ARCHITECT IDIGOXIN AND ARCHITECT IDIGOXIN CALIBRATORS, MODELS 1P32-25 AND IP32-01

K082953 · Biokit, S.A. · KXT · Dec 22, 2008 · Clinical Toxicology

Device Facts

• Record ID: K082953
• Device Name: ARCHITECT IDIGOXIN AND ARCHITECT IDIGOXIN CALIBRATORS, MODELS 1P32-25 AND IP32-01
• Applicant: Biokit, S.A.
• Product Code: KXT · Clinical Toxicology
• Decision Date: Dec 22, 2008
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 862.3320
• Device Class: Class 2

Indications for Use

The ARCHITECT iDigoxin assay is an in vitro chemiluminescent microparticle immunoassay (CMIA) for the quantitative measurement of digoxin in human serum or plasma on the ARCHITECT i System with STAT protocol capability. The measurements obtained are used to aid in the diagnosis and treatment of digoxin overdose and in monitoring levels of digoxin to help ensure appropriate therapy. The ARCHITECT iDigoxin Calibrators are for the calibration of the ARCHITECT i System with STAT protocol capability when used for the quantitative determination of digoxin in human serum or plasma. For in vitro diagnostic use

Device Story

ARCHITECT iDigoxin is an in vitro chemiluminescent microparticle immunoassay (CMIA) for quantitative digoxin measurement in human serum or plasma. Used on ARCHITECT i System with STAT protocol. Principle: one-step competitive immunoassay; sample, antidigoxin-coated paramagnetic microparticles, assay diluent, and digoxigenin acridinium-labeled conjugate combined. Microparticles bind to digoxin in sample and labeled conjugate. After washing, pre-trigger solutions added; chemiluminescent reaction measured as relative light units (RLUs). Indirect relationship between digoxin concentration and RLUs. Operated by laboratory personnel in clinical settings. Output used by clinicians to assess digoxin toxicity and therapeutic levels, aiding clinical decision-making for patient treatment.

Clinical Evidence

Clinical performance demonstrated via method comparison against predicate Aeroset Multigent Digoxin. Study yielded a Pearson correlation coefficient of 0.993. Non-clinical data included precision, linearity, and interference testing.

Technological Characteristics

Chemiluminescent microparticle immunoassay (CMIA). Components: antidigoxin-coated paramagnetic microparticles, digoxigenin acridinium-labeled conjugate. Detection: chemiluminescence measured as relative light units (RLUs). Platform: ARCHITECT i System. In vitro diagnostic use.

Indications for Use

Indicated for quantitative measurement of digoxin in human serum or plasma to aid in diagnosis/treatment of digoxin overdose and monitoring therapy levels. No specific age or gender restrictions provided; contraindications include use of antibody fragment therapy (e.g., DIGIBIND) which interferes with immunoassay measurements.

Regulatory Classification

Identification

A digoxin test system is a device intended to measure digoxin, a cardiovascular drug, in serum and plasma. Measurements obtained by this device are used in the diagnosis and treatment of digoxin overdose and in monitoring levels of digoxin to ensure appropriate therapy.

Predicate Devices

• Aeroset Multigent Digoxin (k023058)

Submission Summary (Full Text)

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# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY ASSAY ONLY TEMPLATE

A. 510(k) Number:
k082953

B. Purpose for Submission:
New device

C. Measurand:
Digoxin

D. Type of Test:
Quantitative

E. Applicant:
Biokit S.A.

F. Proprietary and Established Names:
ARCHITECT iDigoxin Reagents
ARCHITECT iDigoxin Calibrators

G. Regulatory Information:

| Product Code | Classification | Regulation Section | Panel |
| --- | --- | --- | --- |
| KXT | Class II | 862.3320 | 91, Toxicology |
| DLJ | Class II | 862.3200 | 91, Toxicology |

H. Intended Use:

1. Intended use(s):
See Indications for Use below.

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2. Indication(s) for use:

The ARCHITECT iDigoxin assay is an in vitro chemiluminescent microparticle immunoassay (CMIA) for the quantitative measurement of digoxin in human serum or plasma on the ARCHITECT i System with STAT protocol capability. The measurements obtained are used to aid in the diagnosis and treatment of digoxin overdose and in monitoring levels of digoxin to help ensure appropriate therapy.

The ARCHITECT iDigoxin Calibrators are for the calibration of the ARCHITECT i System with STAT protocol capability when used for the quantitative determination of digoxin in human serum or plasma.

For in vitro diagnostic use

3. Special conditions for use statement(s):

For prescription use only

4. Special instrument requirements:

ARCHITECT i System

I. Device Description:

The ARCHITECT iDigoxin assay is an in vitro chemiluminescent microparticle immunoassay (CMIA) for the quantitative measurement of digoxin in human serum or plasma on the ARCHITECT i System with STAT protocol capability. The measurements obtained are used to aid in the diagnosis and treatment of digoxin overdose and in monitoring levels of digoxin to help ensure appropriate therapy.

Each iDigoxin Reagent kit contains 1 bottle of each component of Microparticles, Conjugate and Assay Diluent.

- Microparticles - 1 bottle (6.6 mL) Anti-digoxin (mouse, monoclonal) coated microparticles in TRIS buffer with protein (bovine) stabilizer. Preservative: ProClin 300.
- Conjugate - 1 bottle (5.9 mL) Digoxigenin acridinium-labeled conjugate in citrate buffer. Preservative: ProClin 300.
- Assay Diluent - 1 bottle (10.0 mL) Assay Diluent containing goat serum with EDTA disodium. Preservative: ProClin 300 and ProClin 950.

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The ARCHITECT iDigoxin Calibrators are for the calibration of the ARCHITECT i System with STAT protocol capability when used for the quantitative determination of digoxin in human serum or plasma.

Each digoxin calibrator kit contains 6 bottles of ARCHITECT iDigoxin Calibrators (4.0 mL each). Calibrators A-F contain normal human serum and digoxin except Calibrator A has no digoxin as shown below.

Cal A 0.0 ng/mL

Cal B 0.5 ng/mL

Cal C 1.0 ng/mL

Cal D 2.0 ng/mL

Cal E 3.0 ng/mL

Cal F 4.0 ng/mL

The normal human serum used in the calibrators has been tested by an FDA approved method and found to be nonreactive for HIV-1/2 Antibody, HCV Antibody, HTLV-1/2 Antibody, HBc Antibody and HBsAg.

J. Substantial Equivalence Information:

1. Predicate device name(s):

The ARCHITECT iDigoxin device is compared to the Aeroset Multigent Digoxin

2. Predicate K number(s):

k023058

3. Comparison with predicate:

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# REAGENTS

Similarities

| Reagents | Device | Predicate |
| --- | --- | --- |
| Intended use | The ARCHITECT i Digoxin assay is an in vitro chemiluminescent microparticle immunoassay (CMIA) for the quantitative measurement of digoxin in human serum or plasma on the ARCHITECT i System with STAT protocol capability. The measurements obtained are used to aid in the diagnosis and treatment of digoxin overdose and in monitoring levels of digoxin to help ensure appropriate therapy. | The MULTIGENT Digoxin assay is used for the quantitative in vitro measurement of digoxin in human serum or plasma on the ARCHITECT c 8000® System and the AEROSET System. |
| Specimen type | Human serum or plasma | Human serum or plasma. |

Differences

| Reagents | Device | Predicate |
| --- | --- | --- |
| Platform | ARCHITECT i System | ARCHITECT c 8000® System and the AEROSET System |
| System Methodology | Chemiluminescent Microparticle Immunoassay (CMIA). | Homogeneous particle-enhanced turbidimetric immunoassay (PETIA) |
| Components | 1 bottle Microparticles: 6.6 mL
1 bottle Conjugate: 5.9 mL
1 bottle Assay Diluent: 10.0 mL | 2 bottles R1: 45 mL
2 bottles R2: 17 mL |

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# CALIBRATORS

Similarities

| Calibrators | Device | Predicate |
| --- | --- | --- |
| Intended use | The ARCHITECT i Digoxin Calibrators are for the calibration of the ARCHITECT i System with STAT protocol capability when used for the quantitative determination of digoxin in human serum or plasma. | The MULTIGENT. Digoxin Calibrators are intended for in vitro diagnostic use with the AEROSET® System and the ARCHITECT® c8000. System for the calibration of the MULTIGENT. Digoxin Assay. |
| Standardization | Internal Reference Calibrators are manufactured gravimetrically using USP Reference Standard Digoxin. The ARCHITECT i Digoxin Calibrators are matched to the internal Reference Calibrators. | MULTIGENT. Digoxin Calibrators are gravimetrically prepared using weighing equipment calibrated to standards that are traceable to NIST weight standards. Digoxin used to prepare calibrators is traceable to digoxin USP. |
| Traceability | USP Reference Standard Digoxin | Digoxin USP |

Differences

| Calibrators | Device | Predicate |
| --- | --- | --- |
| Platform | ARCHITECT i System | ARCHITECT c 8000® System and the AEROSET System |
| System Methodology | Chemiluminescent Microparticle Immunoassay (CMIA). | Homogeneous particle-enhanced turbidimetric immunoassay (PETIA) |
| Calibration Range/Levels | A: 0.00 ng/mL (0.00 nmol/L) B: 0.05 ng/mL (0.64 nmol/L) C: 1.00 ng/mL (1.28 nmol/L) D: 2.00 ng/mL (2.56 nmol/L) E: 3.00 ng/mL (3.84 nmol/L) F: 4.00 ng/mL (5.12 nmol/L) | 1: 0.00 ng/mL (0.00 nmol/L) 2: 0.05 ng/mL (0.64 nmol/L) 3: 1.00 ng/mL (1.28 nmol/L) 4: 2.00 ng/mL (2.56 nmol/L) 5: 3.00 ng/mL (3.84 nmol/L) 6: 5.00 ng/mL (6.40 nmol/L) |
| Components | 6 bottles of 4.0 mL each. | Cal 1: 1 bottle of 4.8 mL. Cal 2 - 6: 1 bottle of 1.8 mL. |
| Matrix | Calibrators A-F contain normal human serum Calibrators B-F contain digoxin. | The MULTIGENT Digoxin Calibrators contain buffer spiked with digoxin. |

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K. Standard/Guidance Document Referenced (if applicable):

Clinical Laboratory Standards Institute; Evaluation of Precision Performance of Quantitative Measurement Methods (CLSI EP5-A2 guideline)

Clinical and Laboratory Standards Institute; Protocols for Determination of Limits of Detection and Limits of Quantitation (CLSI EP17-A guideline)

Clinical and Laboratory Standards Institute; Interference Testing in Clinical Chemistry (CLSI EP7-A2)

L. Test Principle:

The ARCHITECT iDigoxin assay is a one-step STAT immunoassay for the quantitative measurement of digoxin in human serum or plasma using CMIA technology with flexible assay protocols, referred to as Chemiflex. Sample, anti-digoxin coated paramagnetic microparticles, assay diluent, and digoxigenin acridinium-labeled conjugate are combined to create a reaction mixture. The anti-digoxin coated microparticles bind to digoxin present in the sample and to the digoxigenin acridinium-labeled conjugate. After washing, pre-trigger and trigger solutions are added to the reaction mixture. The resulting chemiluminescent reaction is measured as relative light units (RLUs). An indirect relationship exists between the amount of digoxin in the sample and the RLUs detected by the ARCHITECT i System optics

M. Performance Characteristics (if/when applicable):

All performance characteristics were established on the ARCHITECT i2000SR system.

1. Analytical performance:

a. Precision/Reproducibility:

Precision was performed with the ARCHITECT iDigoxin assay based on the National Committee for Clinical Laboratory Standards (CLSI EP5-A2 guideline).

Two ARCHITECT i 2000SR Systems were used along with 2 lots of reagents and 2 lots of calibrators. The assay was run twice a day for 20 days using 3 Multi-constituent Controls and 3 human serum based panels in replicates of 2.

The 3 human serum based panels were prepared by adding digoxin concentrations into a pool of human sera at final concentrations targeted at 0.80, 2.00 and 3.60 ng/mL.

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The table below summarizes the precision study results and is included in the reagent package insert.

| Sample | Instrument | Reagent Lot | n | Mean (ng/mL) | Within Run | | Total | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | | | SD | %CV | SD | %CV |
| Level1 | 1 | 1 | 80 | 0.81 | 0.020 | 2.5 | 0.024 | 3.0 |
| | 2 | 2 | 80 | 0.82 | 0.020 | 2.4 | 0.027 | 3.3 |
| Level 2 | 1 | 1 | 80 | 1.72 | 0.032 | 1.9 | 0.053 | 3.1 |
| | 2 | 2 | 80 | 1.73 | 0.030 | 1.7 | 0.040 | 2.3 |
| Level 3 | 1 | 1 | 80 | 2.88 | 0.069 | 2.4 | 0.075 | 2.6 |
| | 2 | 2 | 80 | 2.89 | 0.055 | 1.9 | 0.059 | 2.0 |
| Panel 1 | 1 | 1 | 80 | 0.66 | 0.024 | 3.6 | 0.029 | 4.4 |
| | 2 | 2 | 80 | 0.68 | 0.017 | 2.5 | 0.025 | 3.7 |
| Panel 2 | 1 | 1 | 80 | 1.70 | 0.039 | 2.3 | 0.059 | 3.5 |
| | 2 | 2 | 80 | 1.72 | 0.026 | 1.5 | 0.035 | 2.0 |
| Panel 3 | 1 | 1 | 80 | 3.53 | 0.064 | 1.8 | 0.118 | 3.3 |
| | 2 | 2 | 80 | 3.57 | 0.056 | 1.6 | 0.087 | 2.4 |

# b. Linearity/assay reportable range:

Five pooled serum samples (1.80, 2.40, 3.00, 3.60 and $3.90\mathrm{ng / mL}$ ) were diluted manually with the ARCHITECT iDigoxin Calibrator A. Each sample was diluted to have 11 concentration levels. Each sample was diluted using the ARCHITECT iDigoxin Calibrator A. The concentration of digoxin was determined using the ARCHITECT iDigoxin assay and the resulting percent deviation from linearity or concentration difference was calculated. For diluted samples reading above $1.0\mathrm{ng / mL}$ , the percent deviation from linearity ranged from 4.0 to $8.8\%$ . For diluted samples below $1.0\mathrm{ng / mL}$ , the concentrations were within $0.1\mathrm{ng / mL}$ of the expected results. The regression equations for the five samples are shown in the table below. The linear range of the assay is 0.3 to $4.0\mathrm{ng / mL}$ .

| Sample A (1.80 ng/mL) | y = 0.9940x + 0.07 |
| --- | --- |
| Sample B (2.40 ng/mL) | y = 0.9845x + 0.07 |
| Sample C (3.00 ng/mL) | y = 0.9943x + 0.05 |
| Sample D (3.60 ng/mL) | y = 0.9599x + 0.05 |
| Sample E (3.90 ng/mL) | y = 0.9925x + 0.04 |

# c. Traceability, Stability, Expected values (controls, calibrators, or methods):

Internal Reference Calibrators are manufactured gravimetrically using

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purified synthetic Digoxin from US Pharmacopeia (USP) Reference Standard Digoxin. The ARCHITECT iDigoxin Calibrators are manufactured using normal human serum and matched to the internal Reference Calibrators.

The normal human serum used in the calibrators has been tested by an FDA approved method and found to be nonreactive for HIV-1/2 Antibody, HCV Antibody, HTLV-1/2 Antibody, HBc Antibody and HBsAg.

Real time stability testing is ongoing. Based on accelerated stability results, the data support an expiration date of 9 months for ARCHITECT iDigoxin Calibrator Kits at 2-8°C.

Open-vial real time stability testing for the calibrators is ongoing. Testing currently supports a storage time of 4 months at 2-8°C.

d. Detection limit:

A study was conducted to determine the limit of the blank (LoB) and the limit of detection (LoD) for the ARCHITECT iDigoxin assay using the ARCHITECT i2000SR. System following CLSI guideline 17-A. The determinations were performed using one blank, assayed 60 times and four samples containing low concentrations of digoxin assayed 15 times. The limit of blank obtained was 0.07 ng/mL and limit of detection was 0.09 ng/mL.

A functional sensitivity study was performed using a series of seven samples ranging from 0.05 to 0.5 ng/mL which were prepared by diluting Calibrator B with Calibrator A. These samples were tested in replicates of ten two times per day for five days using one reagent and calibrator lot for a total of 100 replicates per panel. The total % CVs were calculated and plotted against the mean concentration. A reciprocal curve was fitted through the data, and the functional sensitivity value was calculated as the concentration corresponding to the 20% CV level of the fitted curve. At the upper 95% confidence limit, the lowest ARCHITECT i Digoxin assay value exhibiting a 20% CV was calculated to be 0.1 ng/mL, which is below the reportable range of the ARCHITECT i Digoxin assay.

The measuring range is 0.3 to 4.0 ng/mL.

e. Analytical specificity:

A study was conducted to evaluate the potential interference from triglycerides, hemoglobin, bilirubin, protein (low and high level), HAMA and Rheumatoid Factor (RF) in the ARCHITECT iDigoxin assay using the ARHITECT i 2000SR system.

Interference testing was performed on the ARCHITECT i System. Testing

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was performed based on guidance from the Clinical and Laboratory Standards Institute document CLSI Document EP7-A2.

No influence from the endogenous interfering substances tested was observed during the study.

Five serum specimens with digoxin levels ranging from 0.35 to 2.84 ng/mL were supplemented with the following potentially interfering compounds. The mean recovery observed during the study ranged from 99.1% to 104.8%. The following table is included in the reagent package insert. Results are shown below:

| Potentially Interfering Compound | Interferent Concentration | % Recovery Range (Individual) |
| --- | --- | --- |
| Bilirubin | 20 mg/dL | 98.9-103.1 |
| Hemoglobin | 750 mg/dL | 100.0-103.2 |
| Triglycerides | 2500 mg/dL | 98.4-105.6 |
| HAMA | 1000 ng/mL | 98.1-101.6 |
| Rheumatoid Factor | 500 IU/mL | 97.1-102.5 |
| Low Protein | 3 g/dL | 94.3-106.8 |
| High Protein | 12 g/dL | 97.6-109.8 |

Cross-reactivity was tested for the major digoxin active metabolites (digoxigenin bis-digitoxoside, digoxigenin mono-digitoxoside, digoxigenin), related compounds (acetyldigoxin, digitoxin, digitoxigenin, ouabain, deslanoside, lanatoside C, proscillaridin) and other therapeutic agents that may be co-administered to determine whether these compounds affect the quantitation of digoxin concentrations using the ARCHITECT i Digoxin assay. The compounds were spiked into a serum pool (control) containing no digoxin and into two therapeutic levels (approximately 0.8 ng/mL and 2.0 ng/mL) of digoxin. The samples were assayed and the digoxin concentrations of the spiked samples were compared to the control serum. The data are summarized in the following table.

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| | Digoxin Concentration (Conc.) (ng/mL) | | | | | |
| --- | --- | --- | --- | --- | --- | --- |
| | | 0.0 | 0.8 | | 2.0 | |
| Test Compound | Test Compound Conc. (ng/mL) | Conc. Difference | Conc. Difference | Cross React. (%) | Conc. Difference | Cross React. (%) |
| Digoxigenin bis-digitoxoside | 1.30 | 2.03 | 1.86 | 143.1 | _c* | _c* |
| Digoxigenin mono-digitoxoside | 1.00 | 1.49 | 0.69 | 69.0 | 0.96 | 96.0 |
| Digoxigenin | 0.80 | 0.15 | 0.02 | 2.5 | -0.05 | -6.3 |
| Acetyldigoxin | 2.50 | 2.70 | 2.34 | 93.6 | _c* | _c* |
| Digitoxin | 25 | 0.04 | 0.07 | 0.3 | -0.09 | -0.4 |
| Digitoxigenin | 15 | 0.00 | 0.04 | 0.3 | -0.08 | -0.5 |
| Ouabain | 860 | 1.38 | 0.28 | 0.0 | 0.22 | 0.0 |
| Deslanoside | 2.25 | 2.03 | 1.65 | 73.3 | 1.66 | 73.8 |
| Lanatoside C | 1.55 | 1.98 | 1.14 | 73.5 | 0.96 | 61.9 |
| Proscillaridin | 340 | 0.21 | 0.26 | 0.1 | 0.08 | 0.0 |
| Spironolactone | 500 | 0.35 | 0.04 | 0.0 | 0.21 | 0.0 |
| Canrenone | 1000 | 0.00 | 0.01 | 0.0 | 0.05 | 0.0 |
| Canrenoic Acid | 1000 | 0.36 | 0.08 | 0.0 | -0.04 | 0.0 |
| Hydrocortisone | 2000 | 0.12 | 0.02 | 0.0 | 0.01 | 0.0 |
| Methylprednisolone | 7000 | 0.02 | 0.08 | 0.0 | -0.05 | 0.0 |
| Prednisolone | 1000 | 0.15 | 0.02 | 0.0 | 0.37 | 0.0 |
| Dexamethasone | 5000 | 0.36 | 0.19 | 0.0 | 0.10 | 0.0 |
| Progesterone | 250 | 0.05 | 0.06 | 0.0 | -0.12 | 0.0 |
| Amiloride | 50 | 0.00 | 0.36 | 0.7 | -0.04 | -0.1 |
| Amrinone | 7000 | 0.15 | -0.11 | 0.0 | 0.11 | 0.0 |
| Clorazepate | 1500 | 0.00 | 0.04 | 0.0 | -0.09 | 0.0 |
| Nabumetone | 37,000 | 0.00 | 0.12 | 0.00 | -0.04 | 0.0 |
| Phenytoin | 80,000 | 0.00 | 0.16 | 0.0 | -0.03 | 0.0 |
| Triamterene | 500 | 0.00 | -0.25 | -0.1 | -0.03 | 0.0 |

_c*: Not determined. The value obtained is outside the assay range

In addition, the labeling contains the following information:

"The sera from patients in specific patient populations (i.e., patients with renal and/or hepatic failure, newborn infants, and pregnant women) have been reported to contain an unidentified component that gives positive results for digoxin with a number of immunoassays. This component has been called digoxin-like immunoreactive factor (DLIF) or substance (DLIS). The presence of DLIF in a sample can result in falsely elevated digoxin assay

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results. The amount of DLIF in these patient samples is extremely variable, but in some cases these levels have been shown to approach concentrations that are in the therapeutic range of digoxin. As with any assay employing mouse antibodies, the possibility exists for interference by HAMA in the sample, which could falsely elevate or depress results. The manufacturer of Digoxin Immune Fab has stated that no immunoassay technique is suitable for quantitating digoxin in serum from patients on antibody fragment therapy. According to the manufacturer's insert, DIGIBIND will interfere with digitalis immunoassay measurements."

"It has been reported in the literature that one in ten patients converts $40\%$ or more of oral digoxin to an inactive reduction product (dihydrodigoxin) via bacteria in the gut. There is little or no cross-reactivity reported for dihydrodigoxin."

f. Assay cut-off:

Not applicable

# 2. Comparison studies:

a. Method comparison with predicate device:

A study was performed using 200 serum and plasma (heparin and EDTA) samples with values ranging from $0.34\mathrm{ng / mL}$ to $3.93\mathrm{ng / mL}$ using the ARCHITECT iDigoxin Reagents on the Architect i2000SR vs. predicate Multigent Digoxin on the Aeroset system. The results are shown in the table below:

| Regression method | Number of observations | Slope (95% CI) | Intercept (95% CI) | Correlation coefficient |
| --- | --- | --- | --- | --- |
| Passing-Bablok | 200 | 0.921 (0.906 to 0.937) | -0.040 (0.061 to -0.018) | 0.993 |

b. Matrix comparison:

Three plasma tube types and one serum specimen tube were collected from 20 individuals. Serum tubes without additives were used as the control. Human serum and plasma specimens were collected in the following tube types:

- serum no additive
- potassium EDTA (K-EDTA)

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- sodium heparin (Na-heparin)
- lithium heparin (Li-heparin)

Each of the 20 sets of serum/plasma tubes were spiked with digoxin to achieve 10 different spiking concentrations (0.30, 0.40, 0.60, 0.80, 1.20, 1.60, 2.00, 2.80, 3.20 and 3.60 ng/mL). Two tubes of each collecting tube type were used for each spiking level. The results are provided in the following table:

| Tube type | N | Mean % recovery vs. Serum |
| --- | --- | --- |
| Serum no additive | 20 | Control |
| K-EDTA | 20 | 98.3 |
| Na-Heparin | 20 | 97.9 |
| Li-Heparin | 20 | 97.5 |

3. Clinical studies:

a. Clinical Sensitivity:

Not applicable

b. Clinical specificity:

Not applicable

c. Other clinical supportive data (when a. and b. are not applicable):

4. Clinical cut-off:

Not applicable

5. Expected values/Reference range:

The Expected Values for ARCHITECT iDigoxin have been established based on bibliography references.

The statement presented in the package insert is as follows:

"The ARCHITECT iDigoxin assay accurately quantitates digoxin concentrations in human serum or plasma at concentrations up to 4.0 ng/mL. Numerous studies have shown a relationship between serum levels of digoxin and its concentration in myocardial and other tissues. Optimum therapeutic effects usually are observed

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when serum levels are in the range from 0.8 to 2.0 ng/mL based on radioimmunoassay, although some clinical benefit may be realized at serum or plasma concentrations below 0.8 ng/mL. The risk of toxicity increases at serum or plasma levels above 2.0 ng/mL. Symptoms of digoxin toxicity may include gastrointestinal disturbances such as anorexia, nausea, vomiting and diarrhea, central nervous system disturbances manifested by blurred or yellow vision, headache, weakness, dizziness, apathy, and confusion, and cardiac rhythm disturbances and tachycardia. There is some evidence that children may tolerate slightly higher serum or plasma concentrations than adults. It is important to note that the distinction between adequate digitalization and toxicity in patients cannot be made on the basis of digoxin concentrations alone. Most studies show a significant overlap between the toxic and nontoxic groups. Additional factors to consider when evaluating the correct therapeutic dosage for each patient are lean body weight, age, renal function, concomitant disease states, concurrent medications, and other clinical factors."

The literature references are provided in the package insert for the statements above.

N. Proposed Labeling:

The labeling is sufficient and it satisfies the requirements of 21 CFR Part 809.10.

O. Conclusion:

The submitted information in this premarket notification is complete and supports a substantial equivalence decision.

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