4-ACO-DMT, O-Acetylpsilocin is a synthetically produced psychoactive drug and has been suggested by David Nichols to be a potentially useful alternative to psilocybin for pharmacological studies, as they are both believed to be prodrugs of psilocin. In the body, 4-AcO-DMT / psilacetin is thought to be deacetylated into psilocin during first pass metabolism and subsequent passes through the liver (evident as psilacetin is also active when injected). This has not been formally proven, however, and is based on reports that most users cannot tell the difference between these two compounds when ingested to the point that they are often considered as indistinguishable from each other in terms of their subjective effects.There are, however, claims of subjective differences in effect between the acetylated and non-acetylated forms of psilocin.