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1.4k questions · page 15 of 60

36 votes0 answers53k views
Does holding at 40 mg for twelve weeks before escalating reduce constipation?

Conditions: 40 mg · twelve weeks · constipation. I want to know whether this is a real physical effect or an artefact of how it is measured. What prompted the…

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
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
asked by linnea_wahlberg 14k · 2.4 years ago
36 votes5 answers53k views
How do I reconcile 98.4% from VendorInvestigate with 96.4% from the supplier?

Concretely: 98.4% · VendorInvestigate · 96.4%. I have two candidate explanations and no way to distinguish them. The same procedure has worked without incident…

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 mira_sundqvist 19k · 21 months ago
36 votes 5 answers53k views
What does the mechanism of dulaglutide predict that SUSTAIN-6 did not test?

Stated plainly: dulaglutide · SUSTAIN-6. The empirical answer seems settled. The explanation does not. If the honest answer is that nobody knows, I would rather hear…

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 greta_holzmann 15k · 20 months ago
36 votes5 answers52k views
Is minus 20 °C an acceptable storage condition for lyophilised tirzepatide?

Conditions: minus 20 °C · tirzepatide. The claim is plausible, which is exactly why I want to check it. I am able to read a paper if someone points me at one. Can…

storage
storage

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

646 questions
peptide-stability
peptide-stability

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

832 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 birk_nordahl 20k · 22 months ago
36 votes 5 answers51k views
Is ecnoglutide at 2 mg/mL stable enough for three weeks of multi-withdrawal use?

The case in front of me: ecnoglutide · 2 mg/mL · three weeks. I want to know whether there is evidence behind this or only repetition. I have checked the obvious…

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 area_percent 13k · 23 months ago
36 votes 5 answers51k views
How do I trace an MKM lot number back to a synthesis date?

I have both a purity figure and a content figure, which is why the discrepancy is visible. I want a method I can write down and repeat, not a rule of thumb. I would…

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
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 rosa_mendieta 13k · 19 months ago
36 votes 4 answers49k views
Does constipation at week six of survodutide usually resolve without a dose change?

What I am working with: constipation · six · survodutide. This is a procedural question rather than a theoretical one, and I would like the procedure rather than the…

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 fill_volume 13k · 23 months ago
36 votes 5 answers49k views
What did the placebo arm of ATTAIN-1 report for constipation?

What I have: ATTAIN-1 · constipation. 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
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 esther_vandeVelde 49k · 17 months ago
36 votes 5 answers49k views
Does fibrillation produce a resolvable peak on a wide-pore C18 column, or does it co-elute?

The specifics, since they change the answer: fibrillation · a wide-pore C18 column. I understand the observation; what I do not understand is the mechanism behind 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
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 zainab_mustafa 16k · 17 months ago
36 votes 5 answers48k views
How do I read a Karl Fischer water content result on a lyophilised vial?

The method section is present, which is unusual enough that I want to make use of it. I would like to know the limits of what can be inferred from this. What I am…

water-content
water-content

Residual moisture in a lyophilised solid, measured by Karl Fischer titration or loss on drying. It drives both the mass balance on a content assay…

39 questions
lyophilisation
lyophilisation

Freeze-drying: primary and secondary drying, collapse temperature, the role of bulking agents and cryoprotectants such as mannitol and trehalose,…

17 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 fresh_bac 13k · 2.3 years ago
36 votes 5 answers48k views
How many vials from an HJ lot should I send for an HPLC purity test?

Concretely: HJ · an HPLC purity test. 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 as…

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 cake_collapsed 13k · 2.1 years ago
36 votes 5 answers48k views
Has anyone independently verified a WXT mazdutide batch COA?

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

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 syringe_ninety 15k · 2.0 years ago
36 votes3 answers47k views
What does 96.4% purity on a C18 column actually tell me about a semaglutide vial?

What I am working with: 96.4% · a C18 column · semaglutide. I have read the primary source rather than the summary, which has left me with more questions. I…

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 plate_count_9k 95k · 2.2 years ago
36 votes 4 answers46k views
What happens to retatrutide after two weeks at 30 °C in solution?

Setup, so nobody has to ask: retatrutide · two weeks · 30 °C. The empirical answer seems settled. The explanation does not. If the honest answer is that nobody knows,…

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_Jonas_Halvorsen 41k · 23 months ago
36 votes 5 answers46k views
What does a 98.8% purity with a purity figure attached let me conclude?

Numbers first: 98.8% · purity figure. I can parse the result. I am less sure what it licenses me to conclude. I have deliberately not looked at anyone else’s…

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 colm_dunphy 16k · 15 months ago
36 votes5 answers45k views
Does the SURMOUNT-4 population resemble anyone asking about liraglutide here?

Conditions: SURMOUNT-4 · liraglutide. The figures are clear enough; the question is what they mean and what they do not. I can supply the numbers if the specifics…

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
asked by drawn_and_capped 15k · 23 months ago
36 votes5 answers45k views
Would you accept 95.2% on liraglutide from ERP without a content assay?

Concretely: 95.2% · liraglutide · ERP. 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 oona_kekkonen 16k · 23 months ago
36 votes5 answers45k views
How many units on a low-dead-space syringe is a 4 mg dose at 1 mg/mL?

Stated plainly: a low-dead-space syringe · 4 mg · 1 mg/mL. The units are where I keep going wrong, so please be explicit about them. I have sanity-checked the order…

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 tadhg_o_riordan 14k · 20 months ago
36 votes 5 answers42k views
Why does dimerisation accelerate at minus 80 °C rather than proceeding linearly?

What I am working with: dimerisation · minus 80 °C. The empirical answer seems settled. The explanation does not. If the honest answer is that nobody knows, I would…

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 stopper_core 50k · 2.3 years ago
36 votes 5 answers42k views
Is 10 mg/mL a sensible working concentration for liraglutide, or should I go lower?

The case in front of me: 10 mg/mL · liraglutide. These are treated as interchangeable and I do not think they are. If both are acceptable I would like to know that,…

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 ahmed_zerouali 19k · 2.2 years ago
36 votes5 answers42k views
Is retatrutide at 20 mg/mL stable enough for six weeks of multi-withdrawal use?

Stated plainly: retatrutide · 20 mg/mL · six weeks. This has the shape of a fact but I cannot find its origin. What I found instead were three secondary sources all…

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 esther_vandeVelde 49k · 2.0 years ago
36 votes 5 answers42k views
Does ApoB tell me anything about hepatic fat on retatrutide?

Numbers first: ApoB · retatrutide. I suspect the usual explanation for this is wrong, or at least incomplete. I am aware this may have a boring answer. I would still…

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 syringe_ninety 15k · 15 months ago
36 votes 3 answers38k views
How much protein in grams do I need at 81 kg on 1,100 kcal a day?

The case in front of me: 81 kg · 1,100 kcal. I want the working, not the result — I need to be able to redo it with different numbers. I care about the precision as…

protein-intake
protein-intake

Protein targets in grams per kilogram, per-meal distribution and the leucine threshold, and the evidence for a higher intake specifically during…

53 questions
nutrition
nutrition

Eating on a suppressed appetite: hitting nutritional targets inside a small energy budget, micronutrient risk, meal structure, and what the trial…

92 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
asked by anouk_desmet 18k · 2.2 years ago
36 votes 5 answers38k views
Is a TFC order from Tianjin likely to hold cold chain to the United Kingdom?

Concretely: TFC · Tianjin · the United Kingdom. I want to decide this in advance so that I am not deciding it under pressure later. Assume I will follow the plan I…

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
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
asked by ahmed_zerouali 19k · 21 months ago