PeptideStack
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Unanswered questions

Questions with no answer at all. Not questions with no accepted answer — those are elsewhere.

741 questions · page 2 of 31

11 votes0 answers3.3k views
What does "net peptide content" mean on a certificate?

I am comparing a supplier certificate against an independent result on the same lot. The figures are clear enough; the question is what they mean and what they do…

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…

438 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…

749 questions
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…

87 questions
asked by unit_math 13k · 40 days ago
10 votes0 answers2.8k views
What does SURMOUNT-2 tell me about constipation at the 8 mg dose?

The particulars: SURMOUNT-2 · constipation · 8 mg. I have the document in front of me and I can read the numbers. What I cannot do is interpret them. I am reasonably…

clinical-trials
clinical-trials

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

913 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…

416 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…

444 questions
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…

14 questions
asked by kofi_mensah 12k · 41 days ago
13 votes0 answers3.8k views
Is cagrilintide at 1 mg/mL stable enough for two weeks of multi-withdrawal use?

Numbers first: cagrilintide · 1 mg/mL · two weeks. I am asking for verification rather than opinion, ideally with something I can read myself. It is possible the…

peptide-stability
peptide-stability

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

832 questions
bacteriostatic-water
bacteriostatic-water

Water for injection containing roughly 0.9 per cent benzyl alcohol as a bacteriostatic agent. It suppresses growth in a multiple-withdrawal vial;…

112 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…

301 questions
asked by forty_units 14k · 43 days ago
5 votes0 answers1.1k views
How many units on a U-100 insulin syringe is a 40 mg dose at 3.33 mg/mL?

Numbers first: a U-100 insulin syringe · 40 mg · 3.33 mg/mL. This should be a straightforward calculation and I keep getting two different answers. The numbers are…

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…

811 questions
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…

268 questions
reconstitution
reconstitution

Taking a lyophilised vial to a solution of known concentration: choice of diluent, volume selection, how to add liquid without shearing the cake,…

330 questions
asked by forty_units 14k · 43 days ago
21 votes0 answers3.9k views
What happens to mazdutide after six weeks at 25 °C in solution?

Details up front: mazdutide · six weeks · 25 °C. I can predict the outcome but I cannot explain it, which means I will get the next case wrong. I would like to know…

peptide-stability
peptide-stability

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

832 questions
storage
storage

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

646 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…

301 questions
asked by Dr_Ravi_Selvarajah 42k · 43 days ago
4 votes0 answers574 views
Is a 31G needle the right choice for drawing ecnoglutide at 3.33 mg/mL?

For reference: a 31G needle · ecnoglutide · 3.33 mg/mL. The comparison I want does not seem to exist anywhere in a form I can evaluate. I have read the arguments for…

needle-gauge
needle-gauge

Gauge and length selection, the trade-off between draw time and tissue trauma, coring risk with larger-bore needles, and why a fixed-needle…

85 questions
injection-technique
injection-technique

Technique questions: angle, pinch versus flat, aspiration, injection speed, air bubbles, and the handling steps that determine whether you deliver…

90 questions
dead-space
dead-space

The volume trapped in the syringe hub and needle after the plunger bottoms out. It is small in absolute terms and large as a fraction of a small…

110 questions
asked by tandem_gradient 85k · 1 months ago
10 votes0 answers2k views
Does the STEP 8 population resemble anyone asking about mazdutide here?

What I am working with: STEP 8 · mazdutide. I would like help reading this properly rather than being told what conclusion to reach. I have the full report including…

clinical-trials
clinical-trials

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

913 questions
harm-reduction
harm-reduction

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

445 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…

360 questions
asked by halvard_ness 42k · 2 months ago
12 votes0 answers2.2k views
How much protein in grams do I need at 74 kg on 800 kcal a day?

Numbers first: 74 kg · 800 kcal. 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 rather…

protein-intake
protein-intake

Protein targets in grams per kilogram, per-meal distribution and the leucine threshold, and the evidence for a higher intake specifically during…

53 questions
nutrition
nutrition

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

92 questions
lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

164 questions
asked by eoin_mcgarry 16k · 2 months ago
18 votes0 answers2.3k views
How many weeks to steady state for a GLP-1 receptor agonist on a weekly schedule?

I am asking mechanistically rather than practically — I want the model, not the protocol. I can do the algebra. I am not confident about the conversion factors. If…

glp1-mechanism
glp1-mechanism

Receptor-level pharmacology: GLP-1R as a class B GPCR, cAMP and PKA signalling, biased agonism, internalisation and resensitisation, and the…

175 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…

444 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…

811 questions
asked by liam_bracken 12k · 2 months ago
8 votes0 answers2.8k views
Does racemisation dominate for retatrutide held at 40 °C?

Numbers first: racemisation · retatrutide · 40 °C. I suspect the usual explanation for this is wrong, or at least incomplete. I am aware this may have a boring…

peptide-stability
peptide-stability

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

832 questions
storage
storage

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

646 questions
hplc
hplc

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

466 questions
asked by syringe_ninety 15k · 2 months ago
7 votes0 answers1.6k views
What does a Karl Fischer water content test add for oral semaglutide that a purity figure does not?

Concretely: a Karl Fischer water content test · oral semaglutide. These are treated as interchangeable and I do not think they are. If both are acceptable I would…

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…

438 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…

788 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…

749 questions
asked by cold_lane 14k · 2 months ago
5 votes0 answers1.7k views
What happens to a GLP-1 receptor agonist after sixteen weeks at minus 80 °C in solution?

Numbers first: a GLP-1 receptor agonist · sixteen weeks · minus 80 °C. I suspect the usual explanation for this is wrong, or at least incomplete. I am aware this may…

peptide-stability
peptide-stability

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

832 questions
storage
storage

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

646 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…

301 questions
asked by claudia_ferrante 46k · 2 months ago
14 votes0 answers4.5k views
Is a laboratory refrigerator good enough for storing reconstituted dulaglutide?

Numbers first: a laboratory refrigerator · dulaglutide. I would rather over-plan the first cycle and simplify later. I am prepared to do the work if someone can tell…

storage
storage

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

646 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…

524 questions
harm-reduction
harm-reduction

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

445 questions
asked by n_takahashi 36k · 2 months ago
6 votes0 answers1.3k views
Does reconstituting semaglutide with sterile water for injection change anything I should know about?

The case in front of me: semaglutide · sterile water for injection. This is one of those things that everyone repeats and nobody derives. This matters practically,…

reconstitution
reconstitution

Taking a lyophilised vial to a solution of known concentration: choice of diluent, volume selection, how to add liquid without shearing the cake,…

330 questions
bacteriostatic-water
bacteriostatic-water

Water for injection containing roughly 0.9 per cent benzyl alcohol as a bacteriostatic agent. It suppresses growth in a multiple-withdrawal vial;…

112 questions
peptide-stability
peptide-stability

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

832 questions
asked by eoin_mcgarry 16k · 2 months ago
8 votes0 answers3k views
How many vials from an SSA lot should I send for an endotoxin test?

For reference: SSA · an endotoxin test. I would like the arithmetic checked rather than the conclusion asserted. I have deliberately not used an online calculator…

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…

865 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…

749 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,…

261 questions
asked by pascal_thibault 13k · 2 months ago
16 votes0 answers2.8k views
What does a residual-solvent screen add for a GLP-1 receptor agonist that a purity figure does not?

Setup, so nobody has to ask: a residual-solvent screen · a GLP-1 receptor agonist. I suspect the honest answer is that it depends, in which case I would like to know…

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…

438 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…

788 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…

749 questions
asked by colm_dunphy 16k · 2 months ago
20 votes0 answers3.4k views
Is lipase a better monitoring choice than potassium on ecnoglutide?

Setup, so nobody has to ask: lipase · potassium · ecnoglutide. I suspect the honest answer is that it depends, in which case I would like to know on what. Assume I…

bloodwork
bloodwork

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

284 questions
kidney-function
kidney-function

eGFR, creatinine, cystatin C and albuminuria: the acute haemodynamic dip that is not injury, the renal outcome data from the FLOW programme, and…

100 questions
lipids
lipids

Lipid response on treatment: triglycerides, LDL-C, non-HDL-C, ApoB and Lp(a), which of them move with weight loss, and why a fasting panel drawn…

112 questions
asked by h_villanueva 50k · 2 months ago
21 votes0 answers5k views
Is 20 mg in 1 mL of bacteriostatic water a sensible presentation for oral semaglutide?

Setup, so nobody has to ask: 20 mg · 1 mL · bacteriostatic water · oral semaglutide. I am trying to build something sustainable rather than something thorough that I…

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…

308 questions
reconstitution
reconstitution

Taking a lyophilised vial to a solution of known concentration: choice of diluent, volume selection, how to add liquid without shearing the cake,…

330 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…

811 questions
asked by kelvin_lam 11k · 2 months ago
11 votes0 answers2.4k views
Would you accept 99.1% on survodutide from KP without a content assay?

The particulars: 99.1% · survodutide · KP. I would like to define my thresholds before I have a result, for obvious reasons. I want a plan with explicit stopping…

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…

788 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…

438 questions
vendor-vetting
vendor-vetting

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

436 questions
asked by coring_risk 17k · 2 months ago
4 votes0 answers1.3k views
What is the reported incidence of injection-site erythema on ecnoglutide in SELECT?

For reference: injection-site erythema · ecnoglutide · SELECT. I want to understand what this actually establishes, as opposed to what it is being used to imply. My…

gi-side-effects
gi-side-effects

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

416 questions
clinical-trials
clinical-trials

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

913 questions
nausea
nausea

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

346 questions
asked by a_lindgren 46k · 2 months ago
2 votes0 answers910 views
Is an SWB order from Suzhou likely to hold cold chain to Australia?

Numbers first: SWB · Suzhou · Australia. I would rather over-plan the first cycle and simplify later. I am prepared to do the work if someone can tell me which work…

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…

524 questions
international-shipping
international-shipping

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

427 questions
vendor-comparison
vendor-comparison

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

351 questions
asked by mg_per_ml 12k · 2 months ago
14 votes0 answers3.1k views
Is room temperature an acceptable storage condition for lyophilised liraglutide?

The case in front of me: room temperature · liraglutide. I want to know whether there is evidence behind this or only repetition. I have checked the obvious…

storage
storage

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

646 questions
peptide-stability
peptide-stability

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

832 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…

301 questions
asked by noor_alhassan 15k · 2 months ago
1 vote0 answers385 views
What does SURPASS-2 actually establish about mazdutide?

What I am working with: SURPASS-2 · mazdutide. I have read the primary source rather than the summary, which has left me with more questions. I understand the…

clinical-trials
clinical-trials

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

913 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…

360 questions
cardiovascular
cardiovascular

Cardiovascular outcomes: the SELECT major-adverse-event result, SOUL, SUSTAIN 6 and REWIND, how to convert a hazard ratio into an absolute risk…

111 questions
asked by ben_akintola 14k · 2 months ago
20 votes0 answers3.9k views
Is an FGP order from Tianjin likely to hold cold chain to the Netherlands?

What I am working with: FGP · Tianjin · the Netherlands. I would like to set this up properly once, rather than adjust it repeatedly. My budget is real but not tight,…

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…

524 questions
international-shipping
international-shipping

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

427 questions
vendor-comparison
vendor-comparison

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

351 questions
asked by juan_esquivel 14k · 2 months ago