November 2025

What a month without the drug does to tolerability

The convention — resume lower, re-escalate — is not caution. It follows directly from the elimination half-life.

What the trials counted as intolerance

We set out the questions that distinguish a symptom to manage from a dose to change.

Do you need the top of the ladder?

The dose-response curve in this class flattens near its top. That has direct consequences for whether the final rung is worth…

The area postrema, and the anatomy of an unwanted effect

Delayed gastric emptying is a mechanism that becomes an adverse effect above a threshold. It is not a complication in the…

The incidence tables, read line by line

Almost every figure in circulation about tolerability comes from six publications. This is what they say.

Delayed emptying explains some of this, and not all of it

The receptor populations that produce satiety and the ones that produce nausea overlap substantially. That is why the ceiling of…

Why the fifth week of a semaglutide dose feels different from the first

An accumulation model, drawn from published parameters, with its assumptions stated.

What happens in solution that does not happen in the cake

Every degradation pathway accelerates by orders of magnitude on reconstitution, because the solvent that lyophilisation removed…

What the four services actually offer, test by test

Endotoxin is the more tractable of the two questions, and a kinetic chromogenic determination is neither slow nor exotic. It is…

The pyrogen question has a price, and it is not the price of a purity run

A compendial sterility test takes fourteen days of incubation and consumes the containers tested. That timescale is incompatible…

Endotoxin is not a microorganism, and killing the bacteria does not remove it

The masking phenomenon known as low endotoxin recovery means a formulation can return a clean result while containing endotoxin…

Reproducibility, measured rather than assumed

The Journal submitted split samples from single lots to three assay services, under names unconnected to this publication, and…

Accreditation, scope, and the question nobody asks Medutest

A manufacturer’s certificate is a self-declaration. An accredited laboratory’s report is a third-party measurement. The trade…

Asparagine, glycine, and the two residues that decide a shelf life

We describe each pathway in enough chemical detail to explain why it is invisible to the method the trade uses, because that is…

What a low result means when intake has halved

Reduced intake is a plausible mechanism for deficiency. Reduced absorption is not, and the two are conflated in most of the…

HbA1c and its lag: what a result three months old is telling you

The assay is not the problem. The interpretation of a lagging integral as a current measurement is the problem.

Load, not cardio: the distinction the general advice keeps losing

Mass and function are different endpoints and training affects them differently. Most coverage treats them as one.

How much of retatrutide weight loss can any instrument actually attribute?

The instrument determines the answer more than the drug does, and the trade quotes the answer without naming the instrument.

What the trials monitored, and what that implies about routine practice

The argument for a baseline panel is that it makes every subsequent result interpretable. The argument against frequent…

How much of cagrilintide weight loss can any instrument actually attribute?

The compartment called lean mass contains water, glycogen, viscera and skin. Only some of it is the tissue anybody is worried…

The one-quarter rule, and the paper that took it apart

Grading six widely repeated claims against the studies actually behind them.

What has to change before a change has happened

A flag is a probability statement about a population. It is not a statement about the person holding the printout.

The retest date and the expiry date are not the same document

What would make a difference is not a regulator. It is three lines on a certificate, all of which are already known to whoever…

Why a 0.036-dalton difference is the hardest number in peptide identity

Calibration drift is real, unremarkable, and the reason serious laboratories run internal standards.

Why a dead-clean sterile filter can pass pyrogen straight through

Bacterial endotoxin is a heat-stable lipopolysaccharide from the outer membrane of Gram-negative organisms. It survives…

Pore size, particle size, and why peptides need the wide pores

Ion-pairing additives sharpen peptide peaks and suppress ionisation in the mass spectrometer, which is why the purity method and…

The reviewer, the approver, and why regulated documents carry two names

A manufacturer’s certificate is a self-declaration. An accredited laboratory’s report is a third-party measurement. The trade…

Adsorption, and the dose that stayed on the glass

An in-use period is established by a dedicated study on a specific formulation in a specific container at a specific…

Sterility is not a percentage, which is the whole difficulty

Every certificate circulating in this market answers a question about molecules. Almost none answers a question about organisms,…

The four testing services and the study none of them can run

We asked twenty companies three questions about stability data and print every answer, refusal and non-response.

Falling ferritin is not always falling iron

A substantial proportion of the abnormal results generated during rapid weight loss are consequences of the weight loss rather…

Why people actually stop, in the order they actually stop

Why the reason for stopping changes what happens afterwards.

The eighteenth month, and the conversation that should have happened in the third

Two withdrawal-design trials tell us what happens when treatment stops. Neither tells us what the lowest effective maintenance…

In-use periods, and the ones nobody can give you

A needle blunts on first use. Reuse is uncomfortable, and it is a documented contributor to lipohypertrophy.

Percentage of loss, absolute kilograms, and the sleight of hand between them

What was pre-specified, what was exploratory, and what was calculated afterwards by people who did not run the trial.

Load, not cardio: the distinction the general advice keeps losing

Mass and function are different endpoints and training affects them differently. Most coverage treats them as one.

Delayed emptying explains some of this, and not all of it

The receptor populations that produce satiety and the ones that produce nausea overlap substantially. That is why the ceiling of…

Maintenance dosing: what is licensed, what is practised, and what is evidenced

Every withdrawal trial compared full dose against nothing. The clinically interesting comparison — full dose against a reduced…

Same material, different gradients, different answers

The Journal submitted split samples from single lots to three assay services, under names unconnected to this publication, and…

The badge is about a sample. The listing is about a product.

Every step between the laboratory report and the product page removes information, and the badge is the last step.

Side effects, cost, supply, target: four reasons with four trajectories

Real-world persistence figures, with their definitions stated, because the definitions are doing most of the work.

How a claim degrades between the bench and the listing

A badge asserts that something was tested. It does not assert what, when, on whose sample, by what method, or whether the lot on…

Maintenance dosing: what is licensed, what is practised, and what is evidenced

Every withdrawal trial compared full dose against nothing. The clinically interesting comparison — full dose against a reduced…

The dose that got you here and the dose that keeps you here

What the labels permit, what clinicians do, and the size of the gap between them.

Why people actually stop, in the order they actually stop

A supply interruption is a discontinuation with no notice, no taper and no plan. That is a distinct clinical situation.

The named comparison we promised two years ago

Duplicate submissions under different names test within-laboratory repeatability, which is a different quantity from…

How much of exenatide weight loss can any instrument actually attribute?

A body-composition report gives four decimal places and no confidence interval. That is the whole difficulty in one sentence.

The cleanroom grade nobody names on the paperwork

The compendial sterility test cannot demonstrate that a batch is sterile. It can only fail a batch that is grossly contaminated.…

Why your laboratory interval differs from the one in the textbook

A flag is a probability statement about a population. It is not a statement about the person holding the printout.

Why the bone question is harder than the muscle question

A plausible mechanism, a measurable change, and no outcome data. This is what an open question looks like.

HbA1c and its lag: what a result three months old is telling you

HbA1c integrates roughly three months of glycaemia with the most recent weeks weighted most heavily. Almost every misreading of…

Why "muscle-sparing" is a marketing term and not a measurement

Grading six widely repeated claims against the studies actually behind them.

Why the independent testing market grew a chemistry arm and not a microbiology one

The absence of microbiological capability in this market is a commercial fact with a straightforward explanation, and it is…

Mapping a rotation that you will actually follow

The evidence base here is the insulin injection-technique literature, which is large and transfers well on tissue questions.

The wavelength decides which impurities exist

Peptide bonds absorb strongly near 214 nm; aromatic side chains absorb near 280 nm. A method reading at 280 is blind to any…

Six lines that would make an identity statement checkable

None of what a checkable identity statement requires is commercially sensitive, and all of it is known to whoever produced the…

How a single percentage came to stand for quality

This piece takes the measurement apart into the decisions it is made of, because each decision moves the answer.

Specification and result are two columns, and only one of them is a measurement

The arithmetic of significant figures, applied to a document that routinely reports four of them.

Why VendorInvestigate may run electrospray where another laboratory runs MALDI

The two ionisation techniques in general use produce different charge distributions, different adducts and different failure…

How a correct calculation becomes a wrong dose

A pharmacist catches most of these in licensed practice. In this market there is no pharmacist, so the checks have to be…