DRUGS COME IN and out of style like clothing or music. It is hard to predict which drugs will be popular in the coming years and how long their popularity will last. Many factors account for a new drug trend: international suppliers may flood the market with a certain drug; talk of the drug in the news or in popular media can help spread its use; and a drop in price or an increase in potency always sparks a new phase of growth. More than any other decade, the 1990s have introduced a whole litany of new drugs to the teenage market—some that may be completely unfamiliar to parents and teachers. Even the well-known drugs such as cocaine, speed, heroin, and marijuana have mutated into other forms, increased in potency, or simply become more available to...