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Unanswered questions

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

739 questions · page 13 of 31

13 votes0 answers10k views
Is GL Biochem worth the price difference against Chinese Peptide Company on measured results?

Details up front: GL Biochem · Chinese Peptide Company. The comparison I want does not seem to exist anywhere in a form I can evaluate. I have read the arguments for…

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
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
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
asked by ilaria_bertone 33k · 11 months ago
12 votes0 answers3.9k views
What is the dead-space loss per draw with a 25G drawing needle at 5 mg/mL?

Setup, so nobody has to ask: a 25G drawing needle · 5 mg/mL. I have worked this out and I would like someone to find the error, because I suspect there is one. My…

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…

117 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…

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
asked by amara_nwachukwu 20k · 11 months ago
17 votes0 answers6.6k views
What interval makes sense for repeating eGFR on orforglipron?

The case in front of me: eGFR · orforglipron. I would rather over-plan the first cycle and simplify later. I am prepared to do the work if someone can tell me which…

bloodwork
bloodwork

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

296 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
a1c
a1c

Glycated haemoglobin as a ninety-day glycaemic average: what a change of half a point means, why it lags, and the conditions under which it…

122 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…

141 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 sinead_gaffney 28k · 11 months ago
11 votes0 answers5.8k views
How does a GLP-1 receptor agonist behave on a C8 column compared to survodutide?

Numbers first: a GLP-1 receptor agonist · a C8 column · survodutide. I have used one of these for a while and I am considering switching, which requires a reason.…

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
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
survodutide
survodutide

A GLP-1 and glucagon receptor dual agonist with a substantial published MASH dataset. Use this tag for its hepatic endpoints, its dose ladder, and…

225 questions
asked by fill_volume 22k · 11 months ago
30 votes0 answers16k views
What is the reported incidence of hair thinning on tirzepatide in SURMOUNT-3?

The case in front of me: hair thinning · tirzepatide · SURMOUNT-3. The figures are clear enough; the question is what they mean and what they do not. I can supply the…

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
clinical-trials
clinical-trials

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

745 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
asked by rune_thoresen 16k · 11 months ago
12 votes0 answers9.4k views
What has Medutest published on SWB lots in the last year?

The case in front of me: Medutest · SWB. I have read the primary source rather than the summary, which has left me with more questions. I understand the headline. I…

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
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-comparison
vendor-comparison

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

388 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 nadia_kowalczyk 20k · 11 months ago
20 votes0 answers5.6k views
What is the reported incidence of constipation on semaglutide in STEP 2?

Setup, so nobody has to ask: constipation · semaglutide · STEP 2. I have read the primary source rather than the summary, which has left me with more questions. I…

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
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 fiadh_cronin 58k · 11 months ago
32 votes0 answers16k views
Is 99.4% a realistic purity ceiling for liraglutide given its chain length?

Concretely: 99.4% · liraglutide. Please show the division. I want to check my own against yours. I would like the general form as well as the specific number, so 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
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
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 olu_babatunde 6.2k · 11 months ago
15 votes0 answers8.7k views
Is a titration interval of two weeks better supported than four weeks for survodutide?

Conditions: two weeks · survodutide. Somebody stated this to me confidently and I would like to check it before repeating it. I would accept a well-reasoned negative…

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
dose-escalation
dose-escalation

The decision to move up a step: what evidence supports a four-week interval, what happens when you compress it, and how trial protocols handled…

103 questions
clinical-trials
clinical-trials

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

745 questions
survodutide
survodutide

A GLP-1 and glucagon receptor dual agonist with a substantial published MASH dataset. Use this tag for its hepatic endpoints, its dose ladder, and…

225 questions
asked by forty_two_c 66k · 11 months ago
27 votes0 answers7.5k views
Is SOUL a fair comparison of a GLP-1 receptor agonist against its comparator arm?

What I am working with: SOUL · a GLP-1 receptor agonist. This is asserted often enough that I assumed it was established, and then I went looking for the source. I…

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
asked by bea_forsberg 11k · 11 months ago
16 votes0 answers7.2k views
What fraction of loss on semaglutide is lean mass according to ESSENCE?

The particulars: semaglutide · ESSENCE. I would like help reading this properly rather than being told what conclusion to reach. I have the full report including 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…

127 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…

39 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…

39 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 mira_sundqvist 7.1k · 11 months ago
3 votes0 answers1.6k views
What happens to cagrilintide after sixteen weeks at 37 °C in solution?

Details up front: cagrilintide · sixteen weeks · 37 °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,…

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
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 g_paskevicius 60k · 11 months ago
23 votes0 answers18k views
What accept/reject threshold would you set for retatrutide before seeing the result?

The method section is present, which is unusual enough that I want to make use of it. I am trying to build something sustainable rather than something thorough that I…

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
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
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
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 seamus_brady 15k · 11 months ago
30 votes0 answers11k views
What does STEP 1 tell me about dizziness at the 2 mg dose?

Stated plainly: STEP 1 · dizziness · 2 mg. I have read the primary source rather than the summary, which has left me with more questions. I understand the headline. I…

clinical-trials
clinical-trials

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

745 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 bridget_nyathi 12k · 11 months ago
31 votes0 answers7.7k views
What would you ask Xi’an Mokemei Biotechnology before a first order that they cannot fake?

The lane and the lead time matter as much as the material for what I am doing. I want a method I can write down and repeat, not a rule of thumb. I would rather…

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
asked by t_oyelaran 79k · 11 months ago
15 votes0 answers9.2k views
Is 4 °C an acceptable storage condition for lyophilised dulaglutide?

Details up front: 4 °C · dulaglutide. I would rather be corrected now than propagate something wrong. I am specifically not interested in a testimonial; I am…

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
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 sinead_gaffney 28k · 12 months ago
2 votes0 answers896 views
Does holding at 12.5 mg for eight weeks before escalating reduce nausea?

What I am working with: 12.5 mg · eight weeks · nausea. The empirical answer seems settled. The explanation does not. If the honest answer is that nobody knows, 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
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
dose-escalation
dose-escalation

The decision to move up a step: what evidence supports a four-week interval, what happens when you compress it, and how trial protocols handled…

103 questions
asked by sample_id 17k · 12 months ago
24 votes0 answers8.5k views
How do I plan for a GLP-1 receptor agonist supply interruption without stockpiling badly?

The material is still sealed, so I have not committed to anything yet. This is a planning question. I know what my options are; I do not know how to weigh them. What…

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
asked by otto_brenner 12k · 12 months ago
14 votes0 answers9.2k views
How would I detect oxidation in an oral semaglutide vial without sending it to Janoshik?

Concretely: oxidation · oral semaglutide · Janoshik. I have done this once and I suspect I got away with it rather than got it right. For context: I keep records of…

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
peptide-stability
peptide-stability

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

908 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
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
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 mira_sundqvist 7.1k · 12 months ago
23 votes0 answers6.8k views
Is 96.8% a realistic purity ceiling for semaglutide given its chain length?

For reference: 96.8% · semaglutide. I would rather understand the derivation than memorise the outcome. Two people I asked gave two answers that differ by a factor of…

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
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 low_dead_space 37k · 12 months ago
30 votes0 answers20k views
Is 1 mg weekly a defensible maintenance dose for semaglutide?

For reference: 1 mg · semaglutide. I would like to define my thresholds before I have a result, for obvious reasons. I want a plan with explicit stopping rules, not…

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
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 coldbox9 41k · 12 months ago
33 votes0 answers21k views
My mazdutide vial sat at 40 °C for twenty-eight days — is testing worth it before use?

What I have: mazdutide · 40 °C · twenty-eight days. I would rather over-plan the first cycle and simplify later. I am prepared to do the work if someone can tell me…

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
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 marta_szymanska 10k · 12 months ago
16 votes0 answers9.8k views
Is a Homopeptide order from Hangzhou likely to hold cold chain to Singapore?

The case in front of me: Homopeptide · Hangzhou · Singapore. I want to decide this in advance so that I am not deciding it under pressure later. Assume I will follow…

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 zainab_mustafa 21k · 12 months ago
11 votes0 answers3.1k views
Should I use a 30G needle to draw and something finer to administer?

I have photographs before and after reconstitution if the visual detail matters. I am trying to do this correctly the first time rather than learn it by getting it…

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…

91 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…

96 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 shear_at_the_front 17k · 12 months ago