Qingdao Sigma Chemical Co., Ltd (International, US, EU, Canada and Australia domestic

[Ecstasy]

"Cloudy" after 1ml doesn't mean it's just hard to dissolve. It's a sign of protein aggregation. When peptides "clump up", they can trigger an immune response.

Pharma Tesa is already known to cause injection site reactions from this "allergic reaction", but aggregates make it worse, and beyond the discomfort, there's a risk of developing antibodies which cause your immune system attack the drug, reducing or even eliminating it's effectiveness. (aka Immunogenicity)

Filtering removes the largest protein aggregates, reducing PIP, and lowering the risk of immunizing yourself against the peptide's effects.

I appreciate the thorough response! Bought some sterile vials and syringe filters. Is it a good idea to filter most of the peptides into new vials or is it just a big thing with Tesamorelin? Thanks!

 

[2old2getswol]

I appreciate the thorough response! Bought some sterile vials and syringe filters. Is it a good idea to filter most of the peptides into new vials or is it just a big thing with Tesamorelin? Thanks!

I’ve not filtered Reta, Tirz, Sema, Cagri, HCG or HGH from QSC and have not experienced any issues so take that for what you will.

 

[Ghoul]

I’ve not filtered Reta, Tirz, Sema, Cagri, HCG or HGH from QSC and have not experienced any issues so take that for what you will.

Of course observational anecdotes have value, so I'm not suggesting what you're saying is useless, however you have no idea how much immunogenicity your peptides are inducing. It's not as if you could typically feel the effects of aggregation and the immune response unless it was really bad.

 

[Ghoul]

I appreciate the thorough response! Bought some sterile vials and syringe filters. Is it a good idea to filter most of the peptides into new vials or is it just a big thing with Tesamorelin? Thanks!

I'm filtering all my peptides now, based on what I've learned. This is an increasing concern with commercial pharma producers as peptides become more widespread therapeutics. Most of the aggregation appears to happen in the final product container once it's in the hands of the user.

I ended up going down this rabbit hole for a few reasons, and a "cloudy" batch of PIP inducing Tesa was one.

The TLDR version is that all protein based therapeutics are susceptible to this aggregation process. Visible particles are the final stage. It's a concern because, at the least, aggregates don't work the way the peptide is intended. It's an altered version of the original product. Depending on various factors, those altered products can cause negative reactions as the immune system responds, maybe something you can feel, maybe not. Finally, aggregates can "train" the immune system to attack the original, unmodified peptide creating "tolerance" and reducing the effect you're seeking. This is referred to as "immunogenicity".

It impossible for end users to filter out all aggregates, especially the smaller ones like dimer. But the common .2um filters will eliminate the largest aggregates, without filtering out even the longest peptides. .1um may be even better. Only "Size Exclusion Chromatography" can eliminate all aggregates leaving behind pure peptide.

Here's a rough diagram showing the concept of proteins subject to various stresses like temp cycling (freeze thaw) contamination(especially silicone from stoppers and syringes), and agitation causing shear stress, all leading to aggregates forming, which then trigger an immune response.



This shows the approximately
aggregate size, with 100um being "visible", aka "cloudy solution", and the smallest aggregates 1um. Often, the larger the aggregate the worse the reaction and greater possibility of immunogenicity developing.

One final thing, developing immunity to a peptide does not typically seem to be anywhere near as long as immunity from something like a vaccine, but still best to be avoided or you could be pointlessly injecting a peptide with diminished or no effects at all.

 

[sushak]

What are the losses encountered when filtering though? Doesn't the filter hold back a lot of the solution? Even .25 ml held up absorbed into the filter would be significant no? Have you measured the before/after volume after filtering say a 2ml reconstitution solution?

 

[Ghoul]

What are the losses encountered when filtering though? Doesn't the filter hold back a lot of the solution? Even .25 ml held up absorbed into the filter would be significant no? Have you measured the before/after volume after filtering say a 2ml reconstitution solution?

That's an excellent question. From what I've found a typical 25mm syringe filter has a .05ml hold up volume.

13mm has a .01ml hold up volume.

Also important to ensure the filter uses a "low protein adhesion" membrane.

Finally, doing an "air purge" into the vial will push most retained liquid out of the filter.

Since smaller aggregates act a "seeds", attracting more peptide to build themselves, you're also likely preserving more unaggregated peptide than losing in the tiny amount of solution retention.

 

[Ghoul]

Here's one of the more detailed reports on protein aggregation. I can't possibly absorb all of it and go down every tangent. For instance they discuss the role of Benzyl Alcohol in multi-vial doses causing aggregation.

One interesting aspect of this has been a focus on why there's such a wide difference in efficacy and side effects between Pharma brands of HGH. Differences in packaging and handling, therefore amounts of aggregation may be the explanation as to why the same peptide has such different results. For instance, single use HGH doses use sterile water for reconstitution. Multi dose products use BAC, containing the (potentially) aggregate encouraging Benzyl Alcohol. Just food for thought...

Aggregation of protein therapeutics enhances their immunogenicity: causes and mitigation strategies

Protein aggregation in biotherapeutics has been identified to increase immunogenicity, leading to immune-mediated adverse effects, such as severe allergic responses including anaphylaxis. The induction of anti-drug antibodies (ADAs) moreover enhances drug clearance rates, and can directly block...

pubs.rsc.org