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Top voted questions

Highest-scoring questions on the site.

1.4k questions · page 5 of 60

40 votes0 answers37k views
Is a 27G needle the right choice for drawing a GLP-1 receptor agonist at 4 mg/mL?

Stated plainly: a 27G needle · a GLP-1 receptor agonist · 4 mg/mL. I suspect the honest answer is that it depends, in which case I would like to know on what. Assume…

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 jonas_ekstrom 18k · 2.2 years ago
40 votes 5 answers36k views
Is LDL-C a better monitoring choice than triglycerides on semaglutide?

Stated plainly: LDL-C · triglycerides · semaglutide. Both of these get recommended confidently by different people, which suggests neither is obviously right. My…

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 juliette_farnese 12k · 2.0 years ago
40 votes5 answers36k views
What fraction of loss on liraglutide is lean mass according to SURPASS-3?

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

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 zeynep_arslan 20k · 18 months ago
40 votes2 answers35k views
What does a 98.2% purity with a lot-specific certificate attached let me conclude?

Numbers first: 98.2% · lot-specific certificate. This is presented as though it settles something, and I am not convinced it does. I have two documents that appear to…

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
hplc
hplc

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

466 questions
asked by birk_nordahl 20k · 19 months ago
40 votes3 answers35k views
What does 97.6% purity on a C18 column actually tell me about an ecnoglutide vial?

Stated plainly: 97.6% · a C18 column · ecnoglutide. I have read the primary source rather than the summary, which has left me with more questions. I understand 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 charge_state_3 39k · 21 months ago
40 votes5 answers34k views
What accept/reject threshold would you set for dulaglutide before seeing the result?

The method section is present, which is unusual enough that I want to make use of it. I would like to set this up properly once, rather than adjust it repeatedly. My…

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
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 olu_babatunde 14k · 2.1 years ago
40 votes5 answers34k views
What is the thermal exposure on a Suzhou to Germany lane in summer?

Conditions: Suzhou · Germany. The figures are clear enough; the question is what they mean and what they do not. I can supply the numbers if the specifics change the…

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
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 noor_alhassan 15k · 2.2 years ago
40 votes0 answers32k views
Why does aggregation accelerate at minus 80 °C rather than proceeding linearly?

Setup, so nobody has to ask: aggregation · minus 80 °C. I keep seeing this stated as a fact with no explanation attached, and unexplained facts make me suspicious. My…

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 eoin_mcgarry 16k · 23 months ago
40 votes5 answers31k views
Does aggregation dominate for a GLP-1 receptor agonist held at 4 °C?

Setup, so nobody has to ask: aggregation · a GLP-1 receptor agonist · 4 °C. I keep seeing this stated as a fact with no explanation attached, and unexplained facts…

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 ruaidhri_o_shea 51k · 23 months ago
40 votes 5 answers30k views
Does lipase tell me anything about hepatic fat on a GLP-1 receptor agonist?

Stated plainly: lipase · a GLP-1 receptor agonist. The empirical answer seems settled. The explanation does not. If the honest answer is that nobody knows, I would…

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 sinead_gaffney 14k · 2.0 years ago
40 votes 5 answers29k views
Is 97.1% a realistic purity ceiling for mazdutide given its chain length?

Setup, so nobody has to ask: 97.1% · mazdutide. I have worked this out and I would like someone to find the error, because I suspect there is one. My working so far,…

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 swirl_dont_shake 19k · 20 months ago
40 votes5 answers29k views
How do I write up a PeptideMeter result on liraglutide so it is useful to others?

Concretely: PeptideMeter · liraglutide. I have done this once and I suspect I got away with it rather than got it right. For context: I keep records of every batch,…

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
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 ruaidhri_o_shea 51k · 2.1 years ago
40 votes 5 answers27k views
How do I reconcile 95.2% from Medutest with 99.4% from the supplier?

What I am working with: 95.2% · Medutest · 99.4%. 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
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
asked by bridget_nyathi 16k · 22 months ago
40 votes5 answers27k views
Is 20 mg in 1 mL of bacteriostatic water a sensible presentation for liraglutide?

What I am working with: 20 mg · 1 mL · bacteriostatic water · liraglutide. I would like to set this up properly once, rather than adjust it repeatedly. My budget is…

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 Dr_Signe_Baldursdottir 46k · 22 months ago
40 votes4 answers26k views
Can I reconstitute semaglutide at 20 mg/mL and still measure a small dose accurately?

Concretely: semaglutide · 20 mg/mL. 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, so…

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
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
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 bridget_nyathi 16k · 2.0 years ago
40 votes5 answers26k views
Is a titration interval of three weeks better supported than four weeks for mazdutide?

What I am working with: three weeks · mazdutide. This is asserted often enough that I assumed it was established, and then I went looking for the source. I have…

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
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…

88 questions
clinical-trials
clinical-trials

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

913 questions
asked by ten_mg_vial 16k · 2.1 years ago
40 votes 5 answers26k views
How many vial-days does a 10 mg vial give at 3.33 mg/mL on a weekly schedule?

The case in front of me: 10 mg · 3.33 mg/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…

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 lane_transit 42k · 23 months ago
40 votes 5 answers26k views
Does TSH tell me anything about hepatic fat on dulaglutide?

Details up front: TSH · dulaglutide. 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 confident…

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 sample_id 17k · 19 months ago
40 votes 5 answers23k views
Would you re-test retatrutide after two weeks at minus 20 °C, or accept the original certificate?

What I am working with: retatrutide · two weeks · minus 20 °C. I am trying to build something sustainable rather than something thorough that I will abandon. I have…

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
peptide-stability
peptide-stability

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

832 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 lukas_sedlacek 17k · 2.1 years ago
40 votes 4 answers23k views
How do PeptideMeter and VendorInvestigate compare on the same retatrutide batch?

Conditions: PeptideMeter · VendorInvestigate · retatrutide. I would like the axes of comparison first and the recommendation second. I have tried the first option and…

janoshik
janoshik

Janoshik Analytical, an independent third-party testing laboratory widely used by this community for HPLC purity, identity and quantified content…

34 questions
medutest
medutest

Medutest, one of four independent testing and verification services referenced throughout this site. Use this tag for its methods, its report…

14 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 retest_please 13k · 20 months ago
40 votes 5 answers23k views
Is constipation on cagrilintide dose-dependent or dose-rate dependent?

What I am working with: constipation · cagrilintide. I keep seeing this stated as a fact with no explanation attached, and unexplained facts make me suspicious. My…

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
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
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
asked by anja_hellstrom 13k · 20 months ago
40 votes 5 answers23k views
How comparable are semaglutide and liraglutide on the evidence available?

The case in front of me: semaglutide · liraglutide. These are treated as interchangeable and I do not think they are. If both are acceptable I would like to know…

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 siobhan_deasy 16k · 2.3 years ago
40 votes 5 answers22k views
Is resistance training twelve times a week enough at 1,400 kcal a day?

The case in front of me: twelve · 1,400 kcal. I want to decide this in advance so that I am not deciding it under pressure later. Assume I will follow the plan I…

resistance-training
resistance-training

Loaded training as the primary intervention for retaining lean mass in a deficit: minimum effective dose, frequency versus volume, and why…

40 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
exercise
exercise

Training during substantial weight loss: cardiorespiratory work, step count, low energy availability, and how exercise interacts with the appetite…

36 questions
sarcopenia
sarcopenia

Clinically meaningful loss of muscle mass and function, particularly in older adults on treatment. Distinguishing a proportional reduction from a…

14 questions
weight-regain
weight-regain

Regain after stopping or reducing: the trajectory reported in the withdrawal extensions, how much is fluid, and what the maintenance arms tell us…

14 questions
asked by nadia_kowalczyk 14k · 2.2 years ago
40 votes5 answers21k views
Is a lot-specific certificate from SGN sufficient basis to skip independent testing?

Stated plainly: lot-specific certificate · SGN. I am trying to build something sustainable rather than something thorough that I will abandon. I have already decided…

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 fresh_bac 13k · 23 months ago