“can i still drive, doc?” interactions between pain medication and driving linda bryant, harish...
Post on 12-Jan-2016
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“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 :
Cases Behavior of certain key medicines used in pain
management Approaches to understanding patient’s functional
status Responsibilities
Low chance of loss of function
Moderate chance of loss of function
High chance of loss of function
Baseline function
Change in medical condition
Stable Medication
New or altered medication
Behaviours
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
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 :
– R arm in cast/sling– Advice re cast– Tramadol
Tramadol
MoA – double whammy– Binds to μ-opiod receptors and inhibitors Nor Adr and serotonin reuptakeSubtle adverse effects– > 10% dizziness– 1 to 10%sedation– 0.01 to 0.01% euphoria, reduced coordination, cognition changes
More problematic in the elderly and with interacting medicines– Pharmacodynamic – additive CNS effects
Antidepressants (serotonin toxicity; reduce seizure threshold) Alcohol, sedatives, cough mixtures (dextromethorphan, antihistamines)
– Pharmacokinetic – interacts with CYP2D6 inhibitors e.g. SSRIs, bupropion Inhibits conversion of tramadol to M1, the active metabolite
Dosing: six hourly – takes 30 to 36 hours to reach steady state– Difficult with prn use. Prescribe limited amounts (e.g. 20 tablets)
Prescriber and treating clinician need to think about the difference their treatment and the new condition have on driving or any other hazardous activity
Advice needs to take into consideration:– New functional impact of medical condition – Changing function with medication– “normal” response and side effect
Two way communication : we need to check our analysis and conclusions on safety have hit home
Leonard
82 yr old man with shingles & neuralgia
– 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
Nortriptyline - TCA of choice
– Usually low dose (10 to 25 mg) Even low dose can have initially effects
– Poor metabolisers (CYP2D6)
Anticholinergic adverse effects– Blurred vision– Confusion / impaired cognition– Postural hypotension / falls– Urinary retention– Sedation – less than other TCAs
Cardiovascular adverse effects– Class I antiarrhythmic (dose related). Not recommended post-MI
Interactions – additive CNS effects– SSRIs, alcohol, sedating antihistamines, gabapentin
Gabapentin
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%
Dizziness Somnolence
– 1 to 5% 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 + …
Each problematic in its own right but …
Benzodiazepines and alcohol – not a good mix
Pharmacokinetically – technically OK
Pharmacodynamically – watch the early problems of additive CNS, cognition, coordination
– 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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