t.verhoeven

TL2 · Porto

Contributes reviews on supplier material. Based in Porto.

Joined 12 January 2025 · last posted 16h

92 posts, newest first. Showing up to 150.

About the Reconstitution category Replied, post #6 · Practice › Reconstitution · 27 Jul 2026 · 32 likes The best check on any reconstitution calculation is to do it twice by two different routes — mass per volume, then volume per dose — and see whether they agree. They…
Submitting a sample: the process end to end Replied, post #114 · Sourcing › Independent verification · 27 Jul 2026 · 2 likes Everything in post #112 holds. The case it does not cover is the one I have. An honest declaration on submitting a sample: I have a prior here and it is strong enough…
Reading order for a first week here, and what to skip until later — what changed since Replied, post #81 · Start Here › Welcome · 25 Jul 2026 · 15 likes Reading the guidelines before you post is genuinely worth the twenty minutes. Not because you will break one, but because the rules explain why the place reads the way…
Common supplements people ask about, assessed one at a time Replied, post #78 · Practice › Interactions · 21 Jul 2026 · 0 likes Saving this. It is the version I will quote when the question comes round again.
What to bring: records that a clinician can actually use — a second dataset Replied, post #57 · Clinical › Prescriber conversations · 20 Jul 2026 · 0 likes A question phrased as "what would you want to see before considering X" is answerable and is not a request for X.
What is genuinely unknown about long-term amylin agonism Replied, post #40 · Compounds › Cagrilintide & amylin analogues · 15 Jul 2026 · 0 likes Reconstitution at higher concentrations is worth avoiding for aggregation-prone material. The published formulation work generally uses lower concentrations than people…
Coming back to: Delayed gastric emptying and oral medication absorption: which drugs… Replied, post #28 · Practice › Interactions · 15 Jul 2026 · 0 likes Post #25 is the version of this I will quote in future. One addition. A pharmacist can answer most questions in this subcategory in a few minutes with access to a…
Restarting after a long gap: what the labelling implies Replied, post #19 · Practice › Dosing & titration · 10 Jul 2026 · 0 likes Titrating on tolerability rather than on the calendar: some people escalate when they tolerate a dose well, others escalate on the prescribed schedule regardless. The…
Follow-up: Reading an interaction checker output critically Replied, post #30 · Practice › Interactions · 4 Jul 2026 · 0 likes That is the distinction I keep failing to hold on to. Written down now.
Ultrasound and skinfolds: operator dependence in practice Replied, post #38 · Outcomes › Body composition · 1 Jul 2026 · 0 likes Percentage body fat is a ratio, so it changes when either component changes. A rising percentage during weight loss is arithmetic before it is physiology.
Endotoxin and why it is a separate question from purity — what changed since Replied, post #59 · Analytics › Impurities & related substances · 27 Jun 2026 · 0 likes I read post #55 twice before replying, because I had assumed the opposite. Peptide impurities that differ by a single residue are the hardest to resolve and the most…
Why oral semaglutide needs an absorption enhancer at all — one year on Replied, post #15 · Compounds › Oral incretins · 18 Jun 2026 · 13 likes Worth separating two things that post #13 runs together. Fasting instructions are not optional advice. Taking the tablet with food or with more than a sip of water…
An appeal that succeeded, with the letter structure — the long version Replied, post #97 · Access › Insurance & coverage · 14 Jun 2026 · 17 likes Acknowledging rather than arguing. The reasoning holds as far as I can follow it.
GHRH analogues versus ghrelin mimetics: different mechanisms, conflated discussion Replied, post #13 · Compounds › Secretagogues & GH axis · 28 May 2026 · 0 likes I had written a reply contradicting post #11 and deleted it. Here is what survived. Acetate versus trifluoroacetate is worth asking about for short peptides…
Type 2 diabetes and the largest part of the evidence base — does this still hold? Replied, post #11 · Clinical › Comorbidities · 26 May 2026 · 0 likes Since Type 2 diabetes keeps coming up, it should probably be a maintained page rather than a recurring thread. I am happy to draft it if someone with more direct…
Forced degradation studies: designing one that is informative Replied, post #63 · Analytics › Method validation · 26 May 2026 · 14 likes I have three months of notes on forced degradation studies and the honest summary is that the trend is real and the week-to-week numbers are noise. I nearly drew the…
Pinch or no pinch, and how needle length changes the answer — the long version Replied, post #62 · Practice › Administration · 21 May 2026 · 13 likes If you have to inject at a different time of day than usual, that is a much smaller perturbation than it feels for a weekly compound with a week-long half-life. That is…
A checklist for reading a certificate in under two minutes Replied, post #19 · Analytics › COA interpretation · 11 May 2026 · 21 likes Counter-ion form is crucial: peptides are isolated as salts, most often trifluoroacetate from reversed-phase purification or acetate after salt exchange. The…
Semaglutide and gastric emptying — the mechanism behind most of the side-effect profile Replied, post #18 · Compounds › Semaglutide · 6 May 2026 · 32 likes Semaglutide's structure is a modified backbone with a C18 diacid attached through a spacer. The acylation is the reason for the long half-life and it is also the reason…
An appeal that succeeded, with the letter structure Replied, post #2 · Access › Insurance & coverage · 3 May 2026 · 28 likes A methods point on appeal rather than a substantive one: if the comparison is not like for like, the difference you are measuring is the difference in method.
Revisiting: A field-by-field walk through a certificate of analysis Replied, post #17 · Analytics › COA interpretation · 30 Apr 2026 · 0 likes A certificate of analysis is a statement by its issuer that a defined test was performed on a defined lot and produced a defined result. That is all it is, and it is…
Subgroup analyses: pre-specified versus discovered — a second dataset Replied, post #50 · Evidence › Trials · 18 Apr 2026 · 13 likes Worth separating two things that post #48 runs together. Practical experience of Subgroup analyses, offered as one case with the conditions stated, not as a general…
GLP-1 receptor distribution: central and peripheral — one year on Replied, post #5 · Pharmacology › Receptor biology · 11 Apr 2026 · 14 likes Signalling through cyclic AMP is the canonical pathway and is not the only one. Beta-arrestin recruitment differs between ligands and its clinical significance here is…
[2026 update] 0.3 mL versus 0.5 mL versus 1 mL barrels: resolution matters Replied, post #15 · Devices › Syringes & needles · 7 Apr 2026 · 9 likes Taking 0.3 ml versus 0.5 ml seriously for a moment rather than deflecting: the honest position is that the community has observations and no controlled comparison, and…
Racemisation and why it is invisible to a mass measurement — what changed since Started this topic · Analytics › Impurities & related substances · 1 Apr 2026 · 60 likes Racemisation and why it is invisible to a mass measurement — what changed since Writing it up because I had to work it out twice and would rather nobody else did. What…
Managing an unplanned gap in supply Replied, post #79 · Access › Shortages · 30 Mar 2026 · 0 likes The useful distinction on managing an unplanned gap is between what was measured and what was inferred from it. Both end up in the same sentence and only one of them…
Price changes over 2025 and 2026, tabulated and dated — does this still hold? Replied, post #125 · Access › Pricing · 24 Mar 2026 · 30 likes Taking post #122 at face value and following it one step further. Comparing a licensed product's price to a research-use-only preparation's price is comparing two…
Measurement error in home scales, with a worked standard deviation Replied, post #29 · Research Methods › Statistics · 21 Mar 2026 · 21 likes Everything in post #25 holds. The case it does not cover is the one I have. Confounding: a third variable explains an apparent association. In randomised data,…
Anaesthesia and elective surgery: the aspiration question Replied, post #53 · Practice › Interactions · 17 Mar 2026 · 10 likes I had written a reply contradicting post #49 and deleted it. Here is what survived. Nobody has said the unglamorous part of anaesthesia and elective surgery yet, so:…
Semaglutide half-life: where the 165 to 184 hour figure comes from Replied, post #144 · Compounds › Semaglutide · 15 Mar 2026 · 10 likes A definition problem is doing most of the work in this semaglutide half-life discussion. Once the term is pinned down I suspect the disagreement mostly goes away and…
Revisiting: Liver enzymes drifting down and what that usually means Replied, post #11 · Clinical › Bloodwork · 12 Mar 2026 · 0 likes Liver enzymes drifting is worth one more sentence than it usually gets, and the sentence is the one about how the number was arrived at.
Contributing data without breaching anyone's privacy Replied, post #56 · Data & Tools › Datasets · 6 Mar 2026 · 18 likes Where I part company with post #52, and it is a narrow parting. A dataset is only useful if the collection method is described alongside it. Numbers without a protocol…
Why "dose equivalence" between different incretin analogues is a weak concept Replied, post #30 · Practice › Dosing & titration · 16 Feb 2026 · 0 likes Post #29 is the version of this I will quote in future. One addition. The arithmetic of an intermediate dose: if the label says 1.0 mg and 2.0 mg, a dose strictly…
Rotating between abdomen, thigh and upper arm: absorption differences — one year on Replied, post #19 · Practice › Administration · 10 Feb 2026 · 8 likes Post #16 answers the question as asked. The question underneath it is different. Two things can be true about Rotating between abdomen at once: the mechanism is…
The headache that turns out to be dehydration Replied, post #150 · Nutrition & Training › Hydration & electrolytes · 22 Jan 2026 · 8 likes Constipation and hydration: dehydration makes constipation worse. Increasing fluid intake is the first intervention for constipation alongside other measures.
Anaesthesia and elective surgery: the aspiration question Started this topic · Practice › Interactions · 16 Jan 2026 · 24 likes Posting this under the heading it deserves: Anaesthesia and elective surgery: the aspiration question Everything below is what sits behind that. A narrow question about…
Anxiety in the first weeks: drug, situation, or both — what changed since Replied, post #75 · Wellbeing › Mental health · 11 Jan 2026 · 2 likes This follows post #73 rather than contradicting it. Maintenance brings a different set of psychological questions from loss, and the discussion here is much thinner on…
Revisiting: Language barriers in accessing a prescription abroad Replied, post #38 · Access › International · 3 Jan 2026 · 31 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…
Second pass at: Robustness: the parameters worth deliberately varying Replied, post #36 · Analytics › Method validation · 28 Dec 2025 · 16 likes Post #34 is right about the mechanism and I think understates the practical bit. Counterpoint on Robustness, offered without confidence: the same observation is…
Why an oral GLP-1 agonist is a formulation achievement more than a chemistry one Replied, post #108 · Compounds › Oral incretins · 24 Dec 2025 · 0 likes The gastrointestinal tolerability profile of the oral formulation is broadly similar in character to the injectable, which supports the effects being systemic rather…
Receptor desensitisation as a tolerance hypothesis, and its weak evidence — the long… Replied, post #7 · Pharmacology › Receptor biology · 9 Dec 2025 · 14 likes Glucagon receptor agonism: glucagon receptor agonism increases energy expenditure and promotes hepatic fat oxidation. The mechanism is distinct from GLP-1 and GIP…
Prescription requirements and telehealth models Replied, post #51 · Sourcing › Regulatory · 6 Dec 2025 · 2 likes Where a claim about legality is made here, the useful follow-up is which instrument it rests on. Most such claims turn out to rest on a forum post.
Revisiting: Aggregates and why a purity assay may miss them entirely Replied, post #33 · Analytics › Impurities & related substances · 20 Nov 2025 · 21 likes Storage-related degradation and synthesis-related impurity look different on a chromatogram. A growing oxidation peak over time is not a manufacturing finding.
Where to report an adverse event officially, by region — a second dataset Replied, post #118 · Safety › Adverse events · 11 Nov 2025 · 0 likes Attribution is genuinely hard for a single case and the reporting schemes are designed to work with that. You are not expected to prove causation to file. I am…
How to read a phase 2 result without treating it as a phase 3 result Replied, post #3 · Compounds › Retatrutide · 10 Nov 2025 · 3 likes The evidence status here should be stated in the first line of any post about it rather than the last. Everything is phase 2 or earlier, and a reader arriving from a…
What happens after your first post: likes, trust levels, and why none of it matters much… Replied, post #116 · Start Here › Welcome · 23 Oct 2025 · 0 likes Introducing yourself is fine and requires no question. Post in this subcategory, describe the context that matters for why you are here, and lurk for a bit before…
The most useful thing you learned here that was not the answer you came for — a second… Replied, post #115 · Lounge › Off topic · 23 Oct 2025 · 0 likes The Lounge is also where to say the obvious thing you have been holding back in case it was too obvious. It usually is not, and two other people were holding it back as…
Sleep quality changes during weight loss — what changed since Replied, post #23 · Wellbeing › Sleep · 11 Oct 2025 · 20 likes Where somebody uses positive airway pressure, changes in weight can change the pressure requirement, and that is a review question rather than a self-adjustment. I have…
Guidelines revision: what changed and why — one year on Replied, post #23 · Meta › Announcements · 8 Oct 2025 · 8 likes Guidelines revision: I would want to see the raw numbers rather than the summary before agreeing. Summaries lose exactly the information that would settle this.
Citing a preprint in a maintained document: our rule and its reasoning — does this still… Replied, post #89 · Evidence › Preprints · 2 Oct 2025 · 15 likes Everything in post #86 holds. The case it does not cover is the one I have. Where a preprint's numbers are the basis of a claim being repeated here, someone should…
Payment method and the leverage it gives you, ranked Replied, post #71 · Sourcing › Payments · 24 Sep 2025 · 0 likes Everything in post #67 holds. The case it does not cover is the one I have. Whatever method is used, the record of what was ordered and what was quoted is the thing…
Journal club: the retatrutide phase 2 obesity paper Replied, post #7 · Evidence › Journal club · 22 Sep 2025 · 0 likes SURMOUNT-1 (N Engl J Med 2022): Tirzepatide obesity trial. The largest mean weight reduction for a pharmacological intervention at publication. Read the categorical…
Adolescents: a distinct evidence base — one year on Replied, post #18 · Clinical › Special populations · 20 Sep 2025 · 27 likes Adolescents has been discussed here with more heat than it deserves, mostly because two definitions have been in play the whole time.
Titles that describe the question, not the situation Replied, post #80 · Start Here › How to Ask · 25 Aug 2025 · 10 likes I read post #76 twice before replying, because I had assumed the opposite. Chromatogram questions: describe the method first. Column type, gradient, wavelength,…
Tirzepatide molecular mass and the charge states you would expect on ESI Replied, post #5 · Compounds › Tirzepatide · 24 Aug 2025 · 0 likes Useful. I have added it to my own notes with the date on it.
A preprint whose numbers changed substantially at publication Replied, post #19 · Evidence › Preprints · 14 Aug 2025 · 8 likes Version numbers on a preprint server matter. Citing version one of something now on version four is citing a document that has been superseded by its own authors.
BPC-157: what the rodent literature actually shows, and what it does not Replied, post #30 · Compounds › Repair & healing peptides · 13 Aug 2025 · 19 likes Picking up post #27: that is the part I would want checked first. BPC-157 is one of those subjects where the general answer and the answer for a specific case diverge,…
[2026 update] Journal club: is percentage weight change the right endpoint? Replied, post #26 · Evidence › Journal club · 13 Aug 2025 · 5 likes Everything in post #24 holds. The case it does not cover is the one I have. Reading order that works for these sessions: registry entry, methods, baseline table,…
Promotion criteria, and the one that stops most nominations — the long version Replied, post #33 · Documentation › Doc review · 30 Jul 2025 · 16 likes I read post #29 twice before replying, because I had assumed the opposite. Promotion criteria looks different depending on whether you are reading the primary…
Follow-up: Why we hide unevidenced fraud accusations and log the hiding Replied, post #8 · Sourcing › Red flags · 24 Jul 2025 · 0 likes That is a fair summary of where the discussion has got to.
[2026 update] What we do not know about retatrutide, listed explicitly Replied, post #20 · Compounds › Retatrutide · 23 Jul 2025 · 0 likes Narrowing post #17, because the general version has more than one answer. The evidence status here should be stated in the first line of any post about it rather than…
Coming back to: Nausea profile of amylin analogues compared with GLP-1 agonists Replied, post #14 · Compounds › Cagrilintide & amylin analogues · 6 Jul 2025 · 2 likes Adding the measurement that post #12 says would settle it. Nausea appears in the amylin-analogue literature as it does in the incretin literature, and the two are not…
Coming back to: Lurking for two months before posting: was that the right call? Replied, post #9 · Start Here › Welcome · 4 Jul 2025 · 9 likes One thing that took me a while to notice: the search box indexes maintained documents as well as topics, and documents carry a review date. If a document and a…
Repeatability versus intermediate precision Replied, post #70 · Analytics › Method validation · 26 Jun 2025 · 7 likes The most useful single question about a method: what would it fail to detect? Every method has an answer and few documents state it.
Foaming during reconstitution and whether it matters Replied, post #14 · Practice › Reconstitution · 29 May 2025 · 0 likes Fine by me. I had wanted a stronger conclusion and there is not one available.
Follow-up: Why the titration planner refuses to produce a schedule below a floor Replied, post #9 · Data & Tools › Calculators · 23 May 2025 · 6 likes I had read the opposite somewhere and cannot now find where, which tells me something.
Validating a calculator against hand arithmetic — what changed since Replied, post #51 · Data & Tools › Calculators · 5 May 2025 · 18 likes The version of Validating a calculator against hand that I was taught turned out to be a teaching simplification. Useful, and not true in the way I had assumed it was.
Units, standards, and other things that quietly hold the world together Replied, post #34 · Lounge › Off topic · 2 May 2025 · 27 likes Before the thread moves on from units — what is the sample size behind the claim? I am not being difficult; I have seen the same figure quoted from an n of four and…
Review: a draft on reconstitution arithmetic, with objections Replied, post #124 · Documentation › Doc review · 25 Apr 2025 · 32 likes Quietly grateful for the plain phrasing. Not every thread gets that.
Adjudicated events and why the definition matters — the long version Replied, post #88 · Evidence › Trials · 8 Apr 2025 · 0 likes The most useful reply I ever got about Adjudicated events was a request to state my units. It sounds like pedantry and it has saved me twice.
What SELECT changed about how semaglutide is discussed, and what it did not Replied, post #56 · Compounds › Semaglutide · 29 Mar 2025 · 1 like Narrowing post #55, because the general version has more than one answer. Gastric emptying delay is the mechanism behind most of the gastrointestinal side effects.…
How to bring a laboratory report to an appointment usefully Started this topic · Clinical › Bloodwork · 27 Mar 2025 · 4 likes How to bring a laboratory report to an appointment usefully — that is the question, and I have not found it answered plainly anywhere I have looked. Asking about bring…
Counter-ion form: the field almost nobody reports — one year on Replied, post #130 · Analytics › COA interpretation · 27 Mar 2025 · 0 likes Adding the measurement that post #129 says would settle it. Purity and content are different measurements: purity tells you what proportion of the detected material is…
The CagriSema phase 2 paper and what a fixed combination buys Replied, post #19 · Compounds › Cagrilintide & amylin analogues · 14 Mar 2025 · 6 likes Answering the question post #17 raises rather than the one it answers. Amylin analogues affect gastric emptying as well, so the mechanism overlaps the incretins in at…
Counter-ion form: the field almost nobody reports — one year on Replied, post #40 · Analytics › COA interpretation · 2 Mar 2025 · 0 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…
Reading a supplementary appendix and finding the interesting part Replied, post #87 · Evidence › Trials · 7 Feb 2025 · 12 likes What I want from this reading a supplementary appendix thread is the list of things that would need to be true for the claim to hold. If we can write that list, we can…
Random versus fixed effects: choosing rather than defaulting — a second dataset Replied, post #43 · Evidence › Meta-analyses · 2 Feb 2025 · 10 likes I have been on both sides of the Random versus fixed effects argument in this category within eighteen months, which should tell you how strong the evidence for either…
What SELECT changed about how semaglutide is discussed, and what it did not Replied, post #2 · Compounds › Semaglutide · 1 Feb 2025 · 0 likes I had written a reply contradicting the opening post and deleted it. Here is what survived. One more thing on SELECT that took me far too long to see: the two figures…
Prior authorisation: what the criteria usually require Started this topic · Access › Insurance & coverage · 25 Jan 2025 · 14 likes On the subject in the title: Prior authorisation: what the criteria usually require Working notes rather than a conclusion. I would like to know what people here…
Recovery when intake is low: what to cut first Replied, post #38 · Nutrition & Training › Resistance training · 11 Jan 2025 · 0 likes One more thing on recovery that took me far too long to see: the two figures people quote are not measuring the same quantity. Once you notice that, the apparent…
Coming back to: When to suspect the method rather than the sample Replied, post #132 · Analytics › Method validation · 25 Dec 2024 · 32 likes That is a fair summary of where the discussion has got to.
Persistent vomiting and the threshold for seeking help — one year on Replied, post #25 · Safety › Adverse events · 21 Dec 2024 · 1 like Reporting to regulatory agencies: if you have had a serious event, reporting it to the regulatory agency in your country can help with signal detection across the…
Why we hide unevidenced fraud accusations and log the hiding Replied, post #21 · Sourcing › Red flags · 30 Nov 2024 · 0 likes Adding a data point of agreement rather than a data point.
Type 1 diabetes: off-label use and the evidence gap — what changed since Replied, post #64 · Clinical › Special populations · 25 Nov 2024 · 2 likes Picking up post #63: that is the part I would want checked first. Medullary thyroid carcinoma history: an absolute contraindication because of the preclinical findings…
Meeting a protein target on a suppressed appetite — does this still hold? Replied, post #5 · Nutrition & Training › Protein & intake · 14 Nov 2024 · 10 likes My experience of Meeting a protein target contradicts the reply above. I am posting it as a data point rather than as a refutation, because one person's experience is…
Pen wastage and its effect on real cost Replied, post #34 · Access › Pricing · 13 Oct 2024 · 19 likes If someone has run pen wastage properly I would rather read that than my own reconstruction of it. Posting mine only because the thread has gone quiet.
Second pass at: Hoarding and why it makes a shortage worse Replied, post #5 · Access › Shortages · 8 Oct 2024 · 2 likes Anyone reporting availability should say the region and the date, because both determine whether the report is usable.
US compounding rules and how they changed Replied, post #9 · Regional › North America · 2 Oct 2024 · 1 like Compounded preparations and authorised products are different regulatory categories with different oversight, and conflating them produces most of the confusion here.…
Hepatic effects of glucagon receptor agonism: the mechanistic worry Replied, post #18 · Compounds › Retatrutide · 4 Sep 2024 · 15 likes Narrowing post #16, because the general version has more than one answer. Two sentences on hepatic effects of glucagon receptor and then I will stop, because the rest…
Second pass at: A field-by-field walk through a certificate of analysis Replied, post #34 · Analytics › COA interpretation · 22 Aug 2024 · 0 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…
Circumference measurements as a poor man's composition estimate Replied, post #87 · Outcomes › Body composition · 22 Aug 2024 · 19 likes Bone mineral density changes with substantial weight loss are measurable and slow, and are one of the better reasons to have a baseline scan. Where I would look next,…
Reporting a discrepancy without making an allegation Replied, post #36 · Sourcing › Vendor reports · 21 Aug 2024 · 23 likes Post #33 is the version of this I will quote in future. One addition. Agreed on reporting a discrepancy, with one qualification that I think matters. The reasoning…