4-Methylphenethylacetylfentanyl

4-Methylphenethylacetylfentanyl (acetylfentanyl 4-methylphenethyl analog) is an opioid analgesic that is an analog (and structural isomer) of fentanyl and has been sold as a designer drug. == Side effects == Side effects of fentanyl analogs are similar to those of fentanyl itself, which include itching, nausea and potentially serious respiratory depression, which can be life-threatening.