American Association for Clinical Chemistry
Better health through laboratory medicine
August 2011 Clinical Laboratory News: Cross Reactivity of Tacrolimus and Sirolimus Major Metabolites

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Table 1
Cross Reactivity of Cyclosporine Major Metabolites
Metabolite Bioactivity
(%)
Concentration
Relative
to Parent (%)
Seimens
ACMIA
Seimens
ADVIA
Microgenics
CEDIA
Roche
EMIT
Syva
EMIT
Abbott
MEIA
AM1 (M17)
1-β-hydroxyl
10–20 80–150 1.8% @
1000 ng/mL
<5% @
1000 ng/mL
4.4% @
1000 ng/mL
<AS @
500 ng/mL
<0.3% @
500 ng/mL -5.9% @
1000 ng/mL
-0.7–1.7% @
1000 ng/mL
AM 9 (M1)
9-γ-hydroxyl
5–10 50–75 2.1% @
1000 ng/mL
15% @
1000 ng/mL
20.0% @
1000 ng/mL
13% @
667 ng/mL
7.3% @
670 ng/mL 5.5% @
1000 ngmL
-3.8–1.9% @
1000 ng/mL
AM 4N (M21)
4-N-demethyl
3–5 5–25 6.0% @
1000 ng/mL
<5% @
1000 ng/mL
16.0% @
1000 ng/mL
5.1% @
500 ng/mL
<0.3% @
500 ng/mL 0.9% @
1000 ng/mL
-2.3–3.1% @
1000 ng/mL
Abbreviations: ACMIA, affinity column-mediated immunoassay; CEDIA, cloned-enzyme donor immunoassay; EMIT, enzyme-multiplied immunoassay; and MEIA, microparticle enzyme immunoassay.

 

Table 2
Cross Reactivity of Sirolimus Major Metabolites
Metabolite Bioactivity %
7, 8
Concentration
Relative
to Parent %
Seimens
ACMIA
Syva
EMIT
Abbott
MEIA
39-O-demethyl
(41-O-demethyl)
10 7 52% @
0 ng/mL 60% @
12 ng/mL
38% @
0 ng/mL 42% @
10 ng/mL
20.3% @
10 ng/mL
16-O-demethyl
(7-O-demethyl)
NS 4 10% @
0 ng/mL 6% @
12 ng/mL
15% @
0 ng/mL 21% @
10 ng/mL
7.6% @
3 ng/mL
12 hydroxyl
(11 hydroxyl)
7 11 46% @
0 ng/mL 53% @
12 ng/mL
4% @
0 ng/mL 6% @
10 ng/mL
36.8% @
10 ng/mL
27, 39-O-didemethyl
(41, 32-O-didemethyl)
NS 31 89% @
0 ng/mL 83% @
12 ng/mL
52% @
0 ng/mL 61% @
10 ng/mL
NS
Abbreviations: NS, not stated; ACMIA, affinity column-mediated immunoassay; EMIT, enzyme-multiplied immunoassay; and MEIA, microparticle enzyme immunoassay.

 

Table 3
Cross Reactivity of Tacrolimus Major Metabolites

Metabolite Bioactivity %
5, 6
Concentration
Relative
to Parent %
Seimens
ACMIA
Microgenics
CEDIA
Syva
EMIT
Abbott
MEIA
M I
13-O-demethyl
6 6 14.8% @
50 ng/mL
37.7% @
20 ng/mL
10.4% @
100 ng/mL
8% @
10 ng/mL
M II
31-O-demethyl
100 15 2.7% @
50 ng/mL
<AS @
20 ng/mL
1.6% @
100 ng/mL
94% @
10 ng/mL
M III
15-O-demethyl
0 6 1.0% @
50 ng/mL
<AS @
20 ng/mL
2.2% @
100 ng/mL
45% @
10 ng/mL
M IV
12 hydroxyl
3.5 NS 18.0% @
50 ng/mL
NS 21.1% @
100 ng/mL
9% @
10 ng/mL
M V
15, 31-O-didemethyl
0 NS 0.5% @
50 ng/mL
NS 2.5% @
100 ng/mL
NS
Abbreviations: AS, analytical sensitivity; NS, not stated; ACMIA, affinity column-mediated immunoassay; CEDIA, cloned-enzyme donor immunoassay; EMIT, enzyme-multiplied immunoassay; and MEIA, microparticle enzyme immunoassay

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