← Product Code [ORI](/submissions/TX/subpart-d%E2%80%94clinical-toxicology-test-systems/ORI) · K232522

# ARK Levetiracetam II Assay (K232522)

_Ark Diagnostics, Inc. · ORI · Feb 27, 2024 · Clinical Toxicology · SESE_

**Canonical URL:** https://fda.innolitics.com/submissions/TX/subpart-d%E2%80%94clinical-toxicology-test-systems/ORI/K232522

## Device Facts

- **Applicant:** Ark Diagnostics, Inc.
- **Product Code:** [ORI](/submissions/TX/subpart-d%E2%80%94clinical-toxicology-test-systems/ORI.md)
- **Decision Date:** Feb 27, 2024
- **Decision:** SESE
- **Submission Type:** Traditional
- **Regulation:** 21 CFR 862.3350
- **Device Class:** Class 2
- **Review Panel:** Clinical Toxicology

## Indications for Use

The ARK Levetiracetam II Assay is a homogeneous enzyme immunoassay intended for the quantitative determination of levetiracetam in human serum or plasma on automated clinical chemistry analyzers. Levetiracetam concentrations can be used as an aid in management of patients treated with levetiracetam.

## Device Story

The ARK Levetiracetam II Assay is a homogeneous enzyme immunoassay (EIA) used in clinical laboratories to measure levetiracetam concentrations in human serum or plasma. The device utilizes a competitive binding mechanism: drug in the patient specimen competes with levetiracetam labeled with bacterial glucose-6-phosphate dehydrogenase (G6PDH) for binding to an anti-levetiracetam monoclonal antibody. When the drug binds the antibody, enzyme activity increases; active enzyme converts NAD to NADH, which is measured spectrophotometrically as a rate of change in absorbance. The assay is performed on automated clinical chemistry analyzers. Healthcare providers use the resulting quantitative concentration to assist in the clinical management of patients undergoing levetiracetam therapy. The assay is not intended for use when brivaracetam is present due to significant cross-reactivity.

## Clinical Evidence

Bench testing only. Performance validated via precision studies (CLSI EP05-A3), linearity (CLSI EP06-Ed2), and interference testing (CLSI EP7-A3). Method comparison study against predicate using 104 patient samples (range 3.4–98.3 μg/mL) yielded Passing-Bablok regression Y = 1.04X - 0.30, R² = 0.99. No clinical trials performed.

## Technological Characteristics

Homogeneous enzyme immunoassay; reagents include anti-levetiracetam monoclonal antibody/substrate (R1) and levetiracetam-labeled bacterial G6PDH enzyme (R2). Measurement via spectrophotometric rate of change in absorbance (NADH production). Validated on Beckman Coulter AU680 automated analyzer. Measurement range 2.0–100.0 μg/mL. Compatible with serum, lithium heparin, sodium heparin, and potassium EDTA plasma.

## Regulatory Identification

A diphenylhydantoin test system is a device intended to measure diphenylhydantoin, an antiepileptic drug, in human specimens. Measurements obtained by this device are used in the diagnosis and treatment of diphenylhydantoin overdose and in monitoring levels of diphenylhydantoin to ensure appropriate therapy.

## Predicate Devices

- ARK Levetiracetam Assay ([K091653](/device/K091653.md))

## Submission Summary (Full Text)

> This content was OCRed from public FDA records by [Innolitics](https://innolitics.com). If you use, quote, summarize, crawl, or train on this content, cite Innolitics at https://innolitics.com.
>
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FDA

U.S. FOOD & DRUG

ADMINISTRATION

# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY

ASSAY ONLY

## I Background Information:

A 510(k) Number

K232522

B Applicant

ARK Diagnostics, Inc.

C Proprietary and Established Names

ARK Levetiracetam II Assay

D Regulatory Information

|  Product Code(s) | Classification | Regulation Section | Panel  |
| --- | --- | --- | --- |
|  ORI | Class II | 21 CFR 862.3350 - Diphenylhydantoin Test System | TX - Clinical Toxicology  |

## II Submission/Device Overview:

A Purpose for Submission:

New device

B Measurand:

Levetiracetam

C Type of Test:

Homogeneous enzyme immunoassay (EIA)

## III Intended Use/Indications for Use:

Food and Drug Administration

10903 New Hampshire Avenue

Silver Spring, MD 20993-0002

www.fda.gov

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K232522 - Page 2 of 8

A Intended Use(s):

See Indications for Use below.

B Indication(s) for Use:

ARK Levetiracetam II Assay: The ARK Levetiracetam II Assay is a homogeneous enzyme immunoassay intended for the quantitative determination of levetiracetam in human serum or plasma on automated clinical chemistry analyzers. Levetiracetam concentrations can be used as an aid in management of patients treated with levetiracetam.

C Special Conditions for Use Statement(s):

Rx - For Prescription Use Only

D Special Instrument Requirements:

The assay has been validated on the Beckman Coulter AU680.

IV Device/System Characteristics:

A Device Description:

The ARK Levetiracetam II Assay consists of reagents R1 anti-levetiracetam monoclonal antibody with substrate and R2 levetiracetam labeled with bacterial G6PDH enzyme.

B Principle of Operation:

The ARK Levetiracetam II Assay is a homogeneous immunoassay based on competition between drug in the specimen and levetiracetam labeled with the enzyme glucose-6-phosphate dehydrogenase (G6PDH) for binding to the antibody reagent. As the latter binds antibody, enzyme activity decreases. In the presence of drug from the specimen, enzyme activity increases and is directly related to the drug concentration. Active enzyme converts the coenzyme nicotinamide adenine dinucleotide (NAD) to NADH that is measured spectrophotometrically as a rate of change in absorbance. Endogenous serum G6PDH does not interfere with the results because the coenzyme NAD functions only with the bacterial enzyme used in the assay.

V Substantial Equivalence Information:

A Predicate Device Name(s):

Ark Levetiracetam Assay

B Predicate 510(k) Number(s):

K091653

C Comparison with Predicate(s):

|  Device & Predicate Device(s): | K232522 | K091653  |
| --- | --- | --- |
|  Device Trade Name | ARK Levetiracetam II | ARK Levetiracetam  |

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|   | Assay | Assay  |
| --- | --- | --- |
|  General Device Characteristic Similarities |  |   |
|  Intended Use/Indications For Use | For the quantitative determination of levetiracetam in human serum or plasma on automated clinical chemistry analyzers. | Same  |
|  Specimen | Serum or plasma | Same  |
|  Methodology | Homogeneous enzyme immunoassay (EIA) | Same  |
|  Platform required | Automated clinical chemistry analyzer | Same  |
|  Accessary reagents | Calibrators (six levels) and controls (three levels) | Same  |
|  Measurement range | 2.0 to 100.0 μg/mL | Same  |
|  General Device Characteristic Differences |  |   |
|  Reagent components | Anti-levetiracetam
Antibody/Substrate Reagent (R1)
containing rabbit monoclonal antibodies to levetiracetam | Anti-levetiracetam
Antibody/Substrate Reagent (R1)
containing rabbit polyclonal antibodies to levetiracetam  |

VI Standards/Guidance Documents Referenced:

CLSI Guideline EP 17-A2: Evaluation of Detection Capability for Clinical Laboratory Measurement Procedures

CLSI Guideline EP5-A3: Evaluation of Precision Performance of Quantitative Measurement Methods

CLSI Guideline EP6-Ed2: Evaluation of the Linearity of Quantitative Measurement Procedures: A Statistical Approach

CLSI Guideline EP7-Ed3: Interference Testing in Clinical Chemistry

CLSI Guideline EP37: Supplemental Tables for Interference Testing in Clinical Chemistry

VII Performance Characteristics (if/when applicable):

A Analytical Performance:

1. Precision/Reproducibility:

K232522 - Page 3 of 8

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Precision studies were performed based upon recommendations in the CLSI EP05-A3 guideline. Tri-level controls and three samples of levetiracetam in three pooled human serum samples were used in the study. Data were collected on a single analyzer over twenty (20) non-consecutive days. Each level was assayed in quadruplicate twice a day. Each of the runs per day was separated by at least two hours. The within run, between day, and total imprecision estimates were calculated. Results are shown below.

|   |   |   | Within Run |   | Between Day |   | Total  |   |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  Sample | N | Mean (μg/mL) | SD | CV (%) | SD | CV (%) | SD | CV (%)  |
|  ARK Levetiracetam II Control  |   |   |   |   |   |   |   |   |
|  Low | 160 | 7.6 | 0.16 | 2.1 | 0.09 | 1.2 | 0.18 | 2.3  |
|  Mid | 160 | 30.5 | 0.45 | 1.5 | 0.34 | 1.1 | 0.60 | 2.0  |
|  High | 160 | 75.7 | 1.41 | 1.9 | 0.99 | 1.3 | 2.19 | 2.9  |
|  Human Serum  |   |   |   |   |   |   |   |   |
|  Low | 160 | 7.7 | 0.11 | 1.4 | 0.06 | 0.8 | 0.12 | 1.6  |
|  Mid | 160 | 32.6 | 0.47 | 1.4 | 0.34 | 1.1 | 0.61 | 1.9  |
|  High | 160 | 80.5 | 1.62 | 2.0 | 0.80 | 1.0 | 1.79 | 2.2  |

2. Linearity:

Linearity studies were performed based upon recommendations in CLSI EP06-Ed2. Ten (10) levels of samples ranging from 2 to 100 μg/mL were prepared from a gravimetrically prepared levetiracetam stock solution and levetiracetam-free serum pools. The averaged results of multiple runs and replicates (n=6) for each sample using the ARK Levetiracetam II Assay were used in the calculations. Regression analyses were performed between the measured mean levetiracetam and the nominal values for each dilution, using weighted linear regression analysis according to CLSI/NCCLS EP6-Ed2 and results are shown below. The regression equation calculated according to EP06-Ed2 is y=1.003x.

|  Estimated Value (μg/mL) | Results (μg/mL) | Predicted Results | % Difference  |
| --- | --- | --- | --- |
|  0.0 | NA | NA | NA  |
|  2.0 | 1.88 | 2.01 | 11.2  |
|  3.0 | 3.2 | 3.04 | 5.9  |
|  4.0 | 3.9 | 4.07 | 3.3  |
|  6.0 | 6.1 | 6.13 | 0.7  |
|  10.0 | 11.0 | 10.25 | -1.5  |
|  20.0 | 20.0 | 20.56 | -3.5  |
|  40.0 | 42.0 | 41.18 | -5.2  |
|  60.0 | 62.1 | 61.80 | -6.4  |

K232522 - Page 4 of 8

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Analytical recovery:

Serum samples across the assay range were prepared containing levetiracetam (sourced from USP). The results of the six replicates were averaged and compared to the theoretical target concentration and the percentage recovery was calculated. Results are shown below.

(Percent Recovery = 100 x Mean recovered concentration/Theoretical concentration)

|  Theoretical Concentration (μg/mL) | Mean Recovered Concentration (μg/mL) | Percent Recovery  |
| --- | --- | --- |
|  2.0 | 1.9 | 95.0  |
|  4.0 | 3.9 | 97.5  |
|  10.0 | 9.8 | 98.0  |
|  20.0 | 20.1 | 100.5  |
|  45.0 | 46.2 | 102.6  |
|  80.0 | 77.8 | 97.3  |
|  100.0 | 100.3 | 100.3  |

A manual dilution protocol has not been validated to enable measurements of concentrations above the measurement range.

3. Analytical Specificity/Interference:

Interference studies were carried out based upon recommendations in CLSI EP7-A3. Interference was tested using serum pools at two levels of levetiracetam, 15 and 50 μg/mL. Each sample was assayed using the ARK Levetiracetam II Assay, along with a serum control of levetiracetam. Bias exceeding 10% is considered significant interference. The highest concentration of interferent tested that did not cause significant interference is summarized in the table below.

|  Percentage Recovery  |   |   |   |
| --- | --- | --- | --- |
|  Interfering Substance | Interferent Concentration | 15 μg/mL Levetiracetam | 50 μg/mL Levetiracetam  |
|  Human Albumin | 12 g/dL | 98.7 | 99.9  |
|  Bilirubin - conjugated | 72 mg/dL | 100.2 | 100.9  |
|  Bilirubin - unconjugated | 72 mg/dL | 101.7 | 97.1  |
|  Cholesterol | 620 mg/dL | 94.9 | 100.8  |
|  Human Gamma-Globulin | 12 g/dL | 102.7 | 98.7  |
|  Hemoglobin | 1050 mg/dL | 100.9 | 95.8  |
|  Intralipid | 2000 mg/dL | 98.7 | 100.4  |

K232522 - Page 5 of 8

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Specificity:
Metabolite 2-pyrrolidone-N-butyric acid (ucb L057) was also tested for cross-reactivity.

|  Metabolite | Concentration (μg/mL) | Percent Recovery  |   |
| --- | --- | --- | --- |
|   |   |  Levetiracetam 15 μg/mL | Levetiracetam 50 μg/mL  |
|  2-pyrrolidone-N-butyric acid | 250.0 | 101.4 | 100.2  |

Drug interference:
Brivaracetam (Briviact) interferes with measurements of levetiracetam (Keppra) in the ARK Levetiracetam II Assay. Patients undergoing a switch in drug therapy involving Keppra and Briviact should not be monitored for levetiracetam using the ARK assay if there is a possibility these drugs are co-present in circulation.

The device was not impacted by other structurally unrelated drugs tested. A high concentration of each compound was spiked into normal human serum with known levels of levetiracetam (approximately 15 and 50 μg/mL) and assayed along with a serum control of levetiracetam. Measurement of levetiracetam resulted in ≤10% error in the presence of drug compounds at the levels tested.

|  Compound | Concentration (μg/mL) | Compound | Concentration (μg/mL)  |
| --- | --- | --- | --- |
|  Acetaminophen | 500 | Nortriptyline | 20  |
|  Acetylsalicylic acid | 1000 | Oxcarbazepine | 50  |
|  Amitriptyline | 20 | Phenobarbital | 200  |
|  Caffeine | 100 | Phenytoin | 200  |
|  Carbamazepine | 120 | Primidone | 100  |
|  Clonazepam | 50 | Probenecid | 600  |
|  Cyclosporin A | 40 | Salicylic Acid | 500  |
|  Diazepam | 50 | Sulfamethoxazole | 400  |
|  Digoxin | 40 | Sulfisoxazole | 400  |
|  Erythromycin | 200 | Theophylline | 250  |
|  Ethosuximide | 250 | Tiagabine | 200  |
|  Felbamate | 250 | Topiramate | 250  |
|  Gabapentin | 100 | Trimethoprim | 40  |
|  Heparin | 200 units/mL | Valproic Acid | 500  |
|  Hydrochlorothiazide | 20 | Verapamil | 100  |
|  Ibuprofen | 500 | Vigabatrin | 150  |

K232522 - Page 6 of 8

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|  Lamotrigine | 250 | Warfarin | 250  |
| --- | --- | --- | --- |
|  Naproxen | 500 | Zonisamide | 250  |

4. Assay Reportable Range:

The manufacturer's claimed assay reportable range is from 2.0 to 100 µg/mL.

5. Traceability, Stability, Expected Values (Controls, Calibrators, or Methods):

The device is traceable to commercially available reference materials.

6. Detection Limit:

The LOQ of the ARK Levetiracetam II Assay was determined using three reagent lots and the results supported an LOQ of 2.0 µg/mL with the manufacturer's acceptance criteria of CV within 20% and recovery within +/-15%.

7. Assay Cut-Off:

Not applicable.

B Comparison Studies:

1. Method Comparison with Predicate Device:

Method comparison studies were performed to evaluate the performance of the ARK Levetiracetam II Assay. 104 serum patient samples spanning the range of 3.4 µg/mL to 98.3 µg/mL were tested on one assay lot with each sample tested in singlicate. Measurements obtained with the ARK Levetiracetam II Assay were made on the Beckman Coulter AU680 analyzer, while measurements of levetiracetam by the predicate assay were made on the Roche Hitachi 917 analyzer. Results from the candidate device were compared to the predicate device and results of the Passing- Bablok regression analysis for the study are shown below.

$$
\mathrm{Y} = 1.04\mathrm{X} - 0.30,\ \mathrm{R}^2 = 0.99
$$

2. Matrix Comparison:

The sponsor provided studies that were adequate to support the use of the following anticoagulants: lithium heparin, sodium heparin, and potassium EDTA with the ARK II Levetiracetam II Assay.

C Clinical Studies:

1. Clinical Sensitivity:

Not applicable.

K232522 - Page 7 of 8

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2. Clinical Specificity:

Not applicable.

3. Other Clinical Supportive Data (When 1. and 2. Are Not Applicable):

D. Clinical Cut-Off:

See expected values.

E. Expected Values/Reference Range:

The following statement is included in the package insert:

A reference range for levetiracetam has not been well established. Reference ranges for seizure control have been proposed, which include serum/plasma trough concentrations from 6 to 46 µg/mL (35 to 270 µmol/L) or 10 to 40 µg/mL (59 to 235 µmol/L) including a laboratory alert level at 50 µg/mL (294 µmol/L). However, these ranges have not been validated by adequate controlled trials, and in general the relationship between these serum concentrations and clinical effect has not been well-defined. Levetiracetam drug concentrations should be used in conjunction with information available from clinical evaluations and other diagnostic procedures. Circulating levels of levetiracetam (serum blood concentrations) may be affected by compliance, renal function, pregnancy, drug-drug interactions and timing of the sample draw. Furthermore, the clinical effect of these serum blood concentrations may be further altered by changes in progression in the severity of the disease and the addition or withdrawal of concomitant drugs which may interact pharmacodynamically with circulating levels of levetiracetam.

The reference range of drug concentrations which is quoted should only imply a lower limit below which a therapeutic response is relatively unlikely to occur, and an upper limit above which toxicity is relatively likely to occur in the specific patient populations studied. Generally, clinicians using reference ranges such as these should be aware that, because of individual variation, patients may achieve therapeutic benefit with serum drug concentrations outside of these ranges and may experience toxicity with levels below the lower limit of the reference range. Sampling time should be standardized such that trough serum concentrations are measured just before the next dosage, preferably in the morning.

VIII. Proposed Labeling:

The labeling support the finding of substantial equivalence for this device.

IX. Conclusion:

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

K232522 - Page 8 of 8

---

**Source:** [https://fda.innolitics.com/submissions/TX/subpart-d%E2%80%94clinical-toxicology-test-systems/ORI/K232522](https://fda.innolitics.com/submissions/TX/subpart-d%E2%80%94clinical-toxicology-test-systems/ORI/K232522)

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