Cost per milligram (revision 13)
Old revision·11:43, 6 May 2025·Peptide_Pete
| Cost per milligramPricing | |
|---|---|
| Purpose | Normalise price across presentations |
| Trap | Nominal milligrams are not peptide milligrams |
| Correction | Divide by content |
| Topic infobox · conventions | |
Cost per milligram normalises price across pack sizes and presentations so that offers can be compared. Its usefulness depends entirely on what the milligram refers to.[1]
A price divided by a nominal label claim is a cost per nominal milligram. The mass of peptide in the vial is the product of fill mass, content and purity, and at typical content values a nominal milligram is appreciably less than a milligram of peptide. See Underfilling and Trifluoroacetate counterion.[1]
The correction is arithmetic and requires figures a certificate may not report. Where content and water are not reported, cost per milligram of peptide cannot be computed at all — only cost per milligram of label claim.[2]
The arithmetic
[edit]Suppose two offers of a nominal 5 mg vial, one at a given price with a certificate reporting 82% peptide content and 5% water, the other cheaper with a certificate reporting purity only.[1]
The first contains about 4.1 mg of peptide, so its cost per milligram of peptide is the price divided by 4.1. The second contains an unknown mass, so no such figure exists for it — the comparison cannot be made, rather than being made and won.
This is the practical consequence of the purity-versus-content distinction that runs through this wiki. A purity figure normalises away the quantity, and quantity is what a price is paid for.[1]
Other axes that a price hides
[edit]| Factor | Effect on a per-milligram comparison |
|---|---|
| Peptide content and water | Direct; often 15–30% |
| Fill accuracy | Direct; see Underfilling |
| Documentation supplied | Not in the price |
| Shipping and cold chain | Sometimes separate |
| Minimum order quantity | Changes effective unit price |
Documentation is the axis most often invisible. A certificate reporting identity, purity, content, water and counterion costs the supplier something to produce, and material supplied with it is not the same product as material supplied without.[2] The records behind such a document cost something to maintain as well.[3]
See also
References
- ^ a b c d United States Pharmacopeia, General Chapter <1503>, Quality Attributes of Synthetic Peptide Drug Substances.
- ^ a b PeptidePedia Wiki community test-report tally, 2024–2026 (self-reported; see Project:Sourcing guidelines).
- ^ International Council for Harmonisation, Q7: Good Manufacturing Practice Guide for Active Pharmaceutical Ingredients (2000).