Zinc m-toluate

Direct observations: clinical cases, poisoning incidents and other

Administrative data

Endpoint:

direct observations: clinical cases, poisoning incidents and other

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

publication

Title:

Comparison of absorption of five zinc preparations in humans using oral zinc tolerance test

Author:

Prasad AS , Beck FWJ & Nowak J

Year:

1993

Bibliographic source:

The Journal of Trace Elements in Experimental Medicine. 6: 109-115

Materials and methods

Study type:

study with volunteers

Endpoint addressed:

basic toxicokinetics

Principles of method if other than guideline:

Oral zinc tolerance test was performed in humans to study the absorption of zinc from various zinc compounds including zinc oxide.

Test material

Test material information

Constituent 1

Reference substance name:

Zinc oxide

EC Number:

215-222-5

EC Name:

Zinc oxide

Cas Number:

1314-13-2

Molecular formula:

ZnO

IUPAC Name:

oxozinc

Details on test material:

- Name of test material (as cited in study report): Zinc oxide

Method

Type of population:

general

Subjects:

- Number of subjects exposed: 10
- Sex: 6(F) + 4(M)
-Age: 51-66 yr
-Race: Six were black and four were white
-Exclusion criteria: Malignancy, diabetes, rheumatoid arthritis, alcoholism, chronic liver or renal disease, malabsorption syndrome, use of medications that may affect zinc metabolism, and any chronically debilitating illness.

Ethical approval:

not specified

Route of exposure:

oral

Reason of exposure:

intentional

Exposure assessment:

measured

Details on exposure:

single orally administration of test material equivalent to 50 mg elemental zinc

Examinations:

plasma zinc levels

Results and discussion

Results of examinations:

absorption: Zinc was least absorbed after oral administration of zinc oxide among all the zinc compounds tested. Peak plasma concentration of 159.3 ± 29.5 µg/dL reached after 2.5 hr of zinc oxide administration. Plasma concentration reached the near baseline value after 4.5 hr. (see table 1 for details).
Area under the curve generated by percent changes in plasma zinc was lowest (~ 500) after zinc oxide administration among all the zinc compounds tested (Refer Fig. 3 of the reference).
Refer to Fig. 1 and Fig. 2 of the reference for the time related changes in plasma zinc levels and percent changes in plasma zinc, respectively.

Any other information on results incl. tables

Table 1.Changes in plasma zinc levels following the oral zinc oxide administration

Time point	Plasma Zinc (µg/dL) (mean±SD)
Base I	113.0 ± 22.0
Base II	105.3 ± 18.8
After Zn administration
30 min	112.9 ± 20.7
1 h 30 min	143.4 ± 43.6
2 h 30 min	159.3 ± 29.5
3 h 30 min	126.3 ± 25.9
4 h 30 min	113.9 ± 29.8
5 h 30 min	98.4 ± 23.1

Applicant's summary and conclusion

Conclusions:

Under the study conditions, zinc oxide was least absorbed among all the zinc compounds tested. A comparison of AUC values for different zinc forms were compared, it appeared that the bioavailability of zinc oxide was about 60% of the bioavailability of the soluble forms.

Executive summary:

Oral zinc tolerance test was performed in humans to study the absorption of zinc from various zinc compounds including zinc oxide.

Six female and four male volunteers were administered orally a zinc compound capsule containing 50 mg elemental zinc. Two blood samples were drawn (15 min. apart) for baseline data at initiation of study. Further samples were drawn at 30 min. and thereafter at hourly intervals for 5 h after drug administration. Various zinc compounds (zinc acetate, zinc oxide, zinc sulfate, zinc aminoate and zinc methionine) were tested as described at same dose level in same individuals after every 2 wk intervals.

Zinc was least absorbed after oral administration of zinc oxide among all the zinc compounds tested. Peak plasma concentration of 159.3 ± 29.5 µg/dL reached after 2.5 h of zinc oxide administration. Plasma concentration reached the near baseline value after 4.5 h. Area under the curve generated by percent changes in plasma zinc was lowest (~ 500) after zinc oxide administration among all the zinc compounds tested. A comparison of AUC values for different zinc forms were compared, it appeared that the bioavailability of zinc oxide was about 60% of the bioavailability of the soluble forms.

Under the study conditions, zinc oxide was least absorbed among all the zinc compounds tested.