Section 3 explained: this guide covers what it means, who it applies to, the step-by-step process, documents required, fees, due dates and penalties in India — so you can stay compliant with confidence and avoid costly mistakes.
Paragraphs 10.4 to 10.11 of the Pharmaceutical Patent Guidelines (October 2014) deal with section 3(d), the provision that most often decides drug applications. They set out the text, explain "efficacy" and "new product" by reference to the Supreme Court's imatinib ruling, say what data the examiner looks for, and give two illustrative examples.
A new form of a known substance (a salt, ester, polymorph, particle size, combination and so on) is treated as the same substance unless it differs significantly in properties with regard to efficacy, and for a medicine efficacy means therapeutic efficacy (10.4 to 10.6). Better bioavailability alone is not enough; whether it leads to better therapeutic efficacy must be specifically claimed and established by research data (10.8). Section 3(d) does not bar all incremental inventions (10.9). The Guidelines are the Patent Office's guidance and do not have the force of law; the Patents Act, 1970 and the Patents Rules, 2003 as now in force prevail.
The Office revises its guidelines, so check the current version on ipindia.gov.in. This document dates from October 2014 and cites IPAB decisions; the IPAB has since been abolished and appeals now go to the High Court (see our post on IPAB dissolution). The statutory text and the case background are in our posts on section 3(d) and TRIPS and evergreening and pharma patent challenges, and the Manual's own treatment is in our article on Manual Chapter 9, section 3(d). A patent objection reply on a 3(d) objection depends on the data described below.
The text and its place (paragraphs 10.4 and 10.5)
The Guidelines reproduce section 3(d) with its Explanation: salts, esters, ethers, polymorphs, metabolites, pure form, particle size, isomers, mixtures of isomers, complexes, combinations and other derivatives of a known substance are the same substance unless they differ significantly in properties with regard to efficacy. They then say that for pharmaceutical inventions the section deserves special attention: an incremental invention based on a known substance with established medicinal activity fails unless it shows significantly improved therapeutic efficacy over that known compound. They quote the Supreme Court in Novartis AG v Union of India, as cited, on the purpose of the provision: a second tier of qualifying standards for chemical and pharmaceutical substances, leaving the door open for genuine inventions while checking repetitive patenting or extension of the patent term on spurious grounds.
What "efficacy" means (paragraph 10.6)
Quoting the same ruling, the Guidelines say efficacy is the ability to produce the desired or intended result, so its test depends on the function of the product, and for a medicine meant to cure a disease it can only be therapeutic efficacy. Not every advantageous property counts, only those that directly relate to efficacy. Each form in the Explanation has properties inherent to that form (solubility for a salt, hygroscopicity for a polymorph), and a mere change of form with those inherent properties is not an enhancement of efficacy.
What "new product" means (paragraph 10.7)
A new product, in chemicals and pharmaceuticals, need not be entirely unfamiliar; it may be different from a recent previous one or regarded as better. But if the product is a new form of a known substance with known efficacy, it must pass sections 2(1)(j) and (ja) and also the enhanced efficacy test.
Bioavailability needs data (paragraph 10.8)
The Guidelines quote the Supreme Court that increased bioavailability alone may not lead to enhanced therapeutic efficacy, and that whether it does in a given case must be specifically claimed and established by research data. In that case there was no material to show enhanced efficacy of the crystalline form over the base form of the known compound in an in vivo animal model.
Section 3(d) does not bar all incremental inventions (paragraph 10.9)
The Guidelines add the Supreme Court's clarification that failing the test in one case does not mean section 3(d) bars patent protection for all incremental inventions of chemical and pharmaceutical substances, and that the ruling should not be read as undoing the change brought by the deletion of the old section 5 for product patents.
"Combination" in the Explanation (paragraph 10.10)
The IPAB, in Ajanta Pharma v Allergan as cited, explained that the combination in the Explanation means a combination of two or more of the listed derivatives, or of one or more derivatives with the known substance, that may result in a significant difference in efficacy.
The two examples (paragraph 10.11)
Example 1: the crystalline form of imatinib mesylate. The application claimed the beta crystalline form of a salt of a known cancer drug, asserting better flow, better thermodynamic stability and lower hygroscopicity than the alpha form, with no efficacy data. After pre-grant oppositions the application was refused on grounds of anticipation, obviousness and section 3(d). The Supreme Court held that the salt was known from the earlier patent, that the claimed form was a new form of a known substance of known efficacy, so section 3(d) applied, and that the applicant had shown no comparison of efficacy, or even solubility, with the known salt. On bioavailability, it repeated the point in paragraph 10.8. The appeal failed.
Example 2: a quinazoline derivative. In Fresenius Kabi Oncology v Glaxo Group, as cited, the IPAB considered a revocation in which the opponent said the compound was only a new form of known compounds. The Board held that the person alleging the ground must plead and prove that the claim is hit by section 3(d) and has the same therapeutic efficacy as the known substance, after which the patentee can counter by showing it is not a derivative or that it has enhanced efficacy. A vague plea that two admitted prior arts exist was not enough, and the ground was not proved.
What the examiner checks, and what to file
| Examiner's question | What the applicant should show |
|---|---|
| Is the claimed compound a salt, ester, polymorph, particle size, complex, combination or other derivative of a known substance? | Whether it is truly a new chemical entity with its own prior art position, or a form of a known one |
| What is the known efficacy of the known substance? | A statement and data for the known substance, taken from the closest prior art |
| Does the new form differ significantly in therapeutic efficacy? | Comparative research data on therapeutic efficacy, not only on stability, flow or solubility |
| Is the claimed advantage inherent to the form? | An effect that goes beyond properties inherent to that kind of form |
| Is bioavailability claimed as the advantage? | Data linking the improved bioavailability to better therapeutic efficacy |
How the objection is usually framed, and how to answer it
| Objection | Answer |
|---|---|
| "The claim is a new form of a known substance without enhanced efficacy" | Show comparative therapeutic data against the known substance, in the specification or in evidence; if none exists, consider whether the claim can stay |
| "The advantage is only better stability or solubility" | Link the property to a therapeutic difference, or concede that the property is inherent to the form |
| "The combination is not enhanced" | Show the combination differs significantly in efficacy, in the sense of paragraph 10.10 |
The Guidelines do not prescribe what data format to use. The Act and Rules as now in force prevail, and the specification as filed is the main place the data should be.
A worked example (invented)
Aarogya Biologics claims a new polymorph of a known antidiabetic compound, saying it is more stable and easier to compress into tablets. The examiner raises section 3(d), relying on the reasoning in Example 1. Aarogya files an affidavit with a head-to-head study showing a significantly greater reduction in blood glucose in an animal model at the same dose, and points to the passage in the original specification stating that the form was developed for improved glucose response. The reply addresses therapeutic efficacy directly, and does not rely on stability alone.
Common lapses
- Citing stability, flow or solubility as the only advantage.
- Filing comparative data against the wrong comparator (a different compound rather than the known substance).
- Raising bioavailability without linking it to therapeutic effect.
- Filing evidence late with nothing in the specification to support it.
Need help with a section 3(d) objection?
These objections are won or lost on comparative therapeutic data and on how the known substance is identified. Our team can review your data against the paragraphs above and prepare the reply. See patent objection reply, and read next on sections 3(b), (c), (e), (i), (j) and (p).
Key takeaways
- Forms of a known substance are treated as the same unless they differ significantly in efficacy.
- For a medicine, efficacy means therapeutic efficacy.
- Better bioavailability needs research data showing better therapeutic efficacy.
- Section 3(d) does not bar all incremental inventions.
- IPAB cases are cited as illustrations; appeals now go to the High Court.
Read next
- Pharmaceutical Patent Guidelines 2014, paragraph 8: inventive step
- Pharmaceutical Patent Guidelines 2014, paragraphs 9 and 10: industrial applicability and section 3(b), (c), (e), (i), (j), (p)
- Manual Chapter 9: section 3(d)
- Pharma Patents in India: Section 3(d) and TRIPS Compliance
Disclaimer: Based on the manuals and guidelines published by the Office of the Controller General of Patents, Designs and Trade Marks that are named in the article, as consulted on 4 October 2026. They are guidance and do not have the force of law; the Patents Act, 1970 and the Patents Rules, 2003 as amended (including the 2024 amendment rules) prevail, and the current versions on ipindia.gov.in should be checked. This article is general information, not legal advice; check the official text before acting.