New street drugs

Popping up faster than lawmakers can ban them and docs can learn them:

When these products appear, they are often so new that legislatures and regulatory bodies have not yet gotten around to banning them. When one of these drugs is outlawed, a new, related but chemically distinct and therefore legal substance takes it place. This means emergency physicians must struggle to keep up with a constantly changing situation, and treat based on clinical presentation rather than precise knowledge of specific drugs involved. It also means that patients who use these drugs are playing a toxicological version of Russian roulette.