Drugs & Driving - a screening system and a survey of results.

J.F. Taylor

M etropolitan Police Forensic Science Laboratory

109 Lam beth Road, London, SE1 7JH, England

Introduction

Drug screening system s are generally dependent upon several limiting

fac to rs . In the forensic toxicological exam ination of samples taken under

the British Road T raffic Act (RTA) the most im portan t a re as follows:

a) The biological samples available for analysis and the ir volumes.

In this Laboratory the samples w ere blood alone (2 m illilitres on average) in

66 per cen t of cases, urine alone (up to 25 millilitres) in 25 per cen t of cases

and blood and urine tog e th e r in 8 per cen t of cases.

b) The classes of drug under exam ination.

In RTA cases we are concerned with those which can impair judgem ent,

psychomotor ac t iv ity e tc . in a way de trim en ta l to driving. This commonly

includes sedatives , tranquill izers , s tim ulan ts , an ti-h is tam ines, an t i­

convulsants, an ti-depressan ts , hallucinogens and narcotics .

c) The pa ram ete rs of identif ication .

Normally a t least two independent (uncorrelated) techniques are required

for positive identification . (e.g. TLC and GC or GC and Mass

Spectrom etry). For many drugs d e tec te d in blood by radio-immunoassay

confirm ation poses such a problem th a t it is the subject of a large

proportion of cu rren t research in toxicological analysis.

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d) The background information available.

In negative or low alcohol RTA cases where drugs analysis is requested , the

following inform ation is routinely sought in the form of a questionnaire to the off icer in the case as follows:

(i) Were there any drugs in the defendant's possession? if so, what?,

where are they now?, could they be subm itted for identification?

(ii) What was the defendant's condition? (e.g. drowsy, asleep, ag ita ted etc).

(iii) Did the police surgeon cert ify im pairm ent?

(iv) Is the subject prescribed any drugs by his own doctor? If so, w hat? ,

when was the last dose taken?, how long has he been taking them ?.

(v) Is the subject a known drug user? (or reg is tered drug addict).

E x trac tion and d e tection of drugs

The general scheme for acidic and neutra l drugs is shown in Figure 1.

Evaporated ex tra c ts are dissolved in acc tone for TLC on silica gel plates in

ch loroform /ace tone (4:1). Spot location is by UV - short wave absorbance

and by spraying with van Urk reagen t (for ca rbam ates and benzodiazepines),

fe rr ic ch loride/ferricyanide reagen t (for paracetam ol etc) and m ercuric

chloride/diphenylcarbazone reagen t (for barb itu ra tes etc). The sam e ex tra c t

is then m ethy la ted with d iazom ethane prior to tem pera tu re programmed GC

on SP2510DA with dual NPD/FID detec tion . Peak identification is based on

re la tive re ten tion to m ethyla ted cyclopal internal standard and d e tec to r

response ra tio followed by GC on Apiezon L and (if necessary) GC-MS. The

general schem e for basic drugs (Figure 2) involves the above mentioned

aliquot of urine. TLC screening is performed on caustic silica gel p lates in

ch lorform /m ethanol (4:1). Spots are located by the ir UV-short wave

absorbance and by spraying separate ly with:

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(i) NQS (B - naphthaquinone sulphonate) reagent

(ii) dilute sulphuric acid (noting UV long wave fluorescense) followed by

iodoplatinate reagen t.

This ex tra c t is then screened by GC on OV-17 with dual AFID/FID

detec tion . This involves tr ip le te m p era tu re isotherm al screening (150, 200

& 260 C) using respectively n icotine, diphenhydramine and methaqualone

as GC m arkers. Nowadays there a re many basic drugs routinely available

and an associated wide range of vola tility ; th e re fo re this form of isothermal

screening is p re fe rred to te m p era tu re program m ed screening because it is

m ore discriminating and the re la tive re ten tion da ta is m ore reproducible.

The general schem e for de tec tion of benzodiazepines (as benzophenones)

and morphine in urine is described in Figure 3. For benzophenones TLC is

perform ed on caus tic silica gel p la tes using chloroform or to luene as eluting

solvent. Spots are located by the ir yellow colour in daylight and the colours produced with

(i) Bratton-M arshall reagen t and

(ii) m ethanolic paradim ethylam ino - benzaldehyde oversprayed with

m ethanolic tr ich loro - a c e t ic acid.

The TLC system for morphine is identical to th a t described for basic drugs.

The details for blood benzodiazepine screening are described la te r under

batch methods of analysis (Figure 5). R ecen t im provem ents in the gas

chrom atography of benzodiazepines by using OV-7 and OV-225 s ta t ionary

phases instead of OV-17 alone have provided a more comprehensive screen

for the m em bers of this class of drugs plus improved resolution of drugs

from co -ex trac tives arising from the rubber septum cap of the blood

con ta iner . The la t t e r has p e rm itted sim plification of the ex trac tion

procedure and we now use a one-step 30-second "whirlymix" ex trac tion on

100 ul blood using 100 j j l b u ty lace ta te as solvent followed by d irec t

injection of an aliquot of the la t te r onto the GC column.

480

During the period of this survey, the radio-immunoussays routinely used were

those for morphine (Abuscree.n), Cannabinoids, Lysergide (LSD) and diazepam.

Batch m e thod of analysis

Due to the increasing number of RTA cases requiring drugs analysis,

the analysis of those cases involving blood alone in batches of six was

investigated. The schemes for analysis are shown in figures 4 and 5. They

were found to have the advantages of being tim e saving (usually only two

calibrations involved), m ore eff ic ien t in use of machine tim e and more

convenient in th a t they enable comparison of case chrom atogram s and quick

de tec tion of spurious peaks from solvent impurities or biological co­

ex trac tives . With careful labelling of ex trac tion and evaporation tubes and

a t ten tion to such details during solvent transfers and analysis, the only

disadvantage appears to be the tedious nature of the batch procedure.

Survey of drugs d e tec te d in 1978 RTA cases

The p a t te rn of frequency of detection of drugs or classes of drug is

shown in figure 6. The benzodiazepine class of drugs is the most prevalent

being encountered in 38 per cent of cases and being in the form of diazepam

in 25 per cen t of cases. Sedatives and tranquillizers account for im pairm ent

in most of the cases and narco tic analgesics were significantly de tec ted in

about 13 per cen t of cases. Cannabis, s tim ulants, anti-h istam ines, an ti­

convulsants and an ti-depressants considered as a whole account for only 10

per cen t of the cases. O ther than anti-convulsants, these drugs and classes

of drugs are mainly those which prove difficult to screen for in small blood

samples. The im portance of also having urine subm itted in RTA cases is

emphasized if we com pare percen tage detection of drugs in all RTA drug

cases with th a t in such cases where only blood was subm itted for analysis

(figure 7). With blood alone the percentage detection of s tim ulants, an ti­

histamines and an ti-depressants falls to zero. It follows th a t , since two

thirds of all cases involved blood alone, the percen tage overall de tec tion of

these classes of drugs may be a gross underestim ate of their involvement in

RTA cases. Since radio-immunoassays for am phetam ine-type drugs and

tricyclic an ti-depressants becam e com mercially available this situation has

481

partly been rec tif ied , the problem now being one of having suff ic ien t blood

sample to analyse. The reasons for no s ignificant change in percen tage

de tec tion of cannabinoids is th a t RIA forms the sole basis for screening both

blood and urine. There a re also no significant d ifferences in the percen tage

de tec tions for benzodiazepines and for barb itu ra te s . As expec ted the

percen tage de tec tion of "no drugs" is noticeably higher in RTA cases

involving blood alone. A previous survey of this nature indicated a much

higher percen tage "negatives" in cases involving only blood:

1976 (Jan to June) 1978 (Jan to Sept)

RTA cases involving urine 32 49

P ercen tage negative 22 <—j 20 <-i

RTA case involving blood alone 39 17 99 8

Pe rcen tage negative 39

The approxim ate one third reduction in the percen tage negatives for

1978 "blood only" cases is due to im provem ent in analytical techniques and,

in par ticu la r , to the introduction of RIA into casework. Also the much

sm aller d ifference in percen tage negatives betw een "blood only" and "urine"

cases in 1978 prompts one to question the need to analyse urine. An

exam ple of results from an RTA case involving blood and urine (table 1)

shows th a t if blood alone had been analysed, the re would have been an

incom plete pic ture of the defendants multiple drug mis-use. Indeed one can

envisage a com peten t counsel rightly dismissing a positive RIA result for

morphine as being non-specific and also assigning the am ylobarbitone and

quinalbarbitone to being residual from a previous night's hypnotic dose. In

o the r words, it is the overall p ic ture of drug taking which is im portant; not

just the de tec tion of a drug and reporting the case as "positive".

"Drugs and Driving"_and "Drug_Abuse"

Cases such as th a t decribed above have led to an investigation of the

degree to which drug abuse is a fac to r in drugs and driving cases. The

results are given in tab le 2. Information concerning the firs t two categories

of drug abusers was obtained from the previously mentioned questionnaire

for background inform ation. In the third category examples of results taken

as indicating drug abuse would be "positive for re s tr ic ted drug(s)", "unusually

482

high barb itu ra te /m ethaqualone level", "strong detection of diethylpropion" e tc .

The findings indicate tha t 35 per cen t of 1978's drugs and driving

cases in London and surrounding counties involved drug abuse. In all

probability the actual percen tage figure is even higher because blood alone

was subm itted in two thirds of our cases and the re was the re fo re an

incom plete pic ture of overall drug consumption.

The public a t large probably think th a t most drugs and driving cases

involve normal pa tien ts undergoing normal drug therapy who, having

consumed alcohol socially and in moderation, are found to have the ir driving

impaired by such a combination of drink and drug(s). Table 2 shows th a t this

is only known to occur in 11 per cent of cases.

C orre la tion of "drugs and driving" and "drug abuse" trends

S ta tis tics for the past eight years (figure 8) show some degree of

corre la tion betw een increase in "drugs and driving" and "illicit drug

possession". Many fac to rs influence such s ta t is t ic s ; for instance, the degree

of police activ ity towards a particu lar type of crim e. However, the

increased incidence of "drugs and driving" is highlighted by the fac t th a t it

has occurred during a period in which the yearly to ta ls for RTA cases

involving alcohol have markedly decreased. This may be a t tr ibu ted to the

m ore serious consequences of "drugs and driving".

The initial upsurge of "drugs and driving" cases from 1972 is probably

partly due to the introduction of large RTA blood specimens coupled with an

increase in expertise which led to drugs analysis being actively

encouraged in RTA cases where low blood alcohol figures had been reported.

483

This survey has shown th a t drug abuse contributes overwhelmingly to

the drugs and driving cases encountered in M etropolitan and neighbouring

County Constabularies. In o ther large c ities , t ra f f ic acc ident studies have

suggested th a t users (and abusers) of narco tics (1), sedative-hypnotics (2)

and cannabis (3) (4) have driving records which do not d iffer significantly

from those of age-m atched m em bers of the general population. However,

the narco tics study has been crit ic ized because of the na tu re of the control

groups who, although not opia te addicts, may have been users of o the r drugs.

Also the findings in rela tion to sedative hypnotics and cannabis are greatly

disputed by studies showing a considerable over-involvem ent of barb itu ra te

users among drivers in fa ta l acc idents (5) and above-normal acc iden t ra tes

for users of cannabis (6). Laboratory studies of sim ulated driving show th a t

all the drugs or classes of drugs examined in the present survey are capable

of producing im pairm ent (7). The fac t th a t , in this survey, they appear

mainly subject to abuse raises the question: should abusers, who are addicted

to such drugs, be prevented from holding a licence to s ta r t with?

Finally, with regard to the preponderance of benzodiazepine

tranquillizers (especially diazepam ) in this survey, it is suggested th a t they

be included in a class similar to the an ti-h is tam ines such th a t th e re is, by

law, a printed warning of the drug's possible adverse e f fe c t upon driving e tc .

and the contra indication of alcohol on the outside of each prescription

con ta iner . The number of court defences where it is alleged th a t the re was

no similar warning by the defendant's physician suggests th a t this is a

problem which may be b e t te r solved by forensic pharm aceutica l controls

ra th e r than by verbal recom m endations le f t to be passed on from an

overworked and som etim es forgetfu l physician to his ailing pa tien t.

R eference

1. Gordon, N.B., "Drugs and Driving", ed. Moskowitz H., Pergam on

Press, (1976).

Discussion

484

2. Nichols, J.L., Drug Use and Highway Safety: A Review of the

l i te ra tu re , United S ta tes D epartm ent of Transportation, National Highway

Traffic Safety Administration , Washington D.C. (1971).

3. Waller, J.A., New England Journal of Medicine, (1965) 273, 1413 - 1420.

4. Waller, J.A. and Goo, J.T., Journal of Safety Research, (1969) 1, 13 - 27.

5. Report on Alcohol, Drugs and Organic Fac tors in Fa ta l Single Vehicle

Traffic Accidents, S ta te of California Highway Patro l, Final Report, (1967).

6. C rance r, A. and Quiring, D.L., Driving records of people a rres ted for

illegal drug use. Report O il . S ta te of Washington, D epartm ent of Motor

Vehicles, A dm inistration Services. May (1968).

7. New R esearch on the role of Alcohol and Drugs in Road Accidents,

Organisation for Economic Co-operation and Development, Paris (1978).

485

F ig u re 1

DETECTION OF ACIDIC & NEUTRAL DRUGS

TLC GC-AFID

BARBITURATES METHAQUALONE UREIDES CHLORMETHIAZOLEANTICONVULSANTS ULNZUD1AZCPINE (OVERDOSES) ANALGESIC/ANTIPYRETICS

F igu re 2

DETECTION OF BASIC DRUGS

TLC GC-AFIDZONAL SCREEN ON OV-17SCREEN 3 ISOTHERMAL TEMPS

DATA AVAILABLE FOR OVER 200 DRUGS. NARCOTIC ANALGESICS STIMULANTS ANTIDEPRESSANTS ANTIHISTAMINESPHENOTHIAZINES ANTIMALARIALSLOCAL ANAESTHETICS

486

DETECTION OF BENZODIAZEPINES (AS BENZO­

PHENONES) AND MORPHINE

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f ig u re 8

YEARLY TOTALS FOR DRUGS & DRIVING CASES ALCOHOL/DRUGS-DRIVING CASES, AND DRUGS POSSESSION CASES

491

t a b l e i

R. v. C. R. BROWNE

DEFENDANT ADMITTED:

FOUND ON ANALYSIS:

URINE

AMYLOBARBITONE

QUIN ALB ARBIT ONE

(PLUS HYDROXY METABOLITES)

AMPHETAMINE

METHYL AMPHETAMINE

EPHEDRINE

PROCAINE

METHADONE (PLUS METABOLITE)

MORPHINE

ASPIRIN

GOLD INJECTION

INDOMETHACIN

METHADONE

BLOOD

ZERO ALCOHOL

AMYLOBARBITONE (1.1 y g/ML)

QUINALBARBITONE (NOT MEASURABLE: Me-TBTH INTERFERED)

MORPHINE RIA POSITIVE ( 28 NG/ML)

(SAMPLE EXHAUSTED)

TABLE 2 : _RTA DRUGS CASES 1978 (January to September)

CASES INVOLVING "REGISTERED" 9.5%OR "SELF-CONFESSED" DRUGADDICTS

CASES INVOLVING "KNOWN" DRUG 15.5%ABUSERS

CASES IN WHICH THE ANALYTICAL 11 %RESULTS INDICATE DRUG ABUSE

CASES WITH NORMAL THERAPEUTIC 11 %BLOOD CONCENTRATION OF DRUG PLUS BELOW-THE-LIMIT ALCOHOL