The Mississippi Press Meth arrests and lab seizures declining in Jackson County Tuesday, September 07, 2010 By CHERIE WARD, The Mississippi Press PASCAGOULA, Mississippi -- A law that took effect in July treating pseudoephedrine as a Schedule III controlled substance - which makes the drug illegal to possess without a prescription - seems to be making a difference in Mississippi and Jackson County.
August cbr 110806 final.inddDrug Testing in Oral Fluid
Olaf H Drummer
Victorian Institute of Forensic Medicine and Department of Forensic Medicine, Monash University, 57-83 Kavanagh St, Southbank, Vic. 3006, Australia For correspondence: Prof Olaf Drummer e-mail: [email protected] Over the last decade there have been considerable developments in the use of oral ﬂ uid (saliva) for drug testing. Oral ﬂ uid can provide a quick and non-invasive specimen for drug testing. However, its collection may be thwarted by lack of available ﬂ uid due to a range of physiological factors, including drug use itself. Food and techniques designed to stimulate production of oral ﬂ uid can also affect the concentration of drugs. Current applications are mainly focused on drugs of abuse testing in employees at workplaces where drug use has safety implications, in drivers of vehicles at the roadside and in other situations where drug impairment is suspected. Testing has included alcohol (ethanol) and a range of clinical tests eg antibodies to HIV, therapeutic drugs and steroids. Its main application has been for testing for drugs of abuse such as the amphetamines, cocaine and metabolites, opioids such as morphine, methadone and heroin, and for cannabis. Oral ﬂ uid concentrations of basic drugs such as the amphetamines, cocaine and some opioids are similar or higher than those in plasma. Tetrahydrocannabinol (THC), the major species present from cannabis use, displays similar concentrations in oral ﬂ uid compared to blood in the elimination phase. However, there is signiﬁ cant local absorption of the drug in the oral cavity which increases the concentrations for a period after use of drug. Depot effects occur for other drugs introduced into the body that allow local absorption, such as smoking of tobacco (nicotine), cocaine, amphetamines, or use of sub-lingual buprenorphine. Screening techniques are usually an adaptation of those used in other specimens, with an emphasis on the parent drug since this is usually the dominant species present in oral ﬂ uid. Conﬁ rmatory techniques are largely based on mass spectrometry (MS) with an emphasis on Liquid Chromatography-Mass Spectrometry (LC-MS), due to low sample volumes and the low detection limits required. Drug testing outside laboratory environments has become widespread and provides presumptive results within minutes of collection of specimens. This review focuses on the developments, particularly over the last 10 years, and outlines the roles and applications of testing for drugs in oral ﬂ uid, describes the difﬁ culties associated with this form of testing and illustrates applications of oral ﬂ uid testing for speciﬁ c drugs. to the high sensitivity and speciﬁ city of MS.2-4 This has Drug testing has undergone major advances, particularly assisted in the development of drug testing in oral ﬂ uid due to over the last 10 years. The use of alternative specimens to the relatively small sample volumes that are usually collected.
blood or urine for establishing exposure to drugs has become The last decade has also seen a signiﬁ cant development in the a signiﬁ cant direction in clinical and forensic toxicology.1 understanding of the target drugs and their pharmacokinetics These alternative specimens include hair, sweat and oral in oral ﬂ uid. This has applied particularly to the abused ﬂ uid. Oral ﬂ uid has been seen as a non-invasive alternative to drugs and what concentrations need to be targeted, and also blood but also as an alternative to urine when substitution or how these concentrations may or may not relate to blood adulteration is suspected. While these attributes are real, oral concentrations and the likely drug effects on the individual.
ﬂ uid cannot be seen as a substitute for blood or urine drug In addition, the use of initial screening cartridges or devices testing. Each specimen has its own distinct advantages and providing an electronic readout has developed and is now widely used. In particular, kits are now designed for on-site drug detection without the need for sophisticated laboratory The introduction of LC-MS as a routine laboratory technique screening equipment. These are able to provide a preliminary has enabled the beneﬁ ts of High Performance Liquid drug result within minutes.
Chromatography (HPLC) separation techniques to be linked Clin Biochem Rev Vol 27 August 2006 I 147 A number of reviews and major papers currently exist for that is used to collect the oral ﬂ uid is added to a diluent. various aspects of drugs and drug testing in oral ﬂ uid. These Following mixing, the solution is used for drug analysis. include its use as a diagnostic tool,5 workplace applications,6 Other devices involve squeezing absorbed oral ﬂ uid from a applications in drugs in driving,7 legal issues associated pad or foam onto the drug-detection device. The collection with drug testing in oral ﬂ uid,8 and detection times and time is typically one to three minutes, however this can vary as pharmacokinetics of selected drugs.9,10 discussed earlier. A number of the devices have some form of indicator to show that sufﬁ cient oral ﬂ uid has been collected.
This review outlines the roles and applications of testing for drugs in oral ﬂ uid, describes the relative advantages The DrugWipe® only involves swiping a collection pad on and disadvantages of this form of testing and illustrates the tongue or skin, a process that takes only seconds (Table 1).
applications of oral ﬂ uid testing for speciﬁ c drugs.
However, there is no oral ﬂ uid for any conﬁ rmatory assay if the result is positive.
Scope of Review
This paper reviews the developments and applications of Oral ﬂ uid production is stimulated by use of agents such as drug testing in oral ﬂ uid particularly over the last 10 years. citric acid candy, chewing gum or other agents. This will Published peer-reviewed literature and other selected inevitably change the pH and concentration of drug in the references in the English language in humans as sourced by oral ﬂ uid. This has been shown to lower concentrations of Medline and Science Direct (since 1995) are reviewed for codeine by about two- to six-fold,12,13 two- to four-fold for clinical and forensic applications of drug testing in oral ﬂ uid. methamphetamine,14 and about ﬁ ve-fold for cocaine.15 It is Publications before this time are included if pivotal or later likely that similar changes will occur for other drugs.
papers were not available. The term oral ﬂ uid refers to saliva and other secretions in the oral cavity. The focus is on testing A number of drugs are known to affect the secretion of oral for drugs of abuse such as the amphetamines, benzodiazepines, ﬂ uid.11 Most commonly these are amphetamines, including cannabis, cocaine and opioids, but other applications will be the designer forms such as ecstasy (MDMA), and cannabis. discussed in the context of abused drugs.
Other drugs include the sedating antihistamines, antipsychotic drugs, anticholinergic drugs and a number of antidepressants. Source of Oral Fluid
There are less commonly used drugs that increase ﬂ ow and Oral ﬂ uid (saliva) is excreted primarily by three glands: the these include clonidine, pilocarpine and beta-2 stimulants parotid, submaxillary and sublingual and by other smaller (salbutamol, terbutaline etc).
glands. Oral ﬂ uid has low protein content (0.3%) and can vary in ﬂ ow rate from zero to several mL per minute depending on Consequently, there is signiﬁ cant intra- and inter-subject inﬂ uences from various factors, including emotional state and variation in relation to drug concentrations depending on the hunger. Dry mouth syndrome is relatively common and can technique used, the physiology of the person and the inﬂ uence be caused by the anxiety of the collection procedure, or even of factors affecting drug concentration in oral ﬂ uid. by lack of proper hydration of the individual. Dry mouths require much longer collection times; often several minutes to Since the collection of oral ﬂ uid specimen can be viewed by a collect 1 mL. On some occasions this may force the collection second person without infringing privacy it does not suffer from of an alternative specimen if collection is too slow, ie blood the same issues regarding possible adulteration or substitution (unpublished data). Aps and Martens provide an excellent as for urine.13 While this can be a distinct advantage, it must review of physiological and pharmacological issues involved be recognised that methods can be employed to potentially in the production of oral ﬂ uid.11 affect the collection of oral ﬂ uid or the concentration of drugs in oral ﬂ uid. The prior administration of drugs and a Collection Techniques and Adulterants
range of physiological factors covered earlier can affect drug Expectoration (or spitting) provides neat oral ﬂ uid, but this concentration. Foodstuffs, various beverages and various is relatively viscous and can be difﬁ cult to work with in toothpastes did not affect the concentration of drugs of abuse the laboratory. It may also be contaminated with food and using the Oratect® device 30 min after exposure.16 The use of other debris from the mouth and will therefore require commercial adulterants or other products capable of acting as centrifugation. More often than not, the volume will be less adulterants, such as Clear Choice®, Fizzy FlushTM Spit and than 1 mL requiring the use of sensitive detection techniques. Clean®/™ mouth wash and Cool Mint Listerine® also had no Some of the commercial collectors available use some form substantial effect after 30 min. In an early study using a small of proprietary diluent to mix with the collected oral ﬂ uid number of volunteers, the consumption of beer immediately (Table 1). In this situation, typically the absorbent pad/foam smoking a marijuana joint appeared to lower concentrations 148 I Clin Biochem Rev Vol 27 August 2006 Table 1. Selection of collection devices reported in literature.
Name of collector
Method of operation
Swipe only (tongue or skin) 62, 66, 67, 93, 94 Cozart® collector Absorbent foam pad plus diluent 75, 76, 93, 95, 96 Dräger DrugTest® Absorbent foam pad with diluent Absorbent foam pad with diluent Absorbent foam pad only, drops applied to device Absorbent foam pad, collector squeezed to apply oral ﬂ uid into test cartridge Direct application to oral cavity, or use of other collectors Absorbent directly connected to device Absorbent foam pad plus diluent Absorbent foam pad, drops applied to device Cotton wool swab which is then ﬁ ltered Absorbent bud, oral ﬂ uid squeezed into syringe and applied to device of THC in oral ﬂ uid at 1 h post dose.17 It is likely that a short Recovery of Drugs from Collectors
rinsing effect is seen with these agents and others, including There is no one type of collection device that is clearly water, for a short period after use. Since the oral ﬂ uid in the superior based on design or ease of use. However, recovery mouth is rapidly turned over, a wait of several minutes should studies conducted on some devices suggest that desorption allow re-equilibration of drug in the surrounding tissues. of drugs may limit the usability of some collection materials. For example, the Salivette® has poor recovery for THC but The rinsing effect with drugs is in some way similar to the is reasonable for codeine,12,19 whereas the Cozart® collector contamination of breath alcohol by recently consumed alcohol has good recovery for THC,20 and methamphetamine in that a wait of 15-20 min allows any mouth alcohol to be (unpublished data). The Quantisal® collection device has a removed by normal physiological processes.18 However, more good recovery for THC,21 although another study found lower research is needed to investigate this phenomenon in oral ﬂ uid recoveries for THC.20 for the various collection techniques.
Clin Biochem Rev Vol 27 August 2006 I 149 Clearly more information is required for all drugs likely from the pH of oral ﬂ uid and blood, the protein binding of the to be measured in oral ﬂ uid, for each collection device. drug and its pKa.13,28 For acidic drugs the equilibrium favours Indeed a device should not be used until recovery and blood, hence oral ﬂ uid concentrations are less than for blood, stability studies have been performed and show adequate while for basic drugs higher oral ﬂ uid concentrations occur. performance. However, it should be emphasised that products The average concentration ratio is shown in Table 2. In the are continually being developed and hence published results absorptive phase there are often higher concentrations in the on an earlier design may not bear any resemblance to more oral ﬂ uid due to local absorption in the mucous membranes recent designs.
of the buccal cavity. This local absorption effect is probably highest for THC due to its higher fat solubility and ease of Applications of Oral Fluid Drug Testing
penetration through membranes and the very low partitioning The use of oral ﬂ uid to detect drugs has potentially wide from blood to oral ﬂ uid. However, as discussed later in this applications. To date its main application has been to provide section this effect is also seen for other drugs.
a non-invasive specimen for testing of possible drug-affected drivers.22 It has also been used for workplace testing, The most commonly detected drug toxicologically, alcohol particularly following a safety incident, to check for possible (ethanol), has been subject to much research in terms of its drug use.23,24 Other applications include testing of persons in presence in oral ﬂ uid. The oral ﬂ uid to plasma concentration prisons and other correctional institutions, the monitoring of is similar to that predicted based on the water content of the drug use by drug courts, or testing of detainees suspected of a two ﬂ uids and averages just over unity and has been used to crime who may be under the inﬂ uence of a drug. assess alcohol exposure.25,29-31 Oral ﬂ uid should not be seen as a specimen that replaces the Subjective intoxication and the increase in heart rate in use of other specimens. As discussed later the pharmacokinetic volunteers taking cannabis correlated well with oral ﬂ uid THC characteristics of drugs are more closely aligned to blood concentrations.32 Oral ﬂ uid concentrations also correlated well concentrations than, for example, urine or hair. Urine should with plasma concentrations.33 still be seen as the specimen of choice if evidence of prior exposure to drugs of abuse is sought (eg routine workplace The administration of 30 mg doses of codeine phosphate screening without cause and drug screening of prisoners). showed a good correlation of plasma and oral ﬂ uid Hair will still be much more useful if a longer time frame of concentrations particularly after 2 h following the initial exposure to drugs is sought. However, if evidence of recent contamination of the oral cavity.34 The individual oral ﬂ uid use (or abstinence) of drugs is sought then either blood or oral to plasma concentration ratios varied substantially and was ﬂ uid are preferred specimens. partly due to the pH of the oral ﬂ uid. Some concordance of the physiologic and subjective effects of codeine and oral ﬂ uid Oral ﬂ uid has the advantage over blood in that it can be concentration occurred following single oral codeine doses to obtained non-invasively in a situation where adulteration or substitution is difﬁ cult. A review of the advantages and Orally administered morphine shows a delay in the appearance disadvantages of specimens is available.25 in oral ﬂ uid compared to its presence in plasma suggesting some rate limiting movement in oral ﬂ uid possibly due to its relatively low lipid solubility.25 6-Acetylmorphine and A recent review of the pharmacokinetics of some drugs in morphine are also present in detectable amounts in oral ﬂ uid oral ﬂ uid has been published.10 As distinct from urine the after use of heroin.27 dominant species in oral ﬂ uid is the parent drug.10 Hence, initial screens and conﬁ rmatory techniques target the parent Buprenorphine is widely used for the treatment of opioid drug. For example, there is almost no carboxy metabolite dependency and is available (amongst other formulations) of THC present in oral ﬂ uid. However, due to the rapid as a sublingual tablet.36,37 The local absorption of drug in the bioconversion of cocaine, benzoylecgonine and ecgonine mucous membranes of the oral cavity produces a depot-like methyl ester they are also detectable in oral ﬂ uid.26,27 Moreover, effect for some hours after administration of drug. In the anhydroecgonine methyl ester is also detected in oral ﬂ uid terminal phase of elimination oral ﬂ uid concentrations were after smoking cocaine.27 similar to plasma.38 Nevertheless, the data suggested that oral ﬂ uid could be used to monitor the use of this opioid. A similar As a general rule there is some similarity between an oral ﬂ uid depot effect occurs with nicotine. Research suggests that concentration and a blood/plasma concentration. In the case measurement of the major metabolite cotinine is more useful of most drugs the oral ﬂ uid concentration can be estimated than nicotine to determine exposure to this drug.39,40 150 I Clin Biochem Rev Vol 27 August 2006 Table 2. Average oral ﬂ uid to blood concentration ratios for selected drugs.
Average oral ﬂ uid to blood concentration Alcohol (ethanol) Methamphetamine (basic) Diazepam (acidic) Methadone (basic) Type refers to physiochemical property of drug, ie acidity, basicity or neutrality. The average ratios are indicative ﬁ gures derived from pharmacokinetic studies and will change depending on a number of factors, including pH of oral ﬂ uid, protein binding and degree of contamination of the membranes in the oral cavity by recently consumed drug.
Slow equilibration between plasma and oral ﬂ uid has also years although it has been increasingly used in a range of been observed for diazepam.41 Since diazepam and other applications. There is some support for its routine application benzodiazepines are highly protein bound and are weakly for some anticonvulsants and theophylline.51,52 Recently acidic they have low oral ﬂ uid concentrations. Mean oral applications for carbamazepine,53 digoxin,51 topirimate,54 ﬂ uid to plasma ratios for diazepam are about 0.01-0.02.42,43 methadone,55 disopyramide,56 and docetaxel and paclitaxel Little data is available for other benzodiazepines, however, have been described.57 they are likely to behave similarly.44,45 Stability problems for the nitrobenzodiazepines (clonazepam, ﬂ unitrazepam and Other clinical applications include testing for HIV- nitrazepam) have been reported in which conversion to the antibodies,58,59 and a number of steroids including cortisol and corresponding 7-amino metabolite also occurs.45,46 The use of dehydroepiandrosterone,60 and 17-hydroxy progesterone.61 ﬂ uoride has been shown to stabilise the drug.45 An often mooted advantage for oral ﬂ uid over serum is the ease of collection and is, of course, less invasive than These data show that the pharmacokinetics of drugs in oral venepuncture. However, care will be needed to avoid changes ﬂ uid is more complex than that of blood. Detection times in in concentration in oral ﬂ uid caused by a variety of factors this specimen will depend on a range of factors including discussed elsewhere in this review.
dose, frequency of use (ie acute versus chronic use) and detection limits of analytical assays. A number of other drugs Initial Testing Techniques
of forensic interest have been measured in oral ﬂ uid. These Initial testing of oral ﬂ uid for drugs can either occur in the include hydromorphone,47 phencyclidine,48 pholcodine,49 and ﬁ eld (other words for this form of testing include on-site or point-of-care testing) or in the laboratory. Therapeutic Drug Monitoring (TDM)
TDM of drugs in oral ﬂ uid has been studied for at least 30 A number of devices are available for ﬁ eld use. These include Clin Biochem Rev Vol 27 August 2006 I 151 instrumental devices providing an electronic readout such Belgium who failed a sobriety assessment but were below the as the Dräger DrugTest® and Orasure Uplink®, Cozart legal limit of alcohol (0.05%). Oral ﬂ uid concentrations were Rapiscan® and Drugread® hand photometer (Securetec) to closely related to plasma concentrations and gave positive hand-held cartridges requiring visual identiﬁ cation such as the predictive values and sensitivities exceeding 90% when DrugWipe® (Securetec AG), iScreen OFDTM (Rapid Detect evaluated against plasma legal cut-offs. The DrugWipe® Inc.), OralScreen® (Avitar Technologies), Oratect® (Branan device through a tongue swipe was not recommended since Medical Corp.), SalivaScreenTM (Craig Medical Inc.) (Table accuracy of more than 90% was only obtained for amphetamine 3). These are optical readers that provide a visual readout of and MDMA.66 The use of Drugread® hand-held photometer intensity of response of the immunoassay signal.
with the DrugWipe® cartridge has been used to assess the detection of MDMA in oral ﬂ uid following a 100 mg single Unfortunately, there is no consistency in the speciﬁ cations dose in volunteers. Detection times ranged up to 10 h post- applied to these devices. For some, cut-off concentrations are dose although it was most reliable to 6 h. The detection limit used to deﬁ ne their detectability, for others concentrations are was about 450 ng/mL.67 The pharmacological effects of the given when drugs can be detected. The apparent sensitivity is drug were most signiﬁ cant up to about 6 h.
often not deﬁ ned in terms of consistency of detection in oral ﬂ uid specimens. This means that at the present moment there A recent study in Victoria, Australia in which over is no objective way to assess performance of these devices or 13,000 motorists were randomly screened for presence of methamphetamines (methamphetamine and MDMA) and THC as part of a campaign to reduce drug affected driving found a In the laboratory, terms such as false positive (FP) and positive rate of 1:40 compared to about 1:100 for alcohol. This false negative (FN) are used. FP refers to a situation when a testing was based on an initial tongue wipe using DrugWipe®, presumptive initial test result is not conﬁ rmed. FN refers to and if positive, repeat testing on the Rapiscan®/™ following a situation when a conﬁ rmation test ﬁ nds a drug present that collection of oral ﬂ uid with the Cozart® collector (unpublished was not detected by the initial test. Sensitivity is often used data). The overall FP rate using both devices was very low in deﬁ ning performance of initial testing kits and refers to the (one cannabis and four methamphetamines). Individually the relative detectability of the kit or device (of positive cases) devices gave more FP for methamphetamines (DrugWipe®) in question over a comparison method. On the other hand, and THC (Rapiscan®/™).
speciﬁ city refers to the percentage of negative results using the kit or device compared to the total number of negative As for urine, immunoassay tests of a drug class will not specimens using a comparison method. The comparison detect all members of the drug class equally. For example, the method is usually a Gas Chromatography-Mass Spectrometry required sensitivities of the initial test for the amphetamine, (GC-MS) or LC-MS method.
opiate and benzodiazepine classes will be different for the various drugs since the concentration of drugs in these classes A number of published studies have evaluated devices either are quite different to that of blood. For example, amphetamines using fortiﬁ ed oral ﬂ uid with known drug concentrations or have higher concentrations in oral ﬂ uid compared to blood and real specimens taken from humans exposed to the drug under benzodiazepines have concentrations only a fraction of those in blood. Hence, it is important that the selection of on-site testing devices has the appropriate sensitivity (and indeed other A number of studies have used the DrugWipe® cartridge. performance characteristics) for the intended applications. These have found a high rate of FN for volunteers given 60 mg codeine over a 24 h period using a limit of quantitation 2. Laboratory Testing of 5 ng/mL.62 The testing for amphetamines, cocaine and There are a number of commercial kits based on ELISA opiates in drivers was reasonably reliable when tested against technology available for laboratory screening of oral ﬂ uids. a GC-MS technique, except for some FN in heroin users.63 Amphetamines and opiates performed better than for benzo- These generally work satisfactorily for amphetamines,68,69 diazepines and THC on the DrugWipe® and Rapiscan®/™ buprenorphine,70 cocaine,65,71-73 methadone,74 and other in a drug driving study in Finland.64 The sensitivity and opioids,72,75,76 and provide a reliable means to screen oral speciﬁ city were all close to 90% for Rapiscan®/™ when ﬂ uid. Cannabis can be more difﬁ cult particularly if the testing for cocaine using a conﬁ rmation cut-off of 30 ng/ immunoassay has little cross-reactivity to THC. Nevertheless mL.65 In a Belgian study the DrugWipe® performed best for enzyme immunoassay has been successfully used for this amphetamines and cocaine.63 The reliability of DrugWipe® drug.77 The same applies for benzodiazepines despite their was assessed on drivers detained at special roadblocks in low concentrations in oral ﬂ uid.78 152 I Clin Biochem Rev Vol 27 August 2006 The power of MS has been used as a screening system for a offs in urine between countries after over 30 years of testing. range of drugs.79 Other general drug screening systems using Moreover, inadvertent exposure may limit the concentrations GC-MS,80,81 or LC-MS have been published that allow multiple that can be used to prove deliberate use. In the case of drugs to be detected and quantiﬁ ed in oral ﬂ uid.81-84 The choice cannabis, a study has found THC concentrations for a short of method is more to do with availability of instrumentation period following high passive exposure in an unventilated and costs since both forms of MS show sufﬁ cient sensitivity room of up to 26 ng/mL.86 Ingestion of poppy seeds in food for most forms of drug detection in oral ﬂ uid.
can cause a positive test result for morphine and exceed the 40 ng/mL SAMHSA cut-off for about one hour following Conﬁ rmatory Analytical Techniques
Conﬁ rmatory techniques for drugs in oral ﬂ uid are for the most part adaptations of their counterparts in blood or plasma/ Nevertheless, numerous papers exist that provide validated serum. Given the larger water component and lower protein methods for the detection of notable drugs in oral ﬂ uid. A content of oral ﬂ uid compared to blood, recovery of drugs summary of these is shown in Table 4. Predominantly, the is not usually a limiting factor. The smaller sample volume preferred technique is MS due to its high sensitivity and and often lower concentrations in oral ﬂ uid require the most speciﬁ city. Consequently the focus is on the use of this adjustments to analytical techniques. The required detection or quantiﬁ cation limit for drugs in oral MS can be in the form of GC-MS or LC-MS including tandem ﬂ uid depend very much on the application and type of screening mass spectrometry (MS-MS) applications for both forms of test employed. For example, in workplace applications the chromatography. Detection limits are within or less than those Substance Abuse & Mental Health Services Administration in mentioned in Table 3 and use volumes of oral ﬂ uid from 0.1- the USA (SAMHSA) has recommended conﬁ rmation cut-offs 0.5 mL. The majority of methods use LC-MS as distinct from for THC, cocaine, morphine and the amphetamines of 4, 8, 40, GC-MS to cater for the lower sample volumes and required and 50 ng/mL, respectively.22 In contrast, the European Union low detection limits, although a number of GC-MS techniques roadside assessment testing study (ROSITA) for impaired have been reported with adequate sensitivity. A review of the drivers have recommended somewhat different cut-offs,22 as pros and cons of LC-MS methods in oral ﬂ uid drug detection has the Australian Draft Standard for the collection, detection has been published.88 and quantiﬁ cation of drugs of abuse in oral ﬂ uid.85 (Table 3) Whatever technique is used it is important that the detection The variable target minimum concentrations probably reﬂ ect limits applied to conﬁ rmation testing is the same, but preferably the relative embryonic stage of drug testing compared to urine lower, than the initial testing threshold concentration. This drugs of abuse testing. It is possible that some international avoids not being able to conﬁ rm an initial on-site positive agreement may exist in the future regarding minimum result because of insufﬁ cient sensitivity and to cater for detectable concentrations (or cut-offs). However, this is presence of some metabolites that cross-react with antibodies unlikely since there are still signiﬁ cant differences in cut- used in immunoassays.
Table 3. Recommended minimum detectable concentrations of drugs in oral ﬂ uid.
Standards Australia proposed target concentrations (ng/mL) 6-AM = 6-Acetylmorphine, MDMA = methylenedioxymethamphetamine, THC = ∆9-tetrahydrocannabinol.
Clin Biochem Rev Vol 27 August 2006 I 153 Table 4. Selected mass spectrometric methods used to quantify some common drugs in oral ﬂ uid.
LOQ (volume of specimen) ng/mL (AM, MA, MDMA, MDEA etc) 500 µL (0.1-0.2 ng/mL) 6-AM = 6-acetylmorphine, AM = amphetamine, APCI = atmospheric pressure chemical ionization, MS2 = MS/MS, MA = methamphetamine, MDMA = methylenedioxymethamphetamine, MDEA = methylenedioxyethylamphetamine, LOQ = limit of quantiﬁ cation – note some methods have used limit of detection in validation, * most methods also measure benzoylecgonine, ecgonine methyl ester and other metabolites of cocaine.
(workplace, street, etc) there is a need to ensure a level of It is now expected that laboratories in many parts of the quality assurance takes place to ensure that the devices are world, including the author's own laboratory, are subject to used as recommended by the manufacturer and sufﬁ cient some form of certiﬁ cation or accreditation process. Most quality issues have been addressed to ensure optimum and commonly laboratories conform, or should conform to the consistent performance. This includes the training of staff, ISO/IEC 17025 standard.89,90 This means that laboratories the running of suitable quality controls and participation in testing batches of specimens would also employ blank external proﬁ ciency tests.85 samples, samples with known concentrations (calibrators) and quality controls to ensure the results of each batch of The principles of good laboratory practice do need to be also specimens meet appropriate laboratory performance criteria. considered for on-site testing. In practice this may be more Only results from those batches where performance criteria are difﬁ cult given that the environmental conditions and location satisfactorily met are therefore accepted. All other results are are much less controlled than a laboratory. Nevertheless, rejected and the analysis repeated. Additionally the methods it is imperative that the collection and testing process is as used must be fully validated and comply with International controlled as is reasonably feasible and the staff performing harmonised guidelines.91 the collection of specimens and the testing are properly trained, otherwise it is likely that initial on-site results will be In addition, most laboratories take part in some form of less reliable. This may produce a higher rate of FP and FN.
proﬁ ciency test to independently assess their ability to detect drugs. One program in oral ﬂ uid has been reported.92 The last decade has seen a revolution in the development of In essence this means that there are checks and balances for alternative specimens for drug analysis. The use of oral ﬂ uid using laboratory-based test kits including their calibrations and has been found to offer signiﬁ cant promise when detection monitoring their performance. When cassettes by themselves of relatively recent use of drugs is sought in a non-invasive or cassettes placed in readers are used in the testing location manner. Technological advances do allow on-site detection of 154 I Clin Biochem Rev Vol 27 August 2006 drugs, but there are technical issues in relation to collection in saliva under stimulated and nonstimulated conditions. of oral ﬂ uid and in the variability of drug concentrations (of J Anal Toxicol 1993;17:338-41.
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Competing interests: None declared.
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