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Newest first. 5.2k questions across 107 tags.

5.2k questions · page 115 of 217

26 votes0 answers16k views
Is there any published stability data for semaglutide at minus 20 °C?

The case in front of me: semaglutide · minus 20 °C. The claim is plausible, which is exactly why I want to check it. I am able to read a paper if someone points me at…

peptide-stability
peptide-stability

The chemistry of peptide degradation: deamidation, oxidation, hydrolysis, aggregation and fibrillation, and how temperature, pH, ionic strength,…

908 questions
storage
storage

Storage conditions and their evidence base: minus twenty degrees for powder, refrigerated for solution, protection from light, and what the…

701 questions
clinical-trials
clinical-trials

Reading the primary literature properly: estimands, intention-to-treat versus per-protocol, confidence intervals, absolute versus relative…

745 questions
semaglutide
semaglutide

A GLP-1 receptor agonist with a fatty-acid-acylated backbone and a roughly one-week half-life, marketed for type 2 diabetes and for weight…

470 questions
asked by area_percent 9.9k · 15 months ago
26 votes 4 answers13k views
How do I compare TFC and GGPeps on lead time to Ireland?

For reference: TFC · GGPeps · Ireland. I would like the axes of comparison first and the recommendation second. I have tried the first option and it works; the…

vendor-comparison
vendor-comparison

Side-by-side comparison of suppliers on measurable axes - independently confirmed purity and content, lead time, cold-chain handling,…

388 questions
international-shipping
international-shipping

Cross-border movement of research material: transit lanes and their thermal profiles, tracked versus untracked, declaration accuracy, and what…

471 questions
cold-chain
cold-chain

Keeping material within a temperature window from manufacture to use: phase-change packs versus dry ice, thermal mass, transit-lane temperature…

578 questions
asked by vial_five 12k · 15 months ago
14 votes5 answers11k views
What does 98.8% purity on a C4 column actually tell me about an orforglipron vial?

Concretely: 98.8% · a C4 column · orforglipron. I would like to know the limits of what can be inferred from this. What I am trying to avoid is over-reading a single…

hplc
hplc

Reverse-phase high-performance liquid chromatography, the workhorse purity method. Column chemistry, mobile-phase choice, gradient slope,…

503 questions
purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

833 questions
coa
coa

Certificates of analysis: what fields a useful one carries, how to tell a real analytical report from a marketing document, batch and lot…

771 questions
orforglipron
orforglipron

A non-peptide, orally bioavailable small-molecule GLP-1 receptor agonist studied in the ATTAIN programme. It is not a peptide, which changes…

219 questions
asked by dmitri_savchuk 27k · 15 months ago
6 votes 4 answers11k views
What is the thermal exposure on a Hangzhou to New Zealand lane in summer?

Details up front: Hangzhou · New Zealand. I want to understand what this actually establishes, as opposed to what it is being used to imply. My concern is that I am…

cold-chain
cold-chain

Keeping material within a temperature window from manufacture to use: phase-change packs versus dry ice, thermal mass, transit-lane temperature…

578 questions
international-shipping
international-shipping

Cross-border movement of research material: transit lanes and their thermal profiles, tracked versus untracked, declaration accuracy, and what…

471 questions
storage
storage

Storage conditions and their evidence base: minus twenty degrees for powder, refrigerated for solution, protection from light, and what the…

701 questions
asked by ten_mg_vial 31k · 15 months ago
6 votes 5 answers14k views
How many freeze-thaw cycles will oral semaglutide at 10 mg/mL tolerate?

The particulars: oral semaglutide · 10 mg/mL. I want a method I can write down and repeat, not a rule of thumb. I would rather over-engineer this than discover a…

freeze-thaw
freeze-thaw

What repeated freezing does to a peptide in solution: ice-crystal shear at the growing front, freeze-concentration of solutes, pH shifts as buffer…

57 questions
peptide-stability
peptide-stability

The chemistry of peptide degradation: deamidation, oxidation, hydrolysis, aggregation and fibrillation, and how temperature, pH, ionic strength,…

908 questions
storage
storage

Storage conditions and their evidence base: minus twenty degrees for powder, refrigerated for solution, protection from light, and what the…

701 questions
oral-glp1
oral-glp1

Oral routes for GLP-1 receptor agonism: peptide formulations rescued by absorption enhancers such as SNAC, and true small molecules that need no…

219 questions
asked by wren_calloway 23k · 15 months ago
13 votes 5 answers13k views
Does AST tell me anything about hepatic fat on semaglutide?

The case in front of me: AST · semaglutide. I would like the mechanism, because I want to be able to reason about the cases nobody has written about. I have tried to…

liver-enzymes
liver-enzymes

ALT, AST, GGT and ALP: what they do and do not indicate about hepatic fat, why enzymes are a poor surrogate for histology, and where non-invasive…

91 questions
mash
mash

Metabolic dysfunction-associated steatohepatitis: histological endpoints, resolution without worsening fibrosis, fibrosis improvement by stage,…

56 questions
bloodwork
bloodwork

Laboratory monitoring: which panels are worth ordering, sensible intervals, reference-range versus optimal-range arguments, and how to read a…

296 questions
semaglutide
semaglutide

A GLP-1 receptor agonist with a fatty-acid-acylated backbone and a roughly one-week half-life, marketed for type 2 diabetes and for weight…

470 questions
asked by rae_oyelowo 17k · 15 months ago
13 votes5 answers8.1k views
Why would VendorInvestigate report 98.4% where the supplier certificate says something higher?

The particulars: VendorInvestigate · 98.4%. An unexpected observation, and I would like a differential rather than reassurance. The conditions were within what I…

purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

833 questions
hplc
hplc

Reverse-phase high-performance liquid chromatography, the workhorse purity method. Column chemistry, mobile-phase choice, gradient slope,…

503 questions
batch-testing
batch-testing

Testing at the batch or lot level: sampling plans, how many vials from a lot need testing to say anything about the lot, and the difference…

910 questions
vendor-investigate
vendor-investigate

VendorInvestigate, an independent vendor review and verification service. Use this tag for questions about its verification criteria, what a…

113 questions
asked by w_okoye 43k · 15 months ago
7 votes 5 answers17k views
What did the placebo arm of PIONEER-4 report for dizziness?

What I am working with: PIONEER-4 · dizziness. I would like help reading this properly rather than being told what conclusion to reach. I have the full report…

clinical-trials
clinical-trials

Reading the primary literature properly: estimands, intention-to-treat versus per-protocol, confidence intervals, absolute versus relative…

745 questions
harm-reduction
harm-reduction

Reducing avoidable risk where a decision has already been made: independent verification before use, sterility practice, dose arithmetic checked…

472 questions
asked by forty_two_c 66k · 15 months ago
12 votes5 answers15k views
Is a 95.2% result from Medutest comparable to 97.1% from Janoshik?

Setup, so nobody has to ask: 95.2% · Medutest · 97.1% · Janoshik. Both of these get recommended confidently by different people, which suggests neither is obviously…

purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

833 questions
batch-testing
batch-testing

Testing at the batch or lot level: sampling plans, how many vials from a lot need testing to say anything about the lot, and the difference…

910 questions
reference-standard
reference-standard

Certified reference materials and in-house standards: traceability, the certificate of the standard itself, system suitability, and why every…

185 questions
medutest
medutest

Medutest, one of four independent testing and verification services referenced throughout this site. Use this tag for its methods, its report…

126 questions
janoshik
janoshik

Janoshik Analytical, an independent third-party testing laboratory widely used by this community for HPLC purity, identity and quantified content…

139 questions
asked by lucia_marchetti 19k · 15 months ago
26 votes5 answers36k views
How long does a Guangzhou to the United States lane usually take with tracking?

Setup, so nobody has to ask: Guangzhou · the United States. I would like help reading this properly rather than being told what conclusion to reach. I have the full…

international-shipping
international-shipping

Cross-border movement of research material: transit lanes and their thermal profiles, tracked versus untracked, declaration accuracy, and what…

471 questions
customs
customs

Customs handling: how declarations are assessed, why a parcel sits at a facility for a week, seizure notices, and the practical difference between…

196 questions
cold-chain
cold-chain

Keeping material within a temperature window from manufacture to use: phase-change packs versus dry ice, thermal mass, transit-lane temperature…

578 questions
asked by esther_vandeVelde 52k · 15 months ago
12 votes 5 answers14k views
Why does aggregation accelerate at 25 °C rather than proceeding linearly?

Setup, so nobody has to ask: aggregation · 25 °C. I keep seeing this stated as a fact with no explanation attached, and unexplained facts make me suspicious. My…

peptide-stability
peptide-stability

The chemistry of peptide degradation: deamidation, oxidation, hydrolysis, aggregation and fibrillation, and how temperature, pH, ionic strength,…

908 questions
storage
storage

Storage conditions and their evidence base: minus twenty degrees for powder, refrigerated for solution, protection from light, and what the…

701 questions
hplc
hplc

Reverse-phase high-performance liquid chromatography, the workhorse purity method. Column chemistry, mobile-phase choice, gradient slope,…

503 questions
asked by dead_volume 56k · 15 months ago
14 votes 5 answers24k views
Is 4 °C an acceptable storage condition for lyophilised cagrilintide?

What I am working with: 4 °C · cagrilintide. This is asserted often enough that I assumed it was established, and then I went looking for the source. I have searched…

storage
storage

Storage conditions and their evidence base: minus twenty degrees for powder, refrigerated for solution, protection from light, and what the…

701 questions
peptide-stability
peptide-stability

The chemistry of peptide degradation: deamidation, oxidation, hydrolysis, aggregation and fibrillation, and how temperature, pH, ionic strength,…

908 questions
shelf-life
shelf-life

How long a preparation remains within specification: labelled expiry for a sealed lyophilised vial, beyond-use dating after reconstitution, and…

327 questions
amylin
amylin

Amylin and its analogues, most prominently cagrilintide, as a satiety mechanism orthogonal to incretin signalling. Includes the pharmacology of…

237 questions
asked by rae_oyelowo 17k · 15 months ago
9 votes 5 answers12k views
My retatrutide vial sat at 4 °C for ten days — is testing worth it before use?

Stated plainly: retatrutide · 4 °C · ten days. I would like to set this up properly once, rather than adjust it repeatedly. My budget is real but not tight, and my…

cold-chain
cold-chain

Keeping material within a temperature window from manufacture to use: phase-change packs versus dry ice, thermal mass, transit-lane temperature…

578 questions
peptide-stability
peptide-stability

The chemistry of peptide degradation: deamidation, oxidation, hydrolysis, aggregation and fibrillation, and how temperature, pH, ionic strength,…

908 questions
batch-testing
batch-testing

Testing at the batch or lot level: sampling plans, how many vials from a lot need testing to say anything about the lot, and the difference…

910 questions
retatrutide
retatrutide

An investigational GLP-1, GIP and glucagon receptor tri-agonist, studied in the TRIUMPH programme. Not approved anywhere. Use this tag for…

251 questions
asked by sunniva_dahl 22k · 15 months ago
2 votes5 answers12k views
Is an ERP order from Hangzhou likely to hold cold chain to the Netherlands?

Details up front: ERP · Hangzhou · the Netherlands. I would like to set this up properly once, rather than adjust it repeatedly. My budget is real but not tight, and…

cold-chain
cold-chain

Keeping material within a temperature window from manufacture to use: phase-change packs versus dry ice, thermal mass, transit-lane temperature…

578 questions
international-shipping
international-shipping

Cross-border movement of research material: transit lanes and their thermal profiles, tracked versus untracked, declaration accuracy, and what…

471 questions
vendor-comparison
vendor-comparison

Side-by-side comparison of suppliers on measurable axes - independently confirmed purity and content, lead time, cold-chain handling,…

388 questions
asked by olu_babatunde 6.2k · 15 months ago
30 votes 5 answers19k views
How do I reconcile 99.1% from Medutest with 96.4% from the supplier?

Stated plainly: 99.1% · Medutest · 96.4%. This is not behaving the way I expected and I want to understand the discrepancy before I act on it. I have photographed the…

purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

833 questions
batch-testing
batch-testing

Testing at the batch or lot level: sampling plans, how many vials from a lot need testing to say anything about the lot, and the difference…

910 questions
coa
coa

Certificates of analysis: what fields a useful one carries, how to tell a real analytical report from a marketing document, batch and lot…

771 questions
medutest
medutest

Medutest, one of four independent testing and verification services referenced throughout this site. Use this tag for its methods, its report…

126 questions
asked by pip_okonjo 13k · 15 months ago
23 votes3 answers13k views
How do I get 15 units out of a vial reconstituted to 1 mg/mL without guessing?

What I have: 15 units · 1 mg/mL. I would like to understand the steps well enough to explain them to someone else. I have access to a refrigerator with a logger and a…

insulin-syringe
insulin-syringe

U-100 and U-40 insulin syringes as measuring instruments. A U-100 syringe is graduated in insulin units where 100 units equals 1 mL, so one unit…

244 questions
dosing-math
dosing-math

The arithmetic itself: milligrams to millilitres to insulin units, concentration after reconstitution, dose per draw, and vial-days per vial. Show…

764 questions
diluent-volume
diluent-volume

Choosing how much diluent to add, which is really a question about what you want your measurement resolution to be. Larger volumes buy you…

295 questions
asked by samir_bennani 15k · 15 months ago
27 votes0 answers20k views
Is a mini-fridge without a thermometer worse than no fridge?

I have continuous temperature data for the period in question, which is unusual and I would like to use it. I would rather over-plan the first cycle and simplify…

storage
storage

Storage conditions and their evidence base: minus twenty degrees for powder, refrigerated for solution, protection from light, and what the…

701 questions
cold-chain
cold-chain

Keeping material within a temperature window from manufacture to use: phase-change packs versus dry ice, thermal mass, transit-lane temperature…

578 questions
harm-reduction
harm-reduction

Reducing avoidable risk where a decision has already been made: independent verification before use, sterility practice, dose arithmetic checked…

472 questions
asked by per_haugen 13k · 15 months ago
33 votes 5 answers22k views
What happens after a seizure notice in the United States?

I have certificates from two lots and an independent result on one of them. This is presented as though it settles something, and I am not convinced it does. I have…

customs
customs

Customs handling: how declarations are assessed, why a parcel sits at a facility for a week, seizure notices, and the practical difference between…

196 questions
import-regulations
import-regulations

The legal framework for personal importation across major jurisdictions, enforcement discretion, and the distinction between a research reference…

53 questions
research-use-only
research-use-only

What "for research use only" means as a legal and practical designation: not approved for human use, no pharmacopoeial release testing, no…

95 questions
asked by retest_please 9.7k · 15 months ago
23 votes 5 answers10k views
How do I plan for a cagrilintide supply interruption without stockpiling badly?

I have continuous temperature data for the period in question, which is unusual and I would like to use it. I would rather over-plan the first cycle and simplify…

storage
storage

Storage conditions and their evidence base: minus twenty degrees for powder, refrigerated for solution, protection from light, and what the…

701 questions
discontinuation
discontinuation

Stopping treatment: tapering versus abrupt cessation, what the trial withdrawal arms measured, clinically driven stops, and the practical planning…

21 questions
cost-analysis
cost-analysis

Cost arithmetic done honestly: cost per milligram after dead-space loss, list versus net price, comparing a multi-dose vial to a fixed-dose pen,…

260 questions
amylin
amylin

Amylin and its analogues, most prominently cagrilintide, as a satiety mechanism orthogonal to incretin signalling. Includes the pharmacology of…

237 questions
asked by ellis_thorne 17k · 15 months ago
31 votes0 answers8.7k views
Is 95.2% a realistic purity ceiling for dulaglutide given its chain length?

Details up front: 95.2% · dulaglutide. I can do the algebra. I am not confident about the conversion factors. If there is a standard way to lay this out, I would…

purity
purity

Purity as chromatographic area per cent - the fraction of detected material that is your target peak. It says nothing about how much material is…

833 questions
hplc
hplc

Reverse-phase high-performance liquid chromatography, the workhorse purity method. Column chemistry, mobile-phase choice, gradient slope,…

503 questions
peptide-mapping
peptide-mapping

Enzymatic digestion followed by LC-MS/MS to confirm sequence rather than just mass. The method that catches a scrambled sequence or a D-amino-acid…

103 questions
dulaglutide
dulaglutide

A once-weekly GLP-1 receptor agonist built on an Fc fusion rather than fatty-acid acylation. Use this tag for questions about the fusion-protein…

200 questions
asked by tyndall_haze 38k · 15 months ago
20 votes 5 answers19k views
Has anyone independently verified a QST liraglutide batch COA?

Setup, so nobody has to ask: QST · liraglutide. I want to know whether there is evidence behind this or only repetition. I have checked the obvious registries and…

vendor-vetting
vendor-vetting

Evaluating a supplier on evidence rather than reputation: testing history across batches, whether certificates are batch-specific, how failures…

454 questions
coa
coa

Certificates of analysis: what fields a useful one carries, how to tell a real analytical report from a marketing document, batch and lot…

771 questions
batch-testing
batch-testing

Testing at the batch or lot level: sampling plans, how many vials from a lot need testing to say anything about the lot, and the difference…

910 questions
liraglutide
liraglutide

A once-daily GLP-1 receptor agonist and the compound that established the class. Still relevant for its shorter half-life, its paediatric and…

235 questions
asked by ekaterina_volk 21k · 15 months ago
18 votes5 answers10k views
What is the reported incidence of nausea on oral semaglutide in SOUL?

The particulars: nausea · oral semaglutide · SOUL. The figures are clear enough; the question is what they mean and what they do not. I can supply the numbers if the…

nausea
nausea

The dominant tolerability signal in every trial of the class: incidence, timing relative to a dose step, duration, and the distinction between…

55 questions
clinical-trials
clinical-trials

Reading the primary literature properly: estimands, intention-to-treat versus per-protocol, confidence intervals, absolute versus relative…

745 questions
oral-glp1
oral-glp1

Oral routes for GLP-1 receptor agonism: peptide formulations rescued by absorption enhancers such as SNAC, and true small molecules that need no…

219 questions
asked by ivo_paunovic 16k · 15 months ago
26 votes5 answers14k views
Is an AHI improvement durable if weight is regained?

My laboratory results are from the same laboratory each time, drawn fasting, which I gather matters. This is one of those things that everyone repeats and nobody…

sleep-apnea
sleep-apnea

Obstructive sleep apnoea and the apnoea-hypopnoea index response to weight loss, including the SURMOUNT-OSA dataset and the question of whether…

6 questions
weight-regain
weight-regain

Regain after stopping or reducing: the trajectory reported in the withdrawal extensions, how much is fluid, and what the maintenance arms tell us…

10 questions
clinical-trials
clinical-trials

Reading the primary literature properly: estimands, intention-to-treat versus per-protocol, confidence intervals, absolute versus relative…

745 questions
asked by tare_and_weigh 12k · 15 months ago
26 votes5 answers28k views
What does TRIUMPH-3 report at the 8 mg dose level?

Conditions: TRIUMPH-3 · 8 mg. The figures are clear enough; the question is what they mean and what they do not. I can supply the numbers if the specifics change the…

clinical-trials
clinical-trials

Reading the primary literature properly: estimands, intention-to-treat versus per-protocol, confidence intervals, absolute versus relative…

745 questions
dosing-math
dosing-math

The arithmetic itself: milligrams to millilitres to insulin units, concentration after reconstitution, dose per draw, and vial-days per vial. Show…

764 questions
titration
titration

Stepwise dose increases over weeks, why the label schedules exist at all, and what tolerability-driven deviation from a schedule looks like in…

456 questions
asked by tamsin_wray 9.9k · 15 months ago