system_suitability

TL3 Analytical chemist · Cork, IE

If the suitability injections failed, the run did not happen. That is most of my contribution here.

Joined 6 February 2025 · last posted 3d · groups: analytical-chemists

125 posts, newest first. Showing up to 150.

Alcohol: what is documented and what is folklore Replied, post #133 · Practice › Interactions · 25 Jul 2026 · 28 likes Post #131 is right about the mechanism and I think understates the practical bit. Agreed on alcohol, with one qualification that I think matters. The reasoning holds…
Second pass at: What a 2 ppm match establishes, and what it does not Replied, post #48 · Analytics › Mass spectrometry · 23 Jul 2026 · 0 likes I think the 2 ppm match question is answerable and has not been answered, which is a more optimistic position than most of this thread.
A pooled estimate that changed when one trial was added Replied, post #27 · Evidence › Meta-analyses · 22 Jul 2026 · 0 likes The number of included studies should be visible in any citation of a pooled figure. "A meta-analysis showed" without it is a claim about nothing in particular.
Revisiting: The best-written scientific paper you have read Replied, post #107 · Lounge › Off topic · 21 Jul 2026 · 14 likes Loosely related and not worth its own topic: the vocabulary here has leaked into how I read everything. I now notice when a press release gives a relative figure and no…
[2026 update] Detection wavelength and why 214 nm and 280 nm disagree Replied, post #57 · Analytics › HPLC & UHPLC · 21 Jul 2026 · 0 likes The question underneath Detection wavelength is usually "how would I tell?" rather than "what is true?", and that one has a method attached to it. Write down what you…
What a certificate commits its issuer to Replied, post #36 · Analytics › COA interpretation · 15 Jul 2026 · 31 likes Coming back to post #33, because the follow-up matters more than the original answer. A chromatogram supplied as a small image is legible for peak shape and not for…
Reading a home test result without over-claiming Replied, post #119 · Analytics › Home & field testing · 14 Jul 2026 · 0 likes Colorimetric tests: colour intensity correlates with concentration, but the relationship is non-linear at extremes and the correlation depends on the exact conditions…
A structured critique template this community uses — a second dataset Replied, post #35 · Evidence › Study critique · 11 Jul 2026 · 3 likes Agreed, and I will stop repeating the version of this I had been repeating.
The anatomy of a question that gets answered within an hour Replied, post #108 · Start Here › How to Ask · 11 Jul 2026 · 11 likes Nothing to add, except that this is the answer I would give if asked.
Revisiting: Why the absence of controlled human data on BPC-157 matters more than people… Replied, post #24 · Compounds › Repair & healing peptides · 11 Jul 2026 · 1 like Dose-response is unstudied in humans for essentially everything in this family, which means the confident numbers in circulation came from somewhere other than a trial.
What to bring: records that a clinician can actually use — a second dataset Replied, post #9 · Clinical › Prescriber conversations · 5 Jul 2026 · 9 likes Post #5 put the caveat in the right place and I want to underline it. Bringing a record of symptoms with dates and severities makes an assessment materially easier and…
Alcohol: what is documented and what is folklore Replied, post #93 · Practice › Interactions · 4 Jul 2026 · 23 likes Post #89 describes the usual case. This is about the unusual one. Before the thread moves on from alcohol — what is the sample size behind the claim? I am not being…
Revisiting: Journal club: SURMOUNT-OSA and a hard endpoint in a soft field Replied, post #80 · Evidence › Journal club · 4 Jul 2026 · 18 likes SURMOUNT-OSA was covered in the wiki last year and the page has a review date on it, which is a better starting point than my memory of a thread.
Purity assay versus content assay: two different numbers Replied, post #11 · Analytics › COA interpretation · 3 Jul 2026 · 28 likes Where two documents for the same lot disagree, the useful question is which was measured and which was transcribed. Most such disagreements are the second. Noting that…
What I would want from a home test that does not exist yet Replied, post #22 · Analytics › Home & field testing · 28 Jun 2026 · 0 likes Following this. I have the same question and no better information than the first post.
Coming back to: Where the four-week escalation interval comes from, and what it is not Replied, post #4 · Practice › Dosing & titration · 28 Jun 2026 · 23 likes Post #2 put the caveat in the right place and I want to underline it. A definition problem is doing most of the work in this four-week escalation interval discussion.…
Reading a home test result without over-claiming Replied, post #90 · Analytics › Home & field testing · 23 Jun 2026 · 0 likes False positives and false negatives: no test has 100% sensitivity and 100% specificity. A negative result does not guarantee absence; a positive result does not…
Journal club: LEADER as the historical anchor Replied, post #89 · Evidence › Journal club · 14 Jun 2026 · 3 likes I had written a reply contradicting post #88 and deleted it. Here is what survived. Reading order that works for these sessions: registry entry, methods, baseline…
Ultrasound and skinfolds: operator dependence in practice Replied, post #16 · Outcomes › Body composition · 14 Jun 2026 · 0 likes Before the thread moves on from ultrasound and skinfolds — what is the sample size behind the claim? I am not being difficult; I have seen the same figure quoted from…
Does dual agonism explain the effect size, or is it dose? Replied, post #34 · Compounds › Tirzepatide · 14 Jun 2026 · 1 like Understood. Thank you for being specific about the limits of it.
Racemisation and why it is invisible to a mass measurement Replied, post #47 · Analytics › Impurities & related substances · 11 Jun 2026 · 5 likes Racemisation sits at the boundary between what this community can usefully discuss and what it cannot, and I think it falls on the discussable side, narrowly.
Coming back to: A structured critique template this community uses Replied, post #30 · Evidence › Study critique · 10 Jun 2026 · 4 likes Generalisability: do the inclusion/exclusion criteria narrow the population so much that results do not apply to real people asking about it? This is a fair criticism…
[2026 update] Temperature indicator cards: worth asking for? Started this topic · Sourcing › Logistics · 30 May 2026 · 0 likes Temperature indicator cards: worth asking for? I have a specific reason for asking rather than idle curiosity, and the context is below. Asking about Temperature…
Why we ask for units every single time, with three examples of what goes wrong Replied, post #7 · Start Here › How to Ask · 29 May 2026 · 12 likes The arithmetic in post #4 is right; the assumption feeding it is the part to check. A photograph of a vial is rarely useful and a photograph of a document usually is.…
Why fasting instructions for oral semaglutide are not optional advice Replied, post #11 · Compounds › Oral incretins · 22 May 2026 · 11 likes The thirty-minute wait before eating is not conservatism. Food in the stomach materially reduces absorption of the oral product, and the instruction exists because the…
Dizziness on standing and the electrolyte explanation — does this still hold? Replied, post #82 · Practice › Side effects · 18 May 2026 · 10 likes The relationship between symptom burden and outcome is not what people assume. Feeling worse is not evidence of a larger effect and feeling nothing is not evidence of…
Hair shedding at month three: mechanism and time course — the long version Replied, post #7 · Practice › Side effects · 5 May 2026 · 3 likes Agreed, and I will stop repeating the version of this I had been repeating.
Research-use-only status: what it means legally and practically Replied, post #37 · Compounds › Other compounds · 4 May 2026 · 22 likes Understood, and I withdraw the assumption I opened with.
Coming back to: Washout: how long is long enough, and for what purpose Replied, post #103 · Pharmacology › Pharmacokinetics · 12 Apr 2026 · 3 likes My position on Washout is current rather than settled. I have revised it once already and I expect to again, so treat it accordingly.
[2026 update] Composite endpoints and the component doing the work Replied, post #62 · Evidence › Trials · 9 Apr 2026 · 0 likes Post #58 describes the usual case. This is about the unusual one. I would rather this thread reach "we do not know" about Composite endpoints than reach a confident…
Transporting a vial for a weekend away — a second dataset Replied, post #22 · Practice › Storage & stability · 6 Apr 2026 · 0 likes The strongest argument against my own position on Transporting a vial, stated as well as I can state it, since nobody else has yet.
Revisiting: Drawing up with one needle and injecting with another Replied, post #33 · Practice › Administration · 3 Apr 2026 · 17 likes Adding the measurement that post #32 says would settle it. Needle length matters less than angle for subcutaneous delivery in most people. A short needle at ninety…
Reused chromatograms across lots: how to spot it Replied, post #31 · Analytics › COA interpretation · 3 Apr 2026 · 2 likes Post #29 describes the usual case. This is about the unusual one. What would change my mind on reused chromatograms across lots is a second dataset collected by someone…
Reading an interaction checker output critically Replied, post #139 · Practice › Interactions · 7 Mar 2026 · 7 likes Vitamins: most vitamins have no significant interaction. Fat-soluble vitamins (A, D, E, K) might be affected by the slowing of fat absorption during weight loss, but…
Revisiting: Language barriers in accessing a prescription abroad Replied, post #144 · Access › International · 4 Mar 2026 · 7 likes Language barriers: if you need to communicate with a supplier, clinician, or regulator in a language not your first language, misunderstanding is possible. Clarify when…
Type 2 diabetes and the largest part of the evidence base Replied, post #16 · Clinical › Comorbidities · 28 Feb 2026 · 16 likes This follows post #13 rather than contradicting it. Registry and observational data covering excluded populations is accumulating and is weaker evidence than a trial…
A widely repeated interaction claim that turns out to be unsupported Replied, post #26 · Practice › Interactions · 8 Feb 2026 · 0 likes Clear enough that I do not think I have a follow-up, which is unusual.
Seven-day rolling means and why weekly readings mislead — one year on Replied, post #7 · Outcomes › Progress reports · 5 Feb 2026 · 18 likes Post #6 answers the question as asked. The question underneath it is different. Self-reported intake is optimistic in a consistent direction, and saying so in your own…
Warfarin and altered intake: the monitoring argument — the long version Replied, post #103 · Practice › Interactions · 2 Feb 2026 · 8 likes I read post #101 twice before replying, because I had assumed the opposite. Anticoagulants: no direct interaction with the compounds in this class. Weight loss and body…
Follow-up: A supplier that answers analytical questions with restated claims Replied, post #67 · Sourcing › Red flags · 28 Jan 2026 · 30 likes Nothing here should be read as an accusation against a named company, and the guidelines exist so that reports remain reports. I would not lead a decision with this,…
About the Pens & autoinjectors category Replied, post #4 · Devices › Pens & autoinjectors · 27 Jan 2026 · 0 likes Suggestion for the wiki post above: it would be worth linking the two or three most-referenced topics in this category directly, since new members reliably ask for…
Warfarin and altered intake: the monitoring argument — the long version Replied, post #89 · Practice › Interactions · 14 Jan 2026 · 1 like The reason Warfarin and altered intake keeps being re-asked is that the answer is conditional and people quote it without the condition. It is not that the answer is…
What "verified" means on our vendor pages, stated narrowly Replied, post #21 · Sourcing › Vendor reports · 30 Dec 2025 · 18 likes Photograph the vial and the label before opening. It costs ten seconds and it is what turns a report into something checkable.
How Janoshik, Medutest, PeptideMeter and VendorInvestigate differ — a second dataset Replied, post #16 · Sourcing › Independent verification · 29 Dec 2025 · 4 likes Worth separating two things that post #13 runs together. Careful with the language on Janoshik. "Not detected" and "not present" are different findings and the first is…
Revisiting: Language barriers in accessing a prescription abroad Replied, post #23 · Access › International · 23 Dec 2025 · 1 like Both are useful and they are different contributions. A first-hand account and a citation answer different halves of the question. That is what I would do. It may not…
Follow-up: A supplier that answers analytical questions with restated claims Replied, post #23 · Sourcing › Red flags · 22 Dec 2025 · 17 likes Worth separating two things that post #19 runs together. I would rather this thread reach "we do not know" about supplier than reach a confident answer that nobody can…
Older adults, sarcopenia risk, and the trade-off nobody quantifies Replied, post #53 · Clinical › Special populations · 16 Dec 2025 · 12 likes Filing a mild objection to the consensus on older adults. Mild because I might be wrong; an objection because nobody has addressed the case that does not fit.
Tracking a preprint to publication: a worked example Replied, post #76 · Evidence › Preprints · 7 Dec 2025 · 3 likes Peer review as a filter: published papers have survived a review process that rejects many submissions. Preprints have not. Neither guarantees correctness, but…
Cost per delivered dose, which is the number that matters Replied, post #28 · Access › Pricing · 7 Dec 2025 · 0 likes Wastage from a concentration choice that leaves an unusable remainder is a real cost and is invisible in a per-milligram figure. I would rather be precise about what I…
Whether protein timing matters at a large deficit Replied, post #6 · Nutrition & Training › Protein & intake · 2 Dec 2025 · 14 likes Where intake has fallen a long way, protein is usually the first thing to fall because it is the least appealing macronutrient when appetite is reduced.
Second pass at: The mass-error checker and its intended scope Replied, post #75 · Data & Tools › Calculators · 28 Nov 2025 · 9 likes I had written a reply contradicting post #71 and deleted it. Here is what survived. Unit-conversion tools are only as good as the assumption they make about the…
Robustness: the parameters worth deliberately varying Replied, post #21 · Analytics › Method validation · 25 Nov 2025 · 10 likes I had written a reply contradicting post #17 and deleted it. Here is what survived. What I would want before treating robustness as settled: the method, the sample, and…
Lurking for two months before posting: was that the right call? Replied, post #57 · Start Here › Welcome · 20 Nov 2025 · 0 likes Understood. Thank you for being specific about the limits of it.
Half-life, steady state, and accumulation worked through — a second dataset Replied, post #19 · Pharmacology › Pharmacokinetics · 14 Nov 2025 · 1 like Adding the measurement that post #16 says would settle it. Washout after stopping takes roughly the same four to five half-lives as reaching steady state. A month after…
Reading a supplier's product description as a marketing document Replied, post #95 · Compounds › Other compounds · 8 Nov 2025 · 3 likes Thymosin alpha-1 has a regulatory history in several jurisdictions and a real clinical literature, which puts it in a different evidential category from most of its…
Run-in periods and the population they select Replied, post #19 · Evidence › Trials · 7 Nov 2025 · 9 likes Where I part company with post #15, and it is a narrow parting. Entry criteria, run-in periods and the self-selection of people willing to enter a multi-year trial all…
Alcohol: what is documented and what is folklore — the long version Replied, post #3 · Practice › Interactions · 6 Nov 2025 · 30 likes Alcohol: no absolute contraindication but it raises gastrointestinal irritation risk and this drug class already does that. The conservative position during titration…
The anatomy of a question that gets answered within an hour — the long version Replied, post #61 · Start Here › How to Ask · 5 Nov 2025 · 0 likes Asking a follow-up: new topic or reply in the old one? If the answer depends on the previous post, reply. If it is a question that makes sense without the previous…
Where to report an adverse event officially, by region — a second dataset Replied, post #83 · Safety › Adverse events · 2 Nov 2025 · 29 likes The published trial rates come from supervised populations on defined schedules and are not comparable to rates derived from who chooses to post.
What a purity-only report leaves out Replied, post #70 · Sourcing › Independent verification · 2 Nov 2025 · 11 likes On purity-only the community has more anecdote than the confidence in this thread implies, and I include my own contribution in that.
Follow-up: What a seizure notice actually says Replied, post #13 · Sourcing › Logistics · 24 Oct 2025 · 5 likes Reshipment after seizure: if a parcel is seized, some suppliers will reship; others will not. That is a supplier choice and should be understood before ordering in a…
Journal club: indirect comparison between two programmes, defended and attacked — one… Replied, post #47 · Evidence › Journal club · 21 Oct 2025 · 1 like Two questions I would want answered before drawing anything from the indirect comparison data above: how were the cases selected, and what happened to the ones that…
A preprint whose numbers changed substantially at publication — what changed since Replied, post #5 · Evidence › Preprints · 18 Oct 2025 · 2 likes If you cite a preprint in a maintained document here, the convention is to label it in the sentence and to note the check date. The document review will catch the update.
Revisiting: German, French and Dutch differences, compared Replied, post #86 · Regional › European Union · 13 Oct 2025 · 32 likes Date every claim. Positions in this subcategory have moved repeatedly and the archive keeps posts permanently. The variance between people here is larger than the…
An orphaned page with no inbound links — the long version Replied, post #19 · Meta › Wiki maintenance · 11 Oct 2025 · 7 likes Understood. Thank you for being specific about the limits of it.
Coming back to: Resolution and tailing factor: real acceptance criteria Replied, post #91 · Analytics › HPLC & UHPLC · 2 Oct 2025 · 0 likes On post #90 — agreed on the reasoning, with one qualification. Particle size and column dimensions determine what resolution is achievable at all. A 5 micrometre 250…
What a regulator's shortage notice actually authorises — what changed since Replied, post #9 · Sourcing › Regulatory · 26 Sep 2025 · 0 likes On post #7 — agreed on the reasoning, with one qualification. Generic or biosimilar entry depends on patent and exclusivity positions that are jurisdiction-specific and…
Power cut for eleven hours: how I assessed it afterwards Replied, post #69 · Practice › Storage & stability · 24 Sep 2025 · 3 likes On power cut for eleven hours: the maintained page in the documentation commons covers the general case with citations and a review date, which is more reliable than…
Documentation that appears only after payment Replied, post #30 · Sourcing › Red flags · 21 Sep 2025 · 8 likes Safety documentation absent: a supplier that cannot provide information about sterility testing, endotoxin testing, or safety documentation when asked is raising flags.
A checklist for reading a certificate in under two minutes — does this still hold? Replied, post #47 · Analytics › COA interpretation · 21 Sep 2025 · 12 likes Building on post #44 rather than restating it. The distinction between release testing and characterisation is one industrial documents make and retail ones usually do…
Documentation that materially improves an appeal's chances Replied, post #5 · Access › Insurance & coverage · 19 Sep 2025 · 15 likes The confident answers on documentation and the well-sourced answers are not the same answers, which is the most useful thing I have learned reading this category.
Coming back to: Resolution and tailing factor: real acceptance criteria Replied, post #74 · Analytics › HPLC & UHPLC · 18 Sep 2025 · 3 likes Adding thanks rather than a view. I do not have a view worth the space.
Aggregated purity results across four services, with caveats — a second dataset Replied, post #111 · Data & Tools › Datasets · 10 Sep 2025 · 24 likes Answering the question post #107 raises rather than the one it answers. Version the file rather than editing in place. A dataset that changes silently under an analysis…
Specification in the result column: why that is a meaningful error Replied, post #42 · Analytics › COA interpretation · 10 Sep 2025 · 29 likes Coming back to post #38, because the follow-up matters more than the original answer. The fields that make one usable: lot identifier matching the container, test date,…
Temperature loggers worth the money — the long version Replied, post #29 · Devices › Cold chain · 23 Aug 2025 · 12 likes The arithmetic in post #28 is right; the assumption feeding it is the part to check. Customs holds are the most common cause of an unexpectedly long transit, and they…
Older adults, sarcopenia risk, and the trade-off nobody quantifies — the long version Replied, post #10 · Clinical › Special populations · 16 Aug 2025 · 20 likes Adding the measurement that post #7 says would settle it. Distinguishing three things in the Older adults discussion that keep getting used interchangeably: the…
An ABAB design with a data table and honest limitations Started this topic · Research Methods › N-of-1 designs · 29 Jul 2025 · 12 likes An ABAB design with a data table and honest limitations Writing it up because I had to work it out twice and would rather nobody else did. An honest uncertainty about…
A ten-fold dose error caught before injection Replied, post #67 · Devices › Syringes & needles · 18 Jul 2025 · 6 likes Insulin syringe graduations: U-100 syringes are marked in units where 100 units = 1 mL. Always confirm your syringe is U-100. Confusion between insulin units and…
Asking about a compound your prescriber has not heard of Replied, post #98 · Clinical › Prescriber conversations · 18 Jul 2025 · 21 likes If the answer is no, asking for the reason is reasonable and the reason is usually specific. It is also what makes an appeal possible where one exists. This has been…
About the Trials category Replied, post #3 · Evidence › Trials · 13 Jul 2025 · 5 likes As a member rather than staff: the most useful thing I did when I started reading this category was to work through the tag pages rather than the topic list. The topic…
Random versus fixed effects: choosing rather than defaulting Replied, post #21 · Evidence › Meta-analyses · 9 Jul 2025 · 20 likes Worth separating two things that post #19 runs together. An observation about random versus fixed effects that I cannot explain and am posting anyway, on the principle…
Why quantitation is the hard part, not detection Replied, post #15 · Analytics › Home & field testing · 6 Jul 2025 · 26 likes Building on post #14 rather than restating it. The reason quantitation is hard to answer is that the obvious measurement and the relevant quantity are not the same…
What this community means by "a source", in practical terms Replied, post #25 · Start Here › Welcome · 5 Jul 2025 · 17 likes The Lounge is a real category rather than a dumping ground. The sourcing rule still applies there, which surprises people, but the register is looser and nobody minds a…
Biological variation versus analytical imprecision Replied, post #2 · Clinical › Bloodwork · 30 Jun 2025 · 9 likes Analytical imprecision: any measurement has an error margin. A small difference in consecutive tests is usually measurement noise, not a real change. Knowing the…
The CagriSema phase 2 paper and what a fixed combination buys — the long version Replied, post #142 · Compounds › Cagrilintide & amylin analogues · 19 Jun 2025 · 4 likes I had written a reply contradicting post #138 and deleted it. Here is what survived. I have three months of notes on CagriSema phase 2 paper and the honest summary is…
Follow-up: Tracking intake honestly when appetite is absent Replied, post #72 · Nutrition & Training › Protein & intake · 12 Jun 2025 · 30 likes Tracking intake for a week rather than permanently is usually enough to find out whether there is a problem. Permanent tracking has its own costs.
Reading a rodent study on a secretagogue without over-extrapolating Replied, post #14 · Compounds › Secretagogues & GH axis · 11 Jun 2025 · 0 likes The reason reading a rodent study is hard to answer is that the obvious measurement and the relevant quantity are not the same thing, and substituting one for the other…
The CagriSema phase 2 paper and what a fixed combination buys — the long version Replied, post #7 · Compounds › Cagrilintide & amylin analogues · 3 Jun 2025 · 2 likes I had written a reply contradicting post #5 and deleted it. Here is what survived. Worth distinguishing the combination product from the two components bought…
Specification in the result column: why that is a meaningful error Replied, post #5 · Analytics › COA interpretation · 2 Jun 2025 · 26 likes A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is enough to sanity-check an integration and not enough to…
Coming back to: Over-dilution: when your dose falls below one readable graduation Replied, post #17 · Practice › Reconstitution · 1 Jun 2025 · 5 likes Picking up post #14: that is the part I would want checked first. Choose the concentration so that a typical dose lands on a graduation you can actually read. A dose…
A comparison of home results against a laboratory result on the same vial Replied, post #2 · Analytics › Home & field testing · 30 May 2025 · 4 likes Answering the question the opening post raises rather than the one it answers. Sample handling matters: if a sample is contaminated or degraded before testing, the test…
Subcutaneous absorption kinetics and site differences Replied, post #5 · Pharmacology › Pharmacokinetics · 27 May 2025 · 0 likes Post #4 is the version of this I will quote in future. One addition. SNAC (the oral bioavailability enhancer): sodium N-(8-[2-hydroxybenzoyl]amino) caprylate…
Journal club: the CagriSema phase 2 combination paper — a second dataset Replied, post #16 · Evidence › Journal club · 26 May 2025 · 2 likes Everything in post #14 holds. The case it does not cover is the one I have. I disagree with the framing of CagriSema phase 2 combination paper above, and I think it is…
Second pass at: Triple agonism: additive, synergistic, or neither? Replied, post #47 · Compounds › Retatrutide · 7 May 2025 · 4 likes The arithmetic in post #45 is right; the assumption feeding it is the part to check. On Triple agonism the community has more anecdote than the confidence in this…
An orphaned page with no inbound links Replied, post #37 · Meta › Wiki maintenance · 6 May 2025 · 0 likes Fair — and in this case it can, because it contains a number. So: one owner, two links. If the premise is wrong, everything after it is decoration.
Publishing an inconvenient result: a case study Replied, post #10 · Sourcing › Independent verification · 20 Apr 2025 · 0 likes Useful. I have added it to my own notes with the date on it.
Hello from a laboratory that does not do peptides Replied, post #3 · Lounge › Introductions · 20 Apr 2025 · 0 likes What to include: your name or handle, how you found the community, what brings you here, maybe something about yourself that seems relevant (clinician, researcher,…
Tirzepatide in type 2 diabetes: the SURPASS programme, summarised honestly Replied, post #63 · Compounds › Tirzepatide · 17 Apr 2025 · 1 like Categorical response thresholds — the proportion reaching ten, fifteen or twenty per cent reduction — are more persuasive and less informative than the mean. They…
Retatrutide dose escalation in the published trials Replied, post #142 · Compounds › Retatrutide · 16 Apr 2025 · 0 likes Nausea and vomiting were dose-related in the phase 2 work, as they are throughout this class. What is not established is whether the tolerability profile differs from…
Carryover and the ghost peak from last week's standard Replied, post #6 · Analytics › HPLC & UHPLC · 1 Apr 2025 · 17 likes I have no financial interest in anything named in this thread and I want to say so before I comment on carryover, because it is the sort of subject where it matters.
Second pass at: Gauge and length selection for subcutaneous injection Replied, post #47 · Devices › Syringes & needles · 28 Mar 2025 · 17 likes Source for the Gauge and length selection figure, since it was asked for. It is in the discussion rather than the abstract, which is why the version circulating is…
Certificates issued by the seller versus by a laboratory Replied, post #18 · Analytics › COA interpretation · 25 Mar 2025 · 0 likes Adding the measurement that post #17 says would settle it. A chromatogram supplied as a small image is legible for peak shape and not for baseline detail. That is…
Second pass at: A history of disordered eating: proceeding carefully Replied, post #17 · Wellbeing › Mental health · 12 Mar 2025 · 9 likes My experience of history of disordered eating contradicts the reply above. I am posting it as a data point rather than as a refutation, because one person's experience…
Charge states for a 4 kDa peptide, worked through Replied, post #55 · Analytics › Mass spectrometry · 9 Mar 2025 · 1 like Counterpoint on charge states, offered without confidence: the same observation is consistent with a much duller explanation, and nobody has ruled the dull one out.
What the published dose-response for semaglutide actually looks like above 2.4 mg — a… Replied, post #73 · Compounds › Semaglutide · 22 Feb 2025 · 9 likes I read post #69 twice before replying, because I had assumed the opposite. Solutions of semaglutide can look faintly opalescent without anything being wrong. Visible…
Oxidation and deamidation mass shifts, tabulated Replied, post #37 · Analytics › Mass spectrometry · 16 Jan 2025 · 0 likes I had written a reply contradicting post #35 and deleted it. Here is what survived. Resolution: "high resolution" commonly means I have deliberately not rounded that,…
Escalating every six weeks instead of four: what I observed over eight months Replied, post #12 · Practice › Dosing & titration · 9 Jan 2025 · 0 likes On escalating every six weeks instead: the maintained page in the documentation commons covers the general case with citations and a review date, which is more reliable…
Follow-up: Dead volume across syringe and needle combinations Replied, post #92 · Devices › Syringes & needles · 1 Jan 2025 · 31 likes I read post #90 twice before replying, because I had assumed the opposite. Syringe barrel size: common sizes are 0.3 mL, 0.5 mL, and 1.0 mL. Smaller barrels are more…
Oral semaglutide bioavailability and its variability between people — a second dataset Replied, post #48 · Compounds › Oral incretins · 26 Dec 2024 · 28 likes Post #45 is right about the mechanism and I think understates the practical bit. A definition problem is doing most of the work in this Oral semaglutide bioavailability…
Molecular mass of semaglutide and why the figure differs between sources — does this… Replied, post #90 · Compounds › Semaglutide · 24 Dec 2024 · 0 likes On identity confirmation: a mass close to 4113.6 Da on the intact molecule is consistent with semaglutide and is also consistent with several closely related species.…
Coming back to: Cost per delivered dose, which is the number that matters Replied, post #6 · Access › Pricing · 22 Dec 2024 · 0 likes Compute cost per delivered dose at your dose if you want a number you can act on. That requires knowing your dose, vial volume, and whether you are using a vial or a pen.
Why mass spectrometry cannot tell you about an epimer Replied, post #5 · Analytics › Mass spectrometry · 16 Dec 2024 · 0 likes An acylated peptide has a mass that reflects the modification, so comparing against the mass of the unmodified backbone gives a mismatch that is not an error.
[2026 update] How to read a forest plot, properly, from scratch Replied, post #37 · Evidence › Trials · 15 Dec 2024 · 11 likes A treatment-policy estimand asks what happens to people assigned to a strategy, including those who abandon it. A hypothetical estimand asks what would have happened…
Follow-up: Tirzepatide's shorter half-life and its one practical consequence Replied, post #84 · Compounds › Tirzepatide · 12 Dec 2024 · 32 likes Agreed on all of that, and I have nothing to add to it.
Follow-up: Dead volume across syringe and needle combinations Replied, post #71 · Devices › Syringes & needles · 25 Nov 2024 · 0 likes Adding the measurement that post #70 says would settle it. Whatever the answer on Dead volume across syringe turns out to be, the method for getting there is the same:…
Amylin analogue mechanism: satiety signalling separate from GLP-1 Replied, post #25 · Compounds › Cagrilintide & amylin analogues · 21 Nov 2024 · 5 likes I had written a reply contradicting post #23 and deleted it. Here is what survived. Reconstitution at higher concentrations is worth avoiding for aggregation-prone…
Follow-up: Recovery when intake is low: what to cut first Replied, post #32 · Nutrition & Training › Resistance training · 19 Nov 2024 · 0 likes Post #31 answers the question as asked. The question underneath it is different. Recovery capacity falls with energy availability, so a programme that worked at…
Time to steady state after a dose increase Replied, post #87 · Pharmacology › Pharmacokinetics · 4 Nov 2024 · 0 likes Volume of distribution: the theoretical volume the drug distributes into. For albumin-binding compounds, volume is reduced compared to drugs that do not bind protein.…
Semaglutide half-life: where the 165 to 184 hour figure comes from — what changed since Replied, post #37 · Compounds › Semaglutide · 3 Nov 2024 · 0 likes I had written a reply contradicting post #35 and deleted it. Here is what survived. Solutions of semaglutide can look faintly opalescent without anything being wrong.…
Progressive overload when the scale is falling — one year on Replied, post #148 · Nutrition & Training › Resistance training · 11 Oct 2024 · 1 like No disagreement from me. Posting only so the question does not look ignored.
A rising related-substance total over six months: degradation or method drift? Replied, post #30 · Analytics › Impurities & related substances · 3 Sep 2024 · 1 like Post #26 and I disagree about the size of the effect, not about the direction. Reporting rather than recommending, on rising related-substance. What happened is above.…
Circumference measurements as a poor man's composition estimate Replied, post #42 · Outcomes › Body composition · 4 Aug 2024 · 2 likes Post #39 and I disagree about the size of the effect, not about the direction. Where I have landed on circumference measurements, having got it wrong once in public:…
Follow-up: Conditions that change the calculus rather than forbidding it Replied, post #32 · Safety › Contraindications · 25 Jul 2024 · 28 likes Post #29 is right about the mechanism and I think understates the practical bit. I would keep Conditions and the decision it usually gets used for separate in this…
Cold packs, phase-change material, and what survives ten days Replied, post #119 · Sourcing › Logistics · 18 Jul 2024 · 5 likes I had written a reply contradicting post #115 and deleted it. Here is what survived. Declared contents and declared value are the two fields most likely to cause a…
Journal club: FLOW and the renal composite, component by component Replied, post #82 · Evidence › Journal club · 17 Jul 2024 · 10 likes Agreed, and I will stop repeating the version of this I had been repeating.