The particulars: liraglutide · 10 mg.
I would like the arithmetic checked rather than the conclusion asserted.
I have deliberately not used an online calculator because I want to be able to check the result.
Can someone show the working rather than just the answer?
10 mg a week is 520 mg a year and 43.3 mg in an average month — put every route on that denominator before comparing anything. Cost per milligram is the only figure that survives the comparison, because the presentations differ: a licensed pen prices a dose, a compounding pharmacy prices a vial, and a research supplier prices a mass. Divide each one's twelve-month cost by 520 mg and the three become the same number in the same unit. Then add what the cheapest route does not include — independent purity and content testing, the vials you discard, and the postage — because a route that needs testing to be trustworthy has that testing in its cost per milligram whether you account for it or not.
Answer first: compare cost per milligram of measured peptide, not per milligram of label claim, because content varies enough to reverse a comparison.
The full calculation: (unit price + carriage share + testing share) ÷ (nominal mg × measured content fraction × (1 − dead-space and wastage fraction)). Every term after the first is routinely omitted.
| Step | Value | Note |
|---|---|---|
| Vial price, 10 mg nominal | £34.00 | As advertised |
| Nominal cost per mg | £3.40 | 34 ÷ 10 |
| Measured content | 9.2 mg | Independent content assay |
| Cost per actual mg | £3.70 | 34 ÷ 9.2 |
| Dead-space loss, 20 draws | 4 % | 80 µL of a 2 mL fill |
| Cost per delivered mg | £3.85 | 3.70 ÷ 0.96 |
| First vial, with £110 assay | £14.85 | Testing dominates a single vial |
Change one number and it reverses: if B assays at 82 per cent, that is 8.2 mg for £52, or £6.34/mg, and the cheaper vial is now the more expensive peptide.
Published content assay results across the independent services show nominal and measured content differing by one to ten per cent, which is the term that makes label-price comparisons unreliable.
The caveat is that optimising cost per milligram optimises for the wrong thing if documentation and consistency are what you actually need.
Divide by measured content, not by label claim. That is the whole correction.
Aggregated, published test results and vendor ratings built from submitted batches. Methodology stated, dataset browsable, no listing fees.
Browse resultsThe short version: unit price, carriage, testing, dead-space loss and wastage. The first is the one everybody compares and rarely the one that decides it.
Worked example. Supplier A: £60 for a 10 mg vial, content 96 per cent, so 9.6 mg for £60, or £6.25/mg before carriage. Supplier B: £52 for the same nominal vial, content 88 per cent, so 8.8 mg for £52, or £5.91/mg. B still wins here, but the gap has narrowed from thirteen per cent on the label to five per cent in reality.
Wastage from a reconstituted vial discarded at the end of its in-use period is a genuine cost, and it is a function of the diluent volume chosen at reconstitution rather than of anything the supplier did.
Carriage on international consignments scales sub-linearly with weight, which is the quantitative basis for order consolidation.
A spreadsheet built on label claim rather than measured content is precise about the wrong number.
Decide whether you are optimising cost or confidence before you build the model.
Ask PeptideStack is a static archive. Posting is closed, but the norms are worth stating: answer the question that was asked, show your working, cite the trial or the certificate, and say plainly where the evidence runs out.