Bromantan gained popularity because it appealed on multiple fronts. But stimulants by themselves function reasonably well as performance-enhancing drugs. Athletes take stimulants to improve endurance, reduce fatigue and increase aggressiveness. And someone trying to qualify for a lower weight class may rely on stimulants for their ability to suppress appetite.
You may think first of amphetamines -- prescription-only "speed" pills -- when you hear of this class of drugs, but not all stimulants require a physician's signature. Ephedrine, for example, is available over the counter in many applications outside of dietary supplements (dietary supplements containing ephedrine are illegal in the U.S.). In these applications, the drug functions as a decongestant, a treatment for menstrual or urine-control problems or a medication to counteract low blood pressure associated with anesthesia. Athletes, of course, aren't interested in these effects. They grab ephedrine for an extra boost of energy despite the warnings that the drug can cause high blood pressure, dizziness, shortness of breath and cardiac arrhythmia.