I don't really see these as Anagathics per se. These drugs are prolonging lifespans, but are not able to completely stop the aging process entirely - 2 different things. Traveller Anagathics can, if taken regularly, allow you to live practically forever, with little loss of physical or mental ability. These drugs appear to slow/reduce the aging effects and extend a person's life by an appreciable amount, but will never be a true anagathic.
As far as I'm aware, Traveller makes some provision for these drugs in the aging rules, which are different from the Anagathics.