By the PharmaTradz BD Team. Published October 2026.
DMF stands for Drug Master File. It is a confidential dossier that a manufacturer submits to a regulator, most often the US FDA, describing exactly how it makes an API, an intermediate, an excipient or a packaging material. The point of a DMF is to let the manufacturer keep its process secret while still allowing customers to rely on it: when a finished-product company files an application, it simply refers the regulator to the supplier's DMF instead of reproducing the supplier's know-how.
For anyone buying APIs, the DMF is one of the first questions to ask. Whether a supplier has a DMF, for which market and in what state, tells you a great deal about how far it can support your registration.
How a DMF works in practice
Imagine an Indian company that makes an API and a US company that wants to launch a generic tablet using it. The API maker files a DMF with the FDA containing its full chemistry, manufacturing and controls (CMC) information: the synthesis route, process controls, specifications, impurity profile, stability data and so on. The FDA does not approve or reject the DMF on its own. Instead, the API maker issues a Letter of Authorization (LoA) to the tablet company, which quotes the DMF number in its own application. The FDA then reviews the DMF as part of that application.
This arrangement protects both sides. The API maker never has to hand its confidential process to a customer, and the customer does not have to generate data it could not produce anyway. It does mean that the DMF holder keeps responsibilities: it must keep the file up to date, notify changes, submit annual reports and answer the regulator's questions.
The types of US DMF
| Type | What it covers |
|---|---|
| Type II | Drug substances (APIs), their intermediates and materials used to make them, or a drug product. By far the most common type. |
| Type III | Packaging materials |
| Type IV | Excipients, colourants, flavours and essences, and the materials used to make them |
| Type V | Other reference information the FDA has agreed to accept |
A Type I DMF once covered manufacturing sites and personnel, but the FDA stopped accepting them many years ago. Since May 2018, DMFs have had to be submitted electronically in eCTD format. For generic products, a Type II API DMF also goes through a completeness assessment once its fee is paid, after which it appears on the FDA's public list of DMFs available for reference.
DMFs outside the United States
The term is used more loosely around the world, so it pays to be precise about which file you mean.
In Europe, the equivalent is the Active Substance Master File (ASMF), which has an open part shared with the customer and a restricted part sent only to the regulator. Many API makers instead obtain a Certificate of Suitability (CEP) from the EDQM, which confirms that the relevant European Pharmacopoeia monograph is suitable to control the quality of the API from that manufacturer, and can replace most of the API data in a European dossier. Our guide to CEP, DMF and ASMF explains which one you need.
Several other regulators run their own master-file systems, including Health Canada, Japan, China and South Korea. In many emerging markets, and in everyday trade talk in India, "DMF" is often used to mean the technical API documentation a supplier shares with a customer, written in the CTD format of Module 3.2.S. That can be perfectly useful, but it is not the same as a DMF on file with the FDA, and the difference matters when you register a product.
What to ask an API supplier about its DMF
Start by asking where the DMF is filed and what its number is. A US DMF number can be checked against the FDA's public DMF list, which shows the holder, the subject and whether the file is active.
Next, ask whether the DMF is active and has passed completeness assessment if you are filing a US generic, and when it was last updated. A file that has not been maintained can delay your application.
Then ask what the supplier will give you. For the US, that is a Letter of Authorization. For Europe, it is either a copy of the CEP or the open part of the ASMF, with the restricted part sent to the regulator. For other markets, it is usually the open part of the technical dossier.
Finally, make sure the DMF covers exactly the material you are buying: the same site, the same route of synthesis and the same salt or crystal form. Our explainer on hydrochloride versus base explains why the salt form in particular catches people out.
Common misunderstandings
A DMF is not an approval. A supplier that says its API is "FDA approved" because it has a DMF is overstating its position; what matters is whether the DMF is active and whether products referencing it have been approved.
A DMF is also not proof of GMP on its own. Inspection history is a separate question, and our guide to verifying a pharmaceutical supplier covers how to check it.
And a US DMF does not automatically help in other markets. Each regulator has its own requirements, even though the underlying data is often the same.
Related explainers
New to the vocabulary? Start with what an API is and drug substance versus drug product, or browse our six-language pharma glossary.
More document explainers
The documents in a supplier's quality pack work together. See also how to read a Certificate of Analysis, what a CoPP is and how importers use it, GMP vs cGMP and what a WHO-GMP certificate is and how to check one.
How PharmaTradz can help
When you send an API enquiry, tell us which market you are registering in and which file you need: US DMF with LoA, CEP, ASMF or a CTD technical package. We match you with manufacturers who hold it and share their document status before you commit. Our documentation and quality pack gathers these documents up front, or you can send us an RFQ directly.
Frequently Asked Questions(FAQs)
What is the full form of DMF in pharma?
DMF stands for Drug Master File: a confidential submission to a regulator, usually the US FDA, describing how a manufacturer makes an API, excipient, intermediate or packaging material.
Is a DMF approved by the FDA?
No. The FDA does not approve or reject a DMF on its own. It reviews the DMF when a finished-product application refers to it through a Letter of Authorization from the DMF holder.
What is a Letter of Authorization (LoA)?
A letter from the DMF holder allowing a specific customer to reference its DMF in that customer's application. It lets the regulator see the confidential data without the customer seeing it.
What is the difference between a DMF and a CEP?
A US DMF is a confidential file reviewed by the FDA when a product application references it. A CEP is a certificate from the EDQM confirming that the European Pharmacopoeia monograph is suitable to control that manufacturer's API, used in Europe and accepted in many other markets.
How can I check a supplier's US DMF?
Ask for the DMF number and look it up in the FDA's public DMF list, which shows the holder, the subject of the file and whether it is active.
