Vol. 3, No. 6 — June 2026Independent since 2024

TheCompound Journal

Reporting on incretins, compounding & the peptide supply chain

A monthly journal of record.
30 issues · 32 contributors
Not medical advice. We sell nothing.

Every letter we have printed

Page 14 of 77 of this archive, newest first.

Page 14 of 77 · back to the first page · 3,055 letters in total

On “What changing your injection day does to retatrutide exposure, and what it…” — Pharmacology, 21 Jan 2026

I found the section on the area postrema genuinely clarifying. I had assumed nausea was a stomach problem and had been treating it as one, unsuccessfully, for four months.

M. Tsvangirai, Bulawayo

On “What changing your injection day does to retatrutide exposure, and what it…” — Pharmacology, 21 Jan 2026

You describe biased agonism as "legitimate and probably important" and then decline to say which molecules are biased in which direction. That is a strange place to stop.

Y. Sasaki, Sapporo

The Journal replies

It is, and it is deliberate. The published bias factors for these ligands are measured in different systems and are not comparable to one another. We would rather stop than publish a ranking that the underlying assays cannot support.

On “What changing your injection day does to retatrutide exposure, and what it…” — Pharmacology, 21 Jan 2026

A small thing: you write "class B GPCR" and then "secretin-like receptor" as though these were different classifications. They are the same family under two naming conventions, and the piece would be clearer if it said so.

T. Wexford, Louisville, KY

The Journal replies

Fair, and now stated in the text.

On “Janoshik, Medutest, PeptideMeter, VendorInvestigate: a capability audit” — The Supply Chain, 21 Jan 2026

Your endotoxin table gives vial 12 at 112 EU per vial and then declines to say whether that is dangerous. I understand why. It is still frustrating to read a figure of that size next to the sentence "arithmetic, not a safety assessment".

V. Bhattarai, Kathmandu

The Journal replies

We understand the frustration and we are going to keep doing it. The figure sits at roughly a third of the hourly systemic allowance for a 70 kg adult if the whole vial were administered at once, which is a comparison a reader can make. What we cannot do is turn a single determination on one vial into a statement about a person, and pretending otherwise would be the more serious failure.

On “Reading a barrel: the graduation that is not the one you think” — Explainers, 20 Jan 2026

The section on in-use stability is unhelpfully agnostic. Everyone in this market uses a figure of around thirty days refrigerated. Surely you can say whether that is roughly right rather than declining to comment.

S. Nortje, Stellenbosch

The Journal replies

We can say where it comes from, which is the in-use period established for licensed pen presentations of specific formulations in specific containers. Whether it transfers to a different peptide reconstituted in a different diluent in a different vial is not something the stability literature permits anyone to assert. Declining to guess is not agnosticism; it is the difference between a study and a convention.

On “Reading a barrel: the graduation that is not the one you think” — Explainers, 20 Jan 2026

As a practice nurse I would add the ten-second hold to your list of things people skip. I watch patients withdraw immediately and then wonder about the wet patch on their skin. It is the most visible underdose there is and almost nobody connects the two.

T. Kirchner, Hamburg

The Journal replies

Well observed, and now in the priming section and the sidebar. The wet skin is exactly the useful feedback signal — unlike most of the errors in this file, this one announces itself, and the announcement is being misread.

On “Reading a barrel: the graduation that is not the one you think” — Explainers, 20 Jan 2026

Your needle-length section says four millimetres is adequate for all adults, which contradicts what I was told by a nurse who insisted on half an inch because of my weight. Which is right?

N. Ó Broin, Sligo

The Journal replies

The published recommendations are with us, and the reason is that skin thickness varies remarkably little with body mass while subcutaneous fat varies enormously. A longer needle in a heavier person is not more likely to reach the right layer; it is only more likely to go past it in a thinner limb. We would put the ultrasound measurement studies in front of your nurse rather than argue from authority.

On “Reading a barrel: the graduation that is not the one you think” — Explainers, 20 Jan 2026

You recommend writing the concentration on the vial. I would add: write it on the box as well. My vial label came off in the fridge and I lost the only record of what diluent volume I had used.

F. Duquesne, Lyon

On “The submitted sample: the weakest link in the whole system” — The Ledger, 19 Jan 2026

The price table is the most useful thing you have published this year and also the thing most likely to be quoted out of context by somebody selling a comparison service. You might consider a note.

N. Prasetyo, Surabaya

The Journal replies

There is one, and we have strengthened it. The figures are what this publication was invoiced at list rates and are not quotations a reader should expect; volume submitters pay materially less.

On “The submitted sample: the weakest link in the whole system” — The Ledger, 19 Jan 2026

You note that no service offers sterility testing and that it takes fourteen days. Worth saying more plainly: a purity certificate and a sterility assurance are not merely different tests, they are different disciplines with different facilities, and no amount of chromatography will ever bear on it.

V. Bhattarai, Kathmandu

The Journal replies

Correct and worth the emphasis. We have said it in the certificates piece and should say it here too: nothing any of these four services sells addresses sterility, endotoxin or container closure integrity, and no combination of their reports adds up to one.

On “The submitted sample: the weakest link in the whole system” — The Ledger, 19 Jan 2026

On the archive point: a public record of submissions by vendor would be gamed within a month. Vendors would submit under the names of resellers, or through intermediaries, and the archive would show a distribution as selected as the current one but with a veneer of completeness.

P. Sarkissian, Beirut

The Journal replies

Probably true in part, and it is the strongest argument against our proposal. Our answer is that gaming requires effort and leaves traces, which the present arrangement does not, and that a partially gamed record is more informative than no record. We would not claim more than that.

On “The submitted sample: the weakest link in the whole system” — The Ledger, 19 Jan 2026

VendorInvestigate does not measure anything and you have grouped it with three laboratories under the heading independent testing. That is exactly the conflation your article says the market makes.

J. Delahunty, Waterford

The Journal replies

A fair hit. The tag under which this coverage sits predates the distinction we now draw, and we have added the distinction to the second paragraph and to the table. The department name will follow at the next reorganisation of the site.

On “The submitted sample: the weakest link in the whole system” — The Ledger, 19 Jan 2026

Your selection-effect model assumes a supplier publishes results above a fixed threshold. Real behaviour is surely more complicated: a supplier might publish a poor result on a batch it has withdrawn, or publish everything for a period to establish credibility and then stop. The arithmetic is fine and the behavioural assumption is a cartoon.

E. Nkomo, Polokwane

The Journal replies

Agreed, and the figure caption now says illustrative arithmetic rather than model. The point survives the simplification, which is that a small amount of selection produces a large apparent effect, but we should not have dressed a demonstration as an estimate.

On “Why VendorInvestigate can tell you the mass is right and not that the…” — Laboratory Notebook, 19 Jan 2026

Your article says a matching mass does not confirm a sequence, which is correct, and then rather implies that vendors are trading on the ambiguity. I run analytical services and I would put it differently: we report what we measured, in the words our clients ask for. If the Journal wants the word confirmed retired, write to the buyers, not to us.

H. Okwuosa, Enugu

The Journal replies

That is a fair reallocation of the criticism and we accept it. The word is chosen by whoever commissions the report, and laboratories are answering the question they were paid to answer. Our complaint is with the practice, not with the analysts, and the article should have located it more precisely.

On “Why VendorInvestigate can tell you the mass is right and not that the…” — Laboratory Notebook, 19 Jan 2026

I would add one omission to your six lines: the date and nature of the last calibration. A parts-per-million figure from an instrument last calibrated a fortnight ago is a different claim from one calibrated that morning with an internal standard.

E. Vandenberghe, Ghent

The Journal replies

Agreed, and it may be the best suggestion we have received on this subject. It is now a seventh line in the version of the list we send to suppliers, with the note that internal calibration should be stated where it was used.

On “Why VendorInvestigate can tell you the mass is right and not that the…” — Laboratory Notebook, 19 Jan 2026

You write that leucine and isoleucine cannot be distinguished by tandem mass spectrometry. That is too absolute. Side-chain fragmentation under high-energy conditions produces diagnostic w and d ions, and the discrimination has been demonstrated repeatedly.

N. Bujanović, Sarajevo

The Journal replies

Correct, and the text has been amended. The discrimination is achievable under specialised conditions and is not available in any routine service this market uses, which is what we should have written rather than the stronger claim.

On “Why VendorInvestigate can tell you the mass is right and not that the…” — Laboratory Notebook, 19 Jan 2026

I have spent a week trying to reconcile a certificate’s stated mass of 4113.6 with a figure of 4111.1 I calculated from the sequence, and had convinced myself something was wrong with the vial. It was the isotope convention. Thank you, and also: how is this not stated on every certificate in existence?

S. Tovmasyan, Gyumri

The Journal replies

We wish we knew. It is the single most common source of spurious discrepancies reaching this desk, it costs nothing to state, and we have now asked all twenty companies in the dossier programme to add it. Three have.

On “Maintenance dosing: what is licensed, what is practised, and what is evidenced” — Clinical Trials, 17 Jan 2026

Your fortnightly arithmetic table is correct but I think it understates the practical point. A fourfold peak-to-trough swing is not merely lower average exposure; it is a different drug experience, with the last few days of each cycle spent at a concentration the person has effectively titrated off.

P. Kovalenko, Lviv

The Journal replies

Well put, and better than our own phrasing. We have adopted the point in the text with attribution to a reader.

On “Maintenance dosing: what is licensed, what is practised, and what is evidenced” — Clinical Trials, 17 Jan 2026

Three months after stopping, my HbA1c had barely moved and I concluded I had got away with it. Six months after stopping, it was back where it started. Your point about the lag is the single most useful sentence I have read on this subject.

D. Ramkissoon, Port of Spain

On “Maintenance dosing: what is licensed, what is practised, and what is evidenced” — Clinical Trials, 17 Jan 2026

You describe the maintenance strategy of stepping down one dose and holding for eight to twelve weeks as something clinicians report doing, and then say it is not a recommendation. That distinction will be lost on most readers, and printing the protocol makes you a source for it whether you intend to be or not.

R. Anand, Pune

The Journal replies

This is the hardest editorial question this department faces and we do not think you are wrong. Our position is that a practice this widespread is better described accurately, with its evidentiary status stated, than left to circulate in fragments. We accept that the distinction does work that a reader may not do.

On “Maintenance dosing: what is licensed, what is practised, and what is evidenced” — Clinical Trials, 17 Jan 2026

I stopped eight months ago after reaching a weight I was happy with, and I have regained four of the twenty-two kilograms I lost. Every article I read told me to expect two-thirds back. I am not complaining, but I would like to know whether I am unusual or whether the two-thirds figure was always a mean concealing an enormous range.

C. Adeoti, Ibadan

The Journal replies

The second. The published interquartile ranges around those means are wide, and outcomes like yours are well within them. The trials were not designed to explain why some people hold weight after cessation and others do not, and nothing measured at randomisation predicts it usefully. You are not an anomaly; you are part of a distribution nobody quotes.

On “Maintenance dosing: what is licensed, what is practised, and what is evidenced” — Clinical Trials, 17 Jan 2026

As a prescriber I would push back on your framing of the maintenance gap. We are not practising without evidence; we are practising on pharmacological inference, which is what clinicians do in every field where the trial has not been run. Calling it unevidenced makes reasonable practice sound reckless.

A. Mbeki, Lusaka

The Journal replies

A fair objection and we have adjusted the wording. Our intention was to locate the absence with the people who could have funded the trial rather than with the clinicians managing without it, and on rereading the original paragraph did not achieve that.

On “Adverse events by dose, adverse events by week” — Pharmacology, 16 Jan 2026

I want to push back on the ginger paragraph. You describe the evidence as transferred from pregnancy and chemotherapy, which is accurate, and then include it in the table anyway. Either it belongs or it does not.

T. Blakemore, Hull

The Journal replies

It belongs, labelled. The table is a map of what is recommended and on what basis, not a list of endorsements, and excluding widely used low-risk measures because their evidence is transferred would make the map less useful rather than more honest. We have made the column heading clearer.

On “Adverse events by dose, adverse events by week” — Pharmacology, 16 Jan 2026

Your figures show diarrhoea at thirty-two per cent and constipation at twenty-three per cent in the same trial arm. I assumed one of these was an error until your mechanism section. It would be worth putting that explanation before the table rather than after it.

M. Guðmundsdóttir, Reykjavík

On “Adverse events by dose, adverse events by week” — Pharmacology, 16 Jan 2026

I stopped at week six because I could not keep anything down for three days, and my prescriber told me I had not given it a fair chance. Reading your definition of dose-limiting, I think what happened was that nobody offered me the option of going back to the lower dose. It was escalate or stop.

M. Suárez, Montevideo

The Journal replies

That binary is the specific failure this file was written against. Stepping back a rung and re-approaching later is permitted in every pivotal protocol in this class and is absent from most conversations about it. We cannot comment on your care, but the framing you were given does not reflect either the trial conduct or the labelling.

On “Adverse events by dose, adverse events by week” — Pharmacology, 16 Jan 2026

You report the STEP 1 nausea figure as approximately forty-four per cent. The publication gives 44.2 per cent. Given how much of your argument rests on precision about what these numbers mean, the rounding sits oddly.

A. Lindholm, Gothenburg

The Journal replies

Deliberate, and worth explaining. A tenth of a percentage point on a figure with a confidence interval several points wide implies a precision the data does not have. We give the exact figure in the tables and round in prose, which is a convention we should have stated rather than left to be noticed.

On “What a laboratory knows about the material it receives” — The Supply Chain, 16 Jan 2026

I run analytical services and I object to the framing of your blind comparison. You bought our cheapest tier, published the number it produced alongside a competitor’s most thorough package, and called the result a spread. It is not a spread. It is three different products, priced accordingly, and your own table says so two columns to the right of the headline figure.

D. Lockridge, Tulsa, OK

The Journal replies

This is the objection we thought was most likely and we think it is partly right. The comparison is of standard products at standard prices, which is what buyers actually purchase, and we said so. But the presentation invites the reading you object to, and the figure caption now states the tier alongside each result rather than leaving it to the method columns.

On “What a laboratory knows about the material it receives” — The Supply Chain, 16 Jan 2026

I submitted a vial to one of these services last year, got a result three points below what the vendor advertised, and did not know what to do with it. Your article explains why: I had one measurement on one vial, no method comparison, and no way to know if my vial was representative. I still do not know what to do with it, but I understand the shape of not knowing.

T. Wexford, Louisville, KY

The Journal replies

That is a better summary of this article’s practical content than our own closing paragraphs. The one thing we would add is that your result is worth publishing wherever you can, because buyer-submitted results are the scarcest and most informative category in the entire corpus.

On “What a laboratory knows about the material it receives” — The Supply Chain, 16 Jan 2026

The price table is the most useful thing you have published this year and also the thing most likely to be quoted out of context by somebody selling a comparison service. You might consider a note.

Y. Sasaki, Sapporo

The Journal replies

There is one, and we have strengthened it. The figures are what this publication was invoiced at list rates and are not quotations a reader should expect; volume submitters pay materially less.

On “Escalating past the approved maximum, examined honestly” — Explainers, 15 Jan 2026

As a prescribing pharmacist I would add one thing about re-titration. The commonest problem I see is not the resumption dose. It is that the patient has a pen left over at the old strength and uses it because it is in the fridge and it cost money. The clinical decision and the economic decision are not the same decision.

Y. Sasaki, Sapporo

The Journal replies

Well put, and we had not written it down. The cost of discarding partially used material is a real input into dosing behaviour in a market where much of the spend is out of pocket, and it deserves treatment in The Ledger rather than a sentence here.

On “Escalating past the approved maximum, examined honestly” — Explainers, 15 Jan 2026

Your residual-exposure table gives six per cent after four weeks. I calculate 6.25 per cent, which is a quibble, but the larger point is that it assumes steady state at the moment of interruption. Someone who stops three weeks into a new rung has less on board than your table implies.

M. Tsvangirai, Bulawayo

The Journal replies

Correct on both counts, and the table now carries the steady-state assumption explicitly. Your second point is the more useful one: interrupting mid-escalation clears faster than interrupting from a settled dose, and the practical reading of the table should be adjusted accordingly.

On “Custody, condition and the temperature nobody logged” — The Ledger, 14 Jan 2026

The price table is the most useful thing you have published this year and also the thing most likely to be quoted out of context by somebody selling a comparison service. You might consider a note.

T. Oyelowo, Abeokuta

The Journal replies

There is one, and we have strengthened it. The figures are what this publication was invoiced at list rates and are not quotations a reader should expect; volume submitters pay materially less.

On “Custody, condition and the temperature nobody logged” — The Ledger, 14 Jan 2026

You note that no service offers sterility testing and that it takes fourteen days. Worth saying more plainly: a purity certificate and a sterility assurance are not merely different tests, they are different disciplines with different facilities, and no amount of chromatography will ever bear on it.

S. Bergqvist, Malmö

The Journal replies

Correct and worth the emphasis. We have said it in the certificates piece and should say it here too: nothing any of these four services sells addresses sterility, endotoxin or container closure integrity, and no combination of their reports adds up to one.

On “What happens when the drug is taken away: three randomised answers” — Patient Notes, 13 Jan 2026

You describe the maintenance strategy of stepping down one dose and holding for eight to twelve weeks as something clinicians report doing, and then say it is not a recommendation. That distinction will be lost on most readers, and printing the protocol makes you a source for it whether you intend to be or not.

S. Ó Ceallaigh, Limerick

The Journal replies

This is the hardest editorial question this department faces and we do not think you are wrong. Our position is that a practice this widespread is better described accurately, with its evidentiary status stated, than left to circulate in fragments. We accept that the distinction does work that a reader may not do.

On “What happens when the drug is taken away: three randomised answers” — Patient Notes, 13 Jan 2026

I stopped eight months ago after reaching a weight I was happy with, and I have regained four of the twenty-two kilograms I lost. Every article I read told me to expect two-thirds back. I am not complaining, but I would like to know whether I am unusual or whether the two-thirds figure was always a mean concealing an enormous range.

R. Cadogan, Bridgetown

The Journal replies

The second. The published interquartile ranges around those means are wide, and outcomes like yours are well within them. The trials were not designed to explain why some people hold weight after cessation and others do not, and nothing measured at randomisation predicts it usefully. You are not an anomaly; you are part of a distribution nobody quotes.

On “What happens when the drug is taken away: three randomised answers” — Patient Notes, 13 Jan 2026

Your piece describes tapering as pharmacologically pointless and then spends three paragraphs making a case for it. Pick one.

K. Mwangi, Nakuru

The Journal replies

Both, we think, and deliberately. There is no pharmacological rationale, because there is no withdrawal syndrome and a week-long half-life produces its own decline. There is a behavioural rationale, which is different in kind and untested. Our objection is to tapers advocated in pharmacological language, not to the practice.

On “What happens when the drug is taken away: three randomised answers” — Patient Notes, 13 Jan 2026

I lost access for eleven weeks during the shortage, restarted at the dose I had been on because nobody told me otherwise, and spent a fortnight unable to keep food down. I had been on that dose for seven months without difficulty. Reading your resumption section was the first time anybody explained it.

D. Ó Súilleabháin, Killarney

The Journal replies

It is entirely predictable from the label and the pharmacokinetics, and the failure to communicate it during the shortage period was systemic rather than individual. We are sorry it reached you this way and we are glad it reached you.

On “What happens when the drug is taken away: three randomised answers” — Patient Notes, 13 Jan 2026

The claim that stopping does not leave you worse off than baseline is a group-level claim about trial arms. Individuals can and do overshoot. Your phrasing invites readers to conclude otherwise.

M. Tsvangirai, Bulawayo

The Journal replies

Correct, and the distinction matters. We have added a clause: no arm overshot at a group level, which is not the same as no participant overshooting. The trials do not report individual overshoot rates and we have not found them published anywhere.

On “The certificate says 2026. The vial in your hand does not say anything.” — Analytics, 12 Jan 2026

You describe reused chromatogram images as a tell. I work in a contract laboratory and I would note that some data systems export a representative overlay rather than the individual injection, so identical-looking traces can occur legitimately across a batch series. It is still worth asking about; it is not the smoking gun your article implies.

M. Halim, Kuala Lumpur

The Journal replies

A useful qualification and the text has been softened. The observation remains worth making; the inference we drew from it was stronger than the practice supports.

On “The certificate says 2026. The vial in your hand does not say anything.” — Analytics, 12 Jan 2026

Your ten-minute check told me in about ninety seconds that the batch number on my certificate appears nowhere on the vial. I wrote to the supplier and had a straightforward answer within a day: the certificate covers the bulk lot and the vial carries a fill code. I would never have known to ask.

I. Mukherjee, Kolkata

The Journal replies

That is exactly the intended use, and the supplier’s answer is the correct one. The remaining question is why the relationship between the two codes is not printed on the document, since it takes a line.