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[159.112.244.19]) by mx.google.com with UTF8SMTPS id 6a1803df08f44-8b53d358ef9si337432656d6.533.2026.05.09.04.49.12 for (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Sat, 09 May 2026 04:49:12 -0700 (PDT) Received-SPF: pass (google.com: domain of bounce+a6cce7.4d1858-tjphuhs=gmail.com@mg2.substack.com designates 159.112.244.19 as permitted sender) client-ip=159.112.244.19; Authentication-Results: mx.google.com; dkim=pass header.i=@mg2.substack.com header.s=mailo header.b=h3iNpaLx; dkim=pass header.i=@mailgun.org header.s=mg header.b=I0uUiPOU; spf=pass (google.com: domain of bounce+a6cce7.4d1858-tjphuhs=gmail.com@mg2.substack.com designates 159.112.244.19 as permitted sender) smtp.mailfrom="bounce+a6cce7.4d1858-tjphuhs=gmail.com@mg2.substack.com"; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=substack.com DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg2.substack.com; q=dns/txt; s=mailo; t=1778327352; x=1778334552; h=List-Unsubscribe-Post: List-Unsubscribe: List-Post: List-Id: List-Archive: List-Owner: Reply-To: In-Reply-To: References: Sender: Sender: Date: Message-Id: To: To: From: From: Subject: Subject: Content-Type: Mime-Version: X-Feedback-Id; bh=oeUpwmp4jkMMQSTrCT8k/sWpFgflZw/28GH636JY5qY=; b=h3iNpaLxKh4AnSW+fceXOmxsypFpRNaelX9hI6g95g7P0qbBxSsLLHstMifK2+wraY+dmq9HLnEv42f0A74ljaVk5mWK5rGeYcNoFcCqFq3mNMlTzwxj53I5OISxOGmawKfRpXAVt+WjBqrlq5zRNadOP9+U8FlMsq8CEsse/28= DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mailgun.org; q=dns/txt; s=mg; t=1778327352; x=1778334552; h=List-Unsubscribe-Post: List-Unsubscribe: List-Post: List-Id: List-Archive: List-Owner: Reply-To: In-Reply-To: References: Sender: Sender: Date: Message-Id: To: To: From: From: Subject: Subject: Content-Type: Mime-Version: X-Feedback-Id; bh=oeUpwmp4jkMMQSTrCT8k/sWpFgflZw/28GH636JY5qY=; b=I0uUiPOUBsOhsceF09mJWUv3K3F5u2ZpFQRc4YEnW/HSjAXmGYnPo+/QqcrWHOCCZubsrwkmKt9z48yoRHDRZGehWVC/+vXwZICP23sBxl8/rJW9QqudOe+iYVQMVdcFAjji8FoM2KxyKEPmpO7onlNbJBs7xoKQOwZYIiKomfQ= X-Mailgun-Sid: WyIxODZiYSIsInRqcGh1aHNAZ21haWwuY29tIiwiNGQxODU4Il0= X-Feedback-Id: postmaster@mg2.substack.com:post:5a78b6d5cd16820001f2a9d4:mailgun Received: by 1f3b5e30e48c2e1365e8a566101fb382781f0318c6663fbab4967ccf6f2582a8 with HTTP id 69ff1f3869e98dfa93d22125; Sat, 09 May 2026 11:49:12 GMT X-Mailgun-Sending-Ip: 159.112.244.19 Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="afdc9808e720578fbbb0ecb7e35cbf1db9b154169664b5897c14fdc5feae" Subject: Two Vials of Tirzepatide Got Lost in the Mail for Two Years. Here's What the Data Showed. From: Derek from Research Radar To: tjphuhs@gmail.com X-Mailgun-Tag: post X-Mailgun-Track-Clicks: false Message-Id: <20260509114904.3.27a3fa7e5a6b2d11@mg2.substack.com> Date: Sat, 9 May 2026 11:49:04 +0000 Feedback-Id: post-197000193:cat-post:pub-3365367:substack Sender: Derek from Research Radar References: In-Reply-To: Reply-To: Derek from Research Radar List-Owner: List-Url: List-Archive: List-Id: List-Post: List-Unsubscribe: List-Unsubscribe-Post: List-Unsubscribe=One-Click X-Mailgun-Variables: {"category": "post", "email_generated_at": "1778327352003", "is_freemail": "true", "post_audience": "everyone", "post_id": "197000193", "post_type": "newsletter", "pub_community_enabled": "true", "publication_id": "3365367", "subdomain": "derekpruski", "user_id": "273622398"} --afdc9808e720578fbbb0ecb7e35cbf1db9b154169664b5897c14fdc5feae Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable View this post on the web at https://derekpruski.substack.com/p/two-vials-o= f-tirzepatide-got-lost A real-world stability test nobody planned for Peptide Crafters recently sent me a story I couldn=E2=80=99t pass up. Back in June 2024, they shipped an order containing two vials of tirzepatid= e. The package never made it. UPS lost it somewhere in the system, and for = the next two years it bounced between warehouses marked =E2=80=9Cdestinatio= n unknown=E2=80=9D =E2=80=94 until one day, almost exactly two years later,= it was returned to sender. No temperature control. No insulation. No light protection. Two vials of ly= ophilized peptide sitting in random shipping facilities through two summers= and two winters. They sent both vials for re-analysis. The results genuinely surprised me. The numbers Baseline (June 2024, Prime Analytical Labs): Net peptide content: 12.34 mg Purity: 100.00% Re-test (May 2026, Janoshik =E2=80=94 both vials tested independently): Net peptide content: 12.60 mg and 12.20 mg Purity: 98.52% and 98.37% If you want to verify the raw data yourself: Baseline 2024 PAL report [ https://substack.com/redirect/0ca1ebb5-2ebf-47cc= -b56d-01ae7281b8b6?j=3DeyJ1IjoiNGl3b2U2In0.sVDxRtmZ85v8kfdamY0krRXGMy3p768B= WtuZifRB-Zs ] Janoshik HPLC re-test [ https://substack.com/redirect/39cba4f1-b464-4366-af= 71-0fd08b2ee9ac?j=3DeyJ1IjoiNGl3b2U2In0.sVDxRtmZ85v8kfdamY0krRXGMy3p768BWtu= ZifRB-Zs ] Janoshik LCMS raw data =E2=80=94 vial 1 [ https://substack.com/redirect/432= 9d454-d17c-45f1-ad15-cca93ab51993?j=3DeyJ1IjoiNGl3b2U2In0.sVDxRtmZ85v8kfdam= Y0krRXGMy3p768BWtuZifRB-Zs ] Janoshik LCMS raw data =E2=80=94 vial 2 [ https://substack.com/redirect/97b= 85a47-d524-4d1a-8399-1a51d6edcc27?j=3DeyJ1IjoiNGl3b2U2In0.sVDxRtmZ85v8kfdam= Y0krRXGMy3p768BWtuZifRB-Zs ] What the content numbers tell us The net peptide content barely moved. Both vials came back essentially identical to the original 12.34 mg baselin= e. The 12.20=E2=80=9312.60 mg spread between the two vials is well within n= ormal analytical variance =E2=80=94 that=E2=80=99s the kind of difference y= ou=E2=80=99d see between any two labs running the same sample on the same d= ay. In other words: no meaningful content loss. What the purity numbers tell us This is where it gets more interesting. The original 100.00% purity reading from 2024 is almost certainly overstate= d. Testing methodology in 2024 wasn=E2=80=99t where it is today, and in my exp= erience the lab that ran the original test (PAL) tended to come in higher o= n purity than other labs analyzing the same material. A more realistic base= line is probably 99.7% to 99.8%. Even if we take the headline 100% at face value, we=E2=80=99re looking at r= oughly 1.5% purity loss over two years of completely uncontrolled shipping = conditions. Adjusting for the likely overstatement, real degradation is clo= ser to 1.2%. There=E2=80=99s a second piece of validation worth pointing out: both vials= came back within a tenth of a percent of each other (98.52% and 98.37%). T= hat=E2=80=99s not a one-off reading. Two separate vials, exposed to the sam= e wandering shipping conditions, landed in the same purity range. That=E2= =80=99s reproducibility. Why this challenges the conventional wisdom A lot of the peptide community operates on the assumption that lyophilized = peptides are extremely fragile outside of cold chain. This data suggests otherwise. Lyophilization works. Removing water from the equation is genuinely protect= ive, and the activation energy required to drive meaningful degradation in = a dry powder is substantially higher than in solution. These vials sat thro= ugh two full summers in non-climate-controlled trucks and warehouses, and c= ame back at 98%+ purity. A few important caveats before anyone runs with this: Don=E2=80=99t leave vials on a hot porch all summer just because this story= exists. Reconstituted material is a completely different stability question =E2=80= =94 once it=E2=80=99s in solution, the rules change entirely. But for shipping windows of days or even weeks at ambient temperature? This= kind of data should make people sleep easier. What=E2=80=99s next Peptide Crafters is planning to run an LCMS baseline on a fresh batch of ti= rzepatide so we can compare side-by-side using the same lab and same method= ology. That removes the lab-swap variable entirely and gives us a much clea= ner picture of true degradation. I=E2=80=99ll share the follow-up data when it comes in. In the meantime, this is exactly the kind of real-world stability evidence = the space needs more of. Marketing claims and theoretical degradation curve= s are one thing. Two vials that survived two years of warehouse purgatory a= nd came back at 98%+ purity is data. =E2=80=94 Derek Strictly research use only. Not for human consumption. Unsubscribe https://substack.com/redirect/2/eyJlIjoiaHR0cHM6Ly9kZXJla3BydXN= raS5zdWJzdGFjay5jb20vYWN0aW9uL2Rpc2FibGVfZW1haWw_dG9rZW49ZXlKMWMyVnlYMmxrSW= pveU56TTJNakl6T1Rnc0luQnZjM1JmYVdRaU9qRTVOekF3TURFNU15d2lhV0YwSWpveE56YzRNe= kkzTXpVeExDSmxlSEFpT2pFNE1EazROak16TlRFc0ltbHpjeUk2SW5CMVlpMHpNelkxTXpZM0lp= d2ljM1ZpSWpvaVpHbHpZV0pzWlY5bGJXRnBiQ0o5LkJTSGRuRnM4LWVmLVFTV19rc2g0dzQzb3F= CVEF3U0JxNTlDakY1SWN2Zk0iLCJwIjoxOTcwMDAxOTMsInMiOjMzNjUzNjcsImYiOnRydWUsIn= UiOjI3MzYyMjM5OCwiaWF0IjoxNzc4MzI3MzUxLCJleHAiOjIwOTM5MDMzNTEsImlzcyI6InB1Y= i0wIiwic3ViIjoibGluay1yZWRpcmVjdCJ9.44Ey4_lfYgO8hUY1xgNC7d3_BC2k0mZkV5sjt8h= cKRA? --afdc9808e720578fbbb0ecb7e35cbf1db9b154169664b5897c14fdc5feae Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable = Two Vials of Tirzepatide Got Lost in the Mail for Two Years. Here's What th= e Data Showed.3D""
A real-world stability test nobody planned for
=
T= 7;     ­͏     ­͏     &= #173;͏     ­͏     ­͏   =   ­͏     ­͏     ­͏= ;     ­͏     ­͏     &#= 173;͏     ­͏     ­͏   &= #8199; ­͏     ­͏     ­͏=     ­͏     ­͏     = 73;͏     ­͏     ­͏   &#= 8199; ­͏     ­͏     ­͏ =     ­͏     ­͏     = 3;͏     ­͏     ­͏   = 199; ­͏     ­͏     ­͏ &= nbsp;   ­͏     ­͏     ­= ;͏     ­͏     ­͏   Q= 99; ­͏     ­͏     ­͏ &n= bsp;   ­͏     ­͏     ­= ͏     ­͏     ­͏   ̳= 9; ­͏     ­͏     ­͏ &nb= sp;   ­͏     ­͏     ­&= #847;     ­͏     ­͏    = ; ­͏     ­͏     ­͏ &nbs= p;   ­͏     ­͏     ­&#= 847;     ­͏     ­͏    = ­͏     ­͏     ­͏  = ;   ­͏     ­͏     ­= 47;     ­͏     ­͏     = ­͏     ­͏     ­͏  =   ­͏     ­͏     ­T= 7;     ­͏     ­͏     &= #173;͏     ­͏     ­͏   =   ­͏     ­͏     ­͏= ;     ­͏     ­͏     &#= 173;͏     ­͏     ­͏   &= #8199; ­͏     ­͏     ­͏=     ­͏     ­͏     = 73;͏     ­͏     ­͏   &#= 8199; ­͏     ­͏     ­͏ =     ­͏     ­͏     = 3;͏     ­͏     ­͏   = 199; ­͏     ­͏     ­͏ &= nbsp;   ­͏     ­͏     ­= ;͏     ­͏     ­͏   Q= 99; ­͏     ­͏     ­͏ &n= bsp;   ­͏     ­͏     ­= ͏     ­͏     ­͏   ̳= 9; ­͏     ­͏     ­͏ &nb= sp;   ­͏     ­͏     ­&= #847;     ­͏     ­͏    = ; ­͏     ­͏     ­͏ &nbs= p;   ­͏     ­͏     ­&#= 847;     ­͏     ­͏    = ­͏     ­͏     ­͏  = ;   ­͏     ­͏     ­= 47;     ­͏     ­͏     = ­͏     ­͏     ­͏  =   ­͏     ­͏     ­T= 7;     ­͏     ­͏     &= #173;͏     ­͏     ­͏   =   ­͏     ­͏     ­͏= ;     ­͏     ­͏     &#= 173;͏     ­͏     ­͏   &= #8199; ­͏     ­͏     ­͏=     ­͏     ­͏     = 73;͏     ­͏     ­͏   &#= 8199; ­͏     ­͏     ­͏ =     ­͏     ­͏     = 3;͏     ­͏     ­͏   = 199; ­͏     ­͏     ­͏ &= nbsp;   ­͏     ­͏     ­= ;͏     ­͏     ­͏   Q= 99; ­͏     ­͏     ­͏ &n= bsp;   ­͏     ­͏     ­= ͏     ­͏     ­͏   ̳= 9; ­͏     ­͏     ­͏ &nb= sp;   ­͏     ­
<= /table>
 
<= /table>
<= tbody>
3D""=
3D""
3D""
3D""
=
 

A real-world stability test nobody planned for

=

Peptide Crafters recently sent me a story I couldn’t pas= s up.

Back in June 2024, they shipped an order containing t= wo vials of tirzepatide. The package never made it. UPS lost it somewhere i= n the system, and for the next two years it bounced between warehouses mark= ed “destination unknown” — until one day, almost exactly = two years later, it was returned to sender.

No temperature = control. No insulation. No light protection. Two vials of lyophilized pepti= de sitting in random shipping facilities through two summers and two winter= s.

They sent both vials for re-analysis. The results genuin= ely surprised me.

The numbers

Baseline (June 2024,= Prime Analytical Labs):

    Net peptide content: = 12.34 mg

  • Purity: = 100.00%

3D""

Re-test (May 2026, Janoshik — both vials tested independently):

  • Net peptide content: 12.60 mg and 12.20 mg

    • =

  • Purity: 98.52% and 98.37%=

3D""

If you = want to verify the raw data yourself:

What the cont= ent numbers tell us

The net peptide content barely moved.<= /p>

Both vials came back essentially identical to the original = 12.34 mg baseline. The 12.20–12.60 mg spread between the two vials is= well within normal analytical variance — that’s the kind of di= fference you’d see between any two labs running the same sample on th= e same day.

In other words: no meaningful content loss.

=
What the purity numbers tell us

Thi= s is where it gets more interesting.

The original 100.00% purity reading from 2024 is almost certainly overstat= ed.

Testing methodology in 2024 wasn’t w= here it is today, and in my experience the lab that ran the original test (= PAL) tended to come in higher on purity than other labs analyzing the same = material. A more realistic baseline is probably 99.7% to 99.8%.

Even if we take the headline 100% at face value, we’re loo= king at roughly 1.5% purity loss over two yea= rs of completely uncontrolled shipping conditions. Adjusting for the likely= overstatement, real degradation is closer to 1.2%<= span>.

There’s a second piece of validation wo= rth pointing out: both vials came back within a tenth of a percent of each = other (98.52% and 98.37%). That’s not a one-off reading. Two separate= vials, exposed to the same wandering shipping conditions, landed in the sa= me purity range. That’s reproducibility.

Wh= y this challenges the conventional wisdom

A lot of the pep= tide community operates on the assumption that lyophilized peptides are ext= remely fragile outside of cold chain.

This data suggests ot= herwise.

Lyophilization works. Removing water from the equa= tion is genuinely protective, and the activation energy required to drive m= eaningful degradation in a dry powder is substantially higher than in solut= ion. These vials sat through two full summers in non-climate-controlled tru= cks and warehouses, and came back at 98%+ purity.

A few imp= ortant caveats before anyone runs with this:

  • Don&= #8217;t leave vials on a hot porch all summer just because t= his story exists.

  • Reconstituted material is a completely different stability = question — once it’s in solution, the rules chan= ge entirely.

But for shipping windows of d= ays or even weeks at ambient temperature? This kind of data should make peo= ple sleep easier.

What’s next

Peptide Crafters is planning to run an LCMS baseline on a fresh batch = of tirzepatide so we can compare side-by-side using the same lab and same m= ethodology. That removes the lab-swap variable entirely and gives us a much= cleaner picture of true degradation.

I’ll share the = follow-up data when it comes in.

In the meantime, this is e= xactly the kind of real-world stability evidence the space needs more of. M= arketing claims and theoretical degradation curves are one thing. Two vials= that survived two years of warehouse purgatory and came back at 98%+ purit= y is data.

— Derek

Strictly researc= h use only. Not for human consumption.

=
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© 2026 Derek Pruski
548 Market Street PMB= 72296, San Francisco, CA 94104
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