In their response to our article (Effects of Schedule I drug laws on neuroscience research and treatment innovation. Nature Rev. Neurosci. 14, 577–585 (2013))1, Stewart and Kalueff (Controlled substances and innovation of biomedicine: a preclinical perspective. Nature Rev. Neurosci.http://dx.doi.org/10.1038/nrn3530-c1 (2013))2 provide additional insights into the burden that is placed on researchers by the current drug laws. Their experiences add to the many e-mails we have received supporting the call for a more rational regulatory approach. Since our article1 was published, there have been several developments in the United Kingdom. On the positive side, the UK Home Office has clarified that 2-bromo-LSD (lysergic acid diethylamide) is not Schedule 1-controlled, which should facilitate research into this drug as a treatment for cluster headaches. However, until it is made public by revising the UK Misuse of Drugs Act 1971, this clarification will not be apparent either to scientists or law enforcers. A similar request for a clear evidence-based decision on the legal status of tetrahydrocannabivarin has not been answered.

On the negative side, a new temporary control drug order (TCDO)3 now places several MDMA analogues under Schedule 1, including 6-APB (also known as 6-(2-aminopropyl)benzofuran) and other compounds that are being developed as new treatments for dyskinesias in Parkinson's disease. This has impeded — and will probably end — the development of these compounds because there is little commercial interest in compounds that are scheduled as a controlled drug. The same TCDO applies to a series of NBOMe compounds, thereby inadvertently banning the most promising positron emission tomography (PET) ligand for the serotonin system — namely, [11C]Cimbi-36 (also known as 25I-NBOMe and 2(4-iodo-2,5-dimethoxyphenyl)-N-((2-methoxyphenyl)methyl)ethanamine) — even though the doses used in PET studies have no subjective effects4.

These regulatory burdens impede both government-employed and academic researchers and therefore call into question the claim made at the recent G8 summit5 that the United Kingdom would lead the world in research into 'new psychoactive substances'. In practice, the forensic science centres find that analyses of new compounds are severely delayed by the requirements to obtain licences to hold and to share samples and analytical standards with other laboratories. Commercial suppliers of certified analytical reference materials typically take weeks or months to supply such standards, which can delay or prevent investigations. Moreover, sharing analytical standards with overseas laboratories requires a separate import or export licence for each laboratory and for each compound, which costs a lot of time and money.

We have been in contact with a number of scientific and medical professional bodies in the United Kingdom: most have ignored requests to engage but the Academy of Medical Sciences (AMS) has taken up the issues raised in the article1 with the Home Office, who have developed a questionnaire for AMS members on their experiences of obtaining licences. The Chair of the Advisory Council on the Misuse of Drugs (ACMD) has acknowledged the problems raised by their recommendation to ban [11C]Cimbi-36 and has asked the Home Office to explore solutions. In the United States, the Drug Enforcement Administration continues to place every new potential psychoactive drug under Schedule I.