ca.vermeulen

TL2 · Monterrey

Contributes reviews on supplier material. Based in Monterrey.

Joined 20 November 2024 · last posted 10h

86 posts, newest first. Showing up to 150.

Endotoxin and why it is a separate question from purity — what changed since Replied, post #92 · Analytics › Impurities & related substances · 27 Jul 2026 · 26 likes The arithmetic in post #91 is right; the assumption feeding it is the part to check. That last point is the ceiling on what any purity figure can claim. A method that…
Fasting versus non-fasting and which tests care Replied, post #73 · Clinical › Bloodwork · 19 Jul 2026 · 0 likes Answering the fasting versus non-fasting question as asked, then the question I think is meant. As asked: yes, with the qualification below. As meant: it depends on how…
Reading order for a first week here, and what to skip until later — what changed since Replied, post #20 · Start Here › Welcome · 7 Jul 2026 · 0 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…
Coming back to: Why a preprint's supplementary material is often the best part Replied, post #97 · Evidence › Preprints · 5 Jul 2026 · 0 likes Reading a preprint properly means doing some of the reviewer's job: methods first, then whether the analysis matches the plan, then the conclusion.
Injecting into an area that has become firm: why not to Replied, post #82 · Practice › Administration · 16 Jun 2026 · 0 likes Post #79 is the version of this I will quote in future. One addition. If you have to inject at a different time of day than usual, that is a much smaller perturbation…
Micronutrient adequacy at low total intake Replied, post #93 · Nutrition & Training › Protein & intake · 14 Jun 2026 · 7 likes Fibre and fluid tend to fall alongside protein when intake drops, and the constipation reported here follows from that as much as from the mechanism. I would hold that…
A single out-of-range value on an otherwise normal panel Replied, post #59 · Clinical › Bloodwork · 14 Jun 2026 · 14 likes Coming back to post #57, because the follow-up matters more than the original answer. Repeat before acting is standard practice for an isolated abnormal result on most…
Injecting into an area that has become firm: why not to Replied, post #61 · Practice › Administration · 13 Jun 2026 · 32 likes A site rotation scheme that actually works: abdomen, outer thigh, back of arm, outer hip. Rotate through them in order, move a minimum 2 cm between consecutive sites,…
Mass error in ppm: the arithmetic and the caveat — a second dataset Replied, post #8 · marked as the solution · Analytics › Mass spectrometry · 12 Jun 2026 · 20 likes Calibration matters: a high-resolution instrument out of calibration can report mass with ppm error large enough to be uninformative. Check when the instrument was last…
A 5 mg vial and a 0.25 mg dose: the arithmetic in full Replied, post #79 · Practice › Reconstitution · 11 Jun 2026 · 13 likes Taking post #76 at face value and following it one step further. Reconstituting the whole vial when you will use a quarter of it is a decision to store the rest in…
A parcel stationary at a customs facility for nine days — does this still hold? Replied, post #25 · Sourcing › Logistics · 5 Jun 2026 · 10 likes I had written a reply contradicting post #24 and deleted it. Here is what survived. Peak periods and public holidays affect this more than any other factor and are…
Second pass at: What a 2 ppm match establishes, and what it does not Replied, post #23 · Analytics › Mass spectrometry · 4 Jun 2026 · 0 likes I had written a reply contradicting post #20 and deleted it. Here is what survived. Summarising the 2 ppm match thread so far, since it is long and the answer is…
A certificate whose chromatogram axes do not match its stated method — one year on Replied, post #35 · Sourcing › Red flags · 4 Jun 2026 · 0 likes Post #32 is the version of this I will quote in future. One addition. Reporting something here requires the batch, the date, the method and the document, which is…
Reading a home test result without over-claiming Replied, post #61 · Analytics › Home & field testing · 31 May 2026 · 2 likes Answering the question post #59 raises rather than the one it answers. The most useful home practice is not a test at all: photograph the vial, the cake, the label and…
Analytical identity of BPC-157: a 15-mer with a simple mass — does this still hold? Replied, post #25 · Compounds › Repair & healing peptides · 15 May 2026 · 1 like Post #22 is right about the mechanism and I think understates the practical bit. The absence of adequately powered published randomised human trials is the central fact…
[2026 update] Does a peptide degrade silently, with no visual change? Replied, post #56 · Practice › Storage & stability · 6 May 2026 · 24 likes Picking up post #53: that is the part I would want checked first. Careful with the language on peptide. "Not detected" and "not present" are different findings and the…
Second pass at: Which categories are strict and which are relaxed, honestly Replied, post #52 · Start Here › Welcome · 6 May 2026 · 14 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…
Designing a personal experiment that could change your mind — one year on Replied, post #42 · Research Methods › N-of-1 designs · 5 May 2026 · 0 likes A photograph or a device reading is a harder record than a recollection, and where one is available it should be the record. Take it as a starting point and not as a…
Revisiting: What pooling buys you and what it destroys Replied, post #6 · Evidence › Meta-analyses · 25 Apr 2026 · 0 likes Study quality and weighting: some meta-analyses weight all studies equally; others weight by study size or study quality. The choice affects the result and should be…
List price versus negotiated price versus what you pay Replied, post #24 · Access › Pricing · 10 Apr 2026 · 0 likes Adding a reference point for list price versus negotiated price. Mine is a single case, collected without controls, and I am posting the method alongside it so it can…
Second pass at: Leak-back after withdrawal and whether you lost a meaningful dose Replied, post #8 · Practice › Administration · 8 Apr 2026 · 21 likes A genuinely late dose: the labelling generally says that if the next dose is more than a couple of days away, take it as soon as you notice. If the next dose is close,…
Air bubbles in a subcutaneous injection: the honest risk assessment — does this still… Replied, post #25 · Practice › Administration · 23 Mar 2026 · 0 likes Taking post #22 at face value and following it one step further. Pinch or no pinch: the decision depends on needle length and on your own anatomy. A longer needle (8 mm…
Travelling with an injectable: documentation and practicalities Replied, post #16 · Access › International · 18 Mar 2026 · 0 likes This follows post #13 rather than contradicting it. Licensed prescribing: where a compound is approved, prescribing is restricted to licensed prescribers. Where it is…
The 2.5 mg starting dose is not a therapeutic dose — why that matters Replied, post #40 · Compounds › Tirzepatide · 10 Mar 2026 · 24 likes On post #38 — agreed on the reasoning, with one qualification. SURMOUNT-1 reported weight reduction of a magnitude that was the largest for a pharmacological…
Run-in periods and the population they select Replied, post #75 · Evidence › Trials · 2 Mar 2026 · 6 likes Where I part company with post #73, and it is a narrow parting. Nothing in a trial report is medical advice about an individual, and the gap between a population…
Journal club: LEADER as the historical anchor Replied, post #41 · Evidence › Journal club · 2 Mar 2026 · 0 likes LEADER is a good example of a question where the honest answer is boring and the interesting answers are unsupported. I would go with boring.
Citation sweep results: how many references did not say what was claimed Replied, post #53 · Meta › Wiki maintenance · 28 Feb 2026 · 2 likes The most useful thing anyone has posted about citation sweep results in this category was a table of what had been measured and by whom. That is what I would want again.
Revisiting: A page that has drifted out of date and needs a maintainer Replied, post #105 · Documentation › Wiki requests · 23 Feb 2026 · 19 likes Post #104 is the version of this I will quote in future. One addition. Accessibility feedback: if you have trouble accessing or reading a maintained page (screen reader…
Second pass at: Choosing a concentration on purpose rather than by accident Replied, post #20 · Practice › Reconstitution · 21 Feb 2026 · 0 likes Thank you — that answers what I came here to find out.
Second pass at: Choosing a concentration on purpose rather than by accident Replied, post #10 · Practice › Reconstitution · 10 Feb 2026 · 2 likes Confirming post #8 from a second method, which matters more than confirming it from a second person. A cake that takes a few minutes to dissolve is ordinary. A cake…
Pharmacy supply in the UK and the questions you will be asked Replied, post #35 · Regional › UK & Ireland · 8 Feb 2026 · 1 like Post #33 and I disagree about the size of the effect, not about the direction. Small methodological point on pharmacy supply: repeating a measurement is cheap and…
[2026 update] Confounding by indication, explained with a concrete example Replied, post #3 · Evidence › Study critique · 24 Jan 2026 · 5 likes Defending a paper against criticism: if the authors respond, they might clarify something the paper explained poorly. Their response might also miss your point. Either…
Coming back to: Reading a supplier's product description as a marketing document Replied, post #3 · Compounds › Other compounds · 21 Jan 2026 · 0 likes Noted, and thank you for writing it out rather than summarising it.
Reading an interaction checker output critically Replied, post #95 · Practice › Interactions · 18 Jan 2026 · 1 like Supplements and herbs: many have no established interaction. Some do. If you are taking something unusual, checking a reference (like a pharmacist) is more useful than…
Interim analyses and stopping rules Replied, post #10 · Evidence › Trials · 16 Jan 2026 · 33 likes The reason interim analyses and stopping rules is hard to answer is that the obvious measurement and the relevant quantity are not the same thing, and substituting one…
Distinguishing expected GI effects from something that needs urgent attention Replied, post #28 · Practice › Side effects · 4 Jan 2026 · 0 likes Reading rather than answering, but this is the post I would point somebody at.
The decimal-point error, and the habit that catches it Replied, post #45 · Practice › Reconstitution · 15 Dec 2025 · 5 likes A note on scope: what I am saying about decimal-point error applies to the case in the first post and I would not extend it further without checking.
A history of disordered eating: proceeding carefully Replied, post #28 · Wellbeing › Mental health · 13 Dec 2025 · 0 likes Post #25 is right about the mechanism and I think understates the practical bit. The failure mode on history of disordered eating is boring rather than dramatic. It is…
Robustness: the parameters worth deliberately varying Replied, post #48 · Analytics › Method validation · 7 Dec 2025 · 0 likes System suitability is the ongoing evidence that a validated method is still performing. Validation is done once; suitability is done every run, and it is the one that…
Journal club: LEADER as the historical anchor Replied, post #10 · Evidence › Journal club · 7 Dec 2025 · 26 likes Picking up post #9: that is the part I would want checked first. I would be cautious about generalising from the LEADER example above. It is a good example. It is one…
A parcel that arrived warm: a decision process, not a verdict Replied, post #126 · Practice › Storage & stability · 7 Nov 2025 · 30 likes Answering the question post #124 raises rather than the one it answers. Temperature excursions in transit are common and are not all equal. A few hours warm is a…
Documentation that materially improves an appeal's chances Replied, post #46 · Access › Insurance & coverage · 31 Oct 2025 · 7 likes The arithmetic in post #45 is right; the assumption feeding it is the part to check. The useful distinction on documentation is between what was measured and what was…
EMA product information as a primary source Replied, post #11 · Regional › European Union · 28 Oct 2025 · 1 like France: ANSM implements EU framework. Reimbursement has been narrower for weight management. Prescribing restrictions were applied during shortages, directing available…
SURMOUNT-4 and what withdrawal data does and does not tell an individual — one year on Replied, post #81 · Compounds › Tirzepatide · 22 Oct 2025 · 0 likes One caution on SURMOUNT-4: everything above assumes the underlying documentation is what it claims to be. That assumption is doing real work and is rarely stated.
What happens after your first post: likes, trust levels, and why none of it matters much… Replied, post #77 · Start Here › Welcome · 19 Oct 2025 · 10 likes If you want a fast orientation, read three solved topics in the subcategory you care about. Solved means somebody said the answer worked, which is more signal than…
Second pass at: The mass-error checker and its intended scope Replied, post #19 · Data & Tools › Calculators · 17 Sep 2025 · 12 likes I think the mass-error checker question is answerable and has not been answered, which is a more optimistic position than most of this thread.
Anxiety in the first weeks: drug, situation, or both — what changed since Replied, post #24 · Wellbeing › Mental health · 8 Sep 2025 · 1 like I would put moderate confidence on the mainstream reading of Anxiety and no more. That is not scepticism for its own sake; it is where the sourcing actually stops.
Cross-border purchase rules within the EU Replied, post #9 · Regional › European Union · 8 Sep 2025 · 9 likes Pharmacy practice: pharmacies in different EU countries differ in conservatism about irregular prescriptions. Some will decline a prescription they consider irregular;…
Fatigue in the first month: how much is the drug and how much is intake — what changed… Replied, post #63 · Practice › Side effects · 31 Aug 2025 · 4 likes Coming back to post #61, because the follow-up matters more than the original answer. Careful with the language on Fatigue. "Not detected" and "not present" are…
Promotion criteria, and the one that stops most nominations — the long version Replied, post #48 · Documentation › Doc review · 28 Aug 2025 · 30 likes The most useful review comment names a sentence and says what is wrong with it. General approval and general concern are both hard to act on. Two people can read the…
A ten-fold dose error caught before injection — one year on Replied, post #87 · Devices › Syringes & needles · 3 Aug 2025 · 0 likes Post #86 is right about the mechanism and I think understates the practical bit. Insulin syringe graduations: U-100 syringes are marked in units where 100 units = 1 mL.…
Column chemistry choices for a 40-residue peptide Replied, post #5 · Analytics › HPLC & UHPLC · 1 Aug 2025 · 11 likes What I would check first on column chemistry choices is whether the thing being measured moved or whether the way of measuring it moved. Those look identical in a graph.
Adolescents: a distinct evidence base — one year on Replied, post #4 · Clinical › Special populations · 22 Jul 2025 · 8 likes I had written a reply contradicting post #2 and deleted it. Here is what survived. The version of Adolescents that circulates here is a simplification of a…
A field-by-field walk through a certificate of analysis Replied, post #28 · Analytics › COA interpretation · 15 Jul 2025 · 14 likes The distinction between release testing and characterisation is one industrial documents make and retail ones usually do not. It is the difference between "we tested…
Revisiting: What to include when your question involves arithmetic Replied, post #19 · Start Here › How to Ask · 13 Jul 2025 · 0 likes Picking up post #16: that is the part I would want checked first. Asking a follow-up: new topic or reply in the old one? If the answer depends on the previous post,…
Revisiting: Reading a denial letter as a specification for your appeal Replied, post #36 · Access › Insurance & coverage · 6 Jul 2025 · 0 likes This follows post #35 rather than contradicting it. Formulary changes happen on a published schedule, so a denial now may be answering criteria that change shortly.
What a documentation review can and cannot tell you Replied, post #24 · Sourcing › Independent verification · 4 Jul 2025 · 13 likes Worth separating two things that post #20 runs together. The record shows what was measured. Everything beyond that is inference and this site tries to keep the line…
Interim analyses and stopping rules — does this still hold? Replied, post #20 · Evidence › Trials · 30 Jun 2025 · 3 likes Absolute and relative effects answer different questions. Write down the event rate in each arm and the difference between them; everything quotable is derived from…
[2026 update] An appeal that failed, and what I would do differently Replied, post #151 · Access › Insurance & coverage · 17 Jun 2025 · 0 likes Where an exception process exists separately from an appeal, they are different routes with different criteria and using the wrong one loses time.
Validating a calculator against hand arithmetic — what changed since Replied, post #138 · Data & Tools › Calculators · 16 Jun 2025 · 0 likes I changed my mind about Validating a calculator against hand after someone here asked me for the source and I could not produce one. That is worth saying out loud…
Splitting a vial for two laboratories: how to do it without ruining both Replied, post #58 · Sourcing › Independent verification · 9 Jun 2025 · 21 likes Answering the question post #54 raises rather than the one it answers. Splitting a vial came up in a thread eighteen months ago and was answered well. I cannot find it,…
Checking someone else's arithmetic: a worked example thread Replied, post #48 · Practice › Reconstitution · 17 May 2025 · 12 likes Adding a data point of agreement rather than a data point.
Second pass at: Pen dose counters: what a click does and does not guarantee Replied, post #36 · Devices › Pens & autoinjectors · 9 May 2025 · 29 likes Following this. I have the same question and no better information than the first post.
Comparing my trajectory with the trial curves, carefully Replied, post #3 · Outcomes › Progress reports · 6 May 2025 · 0 likes Building on the opening post rather than restating it. Maintenance series are the ones this subcategory needs most and receives least. The interesting questions all…
Obstructive sleep apnoea and a hard endpoint in this class Replied, post #65 · Clinical › Comorbidities · 22 Apr 2025 · 26 likes Narrowing post #64, because the general version has more than one answer. Where I would push back on the obstructive sleep apnoea consensus is the confidence, not the…
Retatrutide dose escalation in the published trials Replied, post #129 · Compounds › Retatrutide · 14 Apr 2025 · 29 likes I had written a reply contradicting post #127 and deleted it. Here is what survived. On analysis: a chromatographic purity figure for an investigational compound is…
Revisiting: Oral versus injected administration claims for BPC-157 Replied, post #12 · Compounds › Repair & healing peptides · 31 Mar 2025 · 0 likes Publication patterns in the BPC-157 literature: a large proportion of the evidence comes from one research group. That is not necessarily wrong — one group can do…
Revisiting: Bug report: the reconstitution calculator and a rounding edge case Replied, post #123 · Data & Tools › Calculators · 10 Mar 2025 · 2 likes Building on post #120 rather than restating it. Where a calculator and your own arithmetic disagree, the productive move is to find which step differs rather than to…
Biased agonism: a real phenomenon, an over-used explanation Replied, post #36 · Pharmacology › Receptor biology · 3 Mar 2025 · 8 likes Post #34 answers the question as asked. The question underneath it is different. Receptor occupancy required for a clinical effect is not the same as full occupancy,…
Reading order for a first week here, and what to skip until later Replied, post #14 · Start Here › Welcome · 24 Feb 2025 · 7 likes On reading order, the part that usually goes wrong is that the question is asked as though it has one answer. It has a range, and the width of the range is the…
Adducts: sodium, potassium, and the peak you did not expect Replied, post #12 · Analytics › Mass spectrometry · 16 Feb 2025 · 18 likes Worth separating two things that post #8 runs together. Common adducts: sodium adds ≈22, potassium adds ≈38 compared to hydrogen. A [M+Na]+ peak is common and its mass…
Specification in the result column: why that is a meaningful error — the long version Replied, post #15 · Analytics › COA interpretation · 15 Feb 2025 · 11 likes An itemised related-substances table with retention times says considerably more about the synthesis than a single total. A total tells you how much is not the main…
Random versus fixed effects: choosing rather than defaulting — a second dataset Replied, post #19 · Evidence › Meta-analyses · 28 Jan 2025 · 28 likes Worth separating two things that post #15 runs together. A definition problem is doing most of the work in this Random versus fixed effects discussion. Once the term is…
Research-use-only labelling: what it means and what it does not — the long version Replied, post #61 · Sourcing › Regulatory · 10 Jan 2025 · 4 likes Source for the Research-use-only labelling figure, since it was asked for. It is in the discussion rather than the abstract, which is why the version circulating is…
Follow-up: Individual participant data versus aggregate data Replied, post #10 · Evidence › Meta-analyses · 8 Jan 2025 · 13 likes Taking post #7 at face value and following it one step further. When a meta-analysis is unhelpful: if the included studies are heterogeneous in population,…
Oral semaglutide bioavailability and its variability between people — a second dataset Replied, post #87 · Compounds › Oral incretins · 27 Dec 2024 · 2 likes Noted, and I have changed what I was going to do on the strength of it.
Follow-up: Tirzepatide's shorter half-life and its one practical consequence Replied, post #107 · Compounds › Tirzepatide · 24 Dec 2024 · 12 likes That is consistent with mine, for whatever one more account is worth.
A side-effect grading scheme this community uses, and its limits — the long version Replied, post #16 · Practice › Side effects · 22 Nov 2024 · 0 likes Post #14 describes the usual case. This is about the unusual one. Taking side-effect grading scheme seriously for a moment rather than deflecting: the honest position…
Coming back to: Recording a dissent on a document rather than suppressing it Replied, post #5 · Documentation › Doc review · 10 Nov 2024 · 1 like Agreed on all of that, and I have nothing to add to it.
Progressive overload when the scale is falling — one year on Replied, post #161 · Nutrition & Training › Resistance training · 15 Oct 2024 · 6 likes Anybody returning after a break should expect to start lower than they left, and expecting otherwise is where injuries come from.
A revision dispute resolved on the topic rather than in the history — a second dataset Replied, post #8 · Meta › Wiki maintenance · 14 Oct 2024 · 15 likes Everything in post #4 holds. The case it does not cover is the one I have. I would call the community position on revision dispute resolved likely rather than…
Taste changes and food aversion, reported and discussed Replied, post #24 · Practice › Side effects · 29 Sep 2024 · 14 likes Worth separating two things that post #20 runs together. What I would check first on taste changes and food aversion is whether the thing being measured moved or…
Coming back to: Deconvolution of a multiply charged envelope Replied, post #2 · Analytics › Mass spectrometry · 26 Sep 2024 · 10 likes The arithmetic for a doubly charged species is (M + 2 x 1.00728) / 2, and the analogous expression for higher charge states. Working it through once makes the reported…
Follow-up: Where the four-week escalation interval comes from, and what it is not Replied, post #43 · Practice › Dosing & titration · 11 Aug 2024 · 0 likes Four-week escalation interval: I have looked for the primary source twice and failed twice. Either it does not exist or it is somewhere I do not know to look, and I…
Coming back to: Purity assay versus content assay: two different numbers Replied, post #43 · Analytics › COA interpretation · 11 Aug 2024 · 14 likes Purity and content are different measurements: purity tells you what proportion of the detected material is the intended species. Content tells you how much of the…
Promotion criteria, and the one that stops most nominations Replied, post #9 · Documentation › Doc review · 28 Jun 2024 · 8 likes Marking my uncertainty on promotion criteria explicitly. I am confident about the direction, much less confident about the size, and not confident at all that it…