1. Introduction: Three Locks, One Compound
Public access to a known compound for a known therapeutic use can be restricted by three independent but interacting mechanisms. First, a method-of-use patent under 35 U.S.C. § 101 grants a 20-year exclusive right to the specific application. Second, FDA regulatory exclusivity provides a 3-to-7-year monopoly awarded to the company that runs the required clinical trial — this is not a patent but a regulatory reward for investing in the trial. Third, the DSHEA drug preclusion clause under FD&C Act § 201(ff)(3)(B) allows the FDA to classify a compound out of the supplement category entirely if it was studied or approved as a drug before being marketed as a dietary supplement. Each mechanism alone is a barrier. Together, they form a squeeze that can convert a nine-cent pill into a nearly five-dollar pill and keep it there for decades.
2. How the Squeeze Works
2.1 The Timeline Race
The DSHEA preclusion clause operates as a race condition. If the compound was marketed as a supplement before any Investigational New Drug (IND) filing, the supplement status is grandfathered — the compound can coexist as both supplement and drug (as omega-3 fatty acids, niacin, and Vitamin D do today).
If the IND was filed first, the compound is precluded from the supplement market.
For compounds already on the market as supplements, a new IND for a new indication creates a gray zone. The compound itself may be grandfathered, but the FDA has not clearly defined when a new clinical investigation on an already-marketed supplement triggers fresh preclusion. The term “substantial clinical investigation” remains deliberately vague.
2.2 The Patent Amplifier
FDA regulatory exclusivity alone is temporary: 3 years for a new clinical investigation, 5 years for a new chemical entity, 7 years for an orphan drug. When exclusivity expires, other companies can seek FDA approval for the same indication.
A method-of-use patent extends the monopoly from 3–7 years to up to 20 years. More critically, the patent provides enforcement teeth that regulatory exclusivity alone does not:
| Scenario | FDA Exclusivity Only | FDA Exclusivity + Patent |
|---|---|---|
| Compound sold OTC as supplement | Yes (if grandfathered) | Yes (if grandfathered) |
| Other companies pursue same indication | Blocked 3–7 years, then free | Blocked up to 20 years |
| Supplement companies discuss use | FDA labeling issue only | Patent infringement — injunction, damages |
| Knowledge of the use case | Public | Commercially enclosed |
| Generics enter after exclusivity | Yes | No — patent survives exclusivity |
The patent converts a temporary regulatory speed bump into a wall. Without the patent, a competitor waits 3 years and files their own application. With the patent, they wait 20 years or license at the holder’s price.
2.3 The Information Lock
The most pernicious effect is on information. A method-of-use patent does not just control the pill — it controls the knowledge of what the pill does. A supplement company selling NAC cannot market it for the patented indication. A practitioner recommending it for that use in a commercial context may expose their employer to contributory infringement claims. The compound remains physically available, but the knowledge of its application is legally enclosed.
3. Case Studies
3.1 Colchicine
Colchicine is an alkaloid extracted from Colchicum autumnale, used to treat gout since at least the 1st century AD. It was sold in the United States as an unapproved drug for pennies per pill.
In 2009, URL Pharma conducted the FDA-required randomized controlled trial for colchicine in acute gout. The FDA granted 3-year marketing exclusivity. URL Pharma also obtained method-of-use patents on specific dosing regimens (US7820681B1, US8927607B1).
With both exclusivity and patents in place, URL Pharma (later acquired by Takeda) raised the price from $0.09 to $4.85 per pill — a 5,300% increase. The FDA then ordered all other colchicine products off the market.
Without the method-of-use patents, a competitor could have filed after the 3-year exclusivity expired and restored generic pricing. With the patents, the monopoly extended for years beyond the exclusivity window.
3.2 N-Acetylcysteine (NAC)
NAC (CAS 616-91-1) was approved as a prescription drug in 1963 for use as a mucolytic agent and acetaminophen overdose treatment. It was subsequently marketed as a dietary supplement for decades.
In 2020, the FDA sent warning letters to supplement companies selling NAC, arguing that because NAC was approved as a drug before being marketed as a supplement, it was precluded under DSHEA § 201(ff)(3)(B). The FDA exercised enforcement discretion in 2022, effectively allowing NAC supplements to remain on the market while pursuing formal rulemaking.
NAC’s case is primarily regulatory, not patent-driven. However, method-of-use patents on NAC for specific indications (e.g., US20210251889A1) add a patent layer on top of the regulatory uncertainty. Each new patented indication strengthens the argument that NAC is “really a drug” — reinforcing the regulatory pressure even if the patent itself does not directly remove OTC access.
3.3 Thrombin-Binding Aptamers
TBA15 (also known as HD1) is a 15-nucleotide DNA aptamer (5’-GGTTGGTGTGGTTGG-3’) that folds into a G-quadruplex structure and binds thrombin’s exosite I. It was first described by Bock et al. in 1992.
As aptamer therapeutics advance, companies are filing method-of-use patents on specific therapeutic applications of known aptamer sequences. The concern: if a company patents the use of a known 15-nucleotide sequence for a specific therapeutic indication, suppliers of that sequence may face infringement claims for selling a product that could be used for the patented purpose.
4. Where Defensive Disclosure Fits
Of the three mechanisms described, only the patent layer is directly addressable through prior art publication:
- FDA exclusivity is a reward for running a clinical trial. Prior art cannot prevent this.
- DSHEA preclusion is a statutory provision. Changing it requires amending the FD&C Act.
- Method-of-use patents are vulnerable to prior art. If the specific use is publicly described before the patent filing date, the patent claim fails the novelty requirement under § 102.
Removing the patent layer does not remove all restrictions. But it removes the longest-duration and broadest-enforcement restriction. Without the patent:
- FDA exclusivity expires in 3–7 years (not 20).
- No infringement claims against supplement companies, practitioners, or competing manufacturers.
- Knowledge of the therapeutic use remains in the public domain.
- Generics can enter immediately after exclusivity expires.
For compounds already on the OTC/supplement market, eliminating the method-of-use patent is arguably the single most impactful intervention that does not require legislative action.
5. Requirements for Effective Disclosure
To serve as anticipatory prior art, a defensive disclosure must meet the enablement standard (MPEP § 2121): a person of ordinary skill must be able to practice the claimed method without undue experimentation.
For pharmacological use cases, the disclosure should include: compound identification (IUPAC name, CAS number, molecular formula), specific indication, dosage and administration details, mechanism of action, supporting literature citations, and an explicit public-domain dedication (e.g., CC0 1.0).
6. Conclusion
The combination of method-of-use patents, FDA regulatory exclusivity, and DSHEA preclusion creates a multi-layered barrier to public access to known compounds. Of these layers, the patent is both the longest-lasting and the most legally enforceable — and it is the one layer that can be preempted through timely, specific, publicly accessible defensive disclosure. A systematic effort to publish enabling descriptions of therapeutic use cases for known compounds into the public domain would not eliminate all barriers to access, but would remove the most durable one and significantly shorten the monopoly window for the rest.
References
- 21 U.S.C. § 321(ff)(3)(B) — Drug preclusion clause.
- Nutraceuticals World. (2022). Understanding Preclusion Provisions.
- Natural Products Insider. (2022). The Dietary Supplement Industry’s Drug Preclusion Predicament.
- FDA. (2026). New Clinical Investigation Exclusivity (3-Year Exclusivity) for Drug Products. Federal Register 2026-04291.
- Kesselheim, A. S., & Solomon, D. H. (2010). Incentives for drug development — the curious case of colchicine. NEJM, 362(22).
- US7820681B1 — Methods for concomitant administration of colchicine.
- US8927607B1 — Methods of colchicine administration.
- FDA. (2022). Policy Regarding N-acetyl-L-cysteine.
- US20210251889A1 — NAC Compositions and Methods.
- Bock, L. C., et al. (1992). Selection of single-stranded DNA molecules that bind and inhibit human thrombin. Nature, 355(6360), 564-566.
- Riccardi, C., et al. (2021). G-quadruplex aptamers targeting thrombin. Pharmacology & Therapeutics, 217, 107649.
- 35 U.S.C. § 102 — Conditions for patentability; novelty.
- MPEP § 2121 — Prior Art; Enablement.