Phentermine has been in the US for some time now. The drug was first approved by the FDA back in 1959. It was given the nod as an appetite suppressant to be used as a diet pill. At that time, it was a different chemical than is known today. In fact, the phentermine hydrochloride combination was not available until then 1970s. This pill was available on its own or in combination with fenfluramine (Fen-Phen). However, the Fen-Phen combination was removed from the marketplace in the United States in 1998, after 24 reports were made the year before of cases of heart valve disease that occurred among the users of that medication.
Today, Phentermine is available in the US as a drug all on its own both in its generic and brand name forms. As of 2012, however, a new combination prescription pill was by the FDA. Qsymia (formerly known as Qnexa in its testing phase) has now received its approval to be sold as a prescription drug. This brand name medication is a combination of Phentermine and topiramate. It is the most recent prescription drug to enter the American diet pill marketplace.
Due to the fact that Phentermine is a chemical that is quite similar to amphetamines, it is not a legally approved substance in every country. Though it is legal as a prescription drug in the United States, many other nations consider it to be a controlled or banned substance.
In the US, the Convention on Psychotropic Substances has deemed Phentermine to be in the category of schedule IV drugs. It is available in both tablet and capsule form, and can be prescribed to a maximum dose of 37.5 milligrams. There is both a standard release and time release version of the pill available, depending on the dosage needs of the patient.