Theophylline

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study (OECD)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1989

Report date:

1989

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

GLP compliance:

no

Test type:

standard acute method

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): Theophyllin-waterfree (anhydrous), micronized
- Physical state/appearance: solid/colorless to whitish cristalline powder
- Analytical purity: 99.5 to 100.5%
- Lot/batch No.: 63748
- Stability under test conditions: Stability was ensured for at least the study period.
- Storage condition of test material: room temperature and excluded from air and light.

Test animals

Species:

rat

Strain:

other: SPF Wistar/Chbb : THOM

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Dr . K . Thomae GmbH, Biberach, Germany.
- Age at study initiation: approx. 8 - 9 weeks
- Mean body weight at study initiation: male animals 266 ± 9.7 g, female animals 190 ± 8.4 g.
- Housing: 5 per cage; without bedding;
- Diet (e.g. ad libitum): KLIBA rat/mouse laboratory diet 24-343-4, 10 mm pellets, Klingentalmuehle AG, Kaiseraugst, Switzerland.
- Water (e.g. ad libitum): drinking water ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24°C
- Humidity (%): 30-70%
- Photoperiod (hrs dark / hrs light): 12h/12h

Administration / exposure

Route of administration:

other: dust aerosol

Type of inhalation exposure:

nose/head only

Vehicle:

other: Aerosil

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Head-nose inhalation system INA 20 (glass-steel construction, BASF AG);
- Exposure chamber volume: ca. 55 L;
- Method of holding animals in test chamber: The animals were restrained in tubes and their snouts projected into the inhalation chamber.
- Source and rate of air: Compressed air, 1500 [L/h]
- Method of conditioning air: The supply air was conditioned via a central air-conditioning system. The exposure system was placed in an air-conditioned laboratory.
- System of generating particulates/aerosols: A dust aerosol was generated by means of a dosing-wheel dust generator (Gericke/BASF). The concentration was adjusted by varying the rotation of the metering disc.
- Temperature, humidity, pressure in air chamber: Temperatures in the exposure system were 19 - 25°C.
By means of an exhaust air system the pressure ratios in the inhalation system were adjusted in such a way that the amount of exhaust air was about 10% lower (excess pressure). This ensured that the mixture of test substance and air was not diluted with laboratory air in the breathing zones of the animals.

TEST ATMOSPHERE
- Nominal concentration: The nominal concentration was calculated from the amount of substance consumed and the air flow.
- Brief description of analytical method used:
(1) Sampling apparatus: Vacuum compressed air pump XX 60 220 50 (Millipore); Filtration equipment with probe, internal diameter: 4 mm, (Millipore); Filter: MN 85/90 Bf (d = 4 .7 cm ); Sampling velocity: 1 .25 m/ s; Sampling amount : 2 - 5 L; Sampling position: immediately adjacent to the animals' noses; Sampling frequency: 1 sample per concentration group about hourly
(2) Analytical determination method: The inhalation atmosphere concentration was determined gravimetrically; Equipment:balance: Mettler AE 240.
The preweighed filter was placed into the filtration equipment. By means of a vacuum compressed air pump a volume of the dust aerosol was drawn through the filter. The dust concentration in mg/l was calculated from the difference between the preweight of the filter and the weight of the filter after sampling, with reference to the sample volume of the inhalation atmosphere. The concentrations were corrected for the amount of the added excipient.
(3) Particle size analysis: Equipment (Stack Sampler Mark III (Andersen); Vacuum Compressed Air Pump XX 60 220 50 (Millipore); Sampling probe (internal diameter 6.9 mm); Balance: Cahn 26 and Mettler AE 240; Evaluation unit (IBM-PC with software PGA).
Procedure: 30 minutes after the beginning of the test, one sample was taken per test group for the particle size analysis.
Before the sampling, the impactor was equipped with glass-fiber collecting discs and a backup particle filter. The impactor was connected to the pump and the test apparatus, and one sample (10.5 - 21 L) was taken. The impactor was taken apart, and the collecting discs and the backup particle filter were weighed. The contents of the pre-impactor as well as the amounts of the material adsorbed on the walls of the impactor and in the sampling probe (wall losses) were also determined quantitatively.

VEHICLE
- Composition of vehicle (if applicable): For technical reasons the test substance was mixed with Aerosil in order to achieve a more uniform dust concentration in air;
- Concentration of test material in vehicle (if applicable): 1 wt % of test substance in test group 1 and 2 wt % of test substance in test group 2;

TEST ATMOSPHERE (if not tabulated)
- Particle size distribution:
EACD 50 % (effective aerodynamic cutoff diameter 50 %): see table below;
- MMAD (Mass median aerodynamic diameter) / GSD (Geometrical standard deviation):
In test group 1, MMAD = 5.8 µm and GSD = 3.1 was calculated from the results of the particle size analysis. A respirable dust fraction that might reach the alveolar region of 69 % was obtained from the results of the particle size analysis.
In test group 2, MMAD = 4.0 µm and GSD = 3.6 was calculated from the results of the particle size analysis. A respirable dust fraction that might reach the alveolar region of 77% was obtained from the results of the particle size analysis.
In spite of the use of Aerosil (2wt .%) the MMAD was > 3 µm. Since this kind of study should be performed in a realistic manner, no further technical measures were taken to reach a smaller particle size.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

2.39 mg/L; 6.7 mg/L (analytical)

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: The body weight of the animals was checked before the beginning of the test, after 7 days and at the end of the observation period after 14 days. Clinical findings were recorded several times during exposure and at least once on each workday in the observation period. A check for dead animals was made daily.
- Necropsy of survivors performed: yes;

Statistics:

The statistical evaluation of the concentration/effect relationship was carried out on the basis of the binomial test (Wittig, H.:Mathematische Statstik 1974, pp. 32 - 35). The calculation of the particle size distribution was carried out in the Department of Toxicology of BASF AG on the basis of mathematical methods for evaluating particle measurements (DIN 66141: Darstellung von Korngroessenverteilungen, DIN 66161: Partikelgroessenanalyse).

Results and discussion

Effect levels

Effect levels 1

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 6.7 mg/L air

Exp. duration:

4 h

Effect levels 2

Sex:

male/female

Dose descriptor:

LC0

Effect level:

>= 6.7 mg/L air

Exp. duration:

4 h

Mortality:

No mortality was observed.

Clinical signs:

other: Clinical signs of toxicity included changes in respiration [irregular (0.5 - 1 h after beginning of exposure), accelerated (1h - 6d after beginning of exposure), intermittent (2 - 4 h after beginning of exposure), and gasping (3 - 4 h after beginning of e

Body weight:

No abnormalities observed.

Gross pathology:

No pathologic findings noted.

Any other information on results incl. tables

	Cascade impactor			Percentage distribution	Cumulative distribution
	Stage	EACD 50 %	Mass
		[µm]	[mg]	[%]	[%]
Group 1
	Pre-impactor	26.6
	0	29.5	1.08	8.9	91.1
	1	18.2	0.84	6.9	84.1
	3	8.5	1.77	14.7	69.4
	4	5.5	2.31	19.2	50.3
	5	2.8	3.33	27.7	22.6
	7	1.2	1.70	14.1	8.5
	Backup filter	< 1.2	1.02	8.5	-
		total	12.04
Group 2	Pre-impactor	26.6
	0	29.5	0.98	7.2	92.8
	1	18.2	0.75	5.5	87.3
	3	8.5	1.44	10.6	76.8
	4	5.5	1.75	12.8	63.9
	5	2.8	3.89	28.5	35.5
	7	1.2	2.63	19.2	16.3
	Backup filter	< 1.2	2.22	16.3	-
		total	13.67