Five addictive books featuring sci-fi drugs

Chris Howard was born and raised in England, and it was there he first began writing stories and songs. He now lives in Denver, Colorado, where he and his wife enjoy mountains, music, and mugs of good coffee. He is the author of Night Speed, as well as the Rootless trilogy.

One of Howard's top five addictive books featuring sci-fi drugs, as shared at Tor.com:
The Strange Case of Dr. Jekyll and