dndgeek said:
So what's the thought process on stacking Reta with Tirz vs Sema? I was thinking Sema would be better because its supplementing only the GLP1 side of Reta which is weaker. Stacking Tirz in my thinking would add more GIP into the equation but Reta already highly favors GIP above all else. I have and still do add Cagri but I really dont think it does anything for me.
This is based more on theory or animal research than proven effects in human studies. I have explained this before in other posts but a lot of the information there is about the relative effects of different GLP drugs on the different receptors is wrong. Standard AI responses are not correct. And it is complex. The simple Ki or binding affinity numbers are not close to the whole story. 99% of the drugs are bound to albumin to start with , and then when they bind to receptors there can be different or even deliberately biased intracellular responses to those drugs. It is the secondary intracellular response that determines what effects they have in the end. Tirzepatide for example is biased towards cAMP signalling over beta-arrestin signalling at the GLP-1 receptor, so it can have a stronger total effect on glp-1 than semaglutide, and less adverse effects, despite much lower binding affinity. And there is less receptor internalisation and inactivation due to the lower beta-arrestin signalling.
My understanding is: Tirzepatide strongest GIP, fairly strong GLP-1, 15mg tirz is possibly stronger than semaglutide 2.4mg on glp-1
Retatrutide weaker GIP than tirz, stronger but not biased glp-1 agonism plus glucagon agonism.
Tirzepatide has probably the least side effects due to the biased agonism on GLP-1, plus the strong GIP agonism counteracts the nausea and malaise response in the brain caused by glp agonism
Reta causes a bit more gi side effects due to the non biased signalling at glp-1 and the weaker GIP agonism, having less of a counteracting effect on glp nausea, but better weight loss due to the added glucagon agonism.
I spent quite a bit of time reading papers and arguing with chatgpt ( with extensive promting ) over whether adding in extra semaglutide to tirzepatide would increase overall glp-1 agonism, and really did not reach a definite conclusion. I thought chatgpt's pharmacology is really very good, though I think promting it to not agree with you without evidence is essential.
I had horrible nausea and malaise from low dose semaglutide so for me it was not really an option.
The most logical add on is almost certainly cagrilintide to retatrutide or tirzepatide. Cagrilintide is not low on side effects so doses need to be very low and slowly increased if already at full doses of reta or tirz. It is a pity the research on combining cagri is with semaglutide, for ownership reasons , combining it with reta is probably state of the art at this stage.
Or switching from tirzepatide to retatrutide for a few extra percent weight loss, but maybe a bit more side effects.
In my case I was pleasantly surprised by how few side effects I got from 15mg of tirzepatide compared to 0.8mg semaglutide, and rather than mess that up added in reta for it's glucagon agonism rather than switched, in theory the extra gip agonism of tirz should cause less nausea even when combined with reta than just reta alone.