The Food and Drug Administration (FDA) has proposed the first Demonstrable Difficulties for Compounding (DDC) lists under Section 503A and Section 503B of the Federal Food, Drug, and Cosmetic Act, the compounding framework built out by the Drug Quality and Security Act (DQSA). A drug or drug category placed on a DDC list loses the compounding exemptions those sections provide. The proposal, published March 20, 2024 under docket FDA-2023-N-0061, names three categories defined by manufacturing process rather than by drug name, so a compounding pharmacy's exposure turns on whether its own formulation matches FDA's definitions, not on checking a drug name against a published list.
The Three Proposed Categories
FDA's proposal reaches both sides of 503A/503B compounding, and it names three categories. Oral solid modified-release drug products that employ coated systems (MRCs) are products with a drug-containing core enclosed in a polymeric coating that releases the active pharmaceutical ingredient at a specified rate through the gastrointestinal tract. Liposome drug products (LDPs) are products in which the active ingredient is contained, or intended to be contained, in liposomes. Drug products produced using hot melt extrusion (HMEs) are made through a continuous process that mixes active and inactive ingredients at or above their melting or glass transition temperatures. FDA has stated it is not aware of any compounded drug currently on the market in these three categories.
How FDA Decides What Belongs on the List
The proposed rule also sets the criteria FDA would use before adding any further category to a DDC list. The agency weighs six complexity factors: formulation complexity, drug-delivery-mechanism complexity, dosage-form complexity, the difficulty of achieving and assessing bioavailability, compounding-process complexity, and the complexity of the physicochemical and analytical testing needed to confirm the finished product. FDA has said it will weigh these factors individually and collectively against the risks and benefits to patients, drawing on adverse event reports and its own scientific review. Cost and convenience to the compounder are not factors FDA says it will consider.
What Listing Means for 503A and 503B Pharmacies
Placement on a DDC list functions as an outright bar on compounding a listed category, not as a flag for added caution. A pharmacy compounding under cGMP-exempt Section 503A or under Section 503B loses that exemption the moment its product falls inside a finalized category, exposing it to the same manufacturing, labeling, and new-drug approval standard as a conventional drug manufacturer.
A drug category placed on FDA's Demonstrable Difficulties for Compounding list is barred from 503A and 503B compounding entirely once the listing takes effect.
Preparing Before a Category Is Finalized
The comment period on the proposed rule closed June 18, 2024, and as of this writing FDA has not published a final rule under docket FDA-2023-N-0061. A pharmacy or outsourcing facility compounding a modified-release, liposome, or hot melt extrusion product today should document why that product falls outside FDA's proposed definitions, and should track the docket for the agency's next action rather than wait for a public announcement. The exemptions at stake differ by registration type, a distinction covered in 503A vs 503B: Which Framework Governs Your Compounding, so a pharmacy weighing 503A against 503B registration should factor the proposed categories into that decision as well.
Why Early Legal Counsel Is Critical
It is critical that compounding pharmacies and outsourcing facilities retain experienced healthcare defense counsel before a proposed category becomes final, not after. Early legal review can confirm whether a current or planned product falls inside FDA's proposed definitions, help prepare comments or supporting documentation for the docket, and preserve the pharmacy's position if FDA finalizes a category the pharmacy did not anticipate. Delaying that review until a warning letter arrives narrows the options considerably.
How Health Law Alliance Can Help
Health Law Alliance has represented 2,500+ clients over 25+ years, including compounding pharmacies and outsourcing facilities navigating FDA's compounding rules. Our compounding pharmacy attorneys review a pharmacy's formulary against FDA's proposed Demonstrable Difficulties for Compounding categories, prepare docket comments, and represent pharmacies once a formulation draws FDA scrutiny. Contact Health Law Alliance for a free, confidential consultation.
