“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)