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5.2k questions · page 149 of 217

10 votes 5 answers24k views
What is the reported incidence of constipation on a GLP-1 receptor agonist in SURPASS-3?

What I am working with: constipation · a GLP-1 receptor agonist · SURPASS-3. I have read the primary source rather than the summary, which has left me with more…

constipation
constipation

Slowed transit as a consequence of delayed gastric emptying and reduced intake: incidence figures, fibre and hydration evidence, and why it often…

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
asked by eoin_mcgarry 18k · 20 months ago
20 votes0 answers23k views
Why would Janoshik report 99.4% where the supplier certificate says something higher?

What I am working with: Janoshik · 99.4%. I noticed this today and I have not touched anything since, in case the state is diagnostic. I have not discarded anything…

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
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 esben_lykke 84k · 20 months ago
8 votes 5 answers9k views
Is 1 mg weekly a defensible maintenance dose for mazdutide?

Setup, so nobody has to ask: 1 mg · mazdutide. I am trying to build something sustainable rather than something thorough that I will abandon. I have already decided…

maintenance-dose
maintenance-dose

Staying put: the lowest dose that holds a result, the difference between the maximum studied dose and the maximum useful dose, and what the…

54 questions
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
mazdutide
mazdutide

A GLP-1 and glucagon receptor dual agonist developed primarily in China, with a distinct dose range and a fast-moving publication record.…

237 questions
asked by ellis_thorne 17k · 20 months ago
25 votes 5 answers36k views
Is a 98.8% result from Medutest comparable to 97.1% from PeptideMeter?

Setup, so nobody has to ask: 98.8% · Medutest · 97.1% · PeptideMeter. I suspect the honest answer is that it depends, in which case I would like to know on what.…

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
peptidemeter
peptidemeter

PeptideMeter, an independent peptide analytics and vendor-rating service. Use this tag for its published datasets, its rating methodology, and how…

107 questions
asked by bridget_nyathi 12k · 20 months ago
26 votes 5 answers43k views
How do I check that two KP lots of retatrutide agree on content assay?

Concretely: KP · retatrutide. I have a result I cannot explain, and I would rather diagnose it than guess. I have checked the obvious explanations and eliminated the…

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
content-assay
content-assay

Quantified content: how many milligrams of peptide are actually in the vial, measured against a calibrated reference standard. A separate test…

476 questions
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
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 liam_bracken 6.9k · 20 months ago
34 votes0 answers36k views
How does reference-standard error propagate into a mazdutide content figure?

This is my second independent submission on material from the same supplier. This should be a straightforward calculation and I keep getting two different answers.…

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
content-assay
content-assay

Quantified content: how many milligrams of peptide are actually in the vial, measured against a calibrated reference standard. A separate test…

476 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
mazdutide
mazdutide

A GLP-1 and glucagon receptor dual agonist developed primarily in China, with a distinct dose range and a fast-moving publication record.…

237 questions
asked by one_ml_bac 18k · 20 months ago
9 votes 5 answers19k views
What did the trials do with participants who could not tolerate a dose step?

I have read the prescribing information and it addresses the adjacent case but not this one. I can parse the result. I am less sure what it licenses me to conclude. I…

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
clinical-trials
clinical-trials

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

745 questions
gi-side-effects
gi-side-effects

The gastrointestinal cluster as a whole - nausea, vomiting, diarrhoea, constipation, reflux, early satiety - with trial incidence rates, dropout…

162 questions
asked by orla_sheridan 18k · 20 months ago
19 votes5 answers19k views
What should a visual inspection of a KP vial cover before reconstitution?

I have a logging thermometer, a box of insulin syringes and no illusions about my worktop being sterile. This is a planning question. I know what my options are; I do…

vial-inspection
vial-inspection

What you can learn by looking: cake morphology, meniscus films, fibres versus stopper fragments versus true particulates, clarity after…

66 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
sterility
sterility

Sterility as a test result rather than an adjective. Covers what a sterility test actually measures, why "sterile filtered" on a document is close…

142 questions
asked by imani_dube 8.9k · 20 months ago
6 votes5 answers20k views
How do I tell vomiting from an energy deficit on 800 kcal a day?

Details up front: vomiting · 800 kcal. I have a result I cannot explain, and I would rather diagnose it than guess. I have checked the obvious explanations and…

fatigue
fatigue

Tiredness on treatment: how much is energy deficit, how much is dehydration or electrolyte drift, how much is genuinely drug-attributable, and…

78 questions
nutrition
nutrition

Eating on a suppressed appetite: hitting nutritional targets inside a small energy budget, micronutrient risk, meal structure, and what the trial…

100 questions
electrolytes
electrolytes

Sodium, potassium and magnesium during reduced intake and GI losses: what the symptoms of a shortfall look like, when a panel is worth drawing,…

72 questions
asked by siobhan_deasy 9.5k · 20 months ago
28 votes 5 answers46k views
What counter-ion should I expect on a KP retatrutide lot?

Concretely: KP · retatrutide. I can parse the result. I am less sure what it licenses me to conclude. I have deliberately not looked at anyone else’s interpretation…

acetate-content
acetate-content

Counter-ion content, most often acetate or trifluoroacetate, and why it matters: the counter-ion and residual water are part of the gross mass you…

88 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
content-assay
content-assay

Quantified content: how many milligrams of peptide are actually in the vial, measured against a calibrated reference standard. A separate test…

476 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 net_peptide 12k · 20 months ago
21 votes 5 answers34k views
How do I check that two SGN lots of retatrutide agree on content assay?

Concretely: SGN · retatrutide. I have a result I cannot explain, and I would rather diagnose it than guess. I have checked the obvious explanations and eliminated the…

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
content-assay
content-assay

Quantified content: how many milligrams of peptide are actually in the vial, measured against a calibrated reference standard. A separate test…

476 questions
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
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 pip_okonjo 13k · 20 months ago
8 votes 5 answers16k views
Does hair thinning at week two of orforglipron usually resolve without a dose change?

For reference: hair thinning · two · orforglipron. I have done this once and I suspect I got away with it rather than got it right. For context: I keep records of…

hair-loss
hair-loss

Telogen effluvium following rapid weight loss versus a drug-attributable effect: the timing signature that distinguishes them, protein and…

50 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
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 coring_risk 27k · 20 months ago
24 votes0 answers19k views
Is identity confirmation by mass spectrometry on one vial from a twenty-person split enough for the whole split?

The specifics, since they change the answer: identity confirmation by mass spectrometry · a twenty-person split. I would like to define my thresholds before I have a…

group-buy
group-buy

Pooled purchasing: how the economics work, what trust structure a pool needs, splitting a single tested lot, and the failure modes when the…

41 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
mass-spec
mass-spec

Mass spectrometry for identity confirmation: electrospray ionisation, multiple charge states, monoisotopic versus average mass, deconvolution, and…

52 questions
asked by jonas_ekstrom 12k · 20 months ago
14 votes5 answers31k views
Why does deamidation accelerate at room temperature rather than proceeding linearly?

The case in front of me: deamidation · room temperature. I would like the mechanism, because I want to be able to reason about the cases nobody has written about. I…

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 Dr_Hanne_Solberg 36k · 20 months ago
6 votes 3 answers18k views
Is a 98.8% result from PeptideMeter comparable to 97.9% from Medutest?

The specifics, since they change the answer: 98.8% · PeptideMeter · 97.9% · Medutest. The comparison I want does not seem to exist anywhere in a form I can evaluate.…

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
peptidemeter
peptidemeter

PeptideMeter, an independent peptide analytics and vendor-rating service. Use this tag for its published datasets, its rating methodology, and how…

107 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 Dr_Rosalind_Achebe 69k · 20 months ago
41 votes 5 answers36k views
My liraglutide vial sat at minus 80 °C for three days — is testing worth it before use?

The specifics, since they change the answer: liraglutide · minus 80 °C · three days. I would like to define my thresholds before I have a result, for obvious reasons.…

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
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 forty_units 16k · 20 months ago
6 votes 5 answers19k views
How comparable are tirzepatide and cagrilintide on the evidence available?

Setup, so nobody has to ask: tirzepatide · cagrilintide. The comparison I want does not seem to exist anywhere in a form I can evaluate. I have read the arguments for…

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
tirzepatide
tirzepatide

A dual GIP and GLP-1 receptor agonist. Questions here cover the SURPASS and SURMOUNT programmes, the practical differences from a pure GLP-1…

370 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 rosa_mendieta 8k · 20 months ago
33 votes 5 answers25k views
What happens to orforglipron after eight weeks at 30 °C in solution?

Stated plainly: orforglipron · eight weeks · 30 °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
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
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 Dr_Aoife_Brennan 20k · 20 months ago
10 votes 5 answers15k views
Is 37 °C an acceptable storage condition for lyophilised mazdutide?

Stated plainly: 37 °C · mazdutide. This is asserted often enough that I assumed it was established, and then I went looking for the source. I have searched the…

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
mazdutide
mazdutide

A GLP-1 and glucagon receptor dual agonist developed primarily in China, with a distinct dose range and a fast-moving publication record.…

237 questions
asked by lucia_marchetti 19k · 20 months ago
29 votes 5 answers30k views
How many freeze-thaw cycles will orforglipron at 20 mg/mL tolerate?

Setup, so nobody has to ask: orforglipron · 20 mg/mL. This is a procedural question rather than a theoretical one, and I would like the procedure rather than the…

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
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 ahmed_zerouali 15k · 20 months ago
33 votes 4 answers15k views
Does orforglipron adsorb measurably to the vial wall at 3.33 mg/mL?

Setup, so nobody has to ask: orforglipron · 3.33 mg/mL. I have worked this out and I would like someone to find the error, because I suspect there is one. My working…

peptide-stability
peptide-stability

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

908 questions
content-assay
content-assay

Quantified content: how many milligrams of peptide are actually in the vial, measured against a calibrated reference standard. A separate test…

476 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
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 zeynep_arslan 16k · 20 months ago
32 votes 5 answers34k views
How long does a Zhuhai to the United Kingdom lane usually take with tracking?

Setup, so nobody has to ask: Zhuhai · the United Kingdom. This is presented as though it settles something, and I am not convinced it does. I have two documents that…

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 gel_pack_warm 13k · 20 months ago
39 votes 5 answers42k views
How does WWB compare to Shanghai ERP Biotechnology on documentation quality?

Conditions: WWB · Shanghai ERP Biotechnology. I have used one of these for a while and I am considering switching, which requires a reason. What I care about is…

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
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
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
asked by pip_okonjo 13k · 20 months ago
17 votes 5 answers23k views
Is a sterility test on one vial from a five-person group buy enough for the whole split?

Setup, so nobody has to ask: a sterility test · a five-person group buy. I would rather over-plan the first cycle and simplify later. I am prepared to do the work if…

group-buy
group-buy

Pooled purchasing: how the economics work, what trust structure a pool needs, splitting a single tested lot, and the failure modes when the…

41 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
sterility
sterility

Sterility as a test result rather than an adjective. Covers what a sterility test actually measures, why "sterile filtered" on a document is close…

142 questions
asked by dana_wexler 11k · 20 months ago