“ Can I still drive , doc? ”

1. “Can I still drive , doc?” Interactions between pain medication and driving Linda Bryant, Harish Kala, Keith Laubscher and Margaret Macky

2. 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

4. 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?

5. 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

6. Tramadol • 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 • 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)

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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)