In 2010, the Finnish drug legislation was improved in order to be able to react to emerging new psychoactive substances (NPS) more effectively. The amended Narcotics Act allows for a more rapid categorization of NPS as illegal narcotics at the initiative of the Finnish government. In this study, we sought to examine the prevalence of MDPV among drivers suspected of driving under the influence of drugs (DUID) in Finland, before and after the amendment of the Narcotics Act. In addition, the prevalence of MDPV in medico-legal autopsy cases was assessed. MDPV is a novel psychoactive drug with stimulant effects. It has been exceptionally popular among users of illegal drugs in Finland. MDPV was the first drug to be scheduled according to the amended Narcotics Act.

Since August 2009, MDPV has been included in the screening of post-mortem toxicology samples in Finland. Accordingly, serum samples from suspected DUID offenders have been analyzed for the presence of MDPV since September 2009. The analysis of MDPV was carried out using LC-MS/MS (DUID) and GC-MS (post-mortem toxicology) systems that have been described in detail elsewhere. We studied the MDPV positive cases between 2009 and 2012. Also, the concomitant use of other psychoactive drugs and the demographics of the users were examined.

In DUID cases, the total number of MDPV positive cases was 486. Of these, 214 were from the time before the scheduling of the substance. In autopsy cases the numbers were 38 and 18 respectively. The number of MDPV positives decreased both in DUID cases and in autopsied after the scheduling of the drug. In most cases, MDPV was detected among several other psychoactive substances, the most prevalent co-findings being amphetamine and benzodiazepines. The mean (median) serum concentration of MDPV in DUID cases was 0.11 (0.03)mg/L. The mean (median) postmortem blood concentration in autopsy cases was 0.55 (0.12)mg/L.

Contrary to the expectations of some experts, MDPV did not completely disappear from the market after its national scheduling as an illegal narcotic. Nevertheless, the number of cases both in DUID suspects and in post-mortem toxicology decreased after the amendment. As seen in some other similar studies, the chances to limit and control the use of new psychoactive drugs by means of national legislation are somewhat limited. However, if no measures are taken in terms of the legal status of NPS, the efficacy of the available methods of controlling distribution, and of limiting harm to users and non-users, will be marginal. It is crucial to act fast in defining the legal status and in informing authorities and consumers about the dangers associated with the drug. This cannot be accomplished without rapid measures in the analyzing laboratories to include new substances into the screening methods. Also, extensive scientific research on these substances must be encouraged in order to better identify potentially dangerous substances.