Equal Milligrams Is Not Equal Molecules

Why a total mass is an ambiguous instruction

KLOW is described by a single number: 80mg, across four components. That number is a mass, and mass is not what a receptor, a transporter or an enzyme responds to - molecules are. Because the four components differ substantially in molecular weight, converting the one into the other changes the answer by a large factor, and the direction of the change depends entirely on an assumption the label does not settle. Two people can read the same 80mg honestly and reasonably and arrive at compositions that differ four-fold in the relative abundance of the smallest and largest components.

The arithmetic, laid out

One milligram of a compound contains 1/M millimoles, where M is its molecular weight in daltons. For these four that gives 2.92 micromoles per milligram for KPV, 2.48 for GHK-Cu, 1.12 for TB-500 and 0.704 for BPC-157. So a milligram of KPV contains 4.15 times as many molecules as a milligram of BPC-157. If the 80mg were split evenly - 20mg of each - the molar ratio would be 4.15 : 3.52 : 1.60 : 1.00 running from KPV down to BPC-157, and the vial would contain four times more KPV molecules than BPC-157 molecules despite containing exactly the same mass of both.

What an equimolar blend would have to look like

Run the calculation the other way. For equal numbers of molecules, the masses must be in proportion to the molecular weights. Across an 80mg total that gives approximately 8.97mg of KPV, 10.56mg of GHK-Cu, 23.29mg of TB-500 and 37.19mg of BPC-157. An equimolar KLOW is therefore 37mg of BPC-157 and 9mg of KPV - a composition that looks nothing like an even split and would appear, to anyone reading masses, to be heavily weighted toward one component when in molecular terms it is perfectly balanced.

Neither reading is more correct than the other

There is no convention that settles this. Equal mass is the simpler thing to manufacture and the more natural reading of an unqualified total. Equal molarity is the more defensible thing pharmacologically, because it puts the components on comparable footing at their targets. A ratio chosen for some other reason - matching the proportions used in the separate literatures, say - is a third possibility and would be as legitimate as either. The problem is not that one is right; it is that the label does not say, and the difference between the readings is large enough to matter to any calculation performed downstream.

Why this compounds every other limitation

The split being unstated is already the known limitation of this format. The molar arithmetic makes the size of that gap concrete rather than abstract. Anyone reconstituting a vial and calculating a concentration is producing a number for the blend as a whole; converting it to a per-component molar concentration requires the split, and the plausible splits are separated by a factor of four at the extremes. That is not a rounding error. It is the difference between two experiments.

What would fix it

A stated per-component mass on the certificate. Not a ratio expressed as a proportion of the total, which is better than nothing but still requires the reader to do this conversion; the actual milligrams of each of the four. That single line would make per-component molar calculation possible and would cost the supplier nothing they do not already know, since the components are weighed separately before combining. Until it appears, any molar figure attached to a blend is an assumption wearing a number's clothes. KLOW and its components are supplied for laboratory research only and none of them holds a marketing authorisation.

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