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1.4k questions · page 58 of 60

12 votes5 answers12k views
What fraction of loss on cagrilintide is lean mass according to STEP 8?

Numbers first: cagrilintide · STEP 8. This is presented as though it settles something, and I am not convinced it does. I have two documents that appear to disagree,…

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 haze_check 17k · 9 months ago
21 votes 3 answers11k views
What is the arithmetic to convert 2.5 mg in 5 mL into units on a U-100 scale?

The case in front of me: 2.5 mg · 5 mL. I want the working, not the result — I need to be able to redo it with different numbers. I care about the precision as well…

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 lukas_sedlacek 17k · 6 months ago
5 votes 4 answers10k views
How many vial-days does a 50 mg vial give at 10 mg/mL on a weekly schedule?

The specifics, since they change the answer: 50 mg · 10 mg/mL. I would like the arithmetic checked rather than the conclusion asserted. I have deliberately not used…

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 swab_stopper 16k · 8 months ago
4 votes1 answer3.5k views
Is a 96.4% result from Janoshik comparable to 97.6% from Medutest?

Details up front: 96.4% · Janoshik · 97.6% · Medutest. I want to know what the trade-off actually is rather than which option is fashionable. I would rather have a…

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 nominal_ten 14k · 7 months ago
16 votes 2 answers6.1k views
Is a list of related substances from MKM sufficient basis to skip independent testing?

Concretely: list of related substances · MKM. I want to decide this in advance so that I am not deciding it under pressure later. Assume I will follow the plan I…

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
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 lucia_marchetti 18k · 9 months ago
24 votes5 answers14k views
Is 4 mg/mL a sensible working concentration for tirzepatide, or should I go lower?

The case in front of me: 4 mg/mL · tirzepatide. I would like the axes of comparison first and the recommendation second. I have tried the first option and it works;…

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 haze_check 17k · 9 months ago
26 votes 5 answers24k views
Would you accept 99.1% on orforglipron from QYB without a content assay?

Details up front: 99.1% · orforglipron · QYB. I would rather over-plan the first cycle and simplify later. I am prepared to do the work if someone can tell me which…

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 p_mkhize 41k · 8 months ago
8 votes5 answers5.3k views
How does semaglutide behave on a C4 column compared to semaglutide?

Concretely: semaglutide · a C4 column · semaglutide. I would like the axes of comparison first and the recommendation second. I have tried the first option and it…

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
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 rania_haddad 17k · 9 months ago
6 votes 5 answers7k views
How is a beyond-use date set for compounded survodutide in sterile water for injection?

Concretely: survodutide · sterile water for injection. I have done this once and I suspect I got away with it rather than got it right. For context: I keep records of…

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
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
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
asked by nkem_obiora 46k · 8 months ago
21 votes 5 answers12k views
Is GGPeps worth the price difference against Qingdao Saber Technology on measured results?

The particulars: GGPeps · Qingdao Saber Technology. The comparison I want does not seem to exist anywhere in a form I can evaluate. I have read the arguments for each…

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
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
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 ines_delacruz 16k · 9 months ago
10 votes 5 answers13k views
Is a warm arrival a reason to test before use, or to discard?

The vial was lyophilised at the time, which I understand may matter a great deal. I want to decide this in advance so that I am not deciding it under pressure later.…

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
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 rune_thoresen 14k · 9 months ago
14 votes 5 answers14k views
Does deamidation of semaglutide at 30 °C show up as a loss of content or of purity?

The specifics, since they change the answer: deamidation · semaglutide · 30 °C. I understand the observation; what I do not understand is the mechanism behind it. 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 bounty_hunter_q 18k · 8 months ago
28 votes 5 answers10k views
Is SWB worth the price difference against Shanghai ERP Biotechnology on measured results?

Numbers first: SWB · 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,…

351 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
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 bounty_hunter_q 18k · 9 months ago
23 votes 5 answers11k views
Does a formic acid mobile phase change the purity number I get for a GLP-1 receptor agonist on a wide-pore C18 column?

What I am working with: a formic acid mobile phase · a GLP-1 receptor agonist · a wide-pore C18 column. I keep seeing this stated as a fact with no explanation…

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
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 nominal_ten 14k · 9 months ago
1 vote 3 answers4k views
Does ferritin tell me anything about hepatic fat on oral semaglutide?

Concretely: ferritin · oral semaglutide. I want to know whether this is a real physical effect or an artefact of how it is measured. What prompted the question is an…

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 jo_vandeberg 19k · 9 months ago
25 votes 5 answers19k views
What is the arithmetic to convert 15 mg in 1 mL into units on a U-100 scale?

For reference: 15 mg · 1 mL. I would rather understand the derivation than memorise the outcome. Two people I asked gave two answers that differ by a factor of ten,…

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 fill_volume 13k · 9 months ago
11 votes 3 answers4.6k views
Would you accept 99.1% on semaglutide from WWB without a content assay?

For reference: 99.1% · semaglutide · WWB. I am at the decision point and I would rather think it through than improvise. I would rather spend money on measurement…

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 · 7 months ago
4 votes5 answers11k views
What counter-ion should I expect on a CPC liraglutide lot?

Concretely: CPC · liraglutide. I would like to know the limits of what can be inferred from this. What I am trying to avoid is over-reading a single result, which I…

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 orla_ferriter 47k · 9 months ago
29 votes5 answers9.3k views
What fraction of loss on tirzepatide is lean mass according to SUSTAIN-6?

For reference: tirzepatide · SUSTAIN-6. 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…

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 leonid_marchuk 15k · 8 months ago
22 votes 1 answer12k views
What is the arithmetic to convert 50 mg in 2 mL into units on a U-100 scale?

The particulars: 50 mg · 2 mL. I would like the arithmetic checked rather than the conclusion asserted. I have deliberately not used an online calculator because I…

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 day_seven_trough 11k · 7 months ago
16 votes0 answers5.2k views
Why would Janoshik report 98.2% where the supplier certificate says something higher?

Setup, so nobody has to ask: Janoshik · 98.2%. This is not behaving the way I expected and I want to understand the discrepancy before I act on it. 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
hplc
hplc

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

466 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 net_peptide 16k · 5 months ago
16 votes5 answers7.5k views
What would you ask ChinaPeptides (QYAOBIO) before a first order that they cannot fake?

I have kept every message, invoice and document, which I gather is the useful habit. I have read the obvious sources and they disagree with each other, so I would…

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 samir_bennani 13k · 10 months ago
5 votes 3 answers5.6k views
How many vials from a QST lot should I send for a sterility test?

Concretely: QST · a sterility test. 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…

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 Dr_Fatima_Belkacem 52k · 7 months ago
24 votes 5 answers16k views
Is tirzepatide at 6.67 mg/mL stable enough for four weeks of multi-withdrawal use?

The specifics, since they change the answer: tirzepatide · 6.67 mg/mL · four weeks. Somebody stated this to me confidently and I would like to check it before…

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 mira_sundqvist 19k · 9 months ago