s.ferreira

TL2 Moderator · Coimbra

Contributes reviews on supplier material. Based in Coimbra.

Joined 19 October 2024 · last posted 1d

91 posts, newest first. Showing up to 150.

Second pass at: What a 2 ppm match establishes, and what it does not Replied, post #50 · Analytics › Mass spectrometry · 27 Jul 2026 · 4 likes post #49 answers the question as asked. The question underneath it is different. Purity and identity are different questions: LC-MS establishes that the species at a…
Private prescribing in the UK: what is actually involved Replied, post #74 · Regional › UK & Ireland · 24 Jul 2026 · 12 likes Private prescribing is legal and widespread, including through remote consultation. Pharmacies must satisfy themselves that a prescription is clinically appropriate.…
Micro-titration: a disputed topic, argued properly Replied, post #106 · Practice › Dosing & titration · 17 Jul 2026 · 18 likes Practical note that does not fit anywhere else. Whatever you conclude from this topic, write down what you did and when. The single most useful thing in your own…
Asking a follow-up: new topic or new reply? Replied, post #45 · Start Here › How to Ask · 9 Jul 2026 · 32 likes Thank you for the correction. I have edited my earlier post with a note rather than silently, so the thread still makes sense to read. The error was mine and it was the…
Revisiting: The best-written scientific paper you have read Replied, post #67 · Lounge › Off topic · 3 Jul 2026 · 3 likes Adjacent and interesting: you might post something about nutrition, bioavailability from a food perspective, or the sociology of weight. Adjacent to this community's…
Designing a personal experiment that could change your mind — one year on Replied, post #64 · Research Methods › N-of-1 designs · 22 Jun 2026 · 3 likes Statistical analysis of n-of-1 data: comparing before versus after with a t-test or similar is one approach. Plotting the data visually is another. Both are valid.
Follow-up: Comparing two chromatograms from different laboratories, properly Replied, post #43 · Analytics › HPLC & UHPLC · 15 Jun 2026 · 5 likes Column chemistry and particle size: smaller particles (1.7 μm) give better resolution and higher efficiency than larger particles (3.5 μm or 5 μm), at the cost of…
Racemisation and why it is invisible to a mass measurement Replied, post #96 · Analytics › Impurities & related substances · 14 Jun 2026 · 0 likes Off-target structures: if the sequence synthesis goes wrong, a completely different amino acid can be incorporated. The resulting off-target peptide is a structural…
Journal club: LEADER as the historical anchor Replied, post #87 · Evidence › Journal club · 10 Jun 2026 · 8 likes Worth separating two things that post #83 runs together. FLOW (N Engl J Med 2024): Semaglutide renal outcomes in type 2 diabetes and chronic kidney disease. Stopped…
I joined for one answer and stayed for a year — what changed my mind Replied, post #15 · Start Here › Welcome · 10 Jun 2026 · 18 likes Practical note that does not fit anywhere else. Whatever you conclude from this topic, write down what you did and when. The single most useful thing in your own…
Revisiting: Journal club: SURMOUNT-OSA and a hard endpoint in a soft field Replied, post #23 · Evidence › Journal club · 8 Jun 2026 · 0 likes On post #19 — agreed on the reasoning, with one qualification. STEP 1 (N Engl J Med 2021): The pivotal obesity trial for semaglutide and the reference point for most…
Follow-up: I have no scientific background — can I still follow the analytics categories? Replied, post #19 · Start Here › Welcome · 8 Jun 2026 · 0 likes Worth separating two things that post #15 runs together. There is no stupid-questions rule and no penalty for asking badly. The response to a poorly framed question is…
Talking to a therapist about this specifically Replied, post #9 · Wellbeing › Mental health · 1 Jun 2026 · 19 likes Body image and weight loss: large weight loss changes a person's relationship with their body in ways that can be psychologically complex. Some of that is positive;…
Follow-up: A parcel that arrived warm: a decision process, not a verdict Replied, post #37 · Practice › Storage & stability · 22 May 2026 · 7 likes I read post #35 twice before replying, because I had assumed the opposite. I want to gently push back on the reply above about storage extrapolation. The advice is…
[2026 update] 0.3 mL versus 0.5 mL versus 1 mL barrels: resolution matters Replied, post #109 · Devices › Syringes & needles · 11 May 2026 · 2 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…
A 5 mg vial and a 0.25 mg dose: the arithmetic in full Replied, post #41 · Practice › Reconstitution · 10 May 2026 · 1 like A vial that will not fully dissolve: check in order: is the diluent genuinely room temperature (some preservatives crystallise in cold), is the vial being warmed gently…
Second pass at: When your prescriber and the evidence disagree Replied, post #19 · Clinical › Prescriber conversations · 8 May 2026 · 8 likes Questions about dose: asking "how will we determine whether this dose is working for me" gets at the monitoring plan. Asking "can we start lower" or "can we escalate…
Does a peptide degrade silently, with no visual change? Replied, post #18 · Practice › Storage & stability · 29 Apr 2026 · 0 likes Beyond-use dating: the date after which a prepared solution should not be used. It is an estimate based on how fast the solution degrades under stated storage, not on…
Reimbursement variation across member states Started this topic · Regional › European Union · 29 Apr 2026 · 41 likes Reimbursement variation across member states Writing it up because I had to work it out twice and would rather nobody else did. A coverage question with the paperwork…
Journal club: is percentage weight change the right endpoint? Replied, post #97 · Evidence › Journal club · 23 Apr 2026 · 29 likes Picking up post #94: that is the part I would want checked first. SURMOUNT-1 (N Engl J Med 2022): Tirzepatide obesity trial. The largest mean weight reduction for a…
Revisiting: Body image changing more slowly than the body Replied, post #3 · Wellbeing › Mental health · 17 Apr 2026 · 0 likes Support and community: some people process weight change through community (online or in-person). Others prefer privacy. Knowing what you need and seeking it…
Second pass at: What "verified" means on our vendor pages, stated narrowly Replied, post #95 · Sourcing › Vendor reports · 16 Apr 2026 · 2 likes This follows post #92 rather than contradicting it. Date the report: when the analysis was done matters. Material can degrade in storage. A report from two years ago is…
Citation sweep results: how many references did not say what was claimed Replied, post #76 · Meta › Wiki maintenance · 12 Apr 2026 · 21 likes This follows post #73 rather than contradicting it. Orphaned pages: if a page has no incoming links and is not reachable from navigation, it is orphaned. Such pages…
List price versus negotiated price versus what you pay Replied, post #42 · Access › Pricing · 11 Apr 2026 · 0 likes I read post #40 twice before replying, because I had assumed the opposite. List prices versus negotiated prices: the price a pharmaceutical company publishes and the…
Subgroup analyses: pre-specified versus discovered — a second dataset Replied, post #35 · Evidence › Trials · 7 Apr 2026 · 2 likes Multiplicity and multiple comparisons: if a trial tests many hypotheses, the chance of a false positive on at least one by random chance increases. This is why…
Choosing which test to pay for, given a fixed budget Replied, post #57 · Sourcing › Independent verification · 6 Apr 2026 · 5 likes Coming back to post #55, because the follow-up matters more than the original answer. Blind sampling: submitting without the laboratory or seller knowing the source…
Personal import allowances, compared — a second dataset Replied, post #85 · Access › International · 14 Mar 2026 · 0 likes Worth separating two things that post #81 runs together. Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather…
Revisiting: Maintainer handover: how it works Replied, post #33 · Meta › Wiki maintenance · 6 Mar 2026 · 4 likes Evidence synthesis: if you think a page should cover recent evidence or a new development, suggesting specific content helps the maintainer prioritise updates.
Grapefruit: why this class is not the class that cares Replied, post #7 · Practice › Interactions · 3 Mar 2026 · 3 likes Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing. The correction was fair and I had…
Managing an unplanned gap in supply Replied, post #46 · Access › Shortages · 1 Mar 2026 · 7 likes Resuming after a gap: after a gap of days or a few weeks, most people resume at the dose they were on when they stopped. Gaps of months might require retitration…
Bioimpedance and hydration: why the number moves Replied, post #12 · Outcomes › Body composition · 27 Feb 2026 · 2 likes Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing. The correction was fair and I had…
The 2.5 mg starting dose is not a therapeutic dose — why that matters Replied, post #18 · Compounds › Tirzepatide · 17 Feb 2026 · 30 likes I read post #16 twice before replying, because I had assumed the opposite. Two things before anyone answers the substance. First, the context in the first post is clear…
Lean mass preservation: what the evidence supports — does this still hold? Replied, post #27 · Outcomes › Body composition · 14 Feb 2026 · 0 likes Bioelectric impedance analysis: less precise than DXA and strongly affected by hydration state. Not reliable for detecting month-to-month changes. Useful for trend over…
Revisiting: A page that has drifted out of date and needs a maintainer Replied, post #56 · Documentation › Wiki requests · 26 Jan 2026 · 1 like Worth separating two things that post #52 runs together. Accessibility feedback: if you have trouble accessing or reading a maintained page (screen reader issues,…
Follow-up: Bug report: the reconstitution calculator and a rounding edge case Replied, post #24 · Data & Tools › Calculators · 16 Jan 2026 · 27 likes Reporting bugs: if you notice a calculator giving wrong results, report it in this subcategory. Bugs are fixed when identified.
Second pass at: How to ask a question when you cannot say why you are asking it Replied, post #52 · Start Here › How to Ask · 13 Jan 2026 · 17 likes I read post #50 twice before replying, because I had assumed the opposite. Questions you cannot explain: "I cannot say why I am asking this, but is this compound stable…
Reading an interaction checker output critically Replied, post #85 · Practice › Interactions · 6 Jan 2026 · 12 likes Food interactions: most interactions are absorption interactions. Some medications absorb better with food, others better on an empty stomach. With an incretin agonist…
Availability by country, dated, with primary sources — one year on Replied, post #10 · Access › International · 25 Dec 2025 · 12 likes Compounding in different countries: some countries allow pharmacy compounding under defined conditions; others do not. The rules are jurisdiction-specific and change.
Prescription requirements and telehealth models Replied, post #66 · Sourcing › Regulatory · 14 Dec 2025 · 21 likes Why this category is maintained as documentation, not as recommendations: the goal is factual accuracy and sourcing, not endorsement of any specific regulatory position.
Tracking a preprint to publication: a worked example Replied, post #135 · Evidence › Preprints · 13 Dec 2025 · 4 likes Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing. The correction was fair and I had…
Filter needles: when they help and what they cost you Replied, post #2 · Devices › Syringes & needles · 8 Dec 2025 · 3 likes Sharps disposal: needles and syringes should be disposed in a sharps container (a rigid, puncture-resistant container). Do not put them in regular trash. Many…
LOD and LOQ: definitions people get wrong Replied, post #2 · Analytics › Method validation · 18 Nov 2025 · 0 likes Range: the concentration range over which the method has been validated. Going outside the validated range is going outside the method's demonstrated performance.
The headache that turns out to be dehydration Replied, post #60 · Nutrition & Training › Hydration & electrolytes · 17 Nov 2025 · 8 likes Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing. The correction was fair and I had…
Where to report an adverse event officially, by region — a second dataset Replied, post #123 · Safety › Adverse events · 12 Nov 2025 · 10 likes Coming back to post #121, because the follow-up matters more than the original answer. Pancreatitis is a genuine serious adverse event to know: severe epigastric pain,…
A parcel that arrived warm: a decision process, not a verdict Replied, post #114 · Practice › Storage & stability · 1 Nov 2025 · 15 likes Vial integrity: once a vial is entered with a needle repeatedly, the rubber closure degrades and the integrity fails. Using the same vial repeatedly over weeks or…
Why "any advice?" is the least effective ending for a post — the long version Replied, post #73 · Start Here › How to Ask · 21 Oct 2025 · 2 likes On post #69 — agreed on the reasoning, with one qualification. Arithmetic questions: write out the steps. "I have a 10 mg vial, I added 2 mL, I want a 0.25 mg dose, and…
Tracking that stops updating and then resumes Replied, post #35 · Sourcing › Logistics · 12 Oct 2025 · 0 likes I read post #33 twice before replying, because I had assumed the opposite. At what point is a parcel genuinely a problem: if it was despatched weeks ago and there has…
Comparing my trajectory with the trial curves, carefully Replied, post #55 · Outcomes › Progress reports · 29 Sep 2025 · 0 likes Exercise volume changes: increasing exercise intensity or duration can mask weight loss (muscle gain) on the scale. Noting exercise changes when reporting weight helps…
A checklist for reading a certificate in under two minutes — does this still hold? Replied, post #49 · Analytics › COA interpretation · 26 Sep 2025 · 0 likes post #48 is right about the mechanism and I think understates the practical bit. For anyone arriving from a search: the marked solution above is the direct answer, and…
Power cut for eleven hours: how I assessed it afterwards Replied, post #67 · Practice › Storage & stability · 22 Sep 2025 · 0 likes Vial integrity: once a vial is entered with a needle repeatedly, the rubber closure degrades and the integrity fails. Using the same vial repeatedly over weeks or…
Severe abdominal pain: why this is not a forum question — one year on Replied, post #2 · Safety › Adverse events · 18 Sep 2025 · 6 likes Allergic reactions: true allergy (anaphylaxis, severe rash) is rare with these peptide compounds but possible. Distinguishing true allergy from GI intolerance matters.
Reverse causation in a cohort study of weight and outcome — a second dataset Replied, post #122 · Evidence › Study critique · 16 Sep 2025 · 0 likes Confounding: in observational data, is there a third variable that explains the apparent association? In randomised data, randomisation should balance unknown…
Asking about a compound your prescriber has not heard of Replied, post #135 · Clinical › Prescriber conversations · 23 Aug 2025 · 30 likes Worth separating two things that post #131 runs together. Practical note that does not fit anywhere else. Whatever you conclude from this topic, write down what you did…
Angle of injection and whether 90 degrees is always right Replied, post #7 · Practice › Administration · 4 Aug 2025 · 19 likes For anyone arriving from a search: the marked solution above is the direct answer, and the replies underneath it add the caveats that make it safe to use.
Coming back to: Lurking for two months before posting: was that the right call? Replied, post #21 · Start Here › Welcome · 3 Aug 2025 · 0 likes Marked solutions are the site's way of saying that someone asked a good question and someone else gave an answer that actually worked. It is not a competition and it…
How to research a compound with no human data without deceiving yourself Replied, post #34 · Compounds › Other compounds · 31 Jul 2025 · 2 likes I disagree with the reply above, and I think the disagreement is substantive rather than terminological. The distinction being drawn does not survive when you look at…
Coming back to: Semaglutide half-life: where the 165 to 184 hour figure comes from Replied, post #85 · Compounds › Semaglutide · 24 Jul 2025 · 0 likes Coming back to post #83, because the follow-up matters more than the original answer. Is there a ceiling dose beyond which the effect plateaus? The trials did not study…
Asking about a compound your prescriber has not heard of Replied, post #100 · Clinical › Prescriber conversations · 20 Jul 2025 · 0 likes On post #96 — agreed on the reasoning, with one qualification. Preparing for an appointment: bring recent bloodwork, a list of current medications with doses and…
Coming back to: Why semaglutide solutions can look faintly opalescent and when that… Replied, post #2 · Compounds › Semaglutide · 20 Jun 2025 · 8 likes I read the opening post twice before replying, because I had assumed the opposite. Two things before anyone answers the substance. First, the context in the first post…
Why plausible mechanism is not evidence of effect Replied, post #14 · Compounds › Repair & healing peptides · 7 Jun 2025 · 19 likes Picking up post #11: that is the part I would want checked first. The absence of adequately powered published randomised human trials is the central fact about BPC-157.…
Pre-registering a personal experiment, seriously Replied, post #32 · Research Methods › N-of-1 designs · 28 May 2025 · 20 likes On post #28 — agreed on the reasoning, with one qualification. Blinding: blinding yourself (not knowing which condition you are in) removes expectation bias. This is…
Triple agonism: additive, synergistic, or neither? Replied, post #41 · Compounds › Retatrutide · 30 Apr 2025 · 1 like On post #37 — agreed on the reasoning, with one qualification. Retatrutide is investigational. Anything obtained outside a trial is by definition research-use-only…
Requesting a page: what makes a good request Replied, post #66 · Documentation › Wiki requests · 22 Apr 2025 · 0 likes Flag a page that has drifted: if you notice a maintained page has information that is outdated (dates that have passed, regulatory changes, new evidence) post a flag so…
Journal club: STEP 1 and the treatment-policy estimand — does this still hold? Replied, post #24 · Evidence › Journal club · 18 Apr 2025 · 12 likes TRIUMPH (ongoing): Retatrutide phase 3. No results yet. Nothing should be attributed to it because it has not finished. When it does, this discussion will return to it.
About the Secretagogues & GH axis category Replied, post #6 · Compounds › Secretagogues & GH axis · 13 Apr 2025 · 20 likes Evidence quality in the secretagogue literature is honestly weaker than in the incretin literature. Large randomised controlled trials are rare. Most evidence is…
Sequence verification for an obscure compound: how it is done Replied, post #11 · Compounds › Other compounds · 12 Apr 2025 · 18 likes AOD-9604 is a fragment of human growth hormone and has been discussed as a potential weight-loss agent based on theoretical mechanism. The fragment hypothesis — that…
A supplier that answers analytical questions with restated claims Replied, post #53 · Sourcing › Red flags · 7 Apr 2025 · 12 likes Documentation quality as a signal: a supplier that reports method identifiers, distinguishes specification from result, and states the counter-ion form is telling you…
Carryover and the ghost peak from last week's standard Replied, post #49 · Analytics › HPLC & UHPLC · 7 Apr 2025 · 0 likes This follows post #46 rather than contradicting it. Detection wavelength: 214 nm detects the peptide bond and is relatively insensitive to composition. 280 nm detects…
A certificate with no method stated: what can you conclude? Replied, post #18 · Analytics › COA interpretation · 2 Apr 2025 · 0 likes Coming back to post #16, because the follow-up matters more than the original answer. What fields matter on a certificate: lot number matching the vial, test date, the…
Second pass at: Gauge and length selection for subcutaneous injection Replied, post #49 · Devices › Syringes & needles · 2 Apr 2025 · 0 likes Thank you for the correction. I have edited my earlier post with a note rather than silently, so the thread still makes sense to read. The error was mine and it was the…
Revisiting: Completing a dose with a second syringe, and the dead-volume arithmetic Replied, post #9 · Practice › Administration · 30 Mar 2025 · 0 likes Leak-back after withdrawal: a small amount of liquid on the skin after withdrawal is ordinary. Whether you lost a "meaningful" dose depends on concentration and your…
Coverage for the indication versus for the drug — a second dataset Replied, post #50 · Access › Insurance & coverage · 29 Mar 2025 · 12 likes Generic versus brand: most of these compounds do not have generic versions yet. Once they do, formulary coverage and pricing will shift.
Coming back to: GHRH analogues versus ghrelin mimetics: different mechanisms, conflated… Replied, post #14 · Compounds › Secretagogues & GH axis · 12 Mar 2025 · 8 likes Two things before anyone answers the substance. First, the context in the first post is clear and specific. Second, the question is framed so that an answer can…
Review: a draft on reconstitution arithmetic, with objections Replied, post #22 · Documentation › Doc review · 14 Feb 2025 · 1 like post #21 is right about the mechanism and I think understates the practical bit. Review of promoted topics: when a topic is nominated for promotion to a maintained…
Second pass at: Cross-border purchase within the EU: the actual rules Replied, post #43 · Access › International · 14 Feb 2025 · 32 likes This follows post #40 rather than contradicting it. Country-by-country legality: compound approval and legal status differ substantially by jurisdiction. Semaglutide…
Revisiting: Heart failure with preserved ejection fraction: symptom endpoints Replied, post #6 · Clinical › Comorbidities · 26 Jan 2025 · 4 likes Practical note that does not fit anywhere else. Whatever you conclude from this topic, write down what you did and when. The single most useful thing in your own…
Research-use-only labelling: what it means and what it does not — the long version Replied, post #54 · Sourcing › Regulatory · 30 Dec 2024 · 0 likes Approval versus licensing: a compound can be approved for a specific indication in one country and not approved at all in another. Tracking jurisdictional approval is…
Why pulsatile secretion matters for interpreting secretagogue claims — a second dataset Replied, post #32 · Compounds › Secretagogues & GH axis · 29 Dec 2024 · 7 likes What a well-designed human trial of a secretagogue would look like: randomised, placebo-controlled, adequate sample size, IGF-1 as primary outcome, muscle and strength…
Converting between mg/mL and units per dose, both directions Replied, post #124 · Practice › Reconstitution · 10 Dec 2024 · 10 likes post #123 answers the question as asked. The question underneath it is different. Thank you for the correction. I have edited my earlier post with a note rather than…
[2026 update] New subcategory: rationale and scope Replied, post #37 · Meta › Announcements · 2 Dec 2024 · 2 likes Archives: older announcements are archived by date. Checking archives is useful if you want to know what changed when.
Athletes in weight-category sports: a different risk calculus — a second dataset Replied, post #27 · Clinical › Special populations · 25 Nov 2024 · 18 likes Pregnancy and planning: these compounds are not approved for use in pregnancy. Planning windows (how long to wait before attempting pregnancy) are not formally…
Washout with a one-week half-life: the arithmetic Replied, post #5 · Research Methods › N-of-1 designs · 22 Nov 2024 · 20 likes I read post #3 twice before replying, because I had assumed the opposite. Designing a personal experiment that could actually change your mind: that is the standard for…
Revisiting: Moderation log format change Replied, post #19 · Meta › Announcements · 7 Nov 2024 · 0 likes post #18 is right about the mechanism and I think understates the practical bit. Archives: older announcements are archived by date. Checking archives is useful if you…
Second pass at: A field-by-field walk through a certificate of analysis Replied, post #91 · Analytics › COA interpretation · 21 Oct 2024 · 19 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…
What a stability-indicating method is and how you demonstrate one — one year on Replied, post #52 · Analytics › Method validation · 15 Oct 2024 · 8 likes Robustness: the method gives consistent results when minor parameters vary. Tested by deliberately varying pH, temperature, flow rate, and mobile phase composition…
Why we hide unevidenced fraud accusations and log the hiding Replied, post #6 · Sourcing › Red flags · 15 Oct 2024 · 2 likes Practical note that does not fit anywhere else. Whatever you conclude from this topic, write down what you did and when. The single most useful thing in your own…
Progressive overload when the scale is falling — one year on Replied, post #150 · Nutrition & Training › Resistance training · 12 Oct 2024 · 16 likes Worth separating two things that post #146 runs together. Cardio and resistance: the interaction between energy-intense cardiovascular training and resistance training…
US compounding rules and how they changed Replied, post #15 · Regional › North America · 7 Oct 2024 · 22 likes This follows post #12 rather than contradicting it. Provincial formularies in Canada are published and are the correct source for coverage information. Coverage for…
How to ask for a dose change without antagonising anyone Replied, post #15 · Clinical › Prescriber conversations · 16 Aug 2024 · 0 likes Prescription logistics: confirm whether it will be filled locally, requires mail order, or will be prescribed off-label and needs a compounding pharmacy. Different…
Promotion criteria, and the one that stops most nominations Replied, post #39 · Documentation › Doc review · 16 Aug 2024 · 6 likes Fact-checking: if you see a factual claim in a maintained page that you have evidence contradicts, post the evidence here. The maintainer will review and correct if you…
Why I ask for the gradient before I discuss the number Replied, post #2 · Analytics › HPLC & UHPLC · 14 Jun 2024 · 1 like Before anything else: what was the gradient, and at what wavelength? Area percent at different wavelengths is not the same number even on the same sample because…