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Basic toxicokinetics

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basic toxicokinetics in vivo
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Basic data given, scientifically acceptable

Data source

Reference Type:
Pharmacokinetic Study of Zeolite A, Sodium Aluminosilicate, Magnesium Silicate, and Aluminium Hydroxide in Dogs
Cefali E, Nolan JC, McConbell WR and Walters DL
Bibliographic source:
Pharmaceut. Res., 12 (2), 270-274

Materials and methods

Objective of study:
Principles of method if other than guideline:
The bioavailability of silicon and aluminium from zeolite A, sodium aluminosilicate, magnesium trisilicate and aluminium hydroxide was compared in dogs.
GLP compliance:
not specified

Test material

Constituent 1
Reference substance name:
Automatically generated during migration to IUCLID 6, no data available
Automatically generated during migration to IUCLID 6, no data available
Details on test material:
- Name of test material (as cited in study report): Zeolite A (N-0974) raw material
- Chemical name: Zeolite, cuboidal, crystalline, synthetic, non-fibrous
- Framework: cuboidal
- Related CAS number: 1318-02-1
- Analytical purity: no data

Test animals

Details on test animals or test system and environmental conditions:
individually housed female dogs (10-13 months; 7.3-11.6 kg of weight)

Administration / exposure

Route of administration:
oral: capsule
other: gelatine
Details on exposure:
Twelve individually housed female dogs received each compound as a single oral dose separated by one week in a randomized four-way crossover-design. Dosing was equimolar based upon silicon content and adjusted to each dog's weight.
Duration and frequency of treatment / exposure:
single oral dose
Doses / concentrations
Doses / Concentrations:
30 mg/kg
No. of animals per sex per dose / concentration:
Control animals:

Results and discussion

Any other information on results incl. tables

The absorption of silicon from Zeolite A was variable revealing elevated mean silicon AUC and Cmax values when compared to a baseline; however, only the AUC from zeolite A was significantly elevated** (One way ANOVA p=0.041, and Tukey's standardized range test p0.05):

Mean plasma silicon AUC values (± SD) mg / h /L
zeolite A**
                                          9.5 ± 4.5
sodium alumino-silicate
    7.7 ± 1.6
magnesium trisilicate
                          8.8 ± 3.0
aluminum hydroxide
                           6.1 ± 1.9

mean plasma silicon Cmax values (± SD) mg/L
zeolite A
                                              1.07 ± 1.06
sodium alumino-silicate
     0.67 ± 0.27
magnesium trisilicate
                          0.75 ± 0.31
aluminum hydroxide
                            0.44 ± 0.17

mean plasma silicon Tmax values (± SD) hr
zeolite A
                                               7.9 ± 6.4
sodium alumino-silicate
     5.8 ± 4.6
magnesium trisilicate
                          6.9 ± 6.3
aluminum hydroxide
                           8.5 ± 3.4

Although the silicon doses were equimolar, the corresponding aluminum doses differed by more than an order of magnitude. The amounts of aluminum delivered by zeolite A and sodium alumino-silicate were 3.36 and 0.90 mg/kg respectively, while the aluminum hydroxide dose of 675 mg was approximately equivalent to 27.77 mg/kg aluminum based on the average weight of the dogs on the day of dosing. The plasma aluminum data during magnesium trisilicate dosing serves as the control treatment for the dietary absorption of aluminum as this compound contains no appreciable amount of aluminum.
There was no statistically significant absorption of aluminum from the other aluminum-containing compounds:

Mean plasma aluminum AUC values (± SD) µg / h /L
zeolite A
                                               342 ± 111
sodium alumino-silicate
     338 ± 167
magnesium trisilicate
                          315 ± 69
aluminum hydroxide
                           355 ± 150

mean plasma aluminum Cmax values (± SD) µg/L
zeolite A
                                               29 ± 9
sodium alumino-silicate
     27 ± 14
magnesium trisilicate
                          24 ± 5
aluminum hydroxide
                           29 ± 11

mean plasma aluminum Tmax values (± SD) hr
zeolite A
                                               3.5 ± 4.1
sodium alumino-silicate
     4.2 ± 4.3
magnesium trisilicate
                          5.7 ± 7.3
aluminum hydroxide
                           5.0 ± 4.7

Applicant's summary and conclusion