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Newest first. 5.2k questions across 107 tags.

5.2k questions · page 106 of 217

26 votes5 answers25k views
How do I convert the STEP 2 hazard ratio into an absolute risk reduction?

I have the full paper rather than the abstract, and the supplementary appendix. I would rather understand the derivation than memorise the outcome. Two people I asked…

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
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
asked by teodora_ilic 15k · 14 months ago
17 votes 5 answers17k views
Does LDL-C tell me anything about hepatic fat on mazdutide?

Stated plainly: LDL-C · mazdutide. I keep seeing this stated as a fact with no explanation attached, and unexplained facts make me suspicious. My background is…

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…

50 questions
mash
mash

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

51 questions
bloodwork
bloodwork

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

284 questions
asked by j_wierzbicki 45k · 14 months ago
27 votes 3 answers9.9k views
How many draws do I need before a lab trend means anything? My ALT went 24 to 41

Baseline ALT was 24 U/L. Fourteen weeks into semaglutide it came back at 41 U/L, still inside the lab's quoted range of 0 to 50 but a 71% rise from where I started. 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
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…

50 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 Dr_Signe_Baldursdottir 46k · 14 months ago
25 votes 5 answers28k views
What temperature does a domestic freezer actually hold?

This is a recurring problem with one particular shipping lane rather than a one-off. I would like help reading this properly rather than being told what conclusion to…

storage
storage

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

646 questions
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…

55 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 ahmed_zerouali 19k · 14 months ago
4 votes 5 answers9k views
Why did my creatinine move after two weeks on survodutide?

Setup, so nobody has to ask: creatinine · two weeks · survodutide. This is not behaving the way I expected and I want to understand the discrepancy before I act on…

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 deamidation_watch 43k · 14 months ago
34 votes 5 answers15k views
How many vial-days does a 20 mg vial give at 2 mg/mL on a weekly schedule?

Stated plainly: 20 mg · 2 mg/mL. I have worked this out and I would like someone to find the error, because I suspect there is one. My working so far, for the record,…

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
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
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
asked by hana_petrikova 19k · 14 months ago
29 votes 5 answers21k views
Has anyone independently verified a WXT a GLP-1 receptor agonist batch COA?

Setup, so nobody has to ask: WXT · a GLP-1 receptor agonist. This is asserted often enough that I assumed it was established, and then I went looking for the source.…

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
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
asked by sunniva_dahl 11k · 14 months ago
19 votes 5 answers15k views
Does splitting a 20 mg weekly dose of cagrilintide across two administrations change anything?

Stated plainly: 20 mg · cagrilintide. I keep seeing this stated as a fact with no explanation attached, and unexplained facts make me suspicious. My background is…

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 tri_gly_ala 48k · 14 months ago
19 votes 5 answers21k views
What does "identity confirmed" mean without a quantified content figure?

I am comparing a supplier certificate against an independent result on the same lot. I would like help reading this properly rather than being told what conclusion to…

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
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
mass-spec
mass-spec

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

38 questions
asked by dermot_kiely 14k · 14 months ago
4 votes5 answers13k views
How long does a Chengdu to the United States lane usually take with tracking?

Setup, so nobody has to ask: Chengdu · 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…

427 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…

186 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
asked by p_mkhize 41k · 14 months ago
31 votes 3 answers13k views
DEXA vs BIA vs BodPod: which of these is actually telling me the truth about lean mass?

I have measured myself three ways inside eight days and got three different stories, and I would like to understand which one to believe before I change anything…

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
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
hydration
hydration

Fluid intake when thirst and intake cues are both blunted: how much of the early scale drop is fluid, how dehydration confounds a renal panel, and…

14 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
asked by eoin_mcgarry 16k · 14 months ago
24 votes0 answers17k views
Is 96.4% a realistic purity ceiling for orforglipron given its chain length?

Details up front: 96.4% · orforglipron. 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…

788 questions
hplc
hplc

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

466 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…

83 questions
asked by assay_blank 39k · 14 months ago
8 votes 4 answers7.7k views
Is a 96.4% result from Janoshik comparable to 95.2% from Janoshik?

Details up front: 96.4% · Janoshik · 95.2% · Janoshik. I have used one of these for a while and I am considering switching, which requires a reason. What I care about…

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
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
reference-standard
reference-standard

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

179 questions
asked by Dr_Tomas_Kral 37k · 14 months ago
18 votes 5 answers21k views
What counter-ion should I expect on a KP orforglipron lot?

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

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
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
asked by tri_gly_ala 48k · 14 months ago
14 votes5 answers20k views
What did the placebo arm of SURMOUNT-OSA report for nausea?

Numbers first: SURMOUNT-OSA · nausea. This is presented as though it settles something, and I am not convinced it does. I have two documents that appear to disagree,…

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 assay_blank 39k · 14 months ago
15 votes 5 answers21k views
What does 96.8% purity on a C4 column actually tell me about a retatrutide vial?

Conditions: 96.8% · a C4 column · retatrutide. The figures are clear enough; the question is what they mean and what they do not. I can supply the numbers if the…

hplc
hplc

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

466 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 fresh_bac 13k · 14 months ago
34 votes 5 answers35k views
What happens to ecnoglutide after twelve weeks at minus 80 °C in solution?

Conditions: ecnoglutide · twelve weeks · minus 80 °C. This is one of those things that everyone repeats and nobody derives. This matters practically, not just…

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 teodora_ilic 15k · 14 months ago
23 votes 5 answers32k views
Would you accept 96.4% on oral semaglutide from BCH without a content assay?

Concretely: 96.4% · oral semaglutide · 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…

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 ruaidhri_o_shea 51k · 14 months ago
35 votes 5 answers44k views
What did the placebo arm of STEP 5 report for early satiety?

The specifics, since they change the answer: STEP 5 · early satiety. I have the document in front of me and I can read the numbers. What I cannot do is interpret…

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 pip_okonjo 11k · 14 months ago
28 votes0 answers18k views
Does fatigue at week three of mazdutide usually resolve without a dose change?

The particulars: fatigue · three · mazdutide. I have read the obvious sources and they disagree with each other, so I would rather ask people who have actually done…

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
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 pieter_maas 22k · 14 months ago
26 votes 5 answers11k views
What does SURPASS-3 tell me about early satiety at the 8 mg dose?

For reference: SURPASS-3 · early satiety · 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
asked by lukas_sedlacek 17k · 14 months ago
30 votes 5 answers18k views
Is a 97.1% result from PeptideMeter comparable to 99.4% from Medutest?

The particulars: 97.1% · PeptideMeter · 99.4% · Medutest. I am trying to choose between two options that are usually discussed as though only one exists. I am not…

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
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
reference-standard
reference-standard

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

179 questions
asked by charge_state_3 39k · 14 months ago
23 votes2 answers16k views
Would you accept 97.6% on a GLP-1 receptor agonist from HJ without a content assay?

Setup, so nobody has to ask: 97.6% · a GLP-1 receptor agonist · HJ. I am trying to build something sustainable rather than something thorough that I will abandon. 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…

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 juan_esquivel 14k · 14 months ago
7 votes0 answers6.2k views
Does dimerisation dominate for cagrilintide held at minus 20 °C?

Stated plainly: dimerisation · cagrilintide · minus 20 °C. The empirical answer seems settled. The explanation does not. If the honest answer is that nobody knows, I…

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 k_szabo 45k · 14 months ago