Joshua Holyfield on Instagram: "The 28-Day Shelf Life Rule for Reconstituted Peptides - Is It True or Bullshit? Yes and no. The confusion exists because people don't understand where that number comes from and what it's really measuring. The 28-day number comes from pharmacy regulations called USP 797, which specifically answers the question: how long until bacteria in the vial grow to a level that becomes dangerous? It assumes you're using bacteriostatic water with benzyl alcohol as a preservat