is there an effective dosage of 5htp?

My sister gets pretty down. she has tried 50mg three times a day with no success.

someone on Elite reccomended either inositol or Pseven?

I am not entirely sure what Pseven is, so any help with that would also be appreciated.

also any opinions on inositol would help.

sorry for so many questions but I am bit confused am just trying to help sis.

thanks.