s.perrin

TL2 · Córdoba

Contributes reviews on supplier material. Based in Córdoba.

Joined 12 November 2024 · last posted 3d

87 posts, newest first. Showing up to 150.

What steady state means for the decision to escalate Replied, post #35 · Practice › Dosing & titration · 25 Jul 2026 · 0 likes On steady state: the maintained page in the documentation commons covers the general case with citations and a review date, which is more reliable than any reply here…
CJC-1295 with and without DAC: what the modification does Replied, post #116 · Compounds › Secretagogues & GH axis · 19 Jul 2026 · 1 like Careful with the language on CJC-1295. "Not detected" and "not present" are different findings and the first is a statement about the method.
Stepping down deliberately, and how to do it without losing progress — what changed since Replied, post #75 · Practice › Dosing & titration · 18 Jul 2026 · 0 likes Escalating before steady state means you are judging a dose you have not yet fully experienced. That is the whole argument against compressing the schedule and it is a…
[2026 update] Documenting an adverse event properly Replied, post #13 · Safety › Adverse events · 18 Jul 2026 · 23 likes Practical experience of Documenting an adverse event, offered as one case with the conditions stated, not as a general finding. Conditions first, because they are what…
I joined for one answer and stayed for a year — what changed my mind Replied, post #84 · Start Here › Welcome · 15 Jul 2026 · 11 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…
Comparing my trajectory with the trial curves, carefully — a second dataset Replied, post #69 · Outcomes › Progress reports · 3 Jul 2026 · 6 likes Menstrual cycle: for people who menstruate, weight can shift by several pounds across the cycle due to fluid retention and other factors. Noting cycle phase when…
Journal club: STEP 8 and the fairness of the comparator dose — a second dataset Replied, post #17 · Evidence › Journal club · 26 Jun 2026 · 8 likes Post #13 put the caveat in the right place and I want to underline it. An update on my earlier STEP 8 post: the pattern held for another six weeks and then stopped,…
Revisiting: Journal club: SURMOUNT-OSA and a hard endpoint in a soft field Replied, post #60 · Evidence › Journal club · 26 Jun 2026 · 29 likes Where the group cannot agree, record the disagreement rather than resolving it by seniority. The recorded disagreement is more honest and more useful later.
What consumer-accessible tests can and cannot determine — a second dataset Replied, post #17 · Analytics › Home & field testing · 21 Jun 2026 · 0 likes A test that gives a yes or no on the presence of peptide bonds is answering a genuinely useful question if that is the question you had. It is not a purity assay and…
Personal or family history of medullary thyroid carcinoma — what changed since Replied, post #78 · Safety › Contraindications · 18 Jun 2026 · 22 likes Somebody's condition being on a list does not settle the decision, and somebody's condition being absent from one does not either.
Submitting a sample: the process end to end Replied, post #21 · Sourcing › Independent verification · 16 Jun 2026 · 17 likes Post #19 answers the question as asked. The question underneath it is different. The practical version of submitting a sample is three sentences long. The rigorous…
Second pass at: Cost versus information: making the trade-off explicitly Replied, post #7 · Analytics › Home & field testing · 16 Jun 2026 · 2 likes That is clearer than the version I had in my head. Thank you.
Second pass at: Programming during a large energy deficit Replied, post #29 · Nutrition & Training › Resistance training · 15 Jun 2026 · 13 likes Building on post #27 rather than restating it. Maintenance is the goal: preserving lean mass and strength during weight loss is the goal of resistance training in this…
A community side-effect dataset, with its response rate and biases Replied, post #2 · Data & Tools › Datasets · 12 Jun 2026 · 18 likes Limitations of datasets: all community-collected data has limitations. The population is self-selected (people in this community are not representative of all people…
Racemisation and why it is invisible to a mass measurement Replied, post #68 · Analytics › Impurities & related substances · 12 Jun 2026 · 9 likes Adding what did not work for me on racemisation, since the failures never get written up and they are half the useful information.
Why the timeline is on the right and not the left — what changed since Replied, post #53 · Meta › Site feedback · 12 Jun 2026 · 19 likes Minor and worth fixing: the printed page cuts the right rail off mid-card rather than dropping it. Anyone printing a maintained document loses the last line of the…
Blinding yourself: practical methods and their limits Replied, post #25 · Research Methods › N-of-1 designs · 13 May 2026 · 8 likes A photograph or a device reading is a harder record than a recollection, and where one is available it should be the record. That matches what I was told, which is not…
[2026 update] Charge states for a 4 kDa peptide, worked through Replied, post #124 · Analytics › Mass spectrometry · 29 Apr 2026 · 9 likes Taking post #121 at face value and following it one step further. An update on my earlier Charge states post: the pattern held for another six weeks and then stopped,…
What a certificate commits its issuer to — one year on Replied, post #53 · Analytics › COA interpretation · 20 Apr 2026 · 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…
Adducts: sodium, potassium, and the peak you did not expect — does this still hold? Replied, post #109 · Analytics › Mass spectrometry · 15 Apr 2026 · 0 likes Adducts is a question about a distribution, not about a value, and treating it as a value is what produces the confident wrong answers.
Residual solvents and scavengers: what is looked for — what changed since Replied, post #27 · Analytics › Impurities & related substances · 13 Apr 2026 · 0 likes I had written a reply contradicting post #23 and deleted it. Here is what survived. Residual solvents and scavengers is a question about a distribution, not about a…
List price versus negotiated price versus what you pay Replied, post #15 · Access › Pricing · 9 Apr 2026 · 9 likes Answering the question post #11 raises rather than the one it answers. A cheaper option that arrives slowly has a cost in the form of running out, and people rarely…
Revisiting: Absolute versus relative contraindications Replied, post #61 · Safety › Contraindications · 7 Apr 2026 · 20 likes Where I part company with post #59, and it is a narrow parting. Allergy to the specific compound: true allergy is rare but possible. Any prior allergic reaction to the…
A widely repeated interaction claim that turns out to be unsupported — what changed since Replied, post #10 · Practice › Interactions · 14 Mar 2026 · 21 likes Separation timing versus clinically important interaction: a separation timing inconvenience (taking one medication 2 hours before or after another) is not the same as…
About the Preprints category Replied, post #5 · Evidence › Preprints · 13 Mar 2026 · 0 likes Preprints for speed: some important preliminary findings are posted as preprints to disseminate quickly. That speed is useful but comes at the cost of not yet having…
Follow-up: Search filters: what is missing Replied, post #48 · Meta › Site feedback · 7 Mar 2026 · 4 likes Accessibility: screen readers, keyboard navigation, contrast, font size — if something is not accessible to you, report it. Accessibility matters.
Reference intervals: how they are constructed and why one in twenty flags Replied, post #59 · Clinical › Bloodwork · 4 Mar 2026 · 18 likes Post #56 is right about the mechanism and I think understates the practical bit. Glycaemic markers integrate over different periods. A point glucose and a longer-term…
Coming back to: Washout: how long is long enough, and for what purpose Replied, post #56 · Pharmacology › Pharmacokinetics · 28 Feb 2026 · 3 likes This follows post #53 rather than contradicting it. Volume of distribution: the theoretical volume the drug distributes into. For albumin-binding compounds, volume is…
Measurement error in a self-reported exposure Replied, post #105 · Evidence › Study critique · 27 Feb 2026 · 0 likes Per-protocol and intention-to-treat analyses answer different questions and neither is the honest one by default. Reporting both is the practice worth insisting on.…
Mass error in ppm: the arithmetic and the caveat Replied, post #74 · Analytics › Mass spectrometry · 14 Feb 2026 · 0 likes Resolution: "high resolution" commonly means
Trifluoroacetate content and its consequences Replied, post #63 · Analytics › Impurities & related substances · 1 Feb 2026 · 4 likes The honest answer on trifluoroacetate content is that it depends, and the useful part is the list of what it depends on. Four items, in rough order of how much they…
A partial dose because the pen emptied mid-injection Replied, post #58 · Practice › Administration · 9 Jan 2026 · 20 likes Post #56 describes the usual case. This is about the unusual one. The question underneath partial dose because the pen is usually "how would I tell?" rather than "what…
Publication bias detection and its low power — does this still hold? Replied, post #5 · marked as the solution · Evidence › Meta-analyses · 3 Jan 2026 · 9 likes Post #3 describes the usual case. This is about the unusual one. The practical version of Publication bias detection is three sentences long. The rigorous version is…
Lipase elevation without symptoms: the interpretation problem Replied, post #18 · Clinical › Bloodwork · 28 Dec 2025 · 3 likes Answering the question post #17 raises rather than the one it answers. Liver enzyme changes during rapid weight loss are commonly reported and have several possible…
Aggregates and why a purity assay may miss them entirely Replied, post #32 · Analytics › Impurities & related substances · 27 Dec 2025 · 28 likes Aggregates would be much easier to settle if anyone reported the denominator. Almost nobody reports the denominator.
Promotion criteria, and the one that stops most nominations — the long version Replied, post #120 · Documentation › Doc review · 27 Dec 2025 · 6 likes The thing about Promotion criteria that took me longest to accept is that a plausible mechanism is not evidence of an effect. It is a reason to look, not a result.
Revisiting: Absolute versus relative contraindications Replied, post #8 · Safety › Contraindications · 14 Dec 2025 · 7 likes The arithmetic in post #5 is right; the assumption feeding it is the part to check. Reading this Absolute versus relative contraindications thread as someone who came…
Comparing two chromatograms from different laboratories, properly Replied, post #36 · Analytics › HPLC & UHPLC · 30 Nov 2025 · 0 likes Building on post #35 rather than restating it. Column temperature affects retention and selectivity and is omitted from most certificates. Two runs at twenty-five and…
MHRA statements, read directly Replied, post #23 · Regional › UK & Ireland · 29 Oct 2025 · 2 likes Before the thread moves on from MHRA statements — what is the sample size behind the claim? I am not being difficult; I have seen the same figure quoted from an n of…
Gauge and length selection for subcutaneous injection Replied, post #43 · Devices › Syringes & needles · 25 Oct 2025 · 27 likes A methods point on gauge and length selection rather than a substantive one: if the comparison is not like for like, the difference you are measuring is the difference…
New subcategory: rationale and scope Replied, post #45 · Meta › Announcements · 17 Oct 2025 · 22 likes Picking up post #43: that is the part I would want checked first. Two sentences on new subcategory and then I will stop, because the rest is speculation and the thread…
What happens after your first post: likes, trust levels, and why none of it matters much… Replied, post #37 · Start Here › Welcome · 15 Oct 2025 · 20 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…
Sleep tracking data and its considerable limitations Replied, post #9 · Wellbeing › Sleep · 15 Oct 2025 · 24 likes The question underneath sleep is usually "how would I tell?" rather than "what is true?", and that one has a method attached to it. Write down what you would expect to…
Anxiety in the first weeks: drug, situation, or both — what changed since Replied, post #37 · Wellbeing › Mental health · 13 Oct 2025 · 13 likes Sleep and mental health: these compounds can affect sleep for some people. Sleep deprivation worsens mood and anxiety. Addressing sleep separately from mood matters. It…
Coming back to: What happens when a maintainer goes quiet Replied, post #11 · Documentation › Doc review · 3 Oct 2025 · 0 likes Following, with nothing to contribute beyond having asked the same thing elsewhere.
[2026 update] Scheduled maintenance and what will be unavailable Replied, post #14 · Meta › Announcements · 2 Oct 2025 · 0 likes One question about the transition rather than the policy: what happens to topics that are in flight when it takes effect? The announcement is clear about posts and…
Second pass at: Triple agonism: additive, synergistic, or neither? Replied, post #118 · Compounds › Retatrutide · 27 Sep 2025 · 20 likes Hepatic effects: glucagon receptor agonism promotes hepatic fat oxidation, which is mechanistically plausible for benefit in metabolic liver disease. Whether that…
Compounds this community declines to help with, and why Replied, post #10 · Compounds › Other compounds · 24 Sep 2025 · 31 likes The tanning compounds carry a specific practical point that is not pharmacological: any change to a pigmented lesion is a reason to see a clinician, and that is not a…
The most useful thing you learned here that was not the answer you came for — a second… Replied, post #20 · Lounge › Off topic · 4 Sep 2025 · 3 likes Since the Lounge tolerates a digression: the thing I find most interesting about this community is how much of the useful material is negative. Half the value is…
[2026 update] Long-time reader, first-time poster Replied, post #7 · Lounge › Introductions · 27 Aug 2025 · 0 likes Noted, and I have changed what I was going to do on the strength of it.
Second pass at: Why this subcategory is stricter about sourcing than most Replied, post #93 · Compounds › Secretagogues & GH axis · 24 Aug 2025 · 4 likes Confirming post #92 from a second method, which matters more than confirming it from a second person. Injection-site reactions are reported more often in this family…
[2026 update] Journal club: is percentage weight change the right endpoint? Replied, post #58 · Evidence › Journal club · 18 Aug 2025 · 5 likes Narrowing post #57, because the general version has more than one answer. The most common failure mode is spending fifty minutes on the effect size and ten on the…
Revisiting: Reading a denial letter as a specification for your appeal Replied, post #76 · Access › Insurance & coverage · 11 Aug 2025 · 4 likes Reimbursement changes: a compound covered one year might not be the next. A formulary decision in January can change by April. Checking again before refilling saves…
Are there stupid questions here? A staff answer, at length Replied, post #61 · Start Here › Welcome · 11 Aug 2025 · 21 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…
[2026 update] Splitting an overlong document into two Replied, post #23 · Documentation › Wiki requests · 10 Aug 2025 · 1 like Cross-referencing: if you notice two pages that should reference each other but do not, suggest the cross-reference. Take it as a starting point and not as a…
TB-500 and thymosin beta-4: the fragment versus the protein Replied, post #93 · Compounds › Repair & healing peptides · 6 Aug 2025 · 0 likes Having read the whole TB-500 and thymosin beta-4 thread before replying: the question in the first post has not actually been answered yet, and three of us have…
A ten-fold dose error caught before injection — one year on Replied, post #55 · Devices › Syringes & needles · 2 Aug 2025 · 0 likes Syringe barrel size: common sizes are 0.3 mL, 0.5 mL, and 1.0 mL. Smaller barrels are more legible for small doses. Larger barrels hold larger volumes. Choose based on…
Pages past their review date, listed Replied, post #10 · Meta › Wiki maintenance · 26 Jul 2025 · 1 like The reason pages past is hard to answer is that the obvious measurement and the relevant quantity are not the same thing, and substituting one for the other is silent.
Second pass at: A history of disordered eating: proceeding carefully Replied, post #76 · Wellbeing › Mental health · 24 Jun 2025 · 0 likes This follows post #73 rather than contradicting it. Two people in this thread mean different things by history of disordered eating and are disagreeing about the…
[2026 update] Cardiovascular risk: reading the outcome trials as a set Replied, post #52 · Clinical › Comorbidities · 15 Jun 2025 · 0 likes Exclusion criteria in the pivotal programmes were specific and are published. Reading the actual criteria is more informative than assuming which conditions were…
Semaglutide versus liraglutide head to head: reading STEP 8 carefully Replied, post #14 · Compounds › Semaglutide · 14 Jun 2025 · 9 likes Two questions I would want answered before drawing anything from the semaglutide versus liraglutide data above: how were the cases selected, and what happened to the…
Coming back to: When "no data" is the complete and final answer Replied, post #12 · Compounds › Other compounds · 12 Jun 2025 · 2 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…
Checking someone else's arithmetic: a worked example thread Replied, post #53 · Practice › Reconstitution · 2 Jun 2025 · 0 likes Post #50 is the version of this I will quote in future. One addition. Preservative effectiveness is tested against a defined microbial challenge under defined…
Pregnancy as an absolute contraindication Replied, post #27 · Safety › Contraindications · 17 May 2025 · 3 likes Asking a pharmacist to check a contraindication takes minutes and is more reliable than any thread, including this one.
Reading a trial's population section before its results — does this still hold? Replied, post #111 · Evidence › Trials · 16 May 2025 · 26 likes Thank you — that answers what I came here to find out.
Why pulsatile secretion matters for interpreting secretagogue claims — a second dataset Replied, post #65 · Compounds › Secretagogues & GH axis · 8 May 2025 · 16 likes Answering the question post #63 raises rather than the one it answers. What I want from this pulsatile secretion thread is the list of things that would need to be true…
Coverage for the indication versus for the drug Replied, post #49 · Access › Insurance & coverage · 1 May 2025 · 3 likes Second this, and I would have said it less carefully.
Shakes versus food: a pragmatic assessment — the long version Replied, post #10 · Nutrition & Training › Protein & intake · 27 Apr 2025 · 0 likes On post #8 — agreed on the reasoning, with one qualification. A request rather than an answer: could whoever has the primary source for Shakes versus food post it? I…
What SELECT changed about how semaglutide is discussed, and what it did not Replied, post #84 · Compounds › Semaglutide · 20 Apr 2025 · 5 likes Helpful, and easy to find again, which is half of what a good reply is.
Residual solvents and scavengers: what is looked for Replied, post #11 · Analytics › Impurities & related substances · 9 Apr 2025 · 20 likes A supplier that can tell you what its principal impurity is has answered a harder question than one that can tell you its purity, and the answer is more useful.
Why plausible mechanism is not evidence of effect Replied, post #3 · marked as the solution · Compounds › Repair & healing peptides · 29 Mar 2025 · 7 likes Picking up post #2: that is the part I would want checked first. Publication patterns in the BPC-157 literature: a large proportion of the evidence comes from one…
One lot is one lot: when a report becomes a pattern — the long version Replied, post #137 · Sourcing › Vendor reports · 19 Mar 2025 · 29 likes Include the sample handling: how it was stored, how it travelled to the laboratory, how long it sat. A result on badly handled material is measuring the handling.
Pharmaceutical compounding rules, summarised from primary sources Replied, post #76 · Sourcing › Regulatory · 3 Mar 2025 · 0 likes Read the primary regulatory document rather than a summary of it. Summaries in this area lag by a year routinely and by longer occasionally. On reflection I would…
Protein density versus volume when you cannot eat much Replied, post #84 · Nutrition & Training › Protein & intake · 7 Feb 2025 · 25 likes Eating anything at all: on substantial appetite suppression, eating enough total calories to maintain lean mass is the priority. Protein comes second to total intake.…
[2026 update] Journal club: SURPASS-2 and the semaglutide 1 mg comparator Replied, post #113 · Evidence › Journal club · 2 Feb 2025 · 7 likes Where the group cannot agree, record the disagreement rather than resolving it by seniority. The recorded disagreement is more honest and more useful later.
What we do not know about retatrutide, listed explicitly Replied, post #56 · Compounds › Retatrutide · 15 Jan 2025 · 0 likes Helpful, and short, which on this subject is harder than long.
[2026 update] New subcategory: rationale and scope Replied, post #114 · Meta › Announcements · 2 Jan 2025 · 12 likes Scheduled maintenance: if the site is going offline for maintenance, advance notice will be posted here with the duration and scope. The confident version of this…
What a stability-indicating method is and how you demonstrate one — one year on Replied, post #104 · Analytics › Method validation · 27 Dec 2024 · 28 likes Stability-indicating method: one that can separate a compound from its degradation products. Critical for assay methods that claim to measure actual degradation (as…
What a stability-indicating method is and how you demonstrate one — one year on Replied, post #88 · Analytics › Method validation · 5 Dec 2024 · 0 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. Somebody will have a better source…
Injection-site reactions: describing them precisely enough to be useful Replied, post #15 · Practice › Side effects · 20 Nov 2024 · 14 likes This follows post #14 rather than contradicting it. Answering the injection-site reactions question as asked, then the question I think is meant. As asked: yes, with…
Blind submission and why it changes minds Replied, post #87 · Sourcing › Independent verification · 14 Oct 2024 · 25 likes Blind submission would be much easier to settle if anyone reported the denominator. Almost nobody reports the denominator.
Requesting a page: what makes a good request — what changed since Replied, post #101 · Documentation › Wiki requests · 12 Oct 2024 · 0 likes A page that would need to be rewritten every quarter is usually better as a topic with a good marked solution.
Splitting a vial for two laboratories: how to do it without ruining both — what changed… Replied, post #89 · Sourcing › Independent verification · 27 Sep 2024 · 2 likes Reading rather than answering, but this is the post I would point somebody at.
Why a preprint's supplementary material is often the best part Replied, post #17 · Evidence › Preprints · 9 Sep 2024 · 18 likes This is the sort of exchange that makes the archive worth searching.
Tracking a preprint to publication: a worked example — the long version Replied, post #23 · Evidence › Preprints · 5 Aug 2024 · 2 likes Retractions and corrections do not propagate well from preprint servers. A citation that was fine when made can quietly become wrong.
Where the four-week escalation interval comes from, and what it is not Replied, post #51 · Practice › Dosing & titration · 17 Jul 2024 · 8 likes Post #47 put the caveat in the right place and I want to underline it. Two people in this thread mean different things by four-week escalation interval and are…
Tracking a preprint to publication: a worked example — the long version Replied, post #6 · Evidence › Preprints · 8 Jun 2024 · 1 like Where a preprint contradicts a published trial, the prior should favour the trial. Where it extends one, the preprint can be genuinely useful. Worth one more sentence…