People often want to compare ephedrine to Clenbuterol. This is fine as long as you realize that they act in different ways. Clenbuterol is a specific beta-2 adrenergic agonist. As such, Clenbuterol interacts directly with beta-2 receptors on muscle and fat tissue. Ephedrine, on the other hand, is not a direct beta-2 agonist. In fact, ephedrine is a poor ligand for the beta-2 receptor. Instead, ephedrine stimulates the release of noradrenaline from sympathetic nerve terminals. The noradrenaline then goes on to interact with muscle and fat cells as a nonspecific adrenergic agonist. This simply means that noradrenaline activates beta-2 receptors, but also other beta-receptors as well as alpha-receptors. So to compare ephedrine and Clenbuterol you must take into account their differences.
The differences between ephedrine and Clenbuterol are important. For example, Clenbuterol is a very potent beta-2 agonist. As a result, within 14 to 21 days, the beta-2 receptors on muscle and fat cells will be drawn into the cell membrane to reduce their availability to Clenbuterol. Then, if you continue to take it, they will be disassembled all together, leaving you insensitive to Clenbuterol. It then takes at least 2-3 weeks for receptors to replenish themselves on muscle and fat cells. Once again, ephedrine is different with respect to down regulation. Ephedrine, being a much weaker agonist, does not cause rapid desensitization and/or down-regulation of adrenergic receptors. This allows ephedrine to be used effectively for many months. Despite these differences, both drugs should be tapered over the course of several weeks before discontinuing them. If you don't, you will quickly replace the fat you just lost due to an increased appetite and a decreased ability of fat cells to mobilize stored fat.