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The Psychemedics Microplate EIA for Oxycodone is an enzyme immunoassay (EIA) for the preliminary qualitative detection of the opiate oxycodone in human head and body hair using an oxycodone calibrator at 2 ng /10 mg hair cutoff for the purpose of identifying oxycodone use. This is an in vitro diagnostic device intended exclusively for Psychemedics use only and is not intended for sale to anyone.

The Psychemedics Microplate EIA oxycodone assay provides only a preliminary analytical test result. A more specific alternative chemical method must be used in order to obtain a confirmed analytical result. Gas or Liquid Chromatography/Mass Spectrometry (GC/MS or LC/MS or LC/MS/MS) is the preferred confirmatory method. Clinical consideration and professional judgment should be exercised with any drug of abuse test result, particularly when the preliminary result is positive.

Device Description

The test consists of two parts; a pre-analytical hair treatment procedure (to convert the solid matrix of hair to a measurable liquid matrix) and the screening assay, the Psychemedics Microplate EIA for Oxycodone. The drug is recovered from the hair using a patented method (U.S. Patent #8,084,215).The screening portion of the test system consists of (1) microplate wells coated with multiple drugs including oxycodone conjugated to bovine serum albumin (BSA) (patent pending), polyclonal rabbit anti-oxycodone, goat anti-rabbit secondary antibody conjugated to HRP (horseradish peroxidase), substrate [3, 3', 5, 5' tetramethylbenzidine (TMB)], HCl to acidify (which stops the reaction), and wash buffer for washing the plates. Absorbance in the wells is read with a microplate reader.

AI/ML Overview

Acceptance Criteria and Device Performance for Psychemedics Microplate EIA for Oxycodone in Hair

The Psychemedics Microplate EIA for Oxycodone in Hair is an enzyme immunoassay for the preliminary qualitative detection of oxycodone in human head and body hair. The device's performance was evaluated through precision studies and agreement testing against LC/MS/MS confirmation.

1. Table of Acceptance Criteria and Reported Device Performance

The direct acceptance criteria for the device are not explicitly stated as numerical targets in the provided document. However, the performance is reported in terms of precision (intra-assay and inter-assay agreement at various concentrations relative to the cutoff) and agreement with the confirmatory method (LC/MS/MS). The implied acceptance criteria are high agreement percentages for both positive and negative samples around the cutoff.

Performance Metric	Acceptance Criteria (Implied)	Reported Device Performance
Precision (Intra-Assay)	High agreement for negative and positive samples at various levels relative to the 2 ng/10 mg hair cutoff.	- Negative (B0, -75%, -50%, -25%): 15/15 reported as NEG- Positive (plus 25%, plus 50%, plus 75%, plus 100%): 15/15 reported as POS
Precision (Inter-Assay)	High agreement for negative and positive samples at various levels relative to the 2 ng/10 mg hair cutoff.	- Negative (B0, -75%, -50%, -25%): 75/75 reported as NEG- Positive (plus 25%, plus 50%, plus 75%, plus 100%): 75/75 reported as POS
Agreement with LC/MS/MS	High concordance between EIA results and LC/MS/MS confirmation, especially for samples around the cutoff.	- 47 Negative HC/MS/MS samples (< -10% of Cutoff): All 47 were EIA Negative.- 4 LC/MS/MS samples (≥10% and < -50% of Cutoff): All 4 were EIA Negative.- 6 LC/MS/MS samples (≥ -50% and < Cutoff): All 6 were EIA Negative.- 87 LC/MS/MS samples (≥ +100% of cutoff): All 87 were EIA Positive.- 2 LC/MS/MS samples (≥ +50% and < +100% of cutoff): All 2 were EIA Positive.
Discordant Results	Discrepant results, if any, should be explainable and primarily occur as EIA positive/confirmatory negative.	All 7 discordant results from the agreement study were EIA Positive but LC/MS/MS Negative (ranging from 1.16 to 1.96 ng oxycodone-equivalents/10 mg hair, below the 2 ng/10 mg hair cutoff). This is explained by the washing procedure used for confirmatory testing but not for screening.
Cross-reactivity	Limited cross-reactivity with non-target compounds.	Significant cross-reactivity (100%) with Oxymorphone and (7.7%) with Hydrocodone. 138 other compounds showed no cross-reactivity.
Interference	No significant interference from common substances (e.g., cosmetic treatments).	- Cosmetic Treatments (Negative Hair): No significant differences in EIA results; all remained negative after treatment (bleach, permanent wave, dye, relaxer, shampoo).- Cosmetic Treatments (Positive Hair): None of the positive samples became negative by EIA or LC/MS/MS after treatment (bleach, permanent wave, dye, relaxer, shampoo).- Other Interferents: 116 compounds tested showed no interference at +/-50% of the cutoff.
Environmental Contamination	Effective removal of external contamination by the wash procedure.	- Soaking in 500 ng oxycodone/mL water: All samples negative after washing (amount remaining 0.05 to 0.94 ng/10 mg hair, below cutoff).- Soaking in 500 ng oxycodone/mL saline: All samples negative after washing (amount remaining 0.11 to 0.42 ng/10 mg hair, below cutoff).
Recovery	High recovery rate of oxycodone from hair.	Averaged 89% recovery from hair in a 2-hour incubation.
Stability	Demonstrated stability of calibrators and controls.	6 months stability shown for calibrator and control solutions (ongoing studies for 1-year stability).

2. Sample Size Used for the Test Set and Data Provenance

Test Set Sample Size for Agreement Testing: 161 samples.
Data Provenance: The document does not explicitly state the country of origin. However, given the submission is to the U.S. FDA, it is likely the data was collected in the U.S. The study involved subjects aged 19-67 years, 92 males and 69 females, various hair colors (82 black, 74 brown, 5 grey), and diverse ethnicities (79 Caucasian, 24 African-American, 34 Hispanic, 24 Asian). It included 134 head hair samples and 27 body hair samples. The study appears to be prospective in nature, as samples were tested in parallel by the EIA and LC/MS/MS, and specific demographic and sample characteristics were recorded for this study. The precision studies involved spiking negative hair samples.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications

Number of Experts: Not applicable in the traditional sense for an analytical device.
Qualifications of Experts: The ground truth for the device's performance was established using LC/MS/MS (Liquid Chromatography/Mass Spectrometry/Mass Spectrometry), which is described as the "preferred confirmatory method" for drug testing. This is an objective, instrumental analytical technique, not reliant on human expert interpretation of images or clinical findings. The validation of the LC/MS/MS method itself would have been performed by qualified analytical chemists or toxicologists in a laboratory setting.

4. Adjudication Method for the Test Set

Adjudication Method: Not applicable. The comparison was made between the preliminary results of the EIA and the objective, quantitative results of LC/MS/MS. There was no human adjudication process described between different readers or interpretations for the test set.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

No Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done. This device is an analytical laboratory assay, not an imaging device or one requiring human interpretation for its primary output. Therefore, an MRMC study comparing human readers with and without AI assistance is not relevant to this type of device.

6. If a Standalone Study Was Done

Yes, a standalone performance study was done for the Psychemedics Microplate EIA for Oxycodone. The "Agreement Testing" section directly details the performance of the EIA device alone (without human interpretation beyond reading the microplate reader output) against the LC/MS/MS ground truth. The agreement data clearly shows the algorithm's performance in categorizing samples as positive or negative based on the prescribed cutoff.

7. The Type of Ground Truth Used

The primary ground truth used was LC/MS/MS (Liquid Chromatography/Mass Spectrometry/Mass Spectrometry) confirmation. This is an objective, quantitative analytical method considered the gold standard for confirming the presence and concentration of drugs in biological samples.

8. The Sample Size for the Training Set

The document does not provide information on a specific training set size. The device is an immunoassay kit, and such kits are typically developed and optimized through iterative chemical and biological experimentation, rather than being "trained" in the machine learning sense on a large dataset. The studies described (precision, agreement, cross-reactivity, interference) are validation studies for the finalized assay.

9. How the Ground Truth for the Training Set Was Established

Since there is no explicit mention of a training set in the context of machine learning, this question is not directly applicable. For the development and optimization of the immunoassay, the "ground truth" for calibrator and control solutions would be established by preparing them from certified standards and validating their concentrations using reference analytical methods, likely including LC/MS/MS.

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