Driving under the influence of drugs other than alcohol

Sections

ABSTRACT
Introduction
Medical and pharmaceutical aspects
The aim of the study
Results
Discussion
Legal aspects of driving under the influence of non-alcoholic drugs
Final remarks

Details

Author: A. SOLARZ
Pages: 13 to 22
Creation Date: 1982/01/01

Driving under the influence of drugs other than alcohol

A. SOLARZ
National Council for Crime Prevention, Stockholm, Sweden

ABSTRACT

This paper illustrates different aspects of the problem of driving under the influence of medicine and is based on a survey carried out in 1976 on three groups of drivers: ( a) drivers consuming prescription drugs and alcohol; ( b) drivers consuming prescription drugs only; and ( c) drivers consuming alcohol only. Traffic accidents and traffic accident risks are approximately equal for all three groups, although the author points out that the frequency of traffic accidents and traffic accident risks involving prescription drug intoxicated drivers is probably larger than indicated by the study, as the sample was drawn from persons suspected of drunken driving. The author recommends epidemiological studies of the problem which would be facilitated if the law permitted blood and urine samples to be taken from any driver stopped on the road. He also suggests the formation of interdisciplinary groups to investigate specific aspects of the problem and closer co-operation between interested countries.

Introduction

In Sweden, driving under the influence of prescription drugs is punishable under section 4, subsection 1 of the law on sanctions for certain traffic offences. According to these regulations, liability occurs if the driver is so intoxicated by a means other than alcohol that it can be assumed that he is unable to drive the vehicle.

The term "other intoxicants" includes those prescription drugs which affect the physical and psychic function of human beings. There are 2,500 registered pharmaceutical specialities on the Swedish pharmaceutical market which altogether contain more than 1,000 different active substances [ 1] .

Medical and pharmaceutical aspects

A study of the literature on the effects of specific prescription drugs on driving ability reveals that it is difficult to obtain a clear-cut picture because of the considerable variations in the effects of different prescription drugs. A large number of prescription drugs are considered to be a danger to road safety when taken in therapeutic doses only; other prescription drugs are dangerous only after an overdose [ 2-5] . In addition, the potential for danger is different when several prescription drugs are combined or prescription drugs are taken in conjunction with alcohol. The effects of different prescription drugs vary greatly, depending on what type of substances they contain, the dosage, how they are administered, what combinations of drugs are used and the patient's condition [ 6-10] . Certain prescription drugs, within the neuroleptic group, for example chlorpromazine, thioridazine, haloperidol and flupentixol, may impair psychomotor skills, even at small therapeutic doses [ 11] . Others, for example diazepam and chlordiazepoxide, in small doses do not impair driving ability to the same extent [ 12] . It is therefore difficult for experts to answer detailed questions, such as at what concentration of certain prescription drugs is there a danger to road safety in every individual case. However, it has been proved that many groups of prescription drugs should, in general, be regarded as a danger to road safety. For certain groups of prescription drugs there is clear proof of negative side effects on driving ability, so manufacturers (who are careful to indicate when pharmaceutical preparations are dangerous to road safety) have included warnings in their description in FASS (a compendium of information on Swedish pharmaceutical products) under the headings "observe" and "warning". In FASS 1976, there were 191 pharmaceutical preparations with this mention [ 13] .

The first step towards a common marking regulation for prescription drugs which are a danger to road safety was taken by an expert group from the Nordic countries. This group identified approximately 300 substances as potentially dangerous to road safety; among them were 100 substances which were noted as especially dangerous. The survey was restricted to therapeutic doses of prescription drugs [ 14] .

The aim of the study

Prescription drugs as a factor in traffic accidents have not received the same attention as alcohol. Because of the interdisciplinary character of the problem, it was necessary to study the sociological, medical, legal and criminological aspects.

An investigation was therefore carried out to ascertain:

  1. To what extent drivers consume prescription drugs prior to or while driving;

  2. If the prescription drugs consumed could be considered dangerous to road safety;

  3. To what extent drivers consuming prescription drugs were involved in road traffic accidents or in near traffic accident situations;

  4. The legal problems involved in making it a criminal act to drive a motor vehicle under the influence of intoxicants other than alcohol.

The following materials were used:

  1. The 1976 protocols of the National Laboratory for Forensic Chemistry concerning people suspected of driving under the influence of alcohol or other intoxicants;

  2. The results of the Laboratory's 1976 analysis of the blood-alcohol concentration of these persons;

  3. The analysis results for 1976 of prescription drugs used by the above-mentioned persons, in cases where the influence of drugs other than alcohol was suspected (so-called T-cases);

  4. Complementary information from police reports on the above-mentioned cases;

  5. Sentences given in cases concerning driving under the influence of drugs other than alcohol;

  6. Extracts from the National Swedish Police Board's Criminal Register.

Of the 21,129 cases analysed by the Laboratory during 1976, all cases from four specific months, January, April, July and October, a total of 6,725, were investigated. The survey covered 31.8 per cent of the year's cases, and was considered to be representative of seasonal variations. In addition, all T-cases were studied.

The investigation material was divided into the following subsurveys:

  1. Survey A - drivers who had taken some prescription drugs, mainly together with alcohol;

  2. Survey B - all T-cases where the Laboratory, at the request of the police authorities, had performed chemical analysis of specimens (drivers who had taken prescription drugs mainly without alcohol);

  3. Survey C - a group of drivers suspected of being under the influence of alcohol only.

Results

Consumption of drugs while driving

In 1976, 761.9 million psychoactive tablets were sold in Sweden [ 15] . From a statistical point of view this would mean that every adult from 18 years of age upwards took 126 tablets of the psychoactive type alone.

In the main survey Sample we noted that approximately 23 per cent of the drivers admitted having taken some form of medicine before driving. The response to a mailed questionnaire on driving under the influence of prescription drugs showed that over 17 per cent of the respondents took prescription drugs; most of them shortly before taking the wheel.

The question arises as to whether in all cases the person has taken a prescription drug that is potentially dangerous to road safety. The answer can be found in tables 1 and 2 which show that 52 per cent of the prescription drugs taken are hypnotics, sedatives, neuroleptics, anti-depressants, psychostimulants and analgesics. Approximately 25 per cent took other groups of prescription drugs which might also be regarded as a potential danger to road safety. This means that at least three out of every four prescription drug consumers took drugs which, according to the list drawn up by an expert group from the Nordic countries, were potentially or especially dangerous to road safety.

Prescription drugs and traffic accidents

Before answering the question as to what extent drivers consuming prescription drugs were involved in traffic accidents or in near-accident situations, I would like to make one remark. The assumption that being under the influence of alcohol or prescription drugs can be regarded as being a risk factor does not mean that every case will lead to a traffic accident or to a near traffic accident situation. In reality these simple situations seldom occur and most accidents are a combination of many factors working together such as the vehicle, the traffic environment and the ability of the driver. When it is suggested that drunken driving or driving under the influence of prescription drugs shows a cause-effect relationship with traffic accidents this should be interpreted with caution.

Table 1

Distribution of prescription drug groups in sample A

 

Subsample A 1 January

Subsample A 2 April

Subsample A 3 July

Subsample A 4 October

Sample A

Prescription drugs named in FASS 1976 [13]
Number
%
Number
%
Number
%
Number
%
Total
%
Respiratory disease agents
13 4.6 15 4.0 38 8.4 31 7.3 97 6.3
Cardiovascular preparations and diuretics
16 5.7 22 5.9 28 6.2 33 7.8 99 6.5
Agents used in allergology (e.g. antihistamines etc.)
9 3.2 7 1.9 12 2.7 8 1.9 36 2.4
Digestants
28 9.9 41 11.1 47 10.4 37 8.7 153 10.0
Blood disease drugs
2 0.7 2 0.5 1 0.2 2 0.5 7 0.5
Chemotherapeutics (e.g. antibiotics)
17 6.0 10 2.7 22 4.9 31 7.3 80 5.2
Human bacteriological preparations (serums, vaccines)
-
-
1 0.3
-
-
-
-
1 0.1
Vitamins
3 1.1 6 1.6 7 1.6 7.6
-
23 1.5
Internal secretion, metabolites
14 4.9 17 4.6 17 3.8 10 2.4 58 3.8
Psychotomimetic drugs
13 4.6 40 10.8 20 4.4 24 5.6 97 6.3
Hypnotics, sedatives, including barbiturates, benzodiazepines and ataractica
48 17.0 50 13.5 85 18.9 80 18.8 263 17.2
Neuroleptics, antipsychotics
15 5.3 17 4.6 24 5.3 18 4.2 74 4.8
Antidepressants
6 2.1 3 0.8 3 0.7 4 0.9 16 1.0
Stimulating agents, appetite-reducing drugs (e.g. amphetamine,
-
-
-
-
-
-
-
-
-
-
methamphetamine)
9 3.2 11 3.0 9 2.0 17 4.0 46 3.0
Antiemetics
-
-
-
-
1 0.2 2 0.5 3 0.2
Anti-epileptics
5 1.8 12 3.2 13 2.9 17 4.0 47 3.1
Muscle relaxants
-
-
6 .6
-
-
-
-
-
6 0.4
Tranquillizers
48 17.0 55 14.8 71 15.8 73 17.2 247 16.2
Gynaecological and obstetrical agents
2 0.7 2 0.5
-
-
-
-
4 0.3
Other drugs
19 6.7 39 10.5 34 7.6 31 7.2 123 8.0
Volatile industrial solvents a
6 21 3 0.8 3 0.7
-
-
12 0.8
No data
10 3.5 12 3.2 15 3.3
-
-
37 2.4
Total
283 100 371 100 450 100 425 100 1529
100

a Solvents are not prescription drugs and are not specifically mentioned in FASS. They are included in the term "intoxicants other than alcohol".

Table 2

Traffic accidents and traffic accident risks. Survey samples A, B and C, subsample A1

 

Traffic accidents

Traffic accident risks

Total traffic accidents plus accident risks

Sample

Number of drivers in the sample

Number

%

Number

%

Number

%

Sample A
1531 365 23.9 246 16.0 611 40.0
Subsample A 1
283 94 33.2 36 12.7 130 45.9
Sample B
339 91 26.8 58 17 1 149 44.0
Sample C
283 61 21.6 56 19.8 117 41.3

What is true is that in certain traffic situations, drunken driving or driving under the influence of some prescription drugs can lead to more traffic accidents because of the negative effect on the driver's psychomotor readiness or the time it takes for him to react. Moreover, in some cases, drivers are influenced to such a degree that they are unable to drive in a straight line, they drive on the wrong side of the road, they drive extremely fast or extremely slowly and cause near-accident situations.

Two examples of near-accident situations are:

  1. A motor vehicle was stopped because it was swerving to the left side of the road. The driver admitted having taken two sleeping tablets. No alcohol was found in the blood sample. However, 0.5 mg butenemal (vinbarbital) and allypropumal (aprobarbital) per 100 g blood was detected;

  2. A car was stopped by the police because it was being driven slowly and nearly ran into a group of schoolchildren. The driver admitted having taken four analgesics. No alcohol was found in the blood sample.

Because of the complicated cause-effect relationship between prescription drugs and traffic accident cases, investigations in this project were built on a statistical comparison of traffic accidents and traffic accident risks for three survey samples:

  1. The driver who had taken prescription drugs combined with alcohol (survey sample A);

  2. The driver who had taken prescription drugs only (survey sample B);

  3. The driver who had taken alcohol only (survey sample C).

The statistical results are shown in table 2 and demonstrate that the frequency of accidents and near-accident situations in the present survey was approximately equal for all groups.

This leads us to conclude that there seems to be a cause-effect relationship between the taking of prescription drugs when driving and traffic accidents, and that some prescription drugs as well as alcohol should be considered as risk factors to road safety.

This latter conclusion is particularly clear in survey sample B where drivers have consumed prescription drugs only (in a few cases prescription drugs combined with alcohol where the blood-alcohol content (BAC) was under 0.05 per cent).

The prescription drugs which showed the strongest cause-effect relationship in traffic accidents in both surveys A and B were sedatives and sleeping preparations as well as analgesics and central stimulants. These drugs were found in 78.1 per cent of the whole B sample and occurred in 77 per cent of the accidents noted in this survey sample.

Age

In comparing the age structure of driving licence holders with drivers consuming prescription drugs, one found that consumers were over-represented among the 15-34 years age group. The 20-34 years age group constituted 37.9 per cent of driving licence holders. On the other hand, 50.5 per cent of the prescription drug consumers from survey A (prescription drugs and alcohol) were found in this age group. In survey B (prescription drugs only), the percentage was even higher and reached 68.1 per cent. A similar distribution of age groups occurred for traffic accidents.

Motives for taking prescription drugs

One would expect the number of drivers consuming prescription drugs to correspond roughly with the number of drivers who were suffering some form of illness. In spite of the fact that the number of sick persons was considerably higher among drivers consuming prescription drugs (surveys A and B), than among drivers who were non-drug consumers (survey C), the number of healthy drivers in surveys A and B was high. In survey A (prescription drugs and alcohol), 30.7 per cent were healthy and in survey B (prescription drugs), 57.1 per cent were healthy. It was therefore clear that drivers did not necessarily take prescription drugs for medical reasons.

It was also interesting to note that young drivers consuming prescription drugs in the 20-29 years age group were heavily over-represented among those who were healthy or only suffering from "nervous troubles". The same over-representation occurred among drivers consuming prescription drugs who were involved in traffic accidents and traffic accident risks.

Sex

The number of women drivers consuming prescription drugs was relatively high compared with those driving under the influence of alcohol. The lowest number of women noted was in the alcohol group, 2.1 per cent; in the prescription drug-alcohol group (survey A), women accounted for 5 per cent, whereas in the prescription drug group (survey B) there were twice as many, i.e. 10 per cent. Women, therefore, in spite of their increasing numbers among car drivers (37.1 per cent in 1976) were still under-represented among those drivers suspected of being intoxicated at the wheel. Their relative number does, on the other hand, tend to rise among prescription drug consumers.

Discussion

A critical analysis of sample B (drivers who had taken prescription drugs only) shows that the number of cases which have been chemically analysed at the Laboratory cannot be considered as representative of the population of drivers who use prescription drugs without alcohol. The survey sample included only those cases of prescription drug consumption which had come to the attention of the Laboratory during 1976 in which the police had asked for an analysis to be carried out.

There are many reasons why the number of non-alcoholic drug cases which are chemically analysed at the Laboratory does not reflect the size of the problem. It is well known that in relatively few cases are blood and urine samples taken from drivers involved in serious traffic accidents. Most of the specimens analysed came from drivers who were not driving normally or whose behaviour showed outward symptoms of intoxication, whereas no alcohol could be detected. Therefore, the frequency of traffic accidents and traffic accident risks involving prescription drug intoxicated drivers was probably larger than indicated by our study.

Whether prescription drugs in combination with alcohol generally increase the risk of accidents could not be clearly proved in this investigation. What did emerge from our study was that the frequency of traffic accidents was significantly higher for drivers who had a BAC of under 0.5 per cent who had taken prescription drugs, than for drivers who had the same concentration of alcohol but had not taken any drugs. To be able to draw firmer conclusions the investigation would have to be broadened so that more years were covered and drivers not suspected of drunken driving were also investigated. To permit such a project to be carried out, a law would be needed, at least a temporary one, which would permit urine specimens to be taken for routine chemical analysis for non-alcoholic drugs. The possibility of developing a cheap screening method would also have to be investigated, at least for certain substances in specific drug groups. The results of such a project could be important for future alternative legal measures.

Such an investigation would be important because the study showed that most of those prescription drug consumers who were suspected of drunken driving used drugs in combination with alcohol, which is thought to compound the negative effects of most drugs. Only approximately 10 per cent of the survey sample were drivers who consumed prescription drugs only. However, these figures came from a survey sample which was made up of drivers suspected of drunken driving (i.e. under the influence of alcohol). To obtain a more objective picture of the number of drivers who consumed prescription drugs alone or in combination with alcohol it should be possible to conduct epidemiological studies by taking blood and urine samples from any driver stopped on the road.

Legal aspects of driving under the influence of non-alcoholic drugs

It is a fact that it is now a criminal act to drive under the influence of drugs other than alcohol, and an annulment of the law is more or less impossible. The present wording of the regulation, however, causes great difficulties for all parties involved.

Legislators in many countries have used the expression "other means of intoxication". One can ask if the expression is understood by the driver. Intoxicating substances used in connexion with driving are generally identified with narcotics and technical solvents. Very seldom are they identified with ordinary prescription drugs obtained from a pharmacist. In my opinion another expression is necessary which needs to be more explicit. Knowledge of the content of the regulation and its aim is a prerequisite for the observance of the law.

The legislator in Sweden accepted criminalization for the "individual degree of influence", "so under the influence of intoxicants other than alcohol that it can be assumed that he/she is unable to drive the vehicle in a satisfactory manner".

This means that the legislator requires that at the time of consuming prescription drugs the driver realizes that the quantity he or she has taken would have an intoxicating effect. It is, however, questionable whether the driver can have enough knowledge about the intoxicating effect of the drug if there are no warnings concerning driving on the label and the doctor's instructions about the prescribed drug are insufficient.

The present wording of the regulation also causes great difficulty when it comes to proof. It is doubtful if, on the basis of witnesses' statements, one can draw any objective conclusion concerning such complicated phenomena as the degree of influence. It can even be difficult for the doctor to draw clear-cut conclusions on the degree of influence of a prescription drug in individual cases. The result of laboratory analysis tells us only which active substances are present in the blood and urine and in what concentration, but nothing directly about the negative effects of the drug. The analysis results from the Laboratory, therefore, cannot serve as direct evidence for the individual degree of influence without a supplementary expert opinion on the relation between the drug concentration and its effect on psychomotor functions.

The preventive effect of the law is reduced still more. Many drivers, charged with being intoxicated with prescription drugs, and having been found not guilty because of the difficulties of proof, can interpret the judgement erroneously: that the non-alcoholic drug taken is not dangerous to road safety.

Swedish law, as well as regulations in many other countries, does not give a clear answer to the question whether driving under the influence of alcohol combined with other drugs is a more severe offence than driving under the influence of alcohol alone at a BAC of less than 1.5 per mille. Therefore, in cases where the influence of non-alcoholic drugs is suspected it is not clear whether the analysis of the drug is to be made independently of the BAC result, or if it is to be dropped if the BAC is punishable. With the latter alternative, the preventive effect of the law disappears. The person who has taken alcohol combined with other drugs could think wrongly that taking non-alcoholic drugs in combination with alcohol is not dangerous to road safety.

The regulation now in force has a limited general preventive effect. Therefore, a discussion on the need to criminalize driving under the influence of prescription drugs should begin. Alternatively, a whole new construction on the wording of the law should be considered. The regulation on driving under the influence of prescription drugs should then be formed with due consideration to the following facts:

  1. Drivers consuming prescription drugs are a group with various motives for drug consumption. Among them are drug addicts, persons who take prescription drugs in excessive quantities or who ignore warnings not to drive after consuming a certain drug;

  2. A majority of drivers consuming prescription drugs in Sweden take drugs in combination with alcohol;

  3. The most dominant group of drivers consuming prescription drugs is the young male, between 20 and 29 years of age, who has alcohol problems and has a relatively high recurrence frequency.

Final remarks

The aim of this report was to outline and illustrate different aspects of the problem of driving under the influence of prescription drugs and to enable us to understand the extent of the problem of drugged driving and its significance as a risk factor to road safety. It would be useful for many aspects of the current problem to be investigated, and substantiated with data, over a period longer than one year. Many problems have an interdisciplinary character as well as an international significance, and attract great interest in many countries. The same or similar legal and scientific problems occur in most countries.

It would be useful to form interdisciplinary groups of chemists, pharmacologists, psychologists, criminologists and lawyers who would investigate special problems, such as the problem of proof, the possibilities of developing simple screening methods and legal and medical aspects. Closer co-operation between countries which take an interest in the question of driving under the influence of prescription drugs would contribute to a speedier solution of the current problem.

References

001

National Board of Health and Welfare, Drugs Department, Information No. 8 , 1977.

002

R. Bonnichsen, "Aspects of drug analyses in relation to road traffic legislation and supervision", Proceedings of the 6th International Conference on Alcohol, Drugs and Traffic Safety , Toronto, 8 - 13 September 1974, p. 495.

003

H. von Linke, "Arzneimittel und Verkehrstüchtigkeit", Das deutsche Gesundheitswesen , vol. 21, No. 13 (1966), pp. 49 - 56.

004

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005

H. Moskowitz, "Alcohol and drug impairment of the driver", Communication 730094, SEA meeting, Detroit, 1973.

006

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007

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008

E.M. Sellers, "The pharmacokinetic component of drug effects on driving skills", Proceedings of the 6th International Conference on Alcohol, Drugs and Traffic Safety , Toronto, 8 - 13 September 1974, pp. 271 - 293.

009

A. Smiley and others, "The combined effects of alcohol and common psychoactive drugs: II. Field studies with an instrumented automobile", Proceedings of the 6th International Conference on Alcohol, Drugs and Traffic Safety , Toronto, 8 - 13 September 1974, pp. 433 - 438.

010

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011

M. Linnoila, "Effects of diazepam, chlordiazepoxide, thioridazine, haloperidol, flupentixol and alcohol on psychomotor skills related to driving", Annales Medicinae Experimentalis et Biologiae Fenniae, vol. 51, March 1973, pp. 125 - 132.

012

B. M. Ashworth, "Drugs and driving", British Journal of Hospital Medicine , vol. 13, No. 2 (1975), pp. 201 - 204.

013

FASS 1976 (Farmaceutiska specialiteter i Sverige) , 1977, pp. 262, 759 - 761,818.

014

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015

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