Having discovered the incredible healing properties of the Tok'ra Queen Egeria in her symbiote form, and unaware of her sentience, the Pangarans used her ability to spawn young to manufacture the tretonin that provided them with long and healthy lives, free from disease and sickness. Egeria's identity was discovered by SG-1 and the Tok'ra, who freed their Queen for long enough to take a willing host and learn of the good that her children had accomplished in their war against the Goa'uld. (6.10 "Cure").
When Egeria died, Tok'ra scientists began work on synthesising tretonin for very good reason: while its effects are short-term and require regular injections, tretonin enables a Jaffa to not only survive, but live a normal life (by human standards) without a symbiote. The drug reinforces the immune system damaged by the implantation of a symbiote.
Thus far, the Tok'ra experimental synthesised drug has been successfully administered to Teal'c and Master Bra'tac. (6.19 "Changeling") In one of the larger clinical trials, the rebel female warrior clan the Ha'ktyl, led by Ishta, High Priestess to Moloc, have been induced to relinquish their symbiotes and switch to tretonin. The death of one of the Ha'ktyl warriors involved in the clinical trial conducted by Dr. Janet Fraiser at the SGC, Mala, revealed that tretonin is not a universal panacea to the Jaffa. (7.10 "Birthright")
However, if the drug can be refined and manufactured in sufficient quantities, tretonin could be the answer the Tok'ra have long sought to ending the mutual interdependency of Goa'uld and Jaffa, freeing the slaves from their 'gods' and thus ending Goa'uld military dominance. After the Goa'uld fell, the use of tretonin had spread amongst the Jaffa population. When Ba'al tried to kill his clones and Jaffa to cover his tracks, one survived because he used tretonin (10.19 "Dominion").
An additional side benefit of the tretonin is that it renders the Jaffa immune to symbiote poison (8.10 "Endgame"). The Tok'ra's poison will kill any Goa'uld, Tok'ra, or Jaffa exposed to it, but tretonin users are immune.
--Alison 16:45, 12 Jan 2005