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Toxicological information

Direct observations: clinical cases, poisoning incidents and other

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Administrative data

Endpoint:
direct observations: clinical cases, poisoning incidents and other
Type of information:
migrated information: read-across based on grouping of substances (category approach)
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

Reference
Name:
Unnamed
Type:
Constituent
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.