A term coined by Gary Henderson, contemporary pharmacologist, meaning an illicitly produced drug of abuse whose structure is a modification of a preexisting drug in order to bypass existing drug laws and regulations for the purpose of marketing. Designer drugs are dangerous and they have serious side effects or are addictive. Also, the compounds are not standardized with respect to potency, toxicity and pharmacology so deaths from overdose may occur.
An example of a designer drug is the street drug ‘ecstasy‘, which is an analogue of methamphetamine. Other examples include fentanyl and its analogues, and phencyclidine hydrochloride (PCP). If taken with alcohol, it is potentially dangerous.