First posted online: 22 March 2022

Why are our regulators seemingly so incapable of filing even the most basic information correctly? Take this example of Pfizer’s saline diluent composition table, found in the FDA’s Summary Basis for Regulatory Action (SBRA). It’s wrong no matter which way it’s interpreted.

As per Pfizer’s instructions for healthcare providers, the frozen 0.450ml vial must first be thawed before being diluted with 1.8ml of 0.9% Sodium Chloride (NaCl) diluent. This accords with a concentration of 9mg NaCl per ml of water for injection (WFI).

Assuming the composition table refers to the relative amounts of NaCl and WFI contributed by adding the saline diluent… The correct volume of WFI would be 0.24ml, yielding the correct 0.9% saline concentration, 9mg NaCl per ml of WFI.

Inversely, if we now assume the composition table refers to the absolute amounts of NaCl and WFI in the final 0.3ml administered dose… The correct weight of NaCl would be 0.36mg + 2.16mg = 2.52mg, again giving the correct 0.9% saline concentration.

This may seem benign, but here’s more weirdness:

  • Table 2 of SBRA from 23 Aug 2021 redacted WFI

  • SBRA informally revised ~Oct 4 2021 to reveal WFI as 0.450ml excipient

  • SBRA formally revised WFI on 8 Nov 2021 with amount q.s.

  • Pfizer’s SDS shows proprietary WFI weight

What possible reason is there to redact the weight of only one single ingredient in the SDS? On the amount of WFI being q.s. (as much as suffices), this matches Pfizer’s raw ingredients table, 3.2.P.1-1, as released for my FOI request.

Correct quantity of WFI if relative contribution is assumed

Correct quantity of WFI if absolute contribution assumed