To the Editor: The drug 5-methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT) has hallucinogenic and mild euphoric properties, similar to those of other tryptamine compounds (1). Hallucinogen-persisting perception disorder is characterized by the transient recurrence of perceptual symptoms experienced while intoxicated with the hallucinogen, often called "flashbacks." LSD-induced flashbacks are well known. It is also reported that hallucinogen-persisting perception disorder is induced by cannabis and methamphetamine. However, to our knowledge, there are no published reports of 5-MeO-DIPT-induced hallucinogen-persisting perception disorder.

The disturbances of serotonergic function may be a factor in hallucinogen-persisting perception disorder, although the pathophysiology remains unclear. Regarding the treatment of LSD-induced flashbacks, the choice of medication is still controversial. The use of various agents, including neuroleptics, serotonin reuptake inhibitors (SSRIs), anticonvulsants, and benzodiazepines, has met with limited success (2). Some researchers report that risperidone, which is a serotonin-dopamine antagonist, exacerbates symptoms of hallucinogen-persisting perception disorder (3). Others note that SSRIs exacerbate flashbacks (4). In this case, his perceptual disturbance symptoms responded to risperidone treatment.

For public safety, 5-MeO-DIPT is a controlled substance in several countries. However, it is available in many areas, and the patient obtained it through the Internet quite easily. We are concerned that the abuse of 5-MeO-DIPT may be more widespread than previously thought. We believe that studies are needed to verify the relationship between 5-MeO-DIPT and hallucinogen-persisting perception disorder and to call public attention to the toxicity of 5-MeO-DIPT.