NAD+ Cycle: Schedules, and the Maths Beneath

The first clock counts portions. A 1000 mg vial drawn in 50 mg portions holds twenty of them, and that count does not change with fill volume, because water adds no material.

The second clock counts weeks. A preserved multi-draw solution is conventionally treated as usable for about four weeks, and that convention is used here as a stated input rather than as a measured property of any particular preparation. Twenty portions and twenty eight days only line up if the portions are taken daily. Any slower interval leaves material in the vial when the water clock expires.

The last column is the finding. Between the top row and the bottom row nothing about the product changed: same vial, same label, same price Q. The cost of what actually got used rose fivefold, purely from the interval. That is a purchasing fact derivable before anything is opened, and it is invisible to every comparison based on shelf price per milligram.

The stranded column deserves its own look, because the instinct on seeing it is to fix it in the wrong direction.

Six hundred milligrams left in a vial at the twice weekly interval is not a small rounding loss. It is more than half the container, and it is the part the buyer paid for and then discarded on a calendar rather than on a decision. The temptation is to keep drawing past the window to avoid the waste, which converts a pricing problem into a handling problem and answers neither.

The mirror instinct is to add less water, on the theory that a smaller volume of solution ages more slowly. It does not follow from anything in the arithmetic. Fill volume sets concentration, and concentration sets how many units hold a portion. It has no term in either clock: the portion count comes from the labelled mass, and the four week convention is about the preserved diluent, not about how much of it there is.

Halving the portion doubles the portion count and doubles the mismatch. A 1000 mg vial drawn in 25 mg portions yields forty portions. At a daily interval that is forty days of material against a twenty eight day window, so twelve portions are stranded where the 50 mg portion stranded none. At every other day it is fourteen portions used out of forty, and twenty six stranded.

This runs against the usual intuition that smaller draws stretch a container further. They do stretch it, in days. Past the point where the days exceed the water clock, the extra days are notional and the extra portions are never taken. Beyond that threshold, a smaller portion buys nothing except a larger write off.

The clean fix sits at the point of purchase, not at the bench. If the interval is known in advance, the container should be chosen so that the portion count lands at or under the days available.

At an every other day interval, fourteen portions fit inside the window. Fourteen portions of 50 mg is 700 mg, so a 500 mg vial is fully consumed with room to spare and a 1000 mg vial is not. At a weekly interval only four portions fit, which is 200 mg, and even a 500 mg vial strands more than half its contents. There is no container size on this site's usual scale that suits a weekly interval, which is a genuine conclusion rather than a shopping tip: the product is packaged for frequent use and priced as though frequency were free.

Two vials of 500 mg used one after the other beat a single 1000 mg vial at any interval slower than daily, provided the second vial stays sealed while the first is in use. Whether that is cheaper depends on the two prices, and the comparison to run is cost per used 100 mg from the table above, not cost per labelled 100 mg from the listing.

The word cycle arrives from a different practice entirely, and the literature attached to this molecule does not use it. The human interventional research is mostly on oral precursors, nicotinamide riboside and nicotinamide mononucleotide, given continuously over a defined study period rather than in on and off blocks. Those trials studied capsules in humans, not injected NAD+ from a vial, and their structure is a study duration, not a cycle length.

So there is no source document to copy a cycle from. What circulates as a NAD+ cycle is a schedule shape borrowed from compounds with a different pharmacology and a different evidence base, applied to a molecule the body already makes, at masses set by what vendors happen to package.

Every interval above is an input, and none is a recommendation. That refusal is not caution for its own sake. It follows from what is missing.

For an interval to be defensible there would have to be an established relationship between an injected mass and an outcome in people, plus something about how long that outcome persists. Neither exists for injected NAD+, and there is no approved product to borrow a schedule from either: no regulator anywhere has issued a marketing authorisation for the injected form, so no assessed label exists to be copied. The precursor trials cannot substitute, because converting an oral precursor amount into an injected one requires the fraction absorbed, the fraction converted onward, and a term relating the routes, and no figure is asserted here for any of those. Three unknowns and one known does not become an answer by being typed into a calculator.

What the arithmetic can do is everything in the tables above: portions per container, days per portion count, material stranded, and cost per used 100 mg. Those are container facts. They stay true whatever the biology turns out to be, and they are the only part of this topic a buyer can verify unaided.