15 - Psychotropic Drugs

15.1About drugs and driving

It is increasingly clear that psychotropic (capable of affecting the mind, emotions or behaviour) drugs contribute to impairment in driving performance.  It has been estimated that at least 10% of all people killed or injured in crashes were taking psychotropic medication, which might have been a contributory factor to the crash.

A 2011 study, Drug use by fatally injured drivers in Canada (2000-2008) by the Canadian Centre on Substance Abuse in Ottawa approximately 35% of people killed in accidents in Canada had drugs (includes legal and illicit drugs) in their system.

This chapter focuses on drugs that are commonly prescribed or used to treat medical conditions, and that are known to have psychotropic effects or potential side effects that could impair functional ability to drive.  Illicit drugs are not considered in this chapter.

Opioids (narcotics)

Opioids are derived from natural opium or a synthetically produced equivalent and are used primarily for moderate to severe pain relief. Opioid drugs include the following:

  • codeine
  • fentanyl [Duragesic®]
  • morphine [MS-Contin®, M-Eslon®]
  • meperidine [Demerol®]
  • methadone
  • pentazocine [Talwin®]
  • hydromorphone [Dilaudid®, Hydromorph Contin®]
  • oxycodone [Percodan®, Percocet®, Endocet®, Supeudol®, Oxy Neo®], and
  • hydrocodone [Hycodan®]

Antidepressants

Antidepressants are used in the treatment of major depression and a variety of other conditions such as chronic pain, anxiety, eating disorders, personality disorders and Obsessive Compulsive Disorder.  Classes of antidepressants and examples of drugs from each class are listed in the table below.

Class Generic Name Brand Name
Tricyclic antidepressants (TCAs) amitriptyline Elavil®
imipramine Tofranil®
nortriptyline Aventyl®
  desipramine Norpramin®
  clomipramine Anafranil®
  doxepin Sinequan®
Serotonin antagonist-reuptake inhibitor (SARIs) trazadone Desyrel®
Class Generic Name Brand Name
Selective serotonin-reuptake inhibitors (SSRIs) fluoxetine Prozac®
fluvoxamine Luvox®
sertraline Zoloft®
citalopram Celexa®
paroxetine Paxil®
Dual action agents (DAAs)    venlafaxine Effexor®
Atypical Antidepressants bupropion Zyban®, Wellbutrin SR®
Monoamine oxidase inhibitors phenelzine Nardil®
moclobemide Various generics
tranylcypromine Parnate®

Antiepileptics

The following are 8 major categories of drugs used in the treatment of epilepsy and other conditions such as mood disorders or pain, in approximate order of the date they were introduced:

  • barbiturates and derivatives (phenobarbital)
  • succinimide derivatives (methsuximide [Celontin®])
  • hydantoin derivatives (phenytoin [Dilantin®])
  • iminostilbene derivatives (carbamazepine [Tegretol®])
  • benzodiazepines (clonazepam [Clonapam®])
  • carboxylic acid derivatives (divalproex sodium [Epival®], valproic acid [Depakene®])
  • various anticonvulsants (lamotrigine [Lamictal®], topiramate [Topamax®])
  • GABA derivatives (gabapentin [Neurontin®]).

Antihistamines

Antihistamines inhibit the activity of histamine, a protein involved in many allergic reactions.  They are commonly prescribed to alleviate the symptoms of allergic reactions.

Examples of older antihistamines include:

  • chlorpheniramine [Chlortripolon®]
  • diphenhydramine [Benadryl®].

Examples of newer antihistamines include:

  • loratadine [Claritin®]
  • cetirizine [Reactine®]
  • desloratadine [Aerius®], and
  • fexofenadine [Allegra®].

Antipsychotics

Antipsychotics are used primarily in the management of serious mental disorders such as Schizophrenia, Bipolar Disorder and organic psychoses (psychiatric symptoms arising from damage to or disease in the brain). The two major groups of antipsychotics are the “typical” or conventional antipsychotics, introduced in the early 1950s, and the “atypical” antipsychotics, introduced in the early 1990s and later.

Examples of typical antipsychotics include:

  • haloperidol [Haldol®], and
  • chlorpromazine [Largactil®]
  • loxapine [Loxapac®]
  • trifluoperazine [Stelazine®].

Examples of atypical antipsychotics include:

  • clozapine [Clozaril®]
  • risperidone [Risperdal®
  • olanzapine [Zyprexa®]
  • aripiprazole [Abilify®]
  • paliperidone [Invega®]
  • quetiapine [Seroquel®], and
  • ziprasidone [Zeldox®].

Non-steroidal anti-inflammatories

Non-steroidal anti-inflammatory drugs (NSAIDs) are used for pain relief, the reduction of fever, and to reduce inflammation.  Examples of NSAIDs include:

  • acetylsalicylic acid [Aspirin®, Entrophen®]
  • diclofenac [Voltaren®]
  • ibuprofen [Motrin®]
  • naproxen [Anaprox®, Aleve®, Naprosyn®]
  • celecoxib [Celebrex®], and
  • indomethacin [Indocid®].

NSAIDs often are used in the treatment of mild to moderate pain, inflammation and fever in both acute and chronic conditions, such as:

  • rheumatoid arthritis and osteoarthritis
  • gout
  • metastatic bone pain
  • headaches and migraines, and
  • mild to moderate pain due to inflammation and tissue injury (e.g. pain associated with tooth extraction, root canal, sports injuries, etc.)
  • menstrual pain.

Sedatives and hypnotics

Sedative and hypnotic drugs are central nervous system depressants.  They are used to treat anxiety, insomnia, alcohol withdrawal, as muscle relaxants, and as anticonvulsants. The major categories are barbiturates, benzodiazepines and a new class of non- benzodiazepine sedatives called Z drugs.

Benzodiazepines can be divided into short acting, (those with a short half-life of 2 to 4 hours), which generally are used to treat insomnia, intermediate acting (those with half-life of 12-24 hours) and long-acting (those with a long half-life of >24 hours), which are used to treat anxiety.

Categories of sedatives and hypnotics and examples of drugs in each category are provided in the table below.

Category Generic Name Brand Name
Barbiturates phenobarbital Various generics
Benzodiazepines with a short half-life triazolam Halcion®
alprazolam Xanax®
oxazepam Serax®
Benzodiazepines with a medium half-life lorazepam Ativan®
temazepam Restoril®
chloridazepoxide Librium®
Benzodiazepines with a long half-life clonazepam Rivotril®
diazepam Valium®
clorazepate Tranxene®
flurazepam Dalmane®
Z drugs (non-benzodiazepines) zopiclone Imovane®
zolpidem Sublinox®

Stimulants (for ADHD, Narcolepsy)

Examples of stimulants used in the treatment of Attention-Deficit/Hyperactivity Disorder (ADHD) and Narcolepsy include:

  • methylphenidate [Ritalin®, Concerta®, Biphentin®)]
  • modafinil [Alertec®]
  • dextroamphetamine [Dexedrine®], and
  • mixed amphetamine salts [Adderall®].

15.2Prevalence

Opioids

No data are available on the use of opioids as a treatment for medical conditions in Canada.

Antidepressants

The most commonly used classes of antidepressants are SSRIs, dual action agents and tricyclics. Research from 2002 showed that SSRIs had a 46.3% market share, dual action agents had 23.9% and tricyclics had 23.7%. The least commonly used class was monoamine oxidase inhibitors, with a 2.1% market share.

Between 1981 and 2000, total prescriptions for antidepressants increased almost five fold, from 3.2 to 14.5 million. The 2002 Canadian Community Health Survey indicated that 5.8% of Canadians were taking antidepressants. Of those who had a major depressive episode in the past year, 40.4% were taking antidepressants.

Antiepileptics

No data on the prevalence of antiepileptic drug use in Canada is available.  Epilepsy itself has a prevalence rate of 0.6% in the Canadian population. The incidence of epilepsy is 15,500 new cases per year, with 60% of these being young children or seniors.  Because of the variability of the presentation of epilepsy among those diagnosed, and the use of antiepileptic drugs for conditions other than epilepsy, it is difficult to extrapolate the prevalence of anticonvulsant drug use based on the prevalence and incidence of epilepsy.

Antihistamines

The general use of antihistamines is difficult to ascertain. However, it has been estimated that allergic conditions that may be treated with antihistamines affect 10% to 25% of the population.

Antipsychotics

Prevalence statistics on the use of antipsychotics in Canada using population based surveys are complicated by low prevalence and questionable validity.

Non-steroidal anti-inflammatories

NSAIDs are among the most commonly used pharmacological agents, with 10 million prescriptions dispensed annually in Canada.  The use of NSAIDs is predicted to increase with the aging population due to the association between age and musculoskeletal disorders such as osteoarthritis and rheumatoid arthritis.

Sedatives and hypnotics

Data from the 2002 Canadian Community Health Survey indicated that the percentage of those who had used a sedative or hypnotic increased with age, moving from 3.1% of the general population 15 years and older, to 11.1% of those 75 and older.  Overall, 7.2% of those with anxiety disorders had taken a sedative-hypnotic over the two days preceding the survey.

Benzodiazepine use made up most of the sedative-hypnotic use in all analyzed demographic and diagnostic groups.  Information from this survey and other studies indicate that benzodiazepines are one of the most frequently used classes of drugs by seniors and women.

Stimulants

No data is available on the prevalence or incidence of the use of stimulants as a treatment for ADHD in Canada.  An indication of the use of stimulants for ADHD may be gleaned from the prevalence of the condition itself.  Research indicates that ADHD affects between 3% and 10% of children and between 4% and 6% of adults. Of adolescents and adults with ADHD, 76% achieve a therapeutic response with stimulant medication.

15.3Psychotropic drugs and adverse driving outcomes

Opioids

Research indicates that the use of opioids can adversely affect driving performance, with the degree of impairment dependent on the particular opioid used, dosage, previous use and developed tolerance, time of day taken.

Antidepressants

Currently, there is little evidence to associate SSRIs or dual action agents with impaired driving performance.  Although limited, research indicates that the use of tricyclic antidepressants is associated with impairments in driving performance.  This is evidenced by elevated crash rates, as well as measures of on-road performance and laboratory tests of psychomotor and cognitive functioning.

Antiepileptics

In general, individuals with epilepsy have an increased risk for adverse driving outcomes, which may be caused by either the episodic impairment (seizures) or persistent impairments caused by the condition or treatment.

Antihistamines

Research indicates that the use of older antihistamines may impair driving performance. However, newer antihistamines used in therapeutic doses do not appear to increase the risk of adverse driving outcomes. Many classes of drugs may be used to treat epilepsy as well as combinations of drugs. Driving outcomes would depend on which medications are used in the treatment.

Antipsychotics

Studies examining the driving performance of individuals treated with antipsychotics (primarily those with Schizophrenia) indicate that those treated with atypical antipsychotics perform better than those treated with typical antipsychotics. However, less than 33% of those on atypical antipsychotics and 5% to 11% of those on typical antipsychotics were found to have adequate driving performance.  It should be noted that these results are based on functional tests conducted in a laboratory setting, and the relationship of these results to actual driving performance has not been established.

Further, it is difficult to determine the relative impact of the underlying condition and antipsychotic treatment on driving performance.

Non-steroidal anti-inflammatories

There is only a small body of literature related to the effects of NSAIDs on driving performance.  These limited studies however indicate that the use of NSAIDs is associated with an increased risk of crash in both young and old drivers.

Sedatives and hypnotics

Research indicates that the use of sedatives and hypnotics is associated with a significant risk for adverse driving outcomes.

Stimulants (for ADHD)

There is some indication that pharmacological treatment of ADHD with stimulants may have a positive effect on driving performance. However, research in this area has primarily relied on driving simulators to measure outcomes.  A few studies have investigated the relationship between pharmacological treatment of ADHD and on-road performance, but methodological limitations, including small sample size (< 20 in all cases), limit the findings.

15.4Effect on functional ability to drive

Condition Type of driving impairment and assessment approach Primary functional ability affected Assessment tools
Use of psychotropic drugs Persistent impairment: Functional assessment Cognitive

Medical assessments

Functional Assessment

Authorities should be primarily concerned with the persistent cognitive impairment associated with the effects or side effects of medication used for ongoing treatment of medical conditions.  Potential temporary impairments from short term treatment or changes in dosage or type of medication are considered transient impairments for licensing purposes.  Where an individual is taking multiple drugs (polypharmacy), authorities must also consider the potential compounding effects. Where relevant, authorities should also consider the potential compounding effect of the use of alcohol or illicit drugs.

Opioids

The use of opioids results in depression of the central nervous system.  Possible effects on the functions necessary for driving include:

  • blurred vision
  • poor night vision
  • slowed reaction times
  • sedation
  • tremors
  • muscle rigidity
  • impairment of short term/working memory and attention, and
  • disorientation or hallucinations.

The effects of opioids on an individual depend on a number of factors, including the length of use, dosage and propensity for abuse or addiction. Tolerance is an important consideration in that adverse effects may be evident during acute use but diminish as tolerance develops.

Antidepressants

The effects of antidepressants on cognitive ability vary by therapeutic class. Depression itself may result in cognitive impairment. While the use of antidepressants may improve cognitive function, the side effects may include cognitive impairment, including:

  • impairment of thought processing
  • attention deficits
  • indecisiveness, and
  • impairment of psychomotor function.

Therefore, distinguishing between the effects of the disorder and the side effects of antidepressants may be a challenge.

Tricyclic antidepressants

The major side effects of TCAs that may affect driving are anticholinergic effects, such as confusion or blurred vision, and sedating effects. The following table outlines the severity of the sedating effect of common TCAs.

Sedating Effect TCAs
Low Desipramine, nortriptyline [Aventyl®],
Moderate imipramine [Tofranil®]
High amitriptyline [Elavil®], doxepin [Sinequan®]

Selective serotonin-reuptake inhibitors

SSRIs generally have fewer side effects than TCAs. Nonetheless, some studies have shown impairments in both cognitive and psychomotor functioning in individuals using SSRIs.

Dual action antidepressants

Research indicates new DAAs, atypical antidepressants (the most recently introduced class of antidepressants), have fewer side effects than TCAs or SSRIs, but cognitive impairment associated with depression and/or treatment may still be present.

Antiepileptics

Anticonvulsants may impair motor and sensory functions, producing:

  • ataxia (lack of coordination; unsteadiness)
  • nystagmus (uncontrollable rapid eye movement)
  • poor concentration
  • slowed thinking
  • blurring and double vision, and/or
  • tremor.

Disruption of normal cognitive function is a frequent and pervasive side effect of anticonvulsant drugs. A variety of cognitive abilities may be affected, including memory, reaction time, executive functioning and problem solving.

The known side effects of first generation anticonvulsant drugs (phenobarbital, phenytoin, benzodiazepines and valproate) include sedation and cognitive dysfunction. Adverse cognitive effects, including impairments in memory and attention, are also evident with the use of more recently introduced anticonvulsant drugs (e.g. topiramate), though these generally have fewer side effects.

Antihistamines

Histamine is involved in many brain functions, including the waking-sleep cycle, attention, memory, learning and excitation. The effects of antihistamines differ depending on their generation. Older antihistamines, such as tripolidine [Actifed®], diphenhydramine [Benadryl®], and clemastine are associated with profound sedation, impaired psychomotor function and blurred vision.

Newer antihistamines, such as:

  • loratadine [Claritin®]
  • cetirizine [Reactine®]
  • fexofenadine [Allegra®], and
  • desloratadine [Aerius®]

are largely free from the sedating effects of the older antihistamines. However, at high doses, significant side effects have been reported, though still less pronounced than those associated with older antihistamines.

Beta-blockers

Beta-blockers include:

  • propanolol [Inderal®], and
  • atenolol [Tenormin®]

Common side effects of beta-blockers include tiredness, sleep disturbances and dizziness. Less common side effects relevant to driving include impairments in attention, mental flexibility (executive functioning) and memory.

The available evidence indicates that impairments in cognitive functioning can be a side effect of beta-blockers. However, results from the majority of studies indicate that there is little in the way of evidence to indicate that beta-blockers negatively impact cognitive performance in the general population of beta-blocker users.

Antipsychotics

Research suggests that atypical antipsychotic drugs may improve cognitive functioning in individuals with Schizophrenia compared to treatment with typical antipsychotics.

Nonetheless, the research indicates that even with atypical antipsychotics, individuals still experience residual cognitive impairments.

Non-steroidal anti-inflammatories

In general, the analgesic and anti-inflammatory effects of NSAIDs result in improvements in functional abilities (e.g. reduction in pain and stiffness in those with osteoarthritis, resulting in increased physical function and improvements in quality of life).  However, there is a suggestion that the use of NSAIDs can impair cognitive ability.

Sedatives and hypnotics

The adverse effects of sedatives and hypnotics may include:

  • sedation
  • drowsiness
  • cognitive and psychomotor impairment
  • impaired coordination
  • vertigo
  • dizziness, and
  • blurred or double vision.

Impairments are greater with higher dosages and with drugs that have a longer half-life.

Those using sedatives and hypnotics are subject to developing dependency, addiction and increasing tolerance of the effects.  Because of this, Health Canada advises that these drugs should only be used for short periods (e.g. less than 2 months for anxiety; 7 to 10 days for insomnia).  Nonetheless, research indicates that long term use is not uncommon. Long term adverse effects of benzodiazepine may include cognitive decline, unwanted sedation and impaired coordination.

Stimulants (for ADHD) and Narcolepsy

There is some indication that stimulants may have a positive effect on driving performance. However, the effect of stimulant medication on the functional ability of drivers with ADHD is unclear because of the methodological limitations of research to date.

15.5Compensation

A driver can’t compensate for the effects of psychotropic drug use.

15.6Guidelines for assessment

15.6.1 Medication - Prescribed - All drivers

This standard applies to prescribed medication including psychotropic drugs and prescribed medical marijuana

National Standard

All drivers eligible for a licence if

  • The functional abilities necessary for driving are not impaired and
  • Where required, a functional assessment shows that the side effects of medication does not affect ability to drive
  • Drivers on a formal methadone maintenance program must provide an addictions specialist report, in addition to meeting the above requirements
BC Guidelines
  • If further information is required, RoadSafetyBC may request
    • a Driver’s Medical Examination Report; or
    • additional information from the treating physician
  • If the treating physician indicates possible impairment of one or more of the functions necessary for driving, RoadSafetyBC may request functional assessment(s) as appropriate for the type(s) of impairment and class of licence held, unless there has been no significant change in the individual’s condition or functional ability since a previous functional assessment
Conditions for maintaining licence None
Reassessment

No re-assessment, other than routine commercial or age-related re-assessment is required, unless

  • the re-assessment guidelines for the underlying condition require re-assessment
  • the treating physician indicates non-compliance or misuse of psychotropic drugs and/or
  • the treating physician or cognitive screening indicates possible persistent cognitive or any functional  impairment
Information from health care providers
  • Types of psychotropic drugs used
  • Details of underlying medical conditions
  • Opinion of treating physician whether the individual is non- compliant or misuses psychotropic drugs
  • Functional impairment, if any
Rationale The use of a psychotropic drug does not mean that a driver is ineligible for a licence.  Where there is some evidence of a persistent cognitive impairment associated with the stable use of a drug, an individual assessment of the effect of the drug is required to determine licence eligibility

15.6.2 Medication - Non prescribed (over the counter) - All drivers

National Standard

All drivers eligible for a licence if

  • The functional abilities necessary for driving are not impaired and,
  • Where required, a functional assessment shows that the side effects of medication does not affect ability to drive
BC Guidelines
  • RoadSafetyBC will not generally request further information
  • If further information is required, RoadSafetyBC may request
    • a Driver’s Medical Examination Report; or
    • additional information from the treating physician
  • If the treating physician indicates possible impairment of one or more of the functions necessary for driving, RoadSafetyBC may request
    • Functional assessment(s) as appropriate for the type(s) of impairment and class of licence held, unless there has been no significant change in the individual’s condition or functional ability since a previous functional assessment
Conditions for maintaining licence None
Reassessment

No re-assessment, other than routine commercial or age-related re-assessment is required, unless

  • the re-assessment guidelines for the underlying condition require re-assessment
  • the treating physician indicates non-compliance or misuse of over-the-counter drugs and/or
  • the treating physician or cognitive screening indicates possible persistent cognitive or any functional  impairment
Information from health care providers
  • Types of drugs used
  • Details of underlying medical conditions
  • Opinion of treating physician whether the individual is non- compliant or misuses drugs
  • Functional impairment, if any
Rationale The use of a psychotropic drug does not mean that a driver is ineligible for a licence.  Where there is some evidence of a persistent cognitive impairment associated with the stable use of a drug, an individual assessment of the effect of the drug is required to determine licence eligibility

15.6.3 Substance abuse or dependence - All drivers

This applies to all drivers who are under the influence of alcohol and illicit drugs such as opioids, cocaine, amphetamines etc.

National Standard

All drivers eligible for a licence if

  • Meets the criteria for remission and/or has abstained from the substance for 12 months
  • Earlier re-licencing may be considered upon favourable recommendation from an addictions specialist and/or treating physician recognized by the licensing authority and the successful completion of a drug rehabilitation program.
  • The functional abilities necessary for driving are not impaired
  • Where required, a road test or other functional assessment shows that the functional abilities for driving are not impaired
BC Guidelines
  • If further information is required, RoadSafetyBC may request:
    • a Driver’s Medical Examination Report or additional information from a physician who  is familiar with client’s past medical history  or  has access to client’s past clinical /medical  records; or
    • an assessment from  a registered psychologist  or an addictions specialist
  • RoadSafetyBC may find individuals with medically documented problematic drug and/or alcohol misuse fit to drive if they meet above standard.
  • Otherwise, RoadSafetyBC may find individuals fit to drive if:
    • the treating physician  who is familiar with client’s past medical history  or  has access to client’s past clinical /medical  records  states that the patient does not have ongoing and significant issues with drugs and/or alcohol,  therefore the required standard for  remission and/or abstinence from the substance for 12 months does not apply;  OR
    • the physician has no concern for the individual’s safety; and /or
    • the physician indicates that the individual is able to separate their drug and/or alcohol use from the task of driving; and/or
    • the physician indicates the individual has  no drug or alcohol related pathology that may interfere with the functions necessary for driving; and
    • RoadSafetyBC has no collateral information that indicates the individual is driving while under the influence.
  • Once the preceding requirements have been met, if the treating physician indicates possible impairment of one or more of the functions necessary for driving, RoadSafetyBC may request
  • functional assessment(s) as appropriate for the type(s) of impairment and class of licence held, unless there has been no significant change in the individual’s condition or functional ability since a previous functional assessment
Conditions for maintaining licence None
Reassessment

No re-assessment, other than routine commercial or age-related re-assessment is required, unless

  • the re-assessment guidelines for the underlying condition require re-assessment
  • the treating physician indicates non-compliance with prescribed treatment and/or
  • the treating physician or cognitive screening indicates possible persistent cognitive or any functional  impairment
Information from health care providers
  • Types of substance used
  • Details of underlying medical conditions
  • Opinion from an addictions specialist and/or treating physician recognized by the licensing authority
  • Details about any planned or completed rehabilitation program
  • Report on whether the individual is abstinent/ and or in remission
Rationale These substances are known to potentially impair the ability to operate a motor vehicle safely

15.6.4 Alcohol and driving - All drivers

National Standard Impaired individuals are not permitted to drive any class of motor vehicle
BC Guidelines
  • If further information is required, RoadSafetyBC may request
    • a Driver’s Medical Examination Report; or
    • additional information from the treating physician
    • see 15.6.3
  • In BC, under 25.1 and 25.2 of the MVA , drivers may be referred to provincial remedial programs if the individual has a driving record that shows a history of drinking and/or drug use and driving. These processes are managed outside of the Driver Medical Fitness Program
Conditions for maintaining licence None
Reassessment

No re-assessment, other than routine commercial or age-related re-assessment is required, unless

  • the re-assessment guidelines for the underlying condition require re-assessment
  • the treating physician indicates non-compliance with prescribed treatment and/or
  • the treating physician or cognitive screening indicates possible persistent cognitive or any functional  impairment
Information from health care providers
  • Details of underlying medical conditions
  • If individual has a substance abuse disorder; the requirements of 15.6.3 apply
Rationale Alcohol is known to impair the ability to operate a motor vehicle safely