FDA Rewrites Drug-Safety Rules to Recognize Non-Animal Testing Methods

The Food and Drug Administration on September 21, 2026, issued a rule that strikes the word “animal” from large parts of its drug-safety regulations, replacing “animal test” and “animal study” with a new umbrella term, “nonclinical test” and “nonclinical study.” The change touches five sections of the federal drug code and formally opens the door to lab-grown organ chips, computer models and cell-based assays as accepted ways to show a drug is safe enough to try in people — but it does not require anyone to use them, and it does not ban animal studies.

What the Rule Actually Does

The rule amends 21 CFR parts 312, 314, 315, 361 and 601 — the regulations governing investigational drug applications, new drug approvals, diagnostic radiopharmaceuticals and biologics licensing. Wherever those rules currently say “animal test,” “animal study,” “preclinical” or “in vitro,” the text now reads “nonclinical.” FDA also added a formal definition of “nonclinical test,” borrowed word for word from a 2022 law, the Food and Drug Omnibus Reform Act (FDORA): a test “conducted in vitro, in silico, or in chemico, or a nonhuman in vivo test” performed before or during a clinical trial, which “may include” cell-based assays, organ chips and microphysiological systems, computer modeling, other biology-based methods such as bioprinting — and, explicitly, animal tests. In other words, animal testing is not replaced; it becomes one listed option among several under a broader legal category that Congress already created three years ago.

Alongside the rule, FDA launched a public database of what it calls New Approach Methodologies (NAMs) in practice: 25 examples drawn from FDA’s own past review files, meant to show sponsors what has already been accepted.

What the Record Shows — and Its Limits

Read against FDA’s own economic analysis filed with the rule, the scope is narrower than the headline suggests. The agency states plainly that the rule “imposes no new requirements on industry and so is expected to generate no costs,” and that while it “may foster the development and use of scientifically valid new testing methodologies,” FDA does “not anticipate being able to quantify these benefits.” The agency classifies the rule itself as a deregulatory action under Executive Order 14192 — a label for changes that remove or ease requirements, not one that adds a scientific mandate. The 25 database entries are retrospective examples, not new validations of any specific method, and the rule sets no threshold for how many nonclinical submissions must use non-animal methods going forward. This is a legal and terminological alignment — bringing FDA’s own regulations into line with wording Congress already put into the FD&C Act in 2022 — rather than a scientific finding that alternative methods now match animal testing across the board.

What Doesn’t Change

FDA is explicit on this point: the rule “does not eliminate or prohibit animal studies, change evidentiary standards or impose new costs or requirements on drug developers.” A method — animal or not — is only usable if it is “adequately validated and appropriate for the product and regulatory question,” a case-by-case judgment FDA retains. Because FDA expects no serious opposition, it used a “direct final rule” procedure, publishing a companion proposed rule in parallel as a fallback: if the agency receives what it defines as a “significant adverse comment” — one that challenges the rule’s underlying reasoning — before the deadline, it will withdraw the direct final version and restart under standard notice-and-comment rulemaking instead.

What’s Still Unknown

The public comment period, open to clinicians, industry, researchers and the public, runs through December 7, 2026. If no significant adverse comments arrive, FDA intends to confirm the rule’s effective date as February 4, 2027. What isn’t known yet: whether any commenters will challenge it, how many drug sponsors will actually shift toward organ chips or computer modeling now that the terminology allows it, and whether this translates into a measurable drop in animal use in pharmaceutical testing — the rule sets no reporting mechanism to track that. The docket is FDA-2026-N-5347.

Why It Matters

Drug developers have complained for years that regulations written decades ago, when animal testing was the only recognized option, created ambiguity about whether newer methods — some now used routinely in early-stage safety screening — would be accepted by FDA reviewers. This rule removes that specific textual ambiguity. It is a case study in how regulatory language lags behind both the law (FDORA passed in 2022) and laboratory practice, and how closing that gap on paper is a distinct step from changing what actually happens on the bench. The database of 25 examples is the more concrete artifact here: it gives sponsors a reference point for what FDA reviewers have already accepted, which may matter more in practice than the definition change itself.

Source: FDA press announcement, September 21, 2026, and the direct final rule published in the Federal Register, September 22, 2026 (Docket FDA-2026-N-5347).