August 2024

Holding a dose is a decision, not a failure

Reducing a dose is not going backwards. In a tolerability-limited class it is the mechanism by which the ceiling is found.

Beta-arrestin, cAMP, and the part of exenatide’s mechanism nobody quotes

The receptor is expressed in more tissues than the popular account allows, and that is the whole story.

Discontinuation rates, read honestly

An effect is dose-limiting when it prevents adequate intake, prevents normal activity, or produces a risk of its own. Discomfort…

Six things incretin pharmacology cannot currently predict

The mechanism is well described. The variance is not.

The limits of mechanism: why receptor data will not tell you who responds

The mechanism is well described. The variance is not.

The area postrema, and the anatomy of an unwanted effect

A single drug producing both constipation and diarrhoea looks contradictory until the motility data is read properly.

Target dose, effective dose, and the distance between them

What the trials measured was continuation against withdrawal. What patients want to know is continuation at a lower dose, and…

Stepping down is part of titration

Nausea and gastric delay attenuate over weeks at an unchanged dose. That single physiological fact is the entire justification…

How a claim degrades between the bench and the listing

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

Everything on the page, in the order a chemist would read it

The header identifies the batch, the table records the tests, and the footer says who is answerable. Two of the three are…

Four ways a peptide comes apart

Reversed-phase chromatography runs in an organic, acidic mobile phase that dissociates most non-covalent aggregates on the way…

One vial, four weeks, and the data that does not exist

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

Accreditation, scope, and the question nobody asks PeptideMeter

Two signatures — one who performed the work, one who approved its release — are the ordinary regulated convention and are almost…

The question no chromatogram has ever answered

The Journal has read several hundred certificates from twenty companies. We set out what the documents actually cover, and what…

Oxidation, and the peroxide that came in with the surfactant

The sequence predicts the failure mode. A methionine predicts oxidation; an asparagine followed by a glycine predicts…

Two scans, six weeks apart, and the arithmetic of believing the difference

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

The substudies, read properly: who was scanned, when, and with what

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

Which results are findings and which are consequences of the weight loss

The estimated glomerular filtration rate is calculated from creatinine, creatinine comes from muscle, and muscle mass is…

Bone density during rapid weight loss: what is known, which is less than you would hope

Density is a proxy for strength and an imperfect one, particularly when soft-tissue thickness over the measurement site is…

Monitoring intervals, and the case against measuring too often

A panel that will not change a decision is a panel that generates work.

The glycated haemoglobin assay, and the eight conditions that break it

The alternatives with shorter windows, what they measure, and why they are rarely ordered.

Grams per kilogram of what? The denominator problem in protein guidance

Where the familiar figures come from, what populations they were measured in, and how far the extrapolation reaches.

Twenty-eight days is a number from somebody else’s product

Bacteriostatic water contains benzyl alcohol at 0.9 per cent, which inhibits microbial growth in a preserved multiple-dose…

LAL, kinetic chromogenic, recombinant factor C: three ways to the same figure

The limit for a parenteral product is calculable from the dose and the body weight in two lines. Almost nobody in this trade…

A named analyst is the cheapest quality signal in this trade

What the Journal asks when a document arrives unsigned, and what the answers have been.

Electrospray, MALDI, and the choice that shapes every spectrum after it

A brief and unromantic tour of the interface between a liquid sample and a vacuum.

We split six vials four ways and posted them

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

The empty half of every certificate of analysis

Purity, content, identity, sterility and endotoxin are five separate determinations. A single sheet of paper carrying one of…

What the sequence tells you about how a peptide will fail

Reversed-phase chromatography runs in an organic, acidic mobile phase that dissociates most non-covalent aggregates on the way…

The reference change value: the number that tells you whether a delta is real

Almost every misreading of a laboratory panel is a misunderstanding of what a reference interval is and how much a result has to…

The effect profile, predicted from an expression map

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

Reflux, early satiety, and the volume the stomach will accept

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

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

The clinical effect profile is almost fully predictable from where the receptor is expressed, which is unusual and useful.

Two-thirds back: the extension nobody expected to be the headline

What was withdrawn, from whom, after how long, and what was measured afterwards.

Diminishing returns, quantified

Where the curve flattens, what flattens with it, and what does not.

The out-of-range flag is a statistical convention with a printer attached

The arithmetic of the reference change value, worked for the analytes that matter here.

Six words a verification badge would need to mean anything

What a verification mark would have to carry to be checkable: a date, a lot, a method, a submitter and a link to the report.

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

A survey of the maintenance evidence, which is shorter than the survey of the withdrawal evidence.

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

Dose reduction is not withdrawal, and the trials that tested withdrawal cannot be read as testing it.

From vial to bench: what is recorded and what is assumed

A result on one vial generalises to a batch only if the vial was drawn in a way that makes it representative — and nobody…

What the placebo arms of the withdrawal trials actually tell us

The evidence on stopping is better than the evidence on almost anything else in this field, because somebody deliberately…

Why a result on one vial says less than the trade needs it to

Every third-party report in this market describes a sample somebody chose to send. That choice is outside the laboratory’s…

What happens when the drug is taken away: three randomised answers

Three randomised withdrawal designs have tested what happens when treatment stops. Their results are consistent and they are…

The badge economy, and what it is actually certifying

The Journal does not treat a badge as evidence and states so wherever it reports one.

Two ways to lift a peptide into a vacuum, and why the answer differs

The ionisation method determines the charge states you see, the adducts you must account for, and the modifications you might…

Two gradients, one sample, two purities

A shallow gradient resolves impurities that a steep one runs into the parent peak. Both methods are legitimate; only one of them…

Which results should be repeated before they are investigated

What the pivotal programmes measured and how often, which is a more defensible template than most published monitoring schedules.

The cake is a record of the cycle that made it

Lyophilisation does not stop degradation. It slows every pathway by removing the solvent that most of them require, and the…

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

Storage instructions in this market are close to uniform and almost never accompanied by the study that would justify them.…

The reference change value: the number that tells you whether a delta is real

The arithmetic of the reference change value, worked for the analytes that matter here.

Four ways a peptide comes apart

The sequence predicts the failure mode. A methionine predicts oxidation; an asparagine followed by a glycine predicts…

Gauge, pain and flow rate

Gauge affects pain and flow rate rather than depth. A finer needle is more comfortable and slower, and with a viscous solution…

Errors ranked by how much dose they move

The most dangerous errors are the ones that leave no trace: nothing looks wrong, the mark is in the same place, and the dose is…

What orthogonal actually means, and what it does not

An orthogonal method separates on a different physical principle, so that species co-eluting in the first are likely to resolve…

The incretin receptors, ranked by how much we actually know about them

The class is described as though every molecule in it did the same thing. At the receptor, they demonstrably do not.

Six tells, in order of how quickly they can be checked

A blank certificate with the numbers left editable is an ordinary internal document. Its circulation as a finished record is the…

A schedule that bends does not break

Nausea and gastric delay attenuate over weeks at an unchanged dose. That single physiological fact is the entire justification…

A peak with no chromophore is a peak with no peak

Non-chromophoric components — counter-ions, salts, some excipients — contribute mass to the vial and nothing at all to the…

Residual stomach content on endoscopy: the studies

This is the single interaction with ordinary medical care that patients most need to disclose, and it is the one most often not…

Two decimal places on a single injection is a rhetorical choice

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