Can I still drive , doc?

Report
“Can I still drive , doc?”
Interactions between pain
medication and driving
Linda Bryant, Harish Kala, Keith Laubscher
and Margaret Macky
Short exploration of the issues we consider when
addressing fitness to drive :
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Cases
Behavior of certain key medicines used in pain
management
Approaches to understanding patient’s functional
status
Responsibilities
Low chance of
loss of function
Baseline function
Change in
medical condition
Stable
Medication
New or altered
medication
Behaviours
Moderate chance High chance of
of loss of function loss of function
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Baseline condition
New medical changes
Behaviour of patient
Behaviour of medications
What is the risk of change to important functions
What is the risk of abrupt loss of function?
Julia
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39 female fall off a horse
fractured radius /ulna .
reduced in ED under regional anaesthetic and cast
applied , Xray check of position
Leaves ED with :
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R arm in cast/sling
Advice re cast
Tramadol
Tramadol
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MoA – double whammy
Binds to μ-opiod receptors and inhibitors Nor Adr and serotonin reuptake
Subtle adverse effects
– > 10%
dizziness
– 1 to 10% sedation
– 0.01 to 0.01%
euphoria, reduced coordination, cognition changes
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More problematic in the elderly and with interacting medicines
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Pharmacodynamic – additive CNS effects
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Pharmacokinetic – interacts with CYP2D6 inhibitors e.g. SSRIs, bupropion
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Antidepressants (serotonin toxicity; reduce seizure threshold)
Alcohol,
sedatives, cough mixtures (dextromethorphan, antihistamines)
Inhibits conversion of tramadol to M1, the active metabolite
Dosing: six hourly – takes 30 to 36 hours to reach steady state
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Difficult with prn use. Prescribe limited amounts (e.g. 20 tablets)
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Prescriber and treating clinician need to think about the
difference their treatment and the new condition have on driving
or any other hazardous activity
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Advice needs to take into consideration:
– New functional impact of medical condition
– Changing function with medication
– “normal” response and side effect
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Two way communication : we need to check our analysis and
conclusions on safety have hit home
Leonard
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82 yr old man with shingles & neuralgia
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mild IHD/hypertension, BPH, Arthritis
Treatment includes Gabapentin , tricyclic has a
supply of oxynorm
regular b blocker,a combined ace inhibitor and
diuretic, asprin and losec
Tricyclic antidepressants
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Nortriptyline - TCA of choice
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Usually low dose (10 to 25 mg)
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Blurred vision
Confusion / impaired cognition
Postural hypotension / falls
Urinary retention
Sedation – less than other TCAs
Cardiovascular adverse effects
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Poor metabolisers (CYP2D6)
Anticholinergic adverse effects
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Even low dose can have initially effects
Class I antiarrhythmic (dose related). Not recommended post-MI
Interactions – additive CNS effects
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SSRIs, alcohol, sedating antihistamines, gabapentin
Gabapentin
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Dosing
Renal excretion – be wary in the very elderly
– Creatinine clearance 30 to 50 ml/min … 300 to 900 mg / day
– S l o w dose titration
Adverse effects
– 5 – 10%
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1 to 5%
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Dizziness
Somnolence
Amnesia
Ataxia
Confusion
Abnormal thinking
Interactions
– Morphine (AUC increased 44%). Used together but …
– Additive effects with other CNZ medicines
Once again there is a need to analyse the situation and be definite for
our patient about driving .
Multiple conditions potentially affecting both the possibility of sudden
loss of function and also concentration , visual function and reaction
times .
We can start to see the additive effects of these risks and be able to
translate this into a unique risk assessment for the patient
 Considered analysis : see additive effects of situation
 Convincing explanations : communicated risk
 Clear about restrictions, time to follow up or responsibilities of
patient
If we are putting some of the decision making at the
driver’s discretion then we need to be clear about
what they are to consider eg
DO not drive within x hrs of opiate,
Do not drive at night
Use the form in LTSA appendix .
Talk to patient about insurance
52 man with back injury, discectomy and ongoing back and
leg pain .
Prior to his accident in 2009 he was a courier driver
 Neuropathic pain
 Possible addiction issues ( alcohol and other??)
 Previous intercurrent severe Depression
 Meds high dose SSRI, prn benzodiazepine , trialing
higher doses of gabapentin
SSRI, benzo, gabapentin, alcohol + …
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Each problematic in its own right but …
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Benzodiazepines and alcohol – not a good mix
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Pharmacokinetically – technically OK
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Pharmacodynamically – watch the early problems of additive
CNS, cognition, coordination
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GABA, serotonin, noradrenalin receptors
Question …. Are the medicines being taken correctly, or is it a
Pick and Mix regimen (so steady state / ‘tolerance’ not
achieved)

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