Why the compendial sterility test is a rejection test and nothing more
The compendial sterility test cannot demonstrate that a batch is sterile. It can only fail a batch that is grossly contaminated. Everything else is process validation.
Perpetua Nwachukwu
Page 3 of 4 of this archive, newest first.
Archive — page 3
73 piecesA reference interval is not a target, and a result outside one is not a diagnosis
The arithmetic of the reference change value, worked for the analytes that matter here.
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 is the reagent most of them need.
A needle is a single-use instrument
For licensed products the in-use period is established by stability data. For a peptide reconstituted at home there is no such data, and the honest answer is that nobody…
What a mass spectrometer does to a peptide before it measures anything
A brief and unromantic tour of the interface between a liquid sample and a vacuum.
The dose that got you here and the dose that keeps you here
The commonest real-world strategy in this drug class is the least studied one.
Mapping a rotation that you will actually follow
Repeated injection into the same small area produces lipohypertrophy — thickened, rubbery subcutaneous tissue with blunted and erratic absorption. It is common, it is…
The dose that got you here and the dose that keeps you here
Every withdrawal trial compared full dose against nothing. The clinically interesting comparison — full dose against a reduced one — has not been randomised.
Set the threshold at a tenth of a per cent and the small impurities vanish
Baseline placement under a tailing peak is a judgement call with a direct effect on the area. It is one of the few places where two competent analysts genuinely disagree.
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.
What “LC-MS: conforms” tells a reader, which is almost nothing
What the Journal asks for when it writes to a supplier about an identity claim, and how often it gets it.
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.
Four ways a peptide comes apart
The sequence predicts the failure mode. A methionine predicts oxidation; an asparagine followed by a glycine predicts deamidation; a cysteine predicts disulphide scrambling.
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 the difference is noticeable.
Rapid weight loss moves eight analytes for reasons that have nothing to do with the drug
Three different explanations for the same abnormal number, and how to tell them apart.
EGFR, cystatin C, and the check on the check
What the renal and hepatic outcome programmes actually measured, and over what duration.
The one-quarter rule, and the paper that took it apart
Almost every practical recommendation in circulation was established in a population that does not resemble the people now following it.
A lyophilised peptide is not stable. It is slow.
We set out what the cycle does, in order, so that a reader can see which of its steps a rushed operation shortens first.
Choosing a needle for a subcutaneous peptide
A 4 mm needle at ninety degrees without a skin pinch is adequate for essentially all adults. The persistence of 12.7 mm needles in this market is habit, not reasoning.
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.