Theophylline

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well documented publication/study report.

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Unnamed

Year:

1988

Reference 2

Reference Type:

secondary source

Title:

Reproductive effects of theophylline in mice and rats.

Author:

Morrissey, R.E.

Year:

1988

Bibliographic source:

Fund. Appl. Toxicol. 10, 525-536; cited in: OECD SIDS for CAS-No. 58-55-9, 2003

Reference 3

Reference Type:

publication

Title:

Unnamed

Year:

1998

Reference 4

Reference Type:

publication

Title:

Theophylline-induced mesenteric periarteritis in F344/N rats.

Author:

Nyska, A.

Year:

1998

Bibliographic source:

Arch. Toxicol. 72, 731-737

Reference 5

Reference Type:

secondary source

Title:

Subchronic Toxicity of Orally Administered (Gavage and Dosed-Feed) Theophylline in Fischer 344 Rats and B6C3F Mice.

Author:

Collins, J.J.

Year:

1988

Bibliographic source:

Fund. Appl. Toxicol. 11, 472-484; cited in: OECD SIDS for CAS-No. 58-55-9, 2003

Reference 6

Reference Type:

secondary source

Title:

Theophylline-induced mesenteric periarteritis in F344/N rats.

Author:

Nyska, A.

Year:

1998

Bibliographic source:

Arch. Toxicol. 72, 731-737; cited in: OECD SIDS for CAS-No. 58-55-9, 2003

Reference 7

Reference Type:

secondary source

Title:

Unnamed

Year:

1998

Materials and methods

Principles of method if other than guideline:

Standard method of the National Toxicology Program (NTP) without recovery period.

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Theophylline

EC Number:

200-385-7

EC Name:

Theophylline

Cas Number:

58-55-9

Molecular formula:

C7H8N4O2

IUPAC Name:

1,3-dimethyl-2,3,6,7-tetrahydro-1H-purine-2,6-dione

Details on test material:

- Name of test material (as cited in study report): theophylline
- Analytical purity: according to Collins et al., 1988, the purity was >99%

Test animals

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: approximately 4 weeks;
- Housing: 5 per cage
- Diet (e.g. ad libitum): NIH-07 open formula rodent feed; pellets for the gavage studies;
- Water (ad libitum):tap water;
- Acclimation period: 2 weeks.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.1 - 25 °C;
- Humidity (%): 35 - 70 %;
- Air changes (per hr): 10;
- Photoperiod (hrs dark / hrs light): 12h/12h.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
- Dose formulations were prepared weekly during the 13-week studies by mixing theophylline with corn oil to give the required concentrations . Homogeneity and stability studies of the dose formulations were performed using HPLC and ultraviolet/visible spectroscopy. Homogeneity was confirmed for the gavage formulations.

DOSING SOLUTION:
- Gavage volume: 5 mL/kg b.w.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Dosage analyses (ultraviolet spectrophotometric) both prior to and after dosing confirmed that the dosage formulation in corn oil (dosage formulations in corn oil were suspensions) were homogenous and were within ±10% of the target concentrations.

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

5 d/w (daily, excluding weekends and holidays, for a total of 65 - 69 dosing days).

Doses / concentrations

Remarks:

Doses / Concentrations:
37.5, 75, 150 mg/kg bw/d
Basis:
actual ingested

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

- Post-exposure recovery period in satellite groups: none

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes;
- Time schedule: twice a day;

DETAILED CLINICAL OBSERVATIONS: Yes;
- Time schedule: once a week;

BODY WEIGHT: Yes;
- Time schedule for examinations: once a week;

HAEMATOLOGY: Yes;
- Time schedule for collection of blood: at terminal kill from the retro-orbital sinus of the rats;
- Anaesthetic used for blood collection: Yes (identity): CO2;
- Parameters examined: The blood was analyzed using an automated hematology analyzer (Ortho ELG-8) for erythrocyte, platelet, and leukocyte counts, hematocrit, hemoglobin, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and mean corpuscular volume. Hematocrit values were based upon erythrocyte counts, and hemoglobin was measured by colorimetric determination of cyanmethemoglobin. Leukocyte differential, reticulocyte counts, and erythrocyte, platelet, and leukocyte morphologies were determined by light microscopy on blood smears stained with a combination of methylene blue and buffered Wright-Giemsa stains.

URINALYSIS: Yes
- Time schedule for collection of urine: overnight;
- Metabolism cages used for collection of urine: Yes;
- Animals fasted: Yes;
- Parameters examined: volume, appearance, specific gravity (using a refractometer), and light - microscopic evaluation of sediment were determined.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes;
HISTOPATHOLOGY: Yes.

Results and discussion

Results of examinations

Details on results:

CLINICAL SIGNS AND MORTALITY
One male and one female of the high dose group died on days 2 and 87, respectively. However, this was not statistically significant.

BODY WEIGHT AND WEIGHT GAIN
Mean body weight gain was significantly increased in high dose females and significantly decreased in high-dose males.

HAEMATOLOGY
Significant shift in the leukocyte differential in mid- and low-dose males (increase in segmented neutrophils, decrease in lymphocytes) and lymphocytes were significantly increased in high-dose females. Other hematalogic parameters demonstrating significant changes were increased mean corpuscular hemoglobin in all male rat treatment groups and increased mean corpuscular volume and mean corpuscular hemoglobin concentration in high-dose males.

CLINICAL CHEMISTRY
No substance-related signs of toxicity were observed.

URINALYSIS
Dose-related increase in urine volume, which was significant in high-dose males and high- and mid-dose females, accompanied by a significant decrease in urine specific gravity in high-dose females.

ORGAN WEIGHTS
All significant organ weight changes in male rats occurred at the high dose, including decreased absolute and relative thymus weights and increased relative kidney weights. In high dose female rats, significant changes included increased absolute liver and kidney weights, decreased absolute and relative thymus and uterus weights, and decreased relative brain weight. Absolute liver weights were also significantly increased in mid-dose females.

GROSS PATHOLOGY
No treatment-related gross observations were noted at necropsy .

HISTOPATHOLOGY: NON-NEOPLASTIC
A dose-dependent increase in incidences of mesenteric and/or pancreatic periarteritis was observed in all treated males (control: 1/10; 37.5 mg/kg 1/10; 75 mg/kg: 2/10; 150 mg/kg: 5/10) and females (0/10; 2/10; 2/10; 3/10, respectively). The periarteritis observed in one control male was more consistent with that commonly observed in aged rats and consisted of minimal, focal lymphocytes accumulation adjacent to the artery. Periateritis was characterized by infiltration of mononuclear and polymorphonuclear leukocytes into the media and adventitia, and the more severe lesions included degeneration of medial smooth muscle and periarterial fibrosis. Theophylline-related arterial lesions were noted in the 2 year study only in male rats given the high dose of 75 mg/kg b.w., this effect was statistically significant (see Nyska et al., 1998, Chapter 7.7).

OTHER FINDINGS
There were no significant differences between control and exposed rats in sperm morphology or vaginal cytology parameters. No histological changes were seen in the sex organs.

Effect levels

Dose descriptor:

LOAEL

Effect level:

37.5 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: Periarteritis in both sexes.

Target system / organ toxicity

Critical effects observed:

not specified