22 is at least 100 in another embodiment the present invention provides an isolated novel deuterium enriched compound of formula i or a pharmaceutically acceptable salt thereof wherein r 1 r 22 are independently selected from h and d and the abundance of deuterium in r 1 r 22 is at least 5 the abundance can also be a at least 9 b at least 14 c at least 18 d at least 23 e at least 27 f at least 32 g at least 36 h at least 41 i at least 45 j at least 50 k at least 55 l at least 59 m at least 64 n at least 68 o at least 73 p at least 77 q at least 82 r at least 86 s at least 91 t at least 95 and u 100 in another embodiment the present invention provides an isolated novel deuterium enriched compound of formula i or a pharmaceutically acceptable salt thereof wherein the abundance of deuterium in r 1 r 6 is at least 17 the abundance can also be a at least 33 b at least 50 c at least 67 d at least 83 and e 100 in another embodiment the present invention provides an isolated novel deuterium enriched compound of formula i or a pharmaceutically acceptable salt thereof wherein the abundance of deuterium in r 7 r 14 is at least 13 the abundance can.