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 6 of 31

19 votes0 answers2.6k views
How long does survodutide stay within specification at minus 20 °C once reconstituted?

The case in front of me: survodutide · minus 20 °C. I am trying to do this correctly the first time rather than learn it by getting it wrong. I have already made one…

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_Elias_Weiss 46k · 5 months ago
18 votes0 answers7.3k views
Does liraglutide adsorb measurably to the vial wall at 4 mg/mL?

The particulars: liraglutide · 4 mg/mL. I would like the arithmetic checked rather than the conclusion asserted. I have deliberately not used an online calculator…

peptide-stability
peptide-stability

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

832 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
storage
storage

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

646 questions
asked by ravi_pillai 16k · 5 months ago
8 votes0 answers2.6k views
Does splitting a 5 mg weekly dose of mazdutide across two administrations change anything?

Stated plainly: 5 mg · mazdutide. The empirical answer seems settled. The explanation does not. If the honest answer is that nobody knows, I would rather hear that…

split-dosing
split-dosing

Dividing a weekly dose across more than one administration. Questions here concern the pharmacokinetic rationale, whether the peak-to-trough ratio…

39 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
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
asked by tare_and_weigh 18k · 5 months ago
17 votes0 answers6.4k views
Why does compounded dulaglutide potency vary between pharmacies?

The pharmacy is accredited and I have verified that on the accreditor register. The empirical answer seems settled. The explanation does not. If the honest answer is…

compounding
compounding

Compounded preparations: what a 503A and a 503B facility may legally prepare and when, base versus salt forms, beyond-use dating under USP…

61 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
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 halvard_ness 42k · 5 months ago
11 votes0 answers4.1k views
How comparable are tirzepatide and semaglutide on the evidence available?

For reference: tirzepatide · semaglutide. The comparison I want does not seem to exist anywhere in a form I can evaluate. I have read the arguments for each and they…

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
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…

162 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…

14 questions
glucagon-receptor
glucagon-receptor

Glucagon receptor agonism as a deliberate component of dual and tri-agonists: what it adds in energy expenditure and hepatic fat mobilisation, and…

14 questions
asked by j_wierzbicki 45k · 5 months ago
4 votes0 answers847 views
Does racemisation dominate for retatrutide held at 25 °C?

What I have: racemisation · retatrutide · 25 °C. I suspect the usual explanation for this is wrong, or at least incomplete. I am aware this may have a boring answer.…

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 ines_delacruz 16k · 5 months ago
9 votes0 answers3.6k views
What is the case for and against phosphate-buffered diluent over sixteen weeks of withdrawals?

What I have: phosphate-buffered diluent · sixteen weeks. I have used one of these for a while and I am considering switching, which requires a reason. What I care…

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
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…

122 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 cal_hennessy 14k · 5 months ago
2 votes0 answers686 views
How long does a GLP-1 receptor agonist stay within specification at 37 °C once reconstituted?

What I have: a GLP-1 receptor agonist · 37 °C. I would like to understand the steps well enough to explain them to someone else. I have access to a refrigerator with…

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 threadlock7 14k · 5 months ago
22 votes0 answers3.6k views
Would you accept 98.8% on liraglutide from BCH without a content assay?

Conditions: 98.8% · liraglutide · BCH. I want to decide this in advance so that I am not deciding it under pressure later. Assume I will follow the plan I write down,…

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 · 5 months ago
24 votes0 answers4.5k views
What does a list of related substances on an MKM report change about how I read it?

Concretely: list of related substances · MKM. The figures are clear enough; the question is what they mean and what they do not. I can supply the numbers if the…

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
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
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 felix_araya 17k · 5 months ago
14 votes0 answers2.3k views
What did the placebo arm of STEP 2 report for constipation?

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

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
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 gel_pack_warm 13k · 5 months ago
16 votes0 answers4.1k views
Why did my LDL-C move after eight weeks on semaglutide?

Stated plainly: LDL-C · eight weeks · semaglutide. I noticed this today and I have not touched anything since, in case the state is diagnostic. I have not discarded…

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 tadhg_o_riordan 14k · 5 months ago
8 votes0 answers2.4k views
What does the mechanism of mazdutide predict that SUSTAIN-6 did not test?

Numbers first: mazdutide · SUSTAIN-6. I can predict the outcome but I cannot explain it, which means I will get the next case wrong. I would like to know how…

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
clinical-trials
clinical-trials

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

913 questions
gip-receptor
gip-receptor

GIP receptor pharmacology, and the still-unsettled question of whether agonism or antagonism at GIPR is the metabolically useful direction.…

83 questions
asked by tare_and_weigh 18k · 5 months ago
15 votes0 answers8k views
What does SURPASS-3 report at the 5 mg dose level?

For reference: SURPASS-3 · 5 mg. I want to understand what this actually establishes, as opposed to what it is being used to imply. My concern is that I am being…

clinical-trials
clinical-trials

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

913 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
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
asked by olu_babatunde 14k · 5 months ago
1 vote0 answers819 views
How many units on a 0.5 mL insulin syringe is a 2 mg dose at 4 mg/mL?

Concretely: a 0.5 mL insulin syringe · 2 mg · 4 mg/mL. I want the working, not the result — I need to be able to redo it with different numbers. I care about the…

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 pascal_thibault 13k · 6 months ago
20 votes0 answers3.9k views
What fraction of loss on survodutide is lean mass according to FLOW?

The case in front of me: survodutide · FLOW. The figures are clear enough; the question is what they mean and what they do not. I can supply the numbers if the…

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
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

82 questions
dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

84 questions
asked by mira_sundqvist 19k · 6 months ago
7 votes0 answers3.9k views
Would you accept 96.8% on mazdutide from Homopeptide without a content assay?

Setup, so nobody has to ask: 96.8% · mazdutide · Homopeptide. I am trying to build something sustainable rather than something thorough that I will abandon. I have…

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 grainne_ahearn 13k · 6 months ago
22 votes0 answers9.7k views
If I reconstitute a 5 mg vial with 0.5 mL of bacteriostatic water, what concentration do I end up with?

What I am working with: 5 mg · 0.5 mL · bacteriostatic water. The units are where I keep going wrong, so please be explicit about them. I have sanity-checked the…

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
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
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 day_seven_trough 11k · 6 months ago
6 votes0 answers1.2k views
Does the SURMOUNT-1 population resemble anyone asking about retatrutide here?

Details up front: SURMOUNT-1 · 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…

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
amylin
amylin

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

14 questions
asked by vial_five 15k · 6 months ago
4 votes0 answers1.3k views
What does a 503A pharmacy need to prepare cagrilintide lawfully?

I have the plan documents and the written criteria, which took two calls to obtain. This is presented as though it settles something, and I am not convinced it does.…

pharmacy-503a
pharmacy-503a

Section 503A traditional compounding pharmacies specifically: patient-specific prescriptions, accreditation such as PCAB and ACHC, USP 797…

17 questions
compounding
compounding

Compounded preparations: what a 503A and a 503B facility may legally prepare and when, base versus salt forms, beyond-use dating under USP…

61 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 fill_volume 13k · 6 months ago
13 votes0 answers5.6k views
Does hydrolysis of retatrutide at 2–8 °C show up as a loss of content or of purity?

What I have: hydrolysis · retatrutide · 2–8 °C. I suspect the usual explanation for this is wrong, or at least incomplete. I am aware this may have a boring answer. I…

peptide-stability
peptide-stability

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

832 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
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
asked by sinead_gaffney 14k · 6 months ago
27 votes0 answers5.5k views
What does ATTAIN-1 actually establish about orforglipron?

Details up front: ATTAIN-1 · orforglipron. This is presented as though it settles something, and I am not convinced it does. I have two documents that appear to…

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 ellis_thorne 17k · 6 months ago
13 votes0 answers6.5k views
Is a bank transfer sensible for an order shipping to the Netherlands?

The particulars: a bank transfer · the Netherlands. I am at the decision point and I would rather think it through than improvise. I would rather spend money on…

payment-privacy
payment-privacy

Payment mechanics and their privacy properties: why suppliers ask for stablecoin transfers, what an on-chain transfer reveals, confirmation…

31 questions
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
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
asked by low_dead_space 42k · 6 months ago
13 votes0 answers7.2k views
Is REDEFINE-1 a fair comparison of ecnoglutide against its comparator arm?

The particulars: REDEFINE-1 · ecnoglutide. I would like to know whether this claim survives contact with evidence. If the answer is "nobody has tested that", I would…

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
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…

162 questions
asked by bea_forsberg 14k · 6 months ago