v) and sampled for radioactivity 6, 24 and 48 h after dosing. Urine and feces were collected 24 and 48 h after dose administration. Cages were washed with a 50% aqueous acetone solution and samples of the wash solution were taken for radiometrie analysis. Blood was obtained from the abdominal aorta 48 h after dosing. Animals were killed by exsanguination after collection of the last blood and excreta samples. Selected tissues were removed, sampled and analyzed for radioactivity. The remaining carcasses were solubilized in 10 N NaOH and samples of this solution were also analyzed for radioactivity. For the pharmacokinetics study, rats were placed in stainless-steel wire metabolism cages. Blood samples (about 0.2 ml) were taken via the jugular cannulae at 5, 15, 30 and 45 min and at 1, 2, 3, 4, 5, 6, 8, 10, 12, 16 and 24 h after dosing.

Radiochemical analyses:
The amount of radioactivity in various samples was measured by liquid scintillation spectrometry. Blood was centrifuged in heparinized capillary tubes to separate into plasma and packed red cells. Portions of other liquid samples, such as plasma, urine and cage washes, were weighed directly into scintillation vials containing 10 ml of Aquasol® (New England Nuclear, Boston, MA). Samples of the C02 trapping solution and solubilized carcass were weighed directly into scintillation vials and counted in a solution of equal volumes of 2-methoxyethanol, dioxane and xylene containing 160:120:1 (w/w/w) of naphthalene, 2,5-diphenyloxazole and 2,2-p-phenylenebis-(5-phenyloxazole). Feces and tissues were solubilized in Soluene 350® (Packard Instrument Co., Downers Grove, IL), oxidized with 30% H202 and counted with 10 ml of Dimilume 30® (Packard Instrument Co., Downers Grove, IL).
Unchanged DET A in the plasma was isolated from other radiolabeled compounds by a modified paper chromatography method. Samples (about 10 µl) were developed ascendingly on Whatman no. 4 paper strips (2 or 4 cm in width by 20 cm in length) in a solvent system of n-butanol, acetic acid and water ( 4: 1: 1, v/v/v) for 2 h. The developed strips were cut into 1-cm segments and the radioactivity in each section was determined by liquid scintillation counting.
Radiolabeled compounds in urine were separated by cation exchange chromatography. The column was packed with 400 mesh or less AG-50-X8 resin in ammonium form (BioRad Labs., Richmond, V A). Ammonium chloride solution was used as the eluting agent. The eluting concentration gradients consisted of solutions of 0.01-0.10 N and 0.10-1.0 N ammonium chloride, (pH 9.0). The column was cleared with 2 N ammonium chloride solution to complete the chromatograms. Fractions of the column eluent were collected and analyzed for radioactivity. Anion exchange chromatography
was carried out in a similar manner except that AG-1-X4 resin in acetate form was used to achieve separations. The eluti on gradients consisted of 0.01-0.10 N and 0.1-1.0 N ammonium acetate (pH 7.0). A solution of 2 N ammonium acetate was used to clear the column.

Pharmacokinetic description:
Curve fitting of the pharmacokinetic data was performed by hand feathering or with the aid of ESTRIP. Parameters estimated included area under the concentration-time curve to infinite time (AUC∞), total clearance and terminal half-lives. The maximal plasma concentration ( Cmax) and time to maximal plasma concentration (tCmax) following oral or endotracheal dosing were estimated from the concentration-time course equation by the Newton-Raphson method of numerical analysis.

Results and discussion

Toxicokinetic / pharmacokinetic studies

Details on absorption:
Table 1 shows the calculated pharmacokinetic parameters for all three routes of administration. The bioavailability was over 90%, suggesting that [14C]-DETA·3HCl was well absorbed following oral or endotracheal dosing. Clearance of absorbed [14C]DETA 3HCl from the plasma was also rapid, with a terminal half-life of 9-16 h.
Details on distribution in tissues:
Table 3 shows the tissue concentrations of radioactivity at 48 h following oral or endotracheal dosing. The DETA was distributed throughout the
body, with the highest concentrations found in the kidney and Iiver. The mean concentration for all tissues in the 500 mg/kg group was about 7.5 times that in the 50 mg/kg group. This was slightly Iower than the 10-fold difference in dosages. Similar to the excretion data, there was no indication that route of administration had any significant effect on tissue concentrations.
Details on excretion:
Table 2 shows the material balance of radioactivity at 48 h following oral or endotracheal dosing with [14C]-DETA·3HCI. Fecal excretion was the major route of excretion, followed closely by elimination in the urine. Only a small percentage of the dose was recovered as expired CO2 or was retained in the tissues and carcasses. No significant differences in the percentages of radioactivity excreted in the urine, feces or CO2 were observed between animals dosed orally or endotracheally.

Metabolite characterisation studies

Metabolites identified:
Details on metabolites:
Table 4 shows the percentage of urinary radioactivity recovered in fractions obtained by cation exchange chromatography. The radioactivity in the urine was eluted in three major (CV 1, CV 22 and CV 36) and one minor (CV 8) fractions. These fractions were designated with a subscript corresponding to the number of column volumes of eluting solution in which the fraction appeared. While the various fractions had not been chemically identified, the cation exchange column was able to resolve unchanged DETA and Ethylenediamine (EDA), the former eluting at CV 36 and the latter at CV 29. The neutral fraction appearing immediately following the void volume (CV 1) had little or no cation exchange properties, and probably consisted of a deaminated metabolite of DETA. Anion exchange chromatography of this neutral fraction revealed that none of the radioactivity was
retained on the resin, indicating that these metabolites did not possess acidic properties characteristic of glucuronic acid or mercapturic acid conjugates. No radioactivity was detected in CV 29 fraction, suggesting that EDA was not present in the urine of [14C]DETA ·3HCl-treated animals. The absence of EDA as a metabolite of [14C]-DETA·3HCl was also confirmed by paper chromatography of the plasma.
There were no significant differences in the metabolite profile between the rats dosed orally or endotracheally. However, there appeared to be a shift to a higher percentage of unchanged DETA (CV 36) in going from a dosage of 50 to 500 mg/kg.

Any other information on results incl. tables

The route of administration, oral or endotracheal, had little effect on the distribution within the body or the elimination of radioactivity from the rat. Feces and urine were the primary routes of excretion with less than 2% of the admininstered dose being expired as 14CO2. More than 96% of the recovered dose was eliminated within 48 hours after dosing. In comparing results from animals receiving the compound at 500 mg/kg with those receiving it at 50 mg/kg there was a significant increase in the percentage of radioactivity excreted in the urine and a significant decrease in that eliminated as14CO2at the higher dose level. The route of administration did not affect the following pharmacokinetic parameters at the 50 mg/kg level.

Applicant's summary and conclusion

Interpretation of results (migrated information): no bioaccumulation potential based on study results
When DETA was administered to rats either orally or endotracheally, it was readily absorbed into the general circulatory system. The primary routes of elimination of radioactivity from the compound were feces and urine with smaller amounts leaving by way of 14CO2. Forty-eight hours after dosing more than 96% of the recovered radioactivity had been eliminated from the animals.

The concentration of radioactivity in tissues of rats receiving DETA at the 500 mg per kg level were 4 to 10 times higher than in rats receiving the compound at 50 mg per kg. There were no significant differences in the concentrations in tissues of rats receiving the compound by different routes of administration. The higher level of dose administration did produce a shift in the pattern of radioactivity in urinary chromatograms with a greater percentage associated with a fraction having characteristics similar to those of the unchanged amine.

There were no apparent biologically important differences in material balance parameters (excretion pattern, tissue distribution patterns or urinary chromatographic profiles) or in the pharmacokinetic parameters among animals receiving DETA by different routes of administration. These observations would give metabolic support for predicting risks from an inhalation exposure based upon data from a chronic feeding toxicity study.
Executive summary:

Leung and Tyler studied the metabolism and disposition of diethylenetriamine (DETA) by oral and endotracheal administration of single doses of [1,2-14C]-DETA.3HCl of ca. 50 and 500 mg/kg bw and intravenous dosing of ca. 50 mg/kg bw to male rats (Fischer 344; n=4-5/group) and following the fate of radiolabelled material for 48 hours. DETA was readily absorbed from the gastrointestinal and respiratory tracts. The time course of radioactivity concentrations in the plasma, determined from intravenous dosing, was best described by a tri-exponential equation. Peak plasma concentrations occurred within one hour following oral and endotracheal administration and the bioavailability was 95 and 90%, respectively. Radioactivity was cleared from the plasma with terminal half-lives of ca. 9, 10, and 16 hours following endotracheal, intravenous, and oral administration, respectively. The apparent volume of distribution (Vd), determined from plasma concentrations following intravenous dosing, indicated distribution in the total body water (Vd: 0.48 L/kg vs. total body water volume of 0.58 L/kg). Radioactivity was distributed throughout the body with generally similar distribution patterns. The kidney and the liver contained the highest concentrations, about 2.5-5 and 3 times that of blood, respectively. A less than proportional increase in tissue concentrations (7.5-fold) between the 2 doses (10- fold) was observed. Faeces and urine accounted for about 72-77 and 87% of the total low and high dose excreted, respectively, with slightly higher amounts in the faeces, while only little radioactivity was exhaled as CO2 (ca. 1.1-1.3 and 0.5- 0.6% of the total low and high dose excreted, respectively). About 2-3% was recovered from the carcass. Cation-exchange chromatography of the urine resulted in 4 radiolabel-containing fractions. The major fraction, accounting for ca. 45 and 70% of the total urinary radioactivity at the low and high dose, respectively, consisted of parent compound indicating only a limited extent of metabolism. The other fractions contained about 17-20, 15-18, and 2% of the radioactivity at the low dose and about 14, 5, and 1% at the high dose. These fractions were not analysed but they did consist of ethylenediamine or acid conjugates. The increase in the proportion of unchanged compound in the urine and the less than proportional increase in tissue concentrations from a dose of 50 to a dose of 500 mg/kg bw indicated saturation of the metabolism of DETA at the dose of 500 mg/kg bw. The study did not reveal significant differences with respect to the route of administration (oral vs. endotracheal)