Phthalimide

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Metabolic and toxic behaviours of phthalimide derivatives in albino rat

Author:

Ackermann H, Faust H, Kagan YS, and Voronina VH

Year:

1978

Bibliographic source:

Arch Toxicol 40: 255-261

Reference 2

Reference Type:

secondary source

Title:

Dimethyl phosphonate - CAS No: 868-85-9 - SIDS Initial Assessment Report.

Author:

OECD

Year:

2004

Bibliographic source:

UNEP Publications

Materials and methods

Objective of study:

other: placental transfer

Principles of method if other than guideline:

Radiolabelled phthalimide (250 mg/kg/day) was administered by gavage to pregnant rats between gestational day (GD) 16 and GD18 in order to study the plancental transfer of phthalimide. After 10, 20, 30, 60, 120, 240, and 360 minutes pregnant animals were decapitated and the fetuses were removed.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Phthalimide

EC Number:

201-603-3

EC Name:

Phthalimide

Cas Number:

85-41-6

Molecular formula:

C8H5NO2

IUPAC Name:

1H-isoindole-1,3(2H)-dione

Details on test material:

- Name of test material (as cited in study report): phthalimide
- Analytical purity: not reported

Radiolabelling:

yes

Remarks:

15N

Test animals

Species:

rat

Strain:

Wistar

Sex:

female

Administration / exposure

Route of administration:

oral: gavage

Duration and frequency of treatment / exposure:

Animals were decapited 10, 20, 30, 60, 120, 240, and 360 minutes after exposure

Doses / concentrations

Remarks:

Doses / Concentrations:
250 mg/kg bw

No. of animals per sex per dose / concentration:

9-12 animals

Control animals:

no

Details on dosing and sampling:

EXPERIMENTAL ARRANGEMENT

STUDIES INTO PLACENTAL TRANSFER OF 15N-PHTHALIMIDE
No impurities were recordable by thin-layer chromatography from the recrystallised synthetic products. Suspended in ethoxose solution, they were applied via stomach tube to pregnant Wistar-strain albino rats between the 16th and 18th days p.c. The dose was 25 mg/100g live weight. 10, 20, 30, 60, 120, 240, and 360 min were allowed to elapse, before the pregnant animals were decapitated under hexobarbital anaesthesia and the foetuses removed and weighed.


DEGRADATION OF CHLOROMETHYL PHTHALIMIDE, OXYMETHYL PHTHALIMIDE, AND PHTHALIMIDE IN ISOLATED RAT FOETUSES
Foetuses removed by caesarean section on the 19th or 20th day p.c. were given an intraperitoneal injection of 25µg of the phthalimide derivative per gram of live weight. The animals then were kept in an incubator at 38° in humidity-saturated atmosphere. Between nine and twelve animals each were decapitated after 10, 20, 30, 60, 120, 240, and 360 min and additionally prepared and processed in a way described below.

CHEMICAL TESTS
Three foetuses each were pooled into one sample, and, following preliminary crushing, 8 g were extracted by intensive homogenisation with some 30 mL of chloroform/methanol (80+20). The organic phase was separated by centrifugation, and the residue was subjected twice to the same treatment with about 30 mL chloroform. The combined chloroform phases were washed in 10 mL of distilled water, dried over sodium sulphate following separation of aqueous phase, and evaporated to dryness in a rotation evaporator. The residue was dissolved in 0.5 mL of chloroform/methanol (80+20).

The phthalimide derivatives were detected and determined following separation by thin-layer chromatography (mobile phase benzene/acetone 9+1). The plate, after being relieved from the solvent, was heated to 180°C for 1 hour, before it was treated 10 min in a chlorine atmosphere. Then, application of ethanol spray was followed by colour reaction of the strains, the latter through sprayed application of a mixture of 1% potassium iodide and 2% starch solution, their quantitative ratio being 1:1. Chloromethyl phthalimide, oxymethyl phthalimide, and phthalimide were displayed as bluish-violet spots, detective sensitivity being between 50 ng and 100 mg per spot. Phthalimic acid, a metabolite with opened phthalimide ring, stayed at the point of departure.


DETERMINATION OF 15N-ABUNDANCE
Aliquote parts of chloroform extract mineralised in the presence of sulphuric acid and selenium reaction mixture. Total nitrogen then was determined photometrically by indophenol-blue method, and the ammonia nitrogen was distilled into hydrochloric acid solution by the usual Kjeldahl technique. A certain amount of unlabelled ammonium chloride then was added, before the distillate was evaporated to dryness and the 15N-abundance determined by emission spectrometry.


IN VITRO DEGRADATION OF CHLOROMETHYL PHTALIMIDE
Freshly obtained blood was mixed with the same volume of 1.15% aqueous potassium chloride solution and centrifuged 15 min at 6000 rpm. The supernatant was used for the test proper. When it came to preparations with liver homogenate, 5 g liver were homogenised with 10 mL 1.15% potassium chloride solution and centrifuged 10 min at 4000 rpm, before, again, the supernatant was used for actual investigation.


APPROACH
2.0 mL Ringer solution, 0.5 mL Co-factors (6 mg NAD+ 122 mg nicotinamide/5 mL Ringer solution), 0.5 mL chloronethyl phthalimide solution (1mg/0.5 mL 2% aqueous ethoxose solution), 2 mL substrate (plasma or liver); time of incubation: 15, 30 and 60 min; temperature: 37°C; shaking frequency: 90/min.

DETERMINATION
The flasks were taken off as soon as their incubation periods had run out. They were diluted with 10 mL of distilled water and immediately extracted twice with 10 mL of chloroform. The combined chloroform extracts were washed in 10 mL of distilled water, dried with sodium sulphate, and evaporated to 1 mL. Chloromethyl phthalimide, oxymethyl phathalimde, and phthalimide were determined by thin-layer chromatography in aliquote parts of the extract.

Heat-treated organ homogenates were used for studies into recovery. Chloromethyl phthalimide and its metabolites were quantitatively recovered, the error of TCL determination being ± 20%.
All calculated standard deviations, therefore, are within the normals of biological deviations, that is between ± 25 and ± 35%.

Results and discussion

Toxicokinetic / pharmacokinetic studies

Transfer into organs

Transfer type:

blood/placenta barrier

Observation:

distinct transfer

Toxicokinetic parameters

Test no.:

#1

Toxicokinetic parameters:

half-life 1st: between 80 and 90 minutes

Any other information on results incl. tables

Maximum radiolabel concentrations were reached in fetuses within 30 min after application. Strong decline in concentration occurred subsequently and appeared to indicate excessive secretion or continued metabolism, and the detection limit was reached after 2 hours.

Determination of Half Life of Phthalimide in Isolated Rat Foetuses

Phathalimide half life was derived from measurements up to 2 hours and found to have been between 80 and 90 minutes. Longer incubation periods were not taken to the record, since some of the animals had died due to excessive alcohol application, which had amounted to 2.5 µL/g live weight. Phthalimide half life, consequently, was clearly above that of imidan or imidoxone.