Demonstration that methadone is being present in the exhaled breath aerosol fraction

New perspectives on 'Breathomics': metabolomic profiling of non-volatile organic compounds in exhaled breath using DI-FT-ICR-MS

Breath analysis offers tremendous potential for diagnostic approaches, since it allows for easy and non-invasive sample collection. "Breathomics" as one major research field comprehensively analyses the metabolomic profile of exhaled breath providing insights into various (patho)physiological processes. Recent research, however, primarily focuses on volatile compounds. This is the first study that evaluates the non-volatile organic compounds (nVOCs) in breath following an untargeted metabolomic approach. Herein, we developed an innovative method utilizing a filter-based device for metabolite extraction. Breath samples of 101 healthy volunteers (female n = 50) were analysed using DI-FT-ICR-MS and biostatistically evaluated. The characterisation of the non-volatile core breathome identified more than 1100 metabolites including various amino acids, organic and fatty acids and conjugates thereof, carbohydrates as well as diverse hydrophilic and lipophilic nVOCs. The data shows gender-specific differences in metabolic patterns with 570 significant metabolites. Male and female metabolomic profiles of breath were distinguished by a random forest approach with an out-of-bag error of 0.0099. Additionally, the study examines how oral contraceptives and various lifestyle factors, like alcohol consumption, affect the non-volatile breathome. In conclusion, the successful application of a filter-based device combined with metabolomics-analyses delineate a non-volatile breathprint laying the foundation for discovering clinical biomarkers in exhaled breath.

Sample Matrices for Mass Spectrometry-Based Adherence Monitoring: A Systematic Critical Review

BACKGROUND

Analytical monitoring of adherence using mass spectrometry (MS) plays an important role in clinical toxicology. Unambiguous detection of drugs (of abuse) and/or their metabolites in body fluids is needed to monitor intake of medication as prescribed or to monitor abstinence as a follow-up to detoxification procedures. This study focused on the advantages and disadvantages of different sample matrices used for MS-based adherence monitoring.

METHODS

Relevant articles were identified through a literature search in the PubMed database. English articles published between January 01, 2017, and December 31, 2022, were selected using the keywords "adherence assess*" or "adherence monit*" or "compliance assess*" or "compliance monit*" in combination with "mass spectrom*" in the title or abstract.

RESULTS

A total of 51 articles were identified, 37 of which were within the scope of this study. MS-based monitoring was shown to improve patient adherence to prescribed drugs. However, MS analysis may not be able to assess whether treatment was rigorously followed beyond the last few days before the sampling event, except when hair is the sample matrix. For medication adherence monitoring, blood-based analyses may be preferred because reference plasma concentrations are usually available, whereas for abstinence control, urine and hair samples have the advantage of extended detection windows compared with blood. Alternative sample matrices, such as dried blood samples, oral fluid, and exhaled breath, are suitable for at-home sampling; however, little information is available regarding the pharmacokinetics and reference ranges of drug (of abuse) concentrations.

CONCLUSIONS

Each sample matrix has strengths and weaknesses, and no single sample matrix can be considered the gold standard for monitoring adherence. It is important to have sufficient information regarding the pharmacokinetics of target substances to select a sample matrix in accordance with the desired purpose.

Detection of abused drugs in human exhaled breath using mass spectrometry: A review

RATIONALE

Human breath analysis has been attracting increasing interest in the detection of abused drugs in forensic and clinical applications because of its noninvasive sampling and distinctive molecular information. Mass spectrometry (MS)-based approaches have been proven to be powerful tools for accurately analyzing exhaled abused drugs. The major advantages of MS-based approaches include high sensitivity, high specificity, and versatile couplings with various breath sampling methods.

METHODS

Recent advances in the methodological development of MS analysis of exhaled abused drugs are discussed. Breath collection and sample pretreatment methods for MS analysis are also introduced.

RESULTS

Recent advances in technical aspects of breath sampling methods are summarized, highlighting active and passive sampling. MS methods for detecting different exhaled abused drugs are reviewed, emphasizing their features, advantages, and limitations. The future trends and challenges in MS-based breath analysis of exhaled abused drugs are also discussed.

CONCLUSIONS

The coupling of breath sampling methods with MS approaches has been proven to be a powerful tool for the detection of exhaled abused drugs, offering highly attractive results in forensic investigations. MS-based detection of exhaled abused drugs in exhaled breath is a relatively new field and is still in the early stages of methodological development. New MS technologies promise a substantial benefit for future forensic analysis.

Correlation of theophylline levels in rat exhaled breath and lung tissue after its intravenous injection

It is important to know the drug level in the target tissue to determine its dose. Some methods rely on blood levels of a drug to estimate its concentration in the tissues, which can be inaccurate. We thought that drug levels in exhaled breath aerosol (EBA) to give a more accurate value of the level of a test drug in the lung. Rats were intravenously injected with the bronchodilator theophylline and exhaled breath was collected up to 10-20 min after administration. Immediately after breath collection, lung, liver, kidney, and blood were collected and the pharmacokinetics were examined using these samples. Awake free-moving rats were used to efficiently collect exhaled breath from rats with low tidal volume. The amount of exhaled breath of rats was estimated by the amount of exhaled water vapor, and the drug concentration in exhaled breath sample was expressed by the amount of water vapor as the denominator. By using the active sampling method in which the adsorbent is sucked by a pump, theophylline in rat exhaled breath could be measured accurately. When the correlation of theophylline concentration in each sample was examined, a high correlation (r²= 0.74) was found only in exhaled breath and lung tissue. EBA was considered better than blood in pharmacokinetic analysis of lung tissue.

SARS-CoV-2: Viral Loads of Exhaled Breath and Oronasopharyngeal Specimens in Hospitalized Patients with COVID-19

Background

SARS-CoV-2 seems mainly transmissible via respiratory droplets. We compared the time-dependent SARS-CoV-2 viral load in serial pharyngeal swab with exhaled breath (EB) samples of hospitalized COVID-19 patients.

Methods

In this prospective proof of concept study, we examined hospitalized patients who initially tested positive for SARS-CoV-2. Paired oronasopharyngeal swab and EB specimens were taken at different days of hospitalization. EB collection was performed through a simple, noninvasive method using an electret air filter-based device. SARS-CoV-2 RNA detection was determined with real-time quantitative reverse transcription polymerase chain reaction.

Results

Of 187 serial samples from 15 hospitalized patients, 87/87 oronasopharyngeal swabs and 70/100 EB specimens tested positive. Comparing the number of SARS-CoV-2 copies, the viral load of the oronasopharyngeal swabs was significantly higher (CI 99%, P<<0,001) than for EB samples. The mean viral load per swab was 7.97 × 10⁶ (1.65 × 10²-1.4 × 10⁸), whereas EB samples showed 2.47 × 10³ (7.19 × 10¹-2.94 × 10⁴) copies per 20 times exhaling. Viral loads of paired oronasopharyngeal swab and EB samples showed no correlation.

Conclusions

Assessing the infectiousness of COVID-19 patients merely through pharyngeal swabs might not be accurate. Exhaled breath could represent a more suitable matrix for evaluating infectiousness and might allow screening for superspreader individuals and widespread variants such as Delta.

Probing for the presence of doping agents in exhaled breath using chromatographic/mass spectrometric approaches

RATIONALE

Exhaled breath (EB) has been demonstrated to be a promising alternative matrix in sports drug testing due to its non-invasive and non-intrusive nature compared with urine and blood collection protocols. In this study, a pilot-test system was employed to create drug-containing aerosols simulating EB in support of the analytical characterization of EB sampling procedures, and the used analytical method was extended to include a broad spectrum of prohibited substances.

METHODS

Artificial and authentic EB samples were collected using sampling devices containing an electret filter, and doping agents were detected by means of liquid chromatography and tandem mass spectrometry with unispray ionization. The analytical approach was characterized with regard to specificity, limits of detection, carry-over, recovery and matrix effects, and the potential applicability to routine doping controls was shown using authentic EB samples collected after single oral dose applications of glucocorticoids and stimulants.

RESULTS

The analytical method was found to be specific for a total of 49 model substances relevant in sports drug testing, with detection limits ranging from 1 to 500 pg per cartridge. Both ion suppression (-62%) and ion enhancement (+301%) effects were observed, and all model compounds applied to EB sampling devices were still detected after 28 days of storage at room temperature. Authentic EB samples collected after the oral administration of 10 mg of prednisolone resulted in prednisolone findings in specimens obtained from 3 out of 6 participants up to 2 h. In octodrine, dimethylamylamine (DMAA) and isopropylnorsynephrine post-administration EB samples, the drugs were detected over a period of 50, 48, and 8 h, respectively.

CONCLUSIONS

With the analytical approach developed within this study, the identification of a broad spectrum of prohibited doping agents in EB samples was accomplished. Application studies and stability tests provided information to characterize EB as a potential matrix in sports drug testing.

Exhaled particles and small airways

BACKGROUND

Originally, studies on exhaled droplets explored properties of airborne transmission of infectious diseases. More recently, the interest focuses on properties of exhaled droplets as biomarkers, enabled by the development of technical equipment and methods for chemical analysis. Because exhaled droplets contain nonvolatile substances, particles is the physical designation. This review aims to outline the development in the area of exhaled particles, particularly regarding biomarkers and the connection with small airways, i e airways with an internal diameter < 2 mm.

MAIN BODY

Generation mechanisms, sites of origin, number concentrations of exhaled particles and the content of nonvolatile substances are studied. Exhaled particles range in diameter from 0.01 and 1000 μm depending on generation mechanism and site of origin. Airway reopening is one scientifically substantiated particle generation mechanism. During deep expirations, small airways close and the reopening process produces minute particles. When exhaled, these particles have a diameter of < 4 μm. A size discriminating sampling of particles < 4 μm and determination of the size distribution, allows exhaled particle mass to be estimated. The median mass is represented by particles in the size range of 0.7 to 1.0 μm. Half an hour of repeated deep expirations result in samples in the order of nanogram to microgram. The source of these samples is the respiratory tract ling fluid of small airways and consists of lipids and proteins, similarly to surfactant. Early clinical studies of e g chronic obstructive pulmonary disease and asthma, reported altered particle formation and particle composition.

CONCLUSION

The physical properties and content of exhaled particles generated by the airway reopening mechanism offers an exciting noninvasive way to obtain samples from the respiratory tract lining fluid of small airways. The biomarker potential is only at the beginning to be explored.

Two techniques to sample non-volatiles in breath-exemplified by methadone

The particles in exhaled breath provide a promising matrix for the monitoring of pathological processes in the airways, and also allow exposure to exogenous compounds to be to assessed. The collection is easy to perform and is non-invasive. The aim of the present study is to assess if an exogenous compound-methadone-is distributed in the lining fluid of small airways, and to compare two methods for collecting methadone in particles in exhaled breath. Exhaled particles were collected from 13 subjects receiving methadone maintenance treatment. Two different sampling methods were applied: one based on electret filtration, potentially collecting exhaled particles of all sizes, and one based on impaction, collecting particles in the size range of 0.5-7 μm, known to reflect the respiratory tract lining fluid from the small airways. The collected samples were analyzed by liquid chromatography mass spectrometry, and the impact of different breathing patterns was also investigated. The potential contribution from the oral cavity was investigated by rinsing the mouth with a codeine solution, followed by codeine analysis of the collected exhaled particles by both sampling methods. The results showed that methadone was present in all samples using both methods, but when using the method based on impaction, the concentration of methadone in exhaled breath was less than 1% of the concentration collected by the method based on filtration. Optimizing the breathing pattern to retrieve particles from small airways did not increase the amount of exhaled methadone collected by the filtration method. The contamination from codeine present in the oral cavity was only detected in samples collected by the impaction method. We conclude that methadone is distributed in the respiratory tract lining fluid of small airways. The samples collected by the filtration method most likely contained a contribution from the upper airways/oral fluid in contrast to the impaction method.

Testing for Drugs in Exhaled Breath Collected With ExaBreath in a Drug Dependence Population: Comparison With Data Obtained in Urine After Liquid Chromatographic-Tandem Mass Spectrometric Analyses

BACKGROUND

Exhaled breath is commonly used in alcohol testing but has been recently demonstrated by scientists from Sweden, Switzerland, and the United States to contain a large number of both volatile and nonvolatile substances that can be measured using dedicated devices. ExaBreath is a sampling device that collects the bio-aerosols particles from the donor. Approximately 1-2 minutes exhaled breath is enough for the test. The device collects the very small bio-aerosols on a filter, which is consecutively incubated into methanol to release the drugs at the laboratory.

METHODS

Eighteen drug addicts from a methadone substitution program were recruited for this study. There were 5 women and 13 men, aged 25-50 years. The daily methadone dosage ranged from 10 to 120 mg, mostly as syrup. Urine (in plastic tubes with no preservative) and exhaled breath were simultaneously collected. In both fluids, methadone and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) were tested using a specific liquid chromatographic-tandem mass spectrometric method, whereas all other compounds were screened by liquid chromatographic-tandem mass spectrometric method using a home made library of more than 800 compounds. Linearity, imprecision, and limit of quantitation were established. In each analytical batch, low and high controls were included.

RESULTS

All 18 urine specimens tested positive for methadone and EDDP. Several other compounds were also identified, including morphine, THC-COOH, benzoylecgonine, nicotine, some antidepressants, and neuroleptics. Methadone and EDDP were identified in exhaled breath from all 18 patients, with concentrations in the range 11-1470 and 29-818 pg per filter, respectively. In 13 cases, the ratio methadone/EDDP in exhaled breath was >1 (range 0.4-2.8). Except nicotine (n = 7), no other substance was detectable in exhaled breath.

CONCLUSION

This study gives further support to the possibility of using exhaled breath as a new matrix to document exposure to drugs.

Potential of Mass Spectrometry in Developing Clinical Laboratory Biomarkers of Nonvolatiles in Exhaled Breath

BACKGROUND

Exhaled breath contains nonvolatile substances that are part of aerosol particles of submicrometer size. These particles are formed and exhaled as a result of normal breathing and contain material from distal airways of the respiratory system. Exhaled breath can be used to monitor biomarkers of both endogenous and exogenous origin and constitutes an attractive specimen for medical investigations.

CONTENT

This review summarizes the present status regarding potential biomarkers of nonvolatile compounds in exhaled breath. The field of exhaled breath condensate is briefly reviewed, together with more recent work on more selective collection procedures for exhaled particles. The relation of these particles to the surfactant in the terminal parts of the respiratory system is described. The literature on potential endogenous low molecular weight compounds as well as protein biomarkers is reviewed. The possibility to measure exposure to therapeutic and abused drugs is demonstrated. Finally, the potential future role and importance of mass spectrometry is discussed.

SUMMARY

Nonvolatile compounds exit the lung as aerosol particles that can be sampled easily and selectively. The clinical applications of potential biomarkers in exhaled breath comprise diagnosis of disease, monitoring of disease progress, monitoring of drug therapy, and toxicological investigations.

Real-time monitoring of exhaled drugs by mass spectrometry

Future individualized patient treatment will need tools to monitor the dose and effects of administrated drugs. Mass spectrometry may become the method of choice to monitor drugs in real time by analyzing exhaled breath. This review describes the monitoring of exhaled drugs in real time by mass spectrometry. The biological background as well as the relevant physical properties of exhaled drugs are delineated. The feasibility of detecting and monitoring exhaled drugs is discussed in several examples. The mass spectrometric tools that are currently available to analyze breath in real time are reviewed. The technical needs and state of the art for on-site measurements by mass spectrometry are also discussed in detail. Off-line methods, which give support and are an important source of information for real-time measurements, are also discussed. Finally, some examples of drugs that have already been successfully detected in exhaled breath, including propofol, fentanyl, methadone, nicotine, and valproic acid are presented. Real-time monitoring of exhaled drugs by mass spectrometry is a relatively new field, which is still in the early stages of development. New technologies promise substantial benefit for future patient monitoring and treatment.

Quantification of cocaine and metabolites in exhaled breath by liquid chromatography-high-resolution mass spectrometry following controlled administration of intravenous cocaine

Breath has been investigated as an alternative matrix for detecting recent cocaine intake; however, there are no controlled cocaine administration studies that investigated the drug's disposition into breath. Breath was collected from 10 healthy adult cocaine users by asking them to breathe into a SensAbues device for 3 min before and up to 22 h following 25 mg intravenous (IV) cocaine dosing on days 1, 5, and 10, and assayed with a validated liquid chromatography-high-resolution mass spectrometry (LC-HRMS) method to quantify breath cocaine, benzoylecgonine (BE), ecgonine methyl ester (EME), and norcocaine. The assay was linear from 25 to 1,000 pg/filter, extraction efficiencies were 83.6-126%, intra- and inter-assay imprecision was <10.6%, and bias was between -8.5 and 16.8%. No endogenous or exogenous interferences were observed for more than 75 tested. Analytes were generally stable under short-term storage conditions. Ion suppression was less than 46%. Of breath specimens collected after controlled cocaine administration, 2.6% were positive for cocaine (26.1-66 pg/filter, 1-9.5 h), 0.72% BE (83.3-151 pg/filter, 6.5-12.5 h), and 0.72% EME (50-69.1 pg/filter, 6.5-12.5 h); norcocaine was not detected. Methanolic extraction of the devices themselves, after filters were removed, yielded 19.2% positive cocaine tests (25.2-36.4 pg/device, 10 min-22 h) and 4.3% positive BE tests (26.4-93.7 pg/device, 10 min-22 h), explaining differences between the two extraction techniques. These results suggest that the device reflects the drug in oral fluid as well as lung microparticles, while the filter reflects only drug-laden microparticles. A sensitive and specific method for cocaine, BE, EME, and norcocaine quantification in breath was developed and validated. Cocaine in breath identifies recent cocaine ingestion, but its absence does not preclude recent use.