Just supposing someone does find a magic formula to slow down the ageing process.
Do you think the powers that be are going to allow it to become public knowledge?
I think, assuming the person or scientists who discovered or worked out its chemical formula (or whatever treatment that has that effect such as gene therapy etc. Actually, I think gene therapy is by far the most likely route) would think like me with vaguely my morality, probably yes but definitely not immediately i.e. before the technology was scaled up to be able to treat EVERYONE who want's it else there would be a risk of causing total chaos that would cause far more harm than good!
This is because if I discovered such a chemical formula (or whatever) then that's what I would plan to do with it. I confess I would selfishly treat myself first with it (I certainly wouldn't do that if I was young and healthy but I am old with medical complications and could without warning suddenly die any time soon of heart attack or stroke and I am scared of just that) and with the intent of eventually publicly admitting that BUT then, for then afterwards, I would think purely altruisticly by striving to secretly scale up its production so to make enough to treat free of charge everyone who wants it and don't go public with it until it is possible to treat everyone as opposed to a privileged few.
I personally would insist on it being given FREE of charge else I would think that unethical for several reasons one of them being a charge would deny access to the very poor and that would be extremely wrong.
It must also be done secretly until everyone can be treated else, well, just think what would happen! Thousands of people coming over to me begging to be the first ones to be treated before its too late for them and with no ability to treat most of them! How to deal with such a situation? Make them draw straws? Or do I personally monstrously choose who lives and who dies! A totally unacceptable situation that must be avoided at all costs hence the reason to initially keep it secrete and ONLY make it public when EVERYONE who wants it can immediately have it!