I’m interested in your comment about correct dilution ratios as I’ve been running various peps for quite awhile including a 2.5mg maintenance dose of Tirz and not sure I’ve ever seen any data on what constitutes correct dilution ratio. I’ve searched around a bit but nothing definitive. If you have a link or something would appreciate it as the immunogenicity thing is something i wish i knew more about when I started using peps. Thanks in advance
Bump to this as well as it makes me wonder was I using proper dilution for peptides, GH. Also he mentioned filtering, which I never used before.
For a peptide available as pharma, the easiest way to establish proper dilution ratio is to see what's used in the pharma product.
For instance:
All doses Tirz, up to 15mg are .5ml.
So for a 30mg vial, you'd want dilution no less than 1ml. More dilution is ok, preferable in fact, less is not.
That's for limiting aggregation that's promoted by higher concentration.
However, despite .5ml being ok for a 15mg dose, in terms of not generating excess aggregate formation, the other reason for a volume of .5ml even for the lowest 2.5mg dose, is pharmacokinetics. Higher volume subcutaneous injections are absorbed more slowly than smaller volumes. By limiting the rate of absorption this way, blood concentration rises more
slowly, reducing the risk of side effects and their intensity.
We can see this control over uptake rate more clearly in Sema, in which Novo Nordisk uses a .5ml volume for all doses up to 1mg, switching to .75ml for 1.7mg and 2.4mg doses. Both those volumes are far beyond what's needed to reconstitute the peptide itself, but .75ml is used to further slow the absorption of the larger doses.
The other reason for reconstitution rate is again, controlling immunogenicity. Higher concentrations of peptides are more easily processed by immune response mechanisms than lower concentrations. Essentially, a greater concentration of an "invader" elicits a more intense immune response, which we want to avoid. You may notice that vaccines, essentially proteins in which we want to maximize the immune response, are given in very concentrated, often site reaction (pain inducing) doses.
For GH, there are many products on the market. Rate of uptake doesn't seem to be a concern. The most concentrate I've seen is .05ml per iu. So no less than 1.8ml per 36iu volume.
However, for UGL it's important to remember that they don't contain the anti-aggregation excipient ingredients used in pharma formulations.
For peptides generally, greater dilution is not a problem, so it's best to err on the side of diluting to the point your dose is somewhere between .3ml and .8ml , which is considered the "ideal" subq volume (for ease of measurement and comfort) when other considerations don't override that range.
If it's a "research" peptide. It's best to reference several studies to see what the researchers are using in human trials, and use that as the guide for dilution.
Finally, I'll point out that since most people understand the closer to "pharma" one can get, the better, use pharma grade BAC like Hospira. It's relatively cheap, especially in case quantities, and since it represents 99% of what's being injected, goes a long way towards approaching "pharma" quality in your reconstituted peptide,
I'll address the other questions a bit later.