What are &quot;inactive ingredients when a safety factor&quot; in the context of vaccines?
<p>I was reading <a href="https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=610.61" rel="nofollow noreferrer">Title 21 of the Code of Federal Regulations</a> when I came upon the following sentence</p>

<blockquote>
  <p>(n) The inactive ingredients when a safety factor, or reference to an enclosed circular containing appropriate information; </p>
</blockquote>

<p>How is it determined if an inactive ingredient is a safety factor?</p>

<p>A partial answer (for a manufacturer) is "<a href="https://www.accessdata.fda.gov/scripts/cder/iig/index.Cfm" rel="nofollow noreferrer">look it up</a>" – that may tell you if a determination has been made by the FDA. If so, it is not new and </p>

<blockquote>
  <p>may require a less extensive review the next time it is included in a
  new drug product. For example, if a particular inactive ingredient has
  been approved in a certain dosage form at a certain potency, a sponsor
  could consider it safe for use in a similar manner for a similar type
  of product</p>
</blockquote>

<p>(<a href="https://www.fda.gov/drugs/drug-approvals-and-databases/inactive-ingredient-search-approved-drug-products-frequently-asked-questions" rel="nofollow noreferrer">the FDA says</a>). The legal part doesn't explain how it is scientifically determine that an inactive ingredient raises safety concerns but to take on example, wheat gluten is in the Inactive Ingredient Guide. <a href="https://weinberggroup.com/blog/iig-evidence-ingredient-safety-fda/" rel="nofollow noreferrer">This article</a> gives a bit of analysis of the factors that sponsors have to consider in shouldering their burden of proof. If you want to manufacture a new vaccine, you have to show (the FDA) that it is safe. If you dilute the vaccine with water, that ingredient is not a "safety factor". Benzalkonium chloride could be (you would have to show that it isn't), and if it is, that regulation requires you to list it. What's not specified clearly is how many adverse reactions per million doses constitute being a safety factor. </p>

<p>It means you list what is in the drug. </p>

<blockquote>
  <p>"Every drug manufacturer is obliged to list every excipient, every little part including coloring and flavors for each drug," says Andrzej Wilk, PhD, senior scientific liaison to USP's Nomenclature, Safety and Labeling Expert Committee. "This can be found on the package of a prescription drug or in the drug's package insert. For over-the-counter drugs, inactive ingredients have to be on the outside of the box."<a href="https://www.consumerreports.org/cro/news/2012/03/q-a-how-can-i-find-out-which-ingredients-are-in-a-medication/index.htm" rel="nofollow noreferrer">https://www.consumerreports.org/cro/news/2012/03/q-a-how-can-i-find-out-which-ingredients-are-in-a-medication/index.htm</a></p>
</blockquote>

<p>If you have some special case where you can not have a specific chemical, you either ask the pharmacist or read the info yourself to decide if it is a safety risk for you. </p>

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