Comparison of plasma and saliva levels of diazepam

Extending the breadth of saliva metabolome fingerprinting by smart template strategies and effective pattern realignment on comprehensive two-dimensional gas chromatographic data

Comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC × GC-TOFMS) is one the most powerful analytical platforms for chemical investigations of complex biological samples. It produces large datasets that are rich in information, but highly complex, and its consistency may be affected by random systemic fluctuations and/or changes in the experimental parameters. This study details the optimization of a data processing strategy that compensates for severe 2D pattern misalignments and detector response fluctuations for saliva samples analyzed across 2 years. The strategy was trained on two batches: one with samples from healthy subjects who had undergone dietary intervention with high/low-Maillard reaction products (dataset A), and the second from healthy/unhealthy obese individuals (dataset B). The combined untargeted and targeted pattern recognition algorithm (i.e., UT fingerprinting) was tuned for key process parameters, the signal-to-noise ratio (S/N), and MS spectrum similarity thresholds, and then tested for the best transform function (global or local, affine or low-degree polynomial) for pattern realignment in the temporal domain. Reliable peak detection achieved its best performance, computed as % of false negative/positive matches, with a S/N threshold of 50 and spectral similarity direct match factor (DMF) of 700. Cross-alignment of bi-dimensional (2D) peaks in the temporal domain was fully effective with a supervised operation including multiple centroids (reference peaks) and a match-and-transform strategy using affine functions. Regarding the performance-derived response fluctuations, the most promising strategy for cross-comparative analysis and data fusion included the mass spectral total useful signal (MSTUS) approach followed by Z-score normalization on the resulting matrix.

Detection Times of Diazepam, Clonazepam, and Alprazolam in Oral Fluid Collected From Patients Admitted to Detoxification, After High and Repeated Drug Intake

BACKGROUND

Clonazepam, diazepam, and alprazolam are benzodiazepines with sedative, anticonvulsant, and anxiolytic effects, but their prevalence in drug abuse and drug overdoses has long been recognized. When detection times for psychoactive drugs in oral fluid are reported, they are most often based on therapeutic doses administered in clinical studies. Repeated ingestions of high doses, as seen after drug abuse, are however likely to cause positive samples for extended time periods. Findings of drugs of abuse in oral fluid collected from imprisoned persons might lead to negative sanctions, and the knowledge of detection times of these drugs is thus important to ensure correct interpretation. The aim of this study was to investigate the time window of detection for diazepam, clonazepam, and alprazolam in oral fluid from drug addicts admitted to detoxification.

METHODS

Twenty-five patients with a history of heavy drug abuse admitted to a detoxification ward were included. Oral fluid was collected daily in the morning and the evening and urine samples every morning for 10 days, using the Intercept device. Whole blood samples were collected if the patient accepted. The cutoff levels in oral fluid were 1.3 ng/mL for diazepam, N-desmethyldiazepam, and 7-aminoclonazepam and 1 ng/mL for clonazepam and alprazolam. In urine, the cutoff levels for quantifications were 30 ng/mL for alprazolam, alpha-OH-alprazolam, and 7-aminoclonazepam, 135 ng/mL for N-desmethyldizepam, and 150 ng/mL for 3-OH-diazepam and for all the compounds, the cutoff for the screening analyses were 200 ng/mL.

RESULTS

The maximum detection times for diazepam and N-desmethyldiazepam in oral fluid were 7 and 9 days, respectively. For clonazepam and 7-aminoclonazepam, the maximum detection times in oral fluid were 5 and 6 days, respectively. The maximum detection time for alprazolam in oral fluid was 2.5 days. New ingestions were not suspected in any of the cases, because the corresponding concentrations in urine were decreasing. Results from blood samples revealed that high doses of benzodiazepines had been ingested before admission, and explains the longer detection times in oral fluids than reported previously after intake of therapeutic doses of these drugs.

CONCLUSIONS

This study has shown that oral fluid might be a viable alternative medium to urine when the abuse of benzodiazepines is suspected.

Detection of 4 benzodiazepines in oral fluid as biomarker for presence in blood

BACKGROUND

Analysis of samples of oral fluid (mixed saliva) is increasingly being used to detect recent drug use. The aim of this investigation was to assess the suitability of testing oral fluid as a biomarker for the presence of 4 benzodiazepines in blood and its possible application in clinical settings and in research on drug use.

METHODS

Paired samples of oral fluid and blood from 4080 individuals in 4 European countries were collected and analyzed for benzodiazepines using gas or liquid chromatography with mass spectroscopic detection.

RESULTS

Concentration data for the 4 most commonly detected benzodiazepines were studied: alprazolam, clonazepam, diazepam, and nordiazepam. Large variations in oral fluid to blood concentration ratios were observed for the studied benzodiazepines. The interquartile ranges for the oral fluid to blood concentrations ratios corresponded to 88%-197% of the median values. Selecting cutoff concentrations in oral fluid that gave the best accuracy in identifying individuals with benzodiazepine concentrations in blood above chosen thresholds produced accuracies of 74%-85% and the fraction of false negatives was 9%-23%.

CONCLUSIONS

The concentration of the 4 studied benzodiazepines in oral fluid can neither be used to accurately estimate the concentrations in blood nor to correctly identify patients with blood drug concentrations below or above recommended therapeutic levels. When using analytical methods with limits of quantitation corresponding to concentrations less than 0.5 ng/mL in undiluted oral fluid, it may be used to confirm a recent intake of benzodiazepines. However, it is likely that some false negatives may occur.

Interpretation of oral fluid tests for drugs of abuse

Oral fluid testing for drugs of abuse offers significant advantages over urine as a test matrix. Collection can be performed under direct observation with reduced risk of adulteration and substitution. Drugs generally appear in oral fluid by passive diffusion from blood, but also may be deposited in the oral cavity during oral, smoked, and intranasal administration. Drug metabolites also can be detected in oral fluid. Unlike urine testing, there may be a close correspondence between drug and metabolite concentrations in oral fluid and in blood. Interpretation of oral fluid results for drugs of abuse should be an iterative process whereby one considers the test results in the context of program requirements and a broad scientific knowledge of the many factors involved in determining test outcome. This review delineates many of the chemical and metabolic processes involved in the disposition of drugs and metabolites in oral fluid that are important to the appropriate interpretation of oral fluid tests. Chemical, metabolic, kinetic, and analytic parameters are summarized for selected drugs of abuse, and general guidelines are offered for understanding the significance of oral fluid tests.

Therapeutic drug concentration monitoring using saliva samples. Focus on anticonvulsants

In the last 30 years there has been great interest in the use of saliva in therapeutic drug monitoring. Numerous investigators have suggested that saliva be used as an alternative body fluid for the therapeutic drug monitoring of anticonvulsant drugs. Not only can saliva be obtained easily on multiple occasions with minimal discomfort to the patient but, more importantly, useful relationships exist between the saliva and blood concentrations of the most commonly used anticonvulsant drugs. The measurement of anticonvulsant drug concentrations in saliva has been applied to pharmacokinetic and pharmacodynamic studies, and for therapeutic drug monitoring in a variety of seizure disorders. However, this simple and non-invasive method is not widely accepted in clinical practice. Several recent developments in sample collection and analytical methods, and the growing interest in free drug concentrations, provide a renewed impetus for saliva sampling for therapeutic drug monitoring of anticonvulsant drugs. Salivary flow rates vary significantly both between individuals and under different conditions. The use of stimulated saliva has several advantages over resting saliva. The salivary flow rate and pH, sampling conditions, contamination and many other pathophysiological factors may influence the concentrations of the medication in saliva. However, under standardised and well-controlled sampling condition, therapeutic drug monitoring of anticonvulsant drugs in saliva can be useful for determining compliance with medication in paediatric patients, for analysing the concentration of free drug and in situations where repeated sampling is necessary. Saliva is an alternative matrix for the therapeutic drug monitoring of carbamazepine, phenytoin, primidone and ethosuximide because the concentrations of these medications in saliva reflect the concentrations of the drug in serum. This is not the case for valproic acid (valproate sodium) and some controversy exists for phenobarbital. Further studies are required to assess the clinical value of monitoring anticonvulsant drugs and their metabolites in saliva, to examine the influence of pathophysiological factors on salivary drug concentrations, to improve the design of special devices to reproducibly and conveniently collect saliva samples, and to develop and use new analytical methods to achieve more sensitive and accurate results.

Drug monitoring in nonconventional biological fluids and matrices

Determination of the concentration of drugs and metabolites in biological fluids or matrices other than blood or urine (most commonly used in laboratory testing) may be of interest in certain areas of drug concentration monitoring. Saliva is the only fluid which can be used successfully as a substitute for blood in therapeutic drug monitoring, while an individual's past history of medication, compliance and drug abuse, can be obtained from drug analysis of the hair or nails. Drug concentrations in the bile and faeces can account for excretion of drugs and metabolites other than by the renal route. Furthermore, it is important that certain matrices (tears, nails, cerebrospinal fluid, bronchial secretions, peritoneal fluid and interstitial fluid) are analysed, as these may reveal the presence of a drug at the site of action; others (fetal blood, amniotic fluid and breast milk) are useful for determining fetal and perinatal exposure to drugs. Finally, drug monitoring in fluids such as cervical mucus and seminal fluid can be associated with morpho-physiological modifications and genotoxic effects. Drug concentration measurement in nonconventional matrices and fluids, although sometimes expensive and difficult to carry out, should therefore be considered for inclusion in studies of the pharmacokinetics and pharmacodynamics of new drugs.

Saliva testing for drugs of abuse

Saliva testing for drugs of abuse can provide both qualitative and quantitative information on the drug status of an individual undergoing testing. Self-administration by the oral, intranasal, and smoking routes often produces "shallow depots" of drug that contaminate the oral cavity. This depot produces elevated drug concentrations that can be detected for several hours. Thereafter, saliva drug concentrations generally reflect the free fraction of drug in blood. Also, many drugs are weak bases and saliva concentrations may be highly dependent upon pH conditions. These factors lead to highly variable S/P ratios for many of the drugs of abuse. Table 3 provides a compilation of experimental and theoretical S/P (total) ratios determined for drugs of abuse. Estimations of the theoretical S/P (total) ratios for acidic and basic drugs were based on the Henderson-Hasselbalch equation. Saliva pH was assumed to be 6.8 unless reported otherwise by the investigators. Generally, there was a high correlation of saliva drug concentrations with plasma, especially when oral contamination was eliminated. Assay methodology varied considerably, indicating that saliva assays could be readily developed from existing methodology. There are many potential applications for saliva testing for drugs of abuse. Table 4 lists several general areas in which information from saliva testing would be useful. Clearly, saliva drug tests can reveal the presence of a pharmacologically active drug in an individual at the time of testing. Significant correlations have been found between saliva concentrations of drugs of abuse and behavioral and physiological effects. Results indicate that saliva testing can provide valuable information in diagnostics, treatment, and forensic investigations of individuals suspected of drug abuse. It is expected that saliva testing for drugs of abuse will develop over the next decade into a mature science with substantial new applications.

Current diagnostic uses of saliva

Most of the information which has been collected on salivary composition in different disease states (with the notable exception of that in digitalis intoxication) has proved of little practical diagnostic value. Diagnostic use of saliva has become more extensive in recent years, particularly in relation to estimation of systemic levels of lipid-soluble drugs and hormones. Thiocyanate levels have been used to validate self-reported frequency of tobacco-smoking, and nitrate levels have been assayed to estimate dietary nitrate intakes. The estimation of steroid hormone concentrations in saliva is now generally recognized as a means of determining systemic steroid levels which offers many advantages over estimation in serum or urine samples. Immunoassay methods now permit measurement of very small concentrations of biologically active substances in saliva.

Comparison of gas chromatography and receptor bioassay in the determination of diazepam in plasma after conventional tablets and controlled release capsules

Plasma levels of diazepam and its metabolites were compared after a controlled release formulation and a regular tablet. Both gas chromatographic analysis of plasma diazepam and desmethyldiazepam and radioreceptor assay of total benzodiazepine activity were used. Also the concentrations of benzodiazepine in saliva samples were analyzed by radioreceptor assay. A typical initial plasma peak was seen after the regular tablet but not after the controlled release capsule. Hence the excessive initial sedation can be avoided and the risk of abuse reduced. Desmethyldiazepam increased for about two days after a single dose of diazepam. The receptor assay correlated in general with the sum of diazepam and its desmethyl derivative. The saliva assay gave about 2.5% of the plasma total benzodiazepine which correlates well with the expected free benzodiazepine. It seems that both the plasma radioreceptor assay and the saliva assay can be used to monitor the total benzodiazepine concentration.

Anticonvulsant drugs. An update

A considerable amount of information is now available concerning the clinical pharmacology of the anticonvulsant drugs. Some of the more important data are reviewed in this article. In recent years, valproic acid (or sodium valproate) has found a place as a major anticonvulsant agent, while older drugs such as troxidone and sulthiame seem to be disappearing from use. Although much information is available, the essential mechanisms of action of the anticonvulsant drugs are still not understood, either at a molecular or at an electrophysiological level. The pharmacokinetics of the anticonvulsants in common use are now reasonably well documented, though some minor questions are still to be answered. Numerous interactions between anticonvulsants and endogenous substances or other drugs administered concurrently (including other anticonvulsants) have been recorded, but much work still needs to be done to elucidate the frequency and mechanisms of the various interactions. Many adverse effects of the anticonvulsants are known, but further unwanted effects of long-established drugs continue to emerge from time to time, including the still somewhat controversial matter of anticonvulsant-related dysmorphogenesis. The use of valproic acid and its sodium salt has been associated with a worrying incidence of serious liver and pancreatic toxicity. Adequate basic data are now available to put the clinical use of anticonvulsants on a rational basis, but much work remains to be done in this area. In particular, the question of 'therapeutic ranges' of plasma concentrations of the various drugs needs to be reinvestigated in a rigorous statistical fashion, and in relation to different clinical types of epilepsy. The usefulness of monitoring free rather than total drug concentrations also needs further investigation. The ultimate test of the validity of all background scientific pharmacological information about anticonvulsants is its usefulness in the treatment of patients with epilepsy.

Psychomotor performance and real driving performance of outpatients receiving diazepam

The primary aim of this study was to compare task performance in a laboratory test and real driving performance of outpatients receiving diazepam medication with those of control subjects. Plasma and saliva samples were taken to investigate a level-response relationship. Real driving performance was measured by trained observers. The design of the laboratory test was based on a vigilance task (high attention) directly followed by a simple eye-hand coordination tasks (low attention). Twenty-two males participated in the study. Diazepam was given orally by prescription, mostly as a maintenance dose of 5 mg three times a day. Patients receiving diazepam showed impaired performance in the driving test and the low-attention task. Furthermore, the results indicate no relationship between plasma or saliva levels of diazepam and/or its metabolite N-desmethyldiazepam and real driving performance and/or laboratory task performance.