This invention relates to novel compounds that are 3-benzazepine derivatives and pharmaceutically acceptable salts thereof. More specifically, this invention relates to novel 3-benzazepine derivatives that are derivatives of lorcaserin. This invention also provides compositions comprising one or more compounds of this invention and a carrier and the use of the disclosed compounds and compositions in methods of treating diseases and conditions that are beneficially treated by administering a 5-HT2C agonist, such as lorcaserin. (I) or a pharmaceutically acceptable salt thereof, wherein: Ring A contains 0-7 deuterium atoms at the substitutable ring carbon positions; and R is CH3, CH2D, CD2H, or CD3; provided that when R is CH3, Ring A contains 1-7 deuterium atoms at the substitutable ring carbon positions.