[MT-45--a dangerous and potentially ototoxic internet drug].

During the last years several synthetic opioids have been introduced on Internet sites selling new psychoactive substances (NPS). One of these, called MT-45, a piperazine derivative originally synthesized as a therapeutic drug candidate in the 1970s, has recently been detected in 21 deaths, according to unpublished data from the Swedish National Board of Forensic Medicine. We present clinical data from 12 analytically confirmed hospital cases of MT-45 poisoning. The cases demonstrate that MT-45, like other opioids, can induce potentially life threatening respiratory depression and loss of consciousness in users and that symptoms are usually reversed by standard doses of the opioid receptor antagonist naloxone. Significant auditory symptoms with transient tinnitus and hearing loss occurred in two cases and a pronounced sensorineural hearing loss still present at two weeks follow-up in one case. This indicates that MT-45 may be an ototoxic substance, illustrating the ubiquitous risk of unintended adverse effects NPSs pose to users.