Mycophenolic Acid

Catalog Number: 04357213190

SYSTEM INFORMATION

For cobas c 311/501 analyzers:

TMPA: ACN 623

For cobas c 502 analyzer:

TMPA: ACN 8623

INTENDED USE

In vitro test for the quantitative determination of total mycophenolic acid in serum or plasma as an aid in the management of mycophenolic acid therapy in renal and cardiac transplant patients on Roche/Hitachi cobas c systems.

STORAGE AND STABILITY

Shelf life at 2 to 8 °C: See expiration date on cobas c pack label
On-board in use and refrigerated on the analyzer:Do not freeze. 12 weeks

APPLICATION FOR SERUM AND PLASMA

cobas c 311 test definition
Assay type Rate-A
Reaction time / Assay points 10 / 40-57
Wavelength (sub/main) 415/340 nm
Reaction direction Increase
Unit µg/mL
Reagent pipetting Diluent (H2O)
R1 180 µL
R2 19 µL
Sample volumes Sample Sample dilution
Sample Diluent (NaCl)
Normal 3.0 µL
Decreased 3.0 µL
Increased 3.0 µL

cobas c 501/502 test definition
Assay type Rate-A
Reaction time / Assay points 10 / 54-70
Wavelength (sub/main) 415/340 nm
Reaction direction Increase
Unit µg/mL
Reagent pipetting Diluent (H2O)
R1 180 µL
R2 19 µL
Sample volumes Sample Sample dilution
Sample Diluent (NaCl)
Normal 3.0 µL
Decreased 3.0 µL
Increased 3.0 µL

Deselect Automatic Rerun for these applications in the Utility menu, Application screen, Range tab.

CALIBRATION

Traceability: The Total MPA Calibrators are prepared to contain known quantities of mycophenolic acid in normal human serum and are traceable to a primary reference method (HPLC).

Calibrators S1-6: Total MPA Calibrators
Calibration mode RCM
Calibration frequency 6-point calibrationafter reagent lot change and every 2 weeksas required following quality control procedures

LIMITS AND RANGES

Measuring range

0.4-15 µg/mL (1.2-46.8 µmol/L)

Extended measuring range

Postdilution factor: 5 recommended

0.4-50 µg/mL (1.2-156.1 µmol/L)

Manually dilute samples above the measuring range with the diluent (equivalent to the 0 µg/mL calibrator) from the Roche Total MPA Calibrators (1 part sample + 4 parts diluent) and reassay. Multiply the result by 5 to obtain the specimen value.

Lower limits of measurement

Lower detection limit of the test

0.3 µg/mL (0.9 µmol/L)

The lower detection limit represents the lowest measurable analyte level that can be distinguished from zero. It is calculated as the value lying 2 standard deviations above that of the 0 µg/mL calibrator (standard A + 2 SD, repeatability, n = 21).

Functional sensitivity

0.4 µg/mL (1.2 µmol/L)

The functional sensitivity is calculated as the lowest concentration from clinical samples with a CV of£ 20 %, tested in triplicate over 10 days (n = 30).

SPECIFIC PERFORMANCE DATA

Representative performance data on the analyzers are given below. Results obtained in individual laboratories may differ.

PRECISION

Precision was determined using human samples and controls in accordance with the CLSI (Clinical and Laboratory Standards Institute) EP5 requirements with repeatability (n = 63) and intermediate precision (3 aliquots per run, 1 run per day, 21 days). The following results were obtained on a Roche/Hitachi cobas c 501 analyzer.

.

Serum/Plasma

Repeatability Mean SD CV
µg/mL (µmol/L) µg/mL (µmol/L) %
Control 1 0.85 (2.65) 0.02 (0.06) 2.4
Control 2 3.46 (10.8) 0.03 (0.1) 0.8
Control 3 12.2 (38.1) 0.1 (0.3) 0.7
HP 1a 1.51 (4.71) 0.03 (0.09) 1.9
HP 2a 6.22 (19.4) 0.08 (0.3) 1.3

Intermediate precision Mean SD CV
µg/mL (µmol/L) µg/mL (µmol/L) %
Control 1 0.85 (2.65) 0.03 (0.09) 3.6
Control 2 3.46 (10.8) 0.06 (0.2) 1.6
Control 3 12.2 (38.1) 0.1 (0.4) 1.0
HP 1a 1.51 (4.71) 0.04 (0.12) 2.4
HP 2a 6.22 (19.4) 0.11 (0.3) 1.8
aHP 1 and HP 2 are non-spiked clinical samples

METHOD COMPARISON

Serum/plasma

Mycophenolic acid values for human plasma samples from renal and cardiac transplant patients were obtained using the cobas c 501 analyzer compared to those determined with a validated MPA HPLC method. These same samples were also compared to values obtained on the COBAS INTEGRA 400/800 analyzers. The sample population for this internal study included 88 renal and 70 cardiac samples from post-transplant patients. Other demographics for this sample population are unknown. Passing-Bablok statistics for the correlation are included in the method comparison table below.21

The following graph shows the correlation testing of the Roche Total MPA assay on the cobas c 501 analyzer vs. HPLC with the combined renal and cardiac samples from the above table.

The same data set from the regression plot above is depicted in the Bland-Altman difference plot shown below.

N = 158

Mean (Y-X) = 0.36

SD (Y-X) = 0.54

1.96 SD = 1.07

Mean + 1.96 SD = 1.43

Mean – 1.96 SD = - 0.70

In a separate study, mycophenolic acid values for human plasma samples obtained with the Roche Total Mycophenolic Acid assay on COBAS INTEGRA analyzers were compared to those using independent validated MPA HPLC methods. Samples from renal and cardiac transplant patients were tested at two external clinical sites with concurrent HPLC testing at each site.

The external trial included a total of 412 samples collected from post-transplant patients. The sample population for the COBAS INTEGRA 400 plus analyzer study included 265 samples (148 renal and 117 cardiac) from a total of 209 “routine” adult transplant recipients. Samples tested on the COBAS INTEGRA 800 analyzer were obtained from an international trial of renal transplant recipients (147 samples from 86 adult patients). The Passing-Bablok statistics of the correlations are shown in the table below.

Methodology Slope(95 % CI) Intercept(95 % CI) CorrelationCoefficient Sample Size SampleRange(µg/mL)
cobas c 501 analyzer vs. HPLC
Renal 1.043(1.025-1.060) 0.054(0.010-0.093) 0.997 88 0.460-13.6
Cardiac 1.109(1.077-1.141) -0.077(-0.147-0.005) 0.991 70 0.573-14.2
Combined 1.062(1.043-1.084) 0.016(-0.029-0.057) 0.994 158 0.460-14.2
cobas c 501 analyzer vs. COBAS INTEGRA 400 analyzer
Combined 0.996(0.990-1.00) -0.032(-0.040-(-0.014)) 1.000 161 0.44-14.0
cobas c 501 analyzer vs. COBAS INTEGRA 800 analyzer
Combined 0.977(0.971-0.984) 0.000(-0.018-0.014) 0.999 160 0.48-15.0

cobas c 501 analyzer (µg/mL) Roche Total MPA cobas c 501 analyzer vs. HPLC
HPLC (µg/mL)

Methodology Slope (95 % CI) Intercept (95 % CI) Correlation Coefficient Sample Size Sample Range (µg/mL)
COBAS INTEGRA 400 plus analyzer vs. HPLC 1.011(1.000-1.025) 0.064(0.038-0.090) 0.993 265 0.4-14.8
COBAS INTEGRA 800 analyzer vs. HPLC 1.100(1.073-1.120) -0.120(-0.192-(-0.066)) 0.994 147 0.5-14.7

ANALYTICAL SPECIFICITY

The following cross-reactive substances were evaluated on the cobas c 501 analyzer in normal human serum spiked with mycophenolic acid at 1.7 µg/mL (5.3 µmol/L) and 8.0 µg/mL (25.0 µmol/L). Cross-reactivity was designated as “not detectable” (ND) if the obtained value was less than the sensitivity of the assay.

The following compounds were tested at the concentrations listed for interference in normal human serum spiked with mycophenolic acid at approximately 1.5 µg/mL (4.7 µmol/L) and 9.0 µg/mL (28.1 µmol/L). No significant interference with the assay was found.

In addition, tests were performed on the following drugs, and no significant interference with the assay was found.

Cross-reactivity (%) = 100 × (analytical result - analyte concentration)
concentration of interferent

Drug Level tested(µg/mL) Cross-reactivity%
Mycophenolic acid glucuronide (MPAG) 1000 ND
Mycophenolic acid acyl glucuronide (AcMPAG) 10 6.5

Compound µg/mL Compound µg/mL
Acetaminophen 60 Isoproterenol 0.18
Acyclovir 45 Itraconazole 6
Albuterol 1.2 Kanamycin 180
Allopurinol 120 Ketoconazole 10.5
Alprazolam 6 Labetalol 0.573
Amikacin 105 Lidocaine 36
Amphotericin B 240 Lovastatin 0.036
Ascorbic Acid 120 Methylprednisolone 36
Atenolol 30 Metoclopramide 1.35
Azathioprene 9 Minoxidil 0.921
Bromocriptine 0.75 Misoprostol 0.018
Caffeine 180 Morphine sulfate 1.5
Captopril 15 N-Acetylprocainamide 120
Carbamazepine 90 Nadolol 3.6
Cefaclor 225 Naproxen 500
Ceftriaxone 2430 Niacin 2400
Cephalosporine 0.3 Nicardipine 0.564
Chloramphenicol 150 Nifedipine 1.2
Chloroquine 2.5 Omeprazole 18
Cimetidine 60 Penicillin G 36
Ciprofloxacin 30 Phenobarbital 300
Clonidine 0.03 Phenytoin 150
Colchicine 0.033 Piperacillin 120
Cyclophosphamide 1125 Prazosin 0.057
Cyclosporine A 1.2 Prednisolone 1.17
Digitoxin 0.075 Prednisone 0.9
Digoxin 0.015 Primidone 120
Diltiazem 0.12 Probucol 2400
Dipyridamole 7.5 Procainamide 72
Disopyramide 30 Promethazine 3.6
Erythromycin 180 Propanolol 6
Ethanol 12000 Quinidine 36
Everolimus 0.12 Ranitidine 18
Fluconazole 225 Rifampicin 192
Flucytosine 240 Salicylic Acid 1800
Folic Acid 0.060 Sirolimus 0.084
Furosemide 180 Spectinomycin 480
Ganciclovir 48 Sulfamethoxazole 1200
Gentamicin 36 Tacrolimus 0.12
Glipzide 6 Theophylline 120
Glyburide 6 Ticlopidine 4.26
Heparin 8000 U/L Tobramycin 36
Hydralazine 1.62 Triamterene 18
Hydrochlorothiazide 18 Trimethoprim 120
Ibuprofen 500 Valproic Acid 1500
Insulin 1320 mU/L Vancomycin 300
Isoniazid 120 Verapamil 6

Acetylcysteine Levodopa
Ampicillin-Na Methyldopa + 1.5 H2O 
Ca-Dobesilate Metronidazole
Cefoxitin Phenylbutazone
Doxycycline (Tetracycline)