Reading a barrel: the graduation that is not the one you think
Dead space in the needle hub is a real and calculable loss, and it matters more at small volumes than anybody expects.
Explainers
Page 3 of 12 of this archive, newest first.
Page 3
Hydration, protein and the two failures that compound each other
The intervention with the clearest evidence is the one nobody frames as an intervention: adjusting the dose.
Escalating past the approved maximum, examined honestly
We looked at what the dose-ranging data supports about going higher, and it is thinner and less flattering than the market assumes.
Calibrated, qualified, accredited: three words that are not synonyms
System suitability is the set of checks demonstrating that the instrument and method were performing adequately when your sample was injected. It is recorded as a matter of…
The ceiling is a tolerability finding, not an efficacy one
Where the curve flattens, what flattens with it, and what does not.
A mass on a WWB certificate is a beginning, not a conclusion
What a single-stage mass measurement supports, what it excludes, and the gap between the two.
Tandem mass spectrometry, and the difference between weighing and reading
An intact mass measurement establishes elemental composition, at best. The number of distinct sequences consistent with a given composition is astronomically large.
What the anaesthetists said, and then said again
A drug that delays gastric emptying complicates the assumption behind every fasting instruction in perioperative medicine. The professional bodies have moved twice on this…
The upper rungs, ranked by evidence
We looked at what the dose-ranging data supports about going higher, and it is thinner and less flattering than the market assumes.
Storage after reconstitution, and the evidence behind the numbers
The air shot before a pen injection removes air from the cartridge and confirms flow. Skipping it can mean a materially reduced dose, and it is skipped constantly.
Residual stomach content on endoscopy: the studies
Holding a dose before a procedure has a kinetic problem: a weekly drug with a seven-day half-life cannot be cleared by skipping one injection.
The interventions with trial support, and the much longer list without
Almost nothing in the standard management repertoire has been tested in a randomised trial in this specific population. We say what is extrapolated and from where.
Baseline construction, and the area that depends on where you draw the line
Chromatographic software does not integrate every fluctuation in the baseline. It applies a threshold, and the threshold changes the reported purity by amounts that matter…
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 fragment lacking an aromatic residue.
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 document.
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 modes. Certificates almost never say which was…
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 structural.