It does not seem that phen-fen is classified as an SSRI at
http://www.fda.gov/cder/news/phen/fenphenqa2.htm .
14. Can selective serotonin reuptake inhibitor (SSRI) antidepressants such as Prozac, Zoloft, Luvox and Paxil be substituted for fenfluramine in the phen/fen combination?
FDA has not reviewed the safety or efficacy of such combinations and has not approved their use. These drugs are active in serotonin metabolism but have somewhat different activity than fenfluramine and dexfenfluramine. No currently available weight-loss drugs have been studied adequately in combinations to permit a recommendation by FDA for combined use.
Now, I'm not too sure about the following, but:
Fenfluramine is a potent releaser of serotonin from serotonergic neurons impinging on the cerebral appetite center. This was from
http://www.usaweightloss.com/anchors%20patent/United%20States%20Patent%205,795,895.htm
This is clearly different from a reuptake inhibitor, but the research I found was that Paxil (not Prozac) had the effect when taken in doses greater than the depression treatment level.
It does not seem that phen-fen is classified as an SSRI at http://www.fda.gov/cder/news/phen/fenphenqa2.htm .You are right it is not a SSRI but both drugs raise the level of serotonin.
This is clearly different from a reuptake inhibitor, but the research I found was that Paxil (not Prozac) had the effect when taken in doses greater than the depression treatment level.
You really need to find out if the research was funded by one of the drug companies. Eli Lilly has a non-disclosure on all of their research. If it doesn't come out the way they want it, it never sees the light of day. Of course if you are a researcher and your research does not come out the way Eli-Lilly wants it to you don't get any more research! The published research may be skewed a little by this.
You may trust this research if you wish.