Amphetamine driving consultation ISCD response

Below is DrugScience's response to the Government's consultation on new regulations on driving with amphetamine in the body.

Question 1
Do you agree with the Government’s proposed limit for amphetamine? If not please provide your reason(s).

No, DrugScience does not agree with the proposed limit of 50µg/L. As stated in our response to the last consultation, DrugScience recommends accepting the advice of the Expert Panel, and more details of our approach can be found by revisiting that consultation response, but also we will address some of the key differences in opinion and elaborate further here.

• DrugScience believes that policy decisions should be made in line with the best scientific advice and evidence. The line of argument that 50µg/L should be decided upon in order to be “in line with some other European countries” is not a rational and respectable way of determining any policy, and indeed of determining the course of people’s lives who are to be charged under these regulations. If there is a desire to move our traffic law into line with the rest of Europe then a 0.05% alcohol limit instead of 0.08% would be the evidence-based place to start as this recent study shows.

• The Road Traffic Act should not be co-opted as a way of ‘sending a message’ on the Government’s values regarding recreational drug use. It is not an appropriate use of this legislation to prosecute drivers who may well not be impaired (whose ability may in fact even be enhanced), because of the Government’s feelings regarding their choice of psychoactive substance. The Misuse of Drugs Act already makes distinctions between legal and illegal drugs which cannot be justified purely on their capacity to harm, the Road Traffic Act has even less justification in drawing arbitrary distinctions between drugs;- between driving after using alcohol and driving after using amphetamines. Risk-based thresholds should be used for both. The Traffic Act is there to maximise road safety. A consistent approach should be taken as discussed in DrugScience’s previous consultation response on Drug Driving.

• Since that response was submitted, the UK’s first motorway pub has opened on the M40. This seems starkly hypocritical alongside the Government’s ‘zero-tolerance’ approach for drugs in order to “send a message” about drugs which cause a fraction of the harm of alcohol on British roads. The UK can already be proud for having safer roads than the European countries which already have such ‘zero-tolerance’ limits. The limit should be set at a high enough level to ensure that there is a reasonable expectation that anyone falling foul of the law is acting irresponsibly, and is a risk to road users, comparable to a driver who is over the alcohol limit.

• The proposed drug driving regulations (the need for which we support in general) will, as we understand it, provide an additional tool for prosecuting drugged drivers on top of the existing law against driving whilst impaired, rather than replacing the older law. Therefore so it may be possible to impose a 600µg/L limit and still have a chance of prosecuting a hypothetical impaired driver with 590µg/L of amphetamine in their blood. Of course proving impairment is difficult and we understand that this does not always provide a solution, so there is a possibility that the hypothetical irresponsible driver will go unpunished. This is a shame, but no different from the irresponsible driver who goes unpunished despite driving whilst very tired. The law cannot hope to punish every dangerous driver; instead education and campaigns promoting responsibility can produce the kind of attitude shift that has brought UK drink driving figures down, thus actually reducing harm. DrugScience believes that reducing harm should be the guiding principle of the law, not expressing a tough “message”.

• We note the apparently popular feeling among the consultation respondents that 600µg/L is self-evidently too high despite no clear challenges to the Expert Panel’s reasoning in reaching the figure. Is it possible that one explanation for this is simply that 600 is quite a large number in comparison to the other recommended limits, such as 5µg/L for THC? Of course this difference simply reflects pharmacological differences in potency.

• The possibility of unintended consequences should be borne in mind if the Government chooses a limit such as 50µg/L that is “close to a zero tolerance approach”. Many legal highs of unknown risks mimic the effects of amphetamine, and so users may switch to these to avoid the risk of detection, just as cannabis users may switch to synthetic cannabinoids. Such displacement may cause additional harm to public health as well as reducing the efficacy of the drug driving law.

• Being ‘tougher’ than the evidence can support is not cost-free. It widens the net, increasing the direct costs of criminalisation to those arrested but also the indirect costs of extra prosecutions to taxpayers, and the knock-on costs to others.

Question 2
Is the approach we are proposing to take when specifying a limit for amphetamine reasonable for those who are driving and being prescribed with dexamphetamine (which is used to treat ADHD and certain sleep disorders such as narcolepsy) and selegiline (which is used to treat Parkinson’s disease)? If not what is the evidence to support your view?

No, the approach is not reasonable, as explained in our previous consultation response. It may be discriminatory, and it also could well be harmful.

• The 50µg/L limit is “close to a zero tolerance approach”, and as the original consultation document itself notes, “This could deter patients from taking their prescribed medicines with the resulting untoward effects of not taking the medicine. It might also deter healthcare professionals from prescribing the medicines a patient needs, for fear of the impact on the patient.” A timely publication of new research demonstrates how any action that reduced the use of ADHD medication by those prescribed them, or that disincentived doctors and patients from initiating treatment, could lead to sharp increases in car accidents involving adults with ADHD. Given this new evidence, the proposal of a limit so low as to capture people on prescribed amphetamines must be urgently reconsidered. See JAMA Psychiatry paper: Serious transport accidents in adults with Attention-Deficit/Hyperactivity disorders and the effect of medication: A Population-Based Study

• Roland Archer of the Committee points out a further major complication to the question of applying reasonable and meaningful limits;- illicit amphetamine is racemic whereas the forms prescribed in the UK (Dexedrine and Elvanse) consist only of the dextrorotary enantiomer of amphetamine (dextroamphetamine) which has different pharmacological and pharmacokinetic properties to the levorotary enantiomer or indeed racemic amphetamine. “People abusing prescription Dexedrine would be far less fit to drive than if they were driving with the same plasma level of illicit racemic amphetamine due to the higher potency of the (S) optical isomer. Furthermore, a paper published by Riffee et. al. (JPET September 1978 vol. 206 no. 3 586-594) suggests that the volume of distribution of (S)-amphetamine is larger than that of (R)-amphetamine in mice. Obviously there are differences between animal models and human pharmacokinetics but using the animal model as a guide for a back-of-the-envelope calculation, a person taking a 2.5mg/kg dose would have a plasma concentration of 542 ug/L if they consumed the more potent (S)-amphetamine and 746 ug/L if they consumed the same amount of the less potent (R)-amphetamine.”

• We asked Professor Philip Asherson for his expert view; “With the limit set at 50µg/L most patients on normal range dosing of Dexamphetamine (Dexedrine) or Elvanse (Lisdexamfetamine dimesylate) would screen positive during periods of treatment. The rules would discriminate against patients with legitimate use of medication – the onus should be on police/others to show that illegal drugs are being used, rather than the patients to prove they are legitimate patients using prescribed drugs.”

• “The rules around driving would further stigmatise ADHD, and especially adult ADHD – it will put some people off from being diagnosed and taking recommended treatments for their condition.”

• “The prevalence adults being treated for ADHD is going up rapidly, so in the future 1% or more of drivers may be receiving legitimate treatments for ADHD. The introduction of Elvanse in addition to DEX means that in the future we can expected many more adults to be legitimately prescribed dexamfetamine or its prodrug. The high rate of ADHD in the adult population needs to be understood.”

Question 3
Are there any other medicines that we have not taken account of that would be caught by the limit we propose for amphetamine and the conditions they treat? This may include medicines that metabolise in the body to amphetamine. If so please give your reason(s).

• One that you may be well aware of already is Lisdexamfetamine dimesylate, called Elvanse, which is a prodrug for the dextrorotary enantiomer of amphetamine. It is fairly new, and with diagnoses rising, it is probable that increasing numbers of drivers will be legitimately taking amphetamine-type drugs in future.

• Another possibility to be borne in mind is that current or future legal highs might conceivably produce amphetamine as a metabolite, although we are not aware of any specific examples. It is also interesting to note that so called ‘legal highs’ continue to occasionally contain illegal substances including amphetamine, raising another possible way in which people may break the law without realising (see Samples of Ivory Dove (S#000030150) and Ivory Dove Ultra (S#000030152) at WEDINOS)