polymeric zinc propylenebis(dithiocarbamate);propineb (ISO)

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

July-1994 to May-1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1995

Report date:

1995

Materials and methods

Objective of study:

absorption

distribution

excretion

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 417 (Toxicokinetics)

Version / remarks:

1984

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

polymeric zinc 1,2-propylenebis(dithiocarbamate)

EC Number:

620-365-5

Cas Number:

9016-72-2

IUPAC Name:

polymeric zinc 1,2-propylenebis(dithiocarbamate)

Test material form:

solid

Remarks:

Powder

Radiolabelling:

yes

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River (UK) Limited
- Weight at study initiation: Males: 188-282 g, Females: 192-204 g
- Housing: Throughout the study period the animals used for the blood kinetics studies were housed individually in polypropylene and stainless steel cages with raised wire mesh floors to inhibit coprophagy. Animals used for the excretion studies were housed individually in all-glass metabolism cages specifically designed for the separate, quantitative collection of urine and faeces.
- Diet: Standard laboratory diet (SDS Rat and Mouse Maintenance Diet No. 1, Special Diets Services, Essex, UK) was available ad libitum.
- Water: Domestic water was available ad libitum.
- Acclimation period: 7 days
- Health status: Animals were carefully observed during the acclimation period to ensure that they were in good health and suitable for inclusion in the study.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18-24°C
- Humidity (%): 33-59%
- Photoperiod (hrs dark / hrs light): 12 h light/dark cycle

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: 0.5% aqueous gum tragacanth

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: [14C]-Propineb (15.22 mg premix, equivalent to 13.25 mg of test substance) was accurately weighed into a 50 mL volumetric flask. The flask was made up to volume with 0.5% aqueous gum tragacanth, and placed into an ultrasonic bath for ca 10 min until a homogeneous suspension appeared to have formed. The dose suspension was then transferred to a conical flask and kept mixing on a magnetic stirrer throughout dose administration. The formulated dose was administered to the animals as soon as possible after preparation.

Duration and frequency of treatment / exposure:

single application

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

100 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

1 mg/kg bw/day (nominal)

No. of animals per sex per dose / concentration:

Sixteen male and 8 female

Control animals:

no

Details on dosing and sampling:

TOXICOKINETIC / PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled: urine, faeces, expired air, blood, plasma, serum, heart, lungs, spleen, kidneys, liver, perirenal fat, testes/ovaries, gastrointestinal tract plus contents, uterus, muscle (leg), brain, thyroids, adrenals, skin remaining carcass, bone mineral, bone marrow, cage washes
- Time and frequency of sampling: Urine: 0-6 h and 6-24h post dose, then at 24 h intervals up to 168 h post dose
Faeces: at 24 h intervals up to 168 h post dose
expired air: at 24 h intervals for the first 48 h post dose tissue: 168 h after dosing
blood: 0.25, 0.5, 1, 2, 4, 6, 8, 24 and 48 hours post dose for blood kinetic; 168 hours post dose for excretion kinetics and tissue retention

ANALYTICAL METHOD
- Complete description including:
thin layer chromatography (TLC): Pooled urine and faeces extracts were analysed by thin-layer chromatography (TLC) and were applied in a 1.5 cm band to silica gel plates (Kieselgel 60F2S4, layer thickness 0.25 mm). All samples were underspotted and run alongside a mixture of the supplied non-radiolabelled reference standards. Samples were applied along the origin marked at 2 cm and run over a distance of 15 cm. Two solvent systems were used, these were as follows:
Solvent System 1 - Chloroform:Methanol:Water; 65:25:4 v/v/v
Solvent System 2 - IsopropanohAmmonia (25%):Water; 75:15:15 v/v/v
The position of each of the supplied non-radiolabelled reference standards were visualised by either quenching under u.v. light, spraying with ninhydrin or by staining with iodine. Radioactive areas of the TLC plates were quantified using a Phosphor Image Analyser (Molecular Dynamics, Model 455A), and the relative % of each radioactive area determined by peak integration. The radioprofile obtained from each sample was evaluated by matching the position of the radioactive areas on TLC plates with the positions of the supplied non-radiolabelled reference standards. It should be noted however that radioprofiling using one dimensional TLC where many components are present may give rise to radiochemical peaks containing more than one component.

Liquid scintillation analysis: All samples were analysed for 5 min using a scintillation analyser (Canberra Packard Limited) with automatic quench correction using an external standard method.
Representative blank samples were analysed and their values subtracted from the biological sample measurements. The activity in each sample was expressed as net d.p.m. A limit of reliable determination of 30 d.p.m. above background has been instituted in these laboratories. If results arise from data 10-30 d.p.m. above background the fact has been noted in the Results section. Similarly, the fact has been noted if results arise from data less than 10 d.p.m. above background.

Combustion analysis: Samples for combustion were weighed into combustocones (Packard Instrument Company Limited) and combusted using a Packard Tri-Carb 306 Automatic Sample Oxidiser. The resultant 14CO2 was absorbed in Carbo-Sorb® and mixed automatically with Permafluor®E"1" scintillation fluid. Combustion efficiency and carry-over were checked routinely several times throughout each production run. The mean combustion efficiency was shown to be greater than 97% throughout the experimental period.

Results and discussion

Main ADME results

Type:

excretion

Results:

49.35% and 52.52% during 168 h post dose in urine of male and female rats, respectively;
46.39% and 44.65% during 168 h post dose in faeces of male and female rats, respectively

Toxicokinetic / pharmacokinetic studies

Details on absorption:

Low dose (1 mg/kg bw): Following administration of [14C]-Propineb, mean concentrations of total radioactivity in whole blood were generally higher in female rats. The mean whole blood concentration time curve, however, followed a similar pattern in both male and female rats.
Absorption was rapid with the mean maximum concentration of total radioactivity in whole blood observed at 2 h (males) and 4 h (females) post dose, representing 0.324 µg equiv./g (range 0.278-0.363 µg equiv./g) and 0.424 µg equiv./g (range 0.375-0.446 µg equiv./g) in male and female rats, respectively. Mean concentrations of total radioactivity in whole blood thereafter declined, representing 0.028 µg equiv./g (range 0.020-0.036 µg equiv./g) and 0.041 µg equiv./g (range 0.028-0.058 µg equiv./g) at 24 h post dose in male and female rats, respectively. Thereafter mean concentrations of total radioactivity in whole blood declined more slowly, representing 0.013 µg equiv./g (range 0.012-0.014 µg equiv./g) and 0.032 µg equiv./g (range 0.015-0.045 µg equiv./g) at 48 h post dose in male and female rats, respectively.
High dose (100 mg/kg bw): Following administration of [14C]-Propineb to male rats, absorption was rapid with the mean maximum concentration of total radioactivity in whole blood observed at 4 h post dose representing 25.2 µg equiv./g (range 21.6-27.0 µg equiv./g). Mean concentrations of total radioactivity in whole blood thereafter declined, representing 4.2 µg equiv./g (range 2.6-7.1 µg equiv./g) at 24 h post dose. Thereafter mean whole blood concentrations of total radioactivity declined more slowly representing 1.1 µg equiv./g (range 0.8-1.5 µg equiv./g) at 48 h post dose.

Details on distribution in tissues:

Low dose (1 mg/kg bw): Mean tissue residues at 168 h post dose accounted for 0.47% (range 0.41-0.57%) and 0.52% (range 0.46-0.63%) of the administered dose in male and female rats, respectively, the majority of which was associated with the residual carcass.
Highest mean concentrations of total radioactivity at 168 h post dose were found in thyroid glands, representing 3.135 µg equiv./g (range 0.882-7.060 µg equiv./g) and 2.853 µg equiv./g (range 1.073-5.774 µg equiv./g) in male and female rats, respectively. All other tissues and organs investigated contained mean concentrations of total radioactivity lower than in whole blood (male and female: 0.007 µg/g), except for kidneys (males = 0.051 µg equiv./g, females = 0.038 µg equiv./g), adrenals (males = 0.015 µg equiv./g, females = 0.021 µg equiv./g), liver (males = 0.012 µg equiv./g, females = 0.009 µg equiv./g) and lungs (males and females = 0.008 µg equiv./g).
The tissue distribution of total radioactivity at 168 h post dose was independent of gender.

High dose (100 mg/kg bw): Mean tissue residues in male rats at 168 h post dose accounted for 0.63% (range 0.49-0.78%) of the administered dose, the majority of which was associated with the residual carcass.
Highest mean concentrations of total radioactivity at 168 h post dose were found in thyroid glands representing 113.75 µg equiv./g (range 101.51-139.83 µg equiv./g). All other tissues and organs investigated contained mean concentrations of total radioactivity lower than in whole blood (0.57 µg equiv./g), except for kidneys (1.66 µg equiv./g), skin (1.50 µg equiv./g), adrenals (1.00 µg equiv./g), bone marrow (0.94 µg equiv./g), liver (0.78 µg equiv./g) and lungs (0.73 µg equiv./g).

Details on excretion:

Low dose (1 mg/kg bw): Following administration of [14C]-Propineb, urinary excretion accounted for a mean of 49.35% (range 45.67-53.40%) and 52.52% (range 48.01-56.84%) of the administered
dose during the 168 h post dose period in male and female rats, respectively. During the same period, a mean of 46.39% (range 40.72-55.11%) and 44.65% (range 37.95-50.11%) of the administered dose was recovered in faeces in male and female rats, respectively. Expired 14CO2 was a minor route of elimination in male and female rats accounting for a mean of 1.47% (range 1.30-1.59%) and 2.01% (range 1.80-2.34%) of the administered dose, respectively over the first 48 h post dose. Radioactivity in the non 14CO2 volatile trap was below the limit of reliable determination in all animals investigated over this period. Excretion was rapid and essentially complete by 48 h post dose, with a mean of 100.42% (range 94.30-104.07%) and 101.00% (range 97.36-103.46%) of the administered dose excreted in male and female rats, respectively during this period. The routes and rates of excretion were essentially independent of gender. The mean total excreted during 168 h post dose in male and female rats was 101.87% (range 95.94-105.03%) and 102.08% (range 98.53-104.41%) of the administered dose, respectively. The mean total recovered during the same period was 102.36% (range 96.52-105.45%) and 102.61% (range 99.04-104.87%) of the administered dose in male and female rats, respectively.
High dose (100 mg/kg bw): Following administration of [14C]-Propineb to male rats, urinary excretion accounted for a mean of 50.19% (range 41.97-59.13%) of the administered dose during 168 h post dose, while faecal elimination accounted for a mean of 40.79% (range 32.66-44.90%) of the administered dose during the same period. Expired 14C02 was a minor route of elimination accounting for a mean of 2.83% of the administered dose (range 1.21-7.42%) over the first 48 h post dose. Radioactivity in the non 14CO2 volatile trap was below the limit of reliable determination in all animals investigated over this period. Excretion was rapid and essentially complete by 48 h post dose, with a mean of 96.99% (range 94.44-100.55%) of the administered dose excreted during this period. The mean total excreted during 168 h post dose was 98.62% (range 96.87-102.96%) of the administered dose. The mean total recovered during the same period was 99.26% (range 97.48-103.74%) of the administered dose.

Metabolite characterisation studies

Details on metabolites:

Pooled 0-24 h Urine:
[14C]-Propineb was extensively metabolised in both male and female rats, since no unchanged Propineb was detected in urine. Similar metabolite profiles were found in the urine of male and female rats at the low dose level (1 mg/kg). BNF 5547 I (propylene thiourea) and propylendiamine co-chromatographed with radioactive peaks in both TLC systems, accounting for ca 45% and 5% of the urinary radioactivity, respectively. At least 9 other radioactive metabolites were present. Most accounted for less than 10% of the applied radioactivity.
At the high dose level (100 mg/kg), absorbed [14C]-Propineb was again extensively metabolised. The radioprofile obtained in urine for male rats, compared to the corresponding profile at the low dose level showed no new radioactive components to be present. BNF 5547 I (propylene thiourea) and propylendiamine co-chromatographed with radioactive peaks in both TLC systems, accounting for ca 40% and 30% of the urinary radioactivity, respectively. At least 4 other radioactive metabolites were present, each accounting for less than 10% of the applied radioactivity. Compared to the low dose level, the relative proportions of propylene thiourea and propylendiamine had changed with fewer unknown radioactive metabolites present.
PU (propylene urea) may also have co-chromatographed with radioactive peaks in both TLC systems at both dose levels. Due to this reference standard running in close proximity to BNF 5547 I (propylene thiourea) the radioactivity associated with propylene urea is not known.

Pooled 0-24 h Faeces:
The extraction efficiency from pooled faeces homogenates at the low and high dose level was 24% and 40%, respectively. This low extraction efficiency may be explained by the presence of unabsorbed parent test material which is insoluble in solvent. The radioprofile obtained in faeces extracts following oral administration at the low dose level (1 mg/kg) was essentially independent of gender, however an additional radioactive peak accounting for ca 15% of the applied radioactivity was observed in female animals. BNF 5547 I (propylene thiourea) and BNF 5547 B (4-methylimidazoline) co-chromatographed with radioactive peaks in both TLC systems, accounting for ca 20% and 30% of the applied radioactivity, respectively. At least 6 other radioactive metabolites were present. Most accounted for less than 20% of the applied radioactivity.
At the high dose level (100 mg/kg) the radioprofile obtained in the faeces extract from male rats compared to the corresponding profile at the low dose level showed no new radioactive components to be present. BNF 55471 (propylene thiourea) and BNF 5547 B (4-methylimidazoline) co-chromatographed with radioactive peaks in both TLC systems, accounting for ca 50% and ca 6% of the applied radioactivity, respectively. At least 3 other radioactive metabolites were present, most accounting for less than 20% of the applied radioactivity. Compared to the low dose level, the relative proportions of propylene thiourea and 4-methylimidazoline had changed with fewer unknown radioactive metabolites present.

Applicant's summary and conclusion

Conclusions:

Following a single oral administration of [14C]-Propineb, excretion was rapid, with the routes and rate of excretion essentially independent of gender and dose. Based on urinary excretion alone, at least 50% of the administered dose was absorbed. Expired 14CO2 accounted for only ca 2% of the administered dose and recovery of radioactivity was complete.

The concentration of total radioactivity in tissues at 168 h post dose was very low. Highest concentrations of total radioactivity were observed in the thyroid, with mean concentrations approximately 400 and 200 times higher than in whole blood at the low and high dose, respectively. The mean tissue concentrations of total radioactivity obtained at each dose level did not always reflect the difference in dose level.

Absorbed [14C]-Propineb was extensively metabolised with the metabolite profiles in urine and extracts from faeces essentially independent of gender at the low dose. At the high dose, no new radioactive metabolites were observed. Co-chromatography in 2 TLC systems suggested propylene thiourea and propylendiamine were present in urine and propylene thiourea and 4-methylimidazoline in faeces extracts. Many other minor unknown radioactive metabolites were also present.