Oral Fluid Drug Testing in Pain Management Practice: Factors to Consider Before Choosing the Alternative Biological Matrix

A Case Study Evaluating the Efficacy of an Ad Hoc Hospital Collection Device for Fentanyl in Infant Oral Fluid

Neonatal drug exposure is currently assessed using meconium, urine, blood, hair, or umbilical cord tissue/blood. Due to the invasiveness, challenges, and limitations of collection, and/or analytical difficulties of these matrices, oral fluid may be a more desirable matrix in diagnosing opioid exposure and risk for opioid withdrawal in neonatal abstinence syndrome. Traditional oral fluid collection devices are not viable options as they are too large for neonates' mouths and may contain chemicals on the collection pad. Unstimulated and stimulated infant oral fluid samples have been used for therapeutic drug monitoring as an alternative matrix to blood. The objective of this study was to assess the viability of a simple oral fluid collection system using a sterile foam-tipped swab rinsed in phosphate-buffered saline. Two infants were administered fentanyl for post-operative pain relief while hospitalized in the Neonatal Intensive Care Units at the Children's Hospital of Richmond of Virginia Commonwealth University. Oral fluid samples were collected at 16 h, 2 days, and/or 7 days following the start of intravenous infusion of fentanyl. Samples were analyzed by ultra-high-pressure liquid chromatography-tandem mass spectrometry for fentanyl and norfentanyl after solid-phase extraction. In one of the three samples tested, fentanyl and norfentanyl were detected at concentrations of 28 and 78 ng/mL, respectively. Based on the infusion rate, the theoretical oral fluid fentanyl concentration at steady state was calculated to be 33 ng/mL.

Stability and Degradation Pathways of Different Psychoactive Drugs in Neat and in Buffered Oral Fluid

Sampling and drug stability in oral fluid (OF) are crucial factors when interpreting forensic toxicological analysis, mainly because samples may not be analyzed immediately after collection, potentially altering drug concentrations. Therefore, the stability of some common drugs of abuse (morphine, codeine, 6-monoacetylmorphine, cocaine, benzoylecgonine, Δ9-tetrahydrocannabinol, cannabidiol, amphetamine, 3,4-methylenedioxymethamphetamine, ketamine) and the more commonly consumed new psychoactive substances in our environment (mephedrone, and N-(adamantan-1-yl)-1-(5-fluoropentyl)-1H-indazole-3-carboxamide 5F-AKB48 also known as 5F-APINACA) was investigated in an OF pool for the presence and absence of M3 Reagent Buffer® up to 1 year of storage. Fortified OF samples were stored at three different temperatures (room temperature, 4 and −20°C) to determine the best storage conditions over time. Control fortified OF samples were stored at −80°C for reference purposes. Compounds with concentration changes within ±15% of initial value were considered stable. The drugs were significantly more stable in M3 Reagent Buffer® than in neat OF samples in all storage conditions. All analytes were stable for 1 year at 4°C and −20°C in M3 Reagent Buffer®. Drugs stability in OF varied depending on the analyte, the presence of a stabilizer, the storage duration and temperature. When immediate sample analysis is not possible, we suggest to store OF samples at 4 or −20°C and test them within 2 weeks. Alternatively, OF samples may be stored at 4 or −20°C with M3 Reagent Buffer® to be tested within 1 year.