2-amino-2-ethylpropanediol

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics

Type of information:

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

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP - guideline study, tested with the source substance Bioban™ CS-1246 biocide.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Objective of study:

absorption

distribution

excretion

metabolism

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 417 (Toxicokinetics)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.36 (Toxicokinetics)

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OTS 798.7485 (Metabolism and Pharmacokinetics)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Bioban CS-1246

IUPAC Name:

Bioban CS-1246

Constituent 2

Reference substance name:

7a-ethyldihydro-1H,3H,5H-oxazolo[3,4-c]oxazole

EC Number:

231-810-4

EC Name:

7a-ethyldihydro-1H,3H,5H-oxazolo[3,4-c]oxazole

Cas Number:

7747-35-5

IUPAC Name:

7a-ethyldihydro-1H-[1,3]oxazolo[3,4-c][1,3]oxazole

Details on test material:

- Name of test material (as cited in study report): Bioban™ CS-1246 (7a-Ethyldihydro-1H,3H,5H-oxazolo(3,4-c)oxazole)
- Molecular formula (if other than submission substance): C7H13NO2
- Molecular weight (if other than submission substance): 143.09
- Physical state: liquid (color: pale yellow)
- Analytical purity: 98.55%
- Lot No.: non-radiolabeled: TC1031LAH3
- Radiochemical purity (if radiolabelling): >98%
- Specific activity (if radiolabelling): radiolabeled 20.92 mCi/mmol
- Locations of the label (if radiolabelling): 7a-Ethyldihydro-1,7-dihydro-[1,7-14C]-oxazolo(3,4-c)oxazole
- Other: Synonyms: 1-Aza-3,7, dioxa-5-ethylbicyclo (3.3.0) octane, 7-Ethyl bicyclooxazolidine (IUPAC name), 5-Ethyl-1-aza-3,7, dioxabicyclo[3.3.0]octane
Supplier: non-radiolabeled: The Dow Chemical Company, Bedford Park, Illinois, USA;
Supplier: radiolabeled: Scynexis Europe Limited, Essex, England (Registry # DA2459)

Radiolabelling:

yes

Remarks:

7a-Ethyldihydro-1,7-dihydro-[1,7-14C]-oxazolo(3,4-c)oxazole

Test animals

Species:

rat

Strain:

other: Crl:CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: jugular cannulated rats: Taconic (Germantown, New York, USA); non-cannulated rats: Charles River Laboratories Inc. (Portage, Michigan, USA)
- Age at study initiation: 9-10 weeks
- Fasting period before study: ~ 16 h
- Housing: animals were housed singly in glass Roth-type metabolism cages, which were designed for the separation and collection of urine, faeces, CO2, and organic volatiles. In the case of Cmax (group 3), plastic tubs were used to house the rats post-dosing (15 min prior to the sacrifice). Group 4 (6 h post dosing) rats were housed in the glass Roth-type metabolism cages for 6 h post dosing.
- Individual metabolism cages: yes
- Diet: Lab Diet Certified Rodent Diet #5002 (PMI Nutrition Internation, St. Louis, Missouri, USA) in pelleted form; ad libitum, except that access to feed was restricted approximately 16 h prior to the administration of radiolabeled test material with the exception of animals in group 6 (dermal group), which were not fasted prior to dosing; analyses of the feed are performed by PMI Nutrition International to confirm the diet provides adequate nutrition and to quantify the level of selected contaminants
- Water: municipal water; ad libitum; periodically analysed for chemical parameters and biological contaminants by the municipal water department
- Acclimation period: non-cannulated animals: at least one week in stainless steel cages (including at least two days in metabolism cages); jugular vein cannulated animals (surgery performed by the supplier): for four days in metabolism cages

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18.2 - 24.7
- Humidity (%): 38 - 78
- Air changes (per hr): 12 - 15
- Photoperiod (hrs dark / hrs light): 12/12 (on at 6:00 a.m. and off at 6:00 p.m.)

Rats in which the plasma/blood 14C time-course was determined were obtained already cannulated in the jugular vein by the supplier.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Appropriate amounts of 14C-labeled and/or non-radiolabeled BIOBAN™ CS-1246 were added to obtain the target dose of 5 or 200 mg BIOBAN™ CS-1246/kg bw. The BIOBAN™ CS-1246 test material was completely dissolved in the corn oil vehicle. Radioactivity in the dose solutions was quantified by liquid scintillation spectrometry (LSS). The dose solution was made once and used within 19 days of preparation.

VEHICLE
- Lot no.: 026K0051

HOMOGENEITY AND STABILITY OF TEST MATERIAL:
LSS analysis of aliquots of the dosing solution taken from various locations in the solution containers was used to confirm homogeneity of the dosing solution.
A previously conducted toxicity study (Stebbins and Card, 2006) had shown BIOBAN™ CS-1246 to be stable for at least 25 days in corn oil at concentrations ranging from 0.025 to 25%.

Duration and frequency of treatment / exposure:

Group1: low single dose: 5 mg/kg bw
Group 2: high single dose: 200 mg/kg bw
Group 3: low single dose: 5 mg/kg bw
Group 4: low single dose: 5 mg/kg bw
Group 5: low multiple (14 d) dose: 5 mg/kg bw (received 14 daily oral doses of non-radiolabeled BIOBAN™ CS-1246 followed by a single oral dose of 5 mg/kg bw 14C-BIOBAN™ CS-1246)

Doses / concentrations

Remarks:

Doses / Concentrations:
radiolabeled: 5 and 200 mg/kg bw
non-radiolabeled: 5 mg/kg bw

No. of animals per sex per dose / concentration:

4

Control animals:

yes

Details on study design:

- Dose selection rationale: The study was conducted on low (5 mg/kg; groups 1, 3-5) and high (200 mg/kg; group 2) dose levels of BIOBAN™ CS-1246. Low dose of 5 mg/kg was lower than the NOEL and high dose where an effect was observed (in a 90-day repeated dose toxicity study, Stebbins et al. (2007) found the NOEL to be 10 mg/kg/day and a thickend limiting ridge of the stomach in all males and females given 250 mg/kg/day).

Details on dosing and sampling:

PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled: urine, faeces, tissues (adrenal, carcass (residual), kidney, skin, testis, blood, fat (perirenal), liver, spleen, thyroid, brain, GI tract (with contents), ovary, stomach (without contents), uterus); also final cage wash
- Time and frequency of sampling:
urine: All urine voided during the study was collected in dry-ice cooled traps. The urine traps were changed at 12-, 24-, and 48-h post-dosing followed by 24-h intervals for the remainder of the study. Urine was collected 6 h post-dosing for the group 4. Equal volume aliquots of urine samples (per time, dose and sex) from the 0-12 h and 12-24 h collection intervals was pooled and stored at -80 °C.
faeces: Faeces were collected in dry-ice chilled containers at 24 h intervals. Faeces were collected 6 h post-dosing for the group 4. Equal volume aliquots of faecal homogenates from each animal were taken from the 0-24 h collection interval and pooled (per dose and sex) and stored at -80 °C. Inadvertently, group 1 samples were stored at -20°C.
tissues: Tissues were collected at sacrifice
final cage wash: following the terminal sacrifice
plasma: Blood was obtained at sacrifice via cardiac puncture and/or inferior vena cava and/or dosal aorta. The blood was centrifuged to separate the plasma and thereafter the plasma was analysed for radioactivity. Equal volume aliquots of plasma collected from groups 3 and 4 was pooled (per time, dose and sex) and stored at -80 °C.

The rats of groups 1 and 2 were fitted with indwelling jugular vein cannulae and plasma and red blood cells (RBC) 14C concentration-time course evaluated to determine peak (Cmax) and half-peak (1/2 Cmax) plasma 14C concentrations. Approximately 0.1-0.2 mL blood was collected at chosen times (0.25, 0.5, 1, 2, 4, 6, 12, 24 h post-dosing and every 24 h thereafter) and plasma and RBC separated by centrifugation. The RBC were oxidised and the plasma and RBC analysed for radioactivity by LSS.

METABOLITE CHARACTERISATION STUDIES
Pooled samples (groups 1, 2, 5; urine and faeces) from selected intervals were analysed in duplicate via HPLC with in-line radiochemical detection or singly if fraction collcetion was required.

Statistics:

Descriptive statistics were used, i.e. mean ± standard deviation. All calculations in the database were conducted using Microsoft Excel spreadsheets and databases in full precision mode (15 digits of accuracy). Certain pharmacokinetics parameters were estimated for both blood (plasma and RBC) and urine data, including AUC (area under the curve), Cmax and elimination rate constants, using a pharmacokinetic computer modeling program. Pharmacokinetic analysis of the time-course plasma and RBC data of groups 1 and 2 was performed using a two-compartmental model that better described the data. For pharmacokinetic analysis, WinNonLin v. 5.0.1 (Pharsight Corp., Mountain View, California, USA) computer modeling software was used.

Results and discussion

Main ADME results

Main ADME results 1

Type:

absorption

Results:

Rapid absorption without any apparent lag time (85-99%)

Main ADME results 2

Type:

distribution

Results:

Only ~1% of the administered dose remained in the tissues after 144 h (high single dose) or after 168 h (low single or multiple dose) post-dosing

Main ADME results 3

Type:

metabolism

Results:

The absorbed test material was completely metabolised, affording 2-amino-2-ethyl-1,3-propanediol as the only metabolite above 5% of the administered dose in all urine and faecal samples analysed from all dose groups.

Main ADME results 4

Type:

excretion

Results:

Rapid excretion in urine (83-97%) within 24 h without any gender difference

Toxicokinetic / pharmacokinetic studies

Details on absorption:

Absorption was estimated from the percent of administered radioactivity recovered in urine and rinse, final cage wash, CO2 and tissues at sacrifice.
Group 1: 92% (males) and 86% (females) of the administered dose was systemically absorbed
Group 2: 85% (males) and 90% (females) of the administered dose was systemically absorbed
Group 5: 96% (males) and 99% (females) of the administered dose was systemically absorbed

(Only for groups 1, 2 and 5, the study was continued until ≥ 95% of the administed dose was recovered in the excreta.)

Details on distribution in tissues:

Group 1:
On average, a total of 1% of the administered dose remained in tissues 168 h after dosing, most of which was found in the residual carcass and skin.
For males, the highest concentrations ranked from skin > carcass > kidney > testes > liver.
For females, the highest concentrations ranked from skin > carcass > kidney = stomach tissue

Group 2:
On average, a total of 1% of the administered dose remained in tissues 144 h after dosing, most of which was found in the residual carcass and skin.
For males, the highest concentrations ranked from kidney ≥ carcass > testes > skin > brain.
For females, the highest concentrations ranked from kidney > carcass > skin > brain.

Group 3:
On average, 91-94% of the administered dose remained inside the animals body at t(max) (0.25 h post-dosing). Most remained unabsorbed and recovered from the GI tract (69% of the administered dose). Besides residual cracass, most of the absorbed dose was found in skin > liver > kidney.
As expected, most (69%) of the radioactivity was found in the GI tract and liver (2%) as the process of absorption was underway from the GI tract to liver through hepatic protal system. Higher levels of radioactivity in kidney (0.5-1.3%) was due to rapid elimination of the absorbed dose in urine through kidneys. Higher percent dose in skin (3-4%) than liver and kidney was unexpected and cannot be explained.

Group 4:
On average, 37% of the administered dose remained in the bodies of animals sacrificed at 6 h post-dosing. Most (~ 15% of the administered dose) was found in the GI tract. Besides residual cracass, most of the absorbed dose was found in whole liver > total skin > whole kidney.
As expected from significant amount (15%) of 14C-BIOBAN™ CS-1246 remaining in the GI tract and its continuous absorption and active elimination, higher radioactivity was detected in stomach (1-2%), liver (3-5%) and in kidney (~1%; primary elimination site). Higher levels of radioactiity in liver > skin >kidney was somewhat consistent to that observed in animals sacrificed 0.25 h post-dosing.

Group 5:
On average, a total of 1% of the administered dose remained in tissues 168 h after dosing, most of which was found in the residual carcass and skin.
For males, the highest concentrations ranked from carcass > liver > kidney > testes > skin.
For females, the highest concentrations ranked from carcass > stomach tissue > kidney = brain ≥ skin

For the most groups, fat and fatty tissues (e.g. brain) generally exhibited the lowest accumulation of 14C- BIOBAN™ CS-1246 -derived residues.

Details on excretion:

Urinary elimination of the administered 14C-BIOBAN™ CS-1246:
Group 1: 90% (males) and 83% (females); males: 81% of the administered dose was excreted within 24 h post-dosing; females: 73% of the administered dose was excreted within 24 h post-dosing.
Group 2: 82% (males) and 87% (females); males: 73% of the administered dose was excreted within 24 h post-dosing; females: 77% of the administered dose was excreted within 24 h post-dosing.
Group 3: not collected
Group 4: 43% of the administered dose was found in the urine of rats sacrificed 6 h post-dosing.
Group 5: 93% (males) and 97% (females); males and females: 85% of the administered dose was excreted within 24 h post-dosing.

Faecal elimination of the administered 14C-BIOBAN™ CS-1246:
A small percentage of the orally dosed 14C-BIOBAN™ CS-1246 was eliminated in faeces, ranging from an average of 9-15% of the administered dose after a single oral dose (5 or 200 mg/kg bw) and 11-13% after multiple dosing.

Metabolite characterisation studies

Metabolites identified:

yes

Details on metabolites:

The absorbed test substance was completely metabolised, affording 2-amino-2-ethyl-1,3-propanediol (AEPD) as the only metabolite above 5% of the administered dose in all urine and faecal samples analysed from all dose groups. Four minor metabolites were also observed above 0.5% of the administered dose, but not identified.

Any other information on results incl. tables

 Kinetic parameters of 14C- BIOBAN™ CS-1246 in RBC and in plasma (see Table 1 and Table 2)

In the rats dosed orally with 14C- BIOBAN™ CS-1246, elimination of the radioactivity from plasma was biphasic with most of elimination occuring during the rapid (α) elimination phase (0.1 - 0.5 h) and a slower (β) elimination phase (4 - 5 h). There was some indication of enterohepatic ciruclation of the biliary eliminated radioactivity between 2 - 6 h post-dosing in the low-dose rats, which became pronounced at the high dose. The AUC of radioactivity in plasma at the high dose was 270 -280 µg*h/g, which was largely dose proportional; 44 - 49 -fold higher than that observed at the low dose. Consistent with dose proportionally of Cmax, AUC and unsaturated kinetics between the low and high doses, clearance remained unchanged between the 2 doses.

The test substance derived radioactivity was also present in RBC, with Cmax concentrations ~75% of the levels seen in plasma. The time-course radioactivity in RBC roughly paralleled the plasma time-course concentration profiles at much lower concentrations. Kinetics (absorption, elimination, AUC, clearance) of radioactivity from RBC were slower than plasma as detectable levels of radioactivity were found in RBC for extended period of time when compared to plasma.

 

Table 1:  Kinetic parameters of 14C- BIOBAN™ CS-1246 in RBC and in plasma (mean ± SD of 4 animals)

Group 1 (5 mg/kg bw)	RBC		Plasma
Parameter	Mean ± SD (males)	Mean ± SD (females)	Mean ± SD (males)	Mean ± SD (females)
t(max) [h]	0.25 ± 0.0	0.25 ± 0.0	0.25 ± 0.0	0.25 ± 0.0
Cmax [µg/g]	1.89 ± 0.57	1.53 ± 0.58	2.85 ± 0.80	2.87 ± 0.20
t½α [h] rapid elimination	0.71 ± 0.42	1.44 ± 1.17	0.46 ± 0.27	0.25 ± 0.08
t½β [h] slow elimination	21.8 ± 9.5	24.4 ± 9.7	3.98 ± 1.13	4.31 ± 0.60
AUC [µg*h/g]	15.9 ± 0.6	19.4 ± 2.3	5.45 ± 0.84	6.35 ± 0.45
Cl [mL/kg/h]	286 ± 14	250± 29	846± 116	757 ± 52
MRT [h]  mean residence time	28.60 ±11.09	32.24 ±11.60	4.36 ± 1.07	5.57 ± 0.60

 

Table 2: Kinetic parameters of 14C- BIOBAN™ CS-1246 in RBC and in plasma (mean ± SD of 4 animals)

Group 2 (200 mg/kg bw)	RBC		Plasma
Parameter	Mean ± SD (males)	Mean ± SD (females)	Mean ± SD (males)	Mean ± SD (females)
t(max) [h]	1.19 ± 1.88	0.88 ± 0.83	0.25 ± 0.0	0.88 ± 0.83
Cmax [µg/g]	60.77 ± 7.13*	64.13 ± 11.42**	97.64 ± 28.66	76.51 ± 41.58
t½α [h] rapid elimination	0.15 ± 0.08	0.08 ± 0.09	0.20 ± 0.06	0.11 ± 0.11
t½α [h] rapid elimination	20.93 ± 8.69	19.72 ± 4.38	5.49 ± 1.70	5.43 ± 0.63
AUC [µg*h/g]	753.51 ± 250.05	793.70 ± 211.14	269.50 ± 27.59	280.52 ± 26.39
Cl [mL/kg/h]	305.75 ± 99.66	287.45 ± 83.26	792.92 ± 99.66	772.36 ± 66.70
MRT [h] mean residence time	29.49 ±12.09	28.14 ± 6.47	7.40 ± 2.57	7.54 ± 0.65

*Mean ± SD of 2 animals

** Mean ± SD of 3 animals

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): no bioaccumulation potential based on study results