Introduction Pharmaceutical use inventions are one of the common types of innovation in drug development: discovering that a known compound can treat a new disease, or discovering that a known drug has unexpected effects in a specific patient group.

The core carrier of such invention patent protection is the claims for pharmaceutical use.

This article starts from the basic form of claims for pharmaceutical use, outlines key points to focus on during drafting, and provides practical references for R&D personnel and IP practitioners.

1. What are claims for pharmaceutical use?

In the pharmaceutical field, patent claims are usually divided into two main categories: product claims and method claims.

Product claims protect the physical substances such as active pharmaceutical substances, compositions, and preparations;
The method claims protect the preparation method and its pharmaceutical use.
Among these, pharmaceutical use claims are the most critical and special type of all pharmaceutical patents—they protect the use of “a particular product to treat a particular disease.”
Article 25 of China’s Patent Law clearly states that methods for disease diagnosis and treatment are not subject to patent rights. If you directly write statements like “compound X is used to treat lung cancer” or “a certain drug as a product for treating diseases,” it will be rejected as a “treatment method.”
Chapter 10 of Part II of the “Patent Examination Guidelines” clearly stipulates: Methods for diagnosing or treating diseases cannot be authorized; However, substances used for pharmaceutical purposes in drug manufacturing belong to the category of protectable method inventions. Within the industry, these claims are uniformly referred to as “Swiss-type” utility claims.

II. Key Points

for Drafting Claims for Pharmaceutical Use 2.1 Technical Features Must Limit

the “Pharmaceutical Process” Although claims for pharmaceutical use are called “pharmaceutical uses,” in practice there are strict rules for determining their scope of protection: Only by producing technical features that practically define the pharmaceutical process can the scope of protection in the claims be affected.
The core criterion for determining whether a technical feature restricts the “pharmaceutical manufacturing process” is: must this feature be realized during the drug manufacturing stage.

• If the feature is part of the drug’s physical form or composition (such as dosage form or content), it is determined by the production side;
• If the characteristic is the behavioral choices made by doctors or patients during medication (such as “intravenous injection” or “once daily”), it is not decided by the production side.

✅ Features that have a limiting effect on the pharmaceutical process:

❌ Characteristics of not having a limiting effect on the pharmaceutical process:

Special Notes:
1. If the method of administration implicitly restricts the dosage form (e.g., “subcutaneous injection” excludes oral dosage forms), then this feature has a limiting effect on the dosage form, but the limitation on the pharmaceutical process is limited to this point.
2. Limiting logic of drug combination: Not all “combination” features are considered limiting.
In practice, if the combination scheme is implemented by preparing compound preparations, drug packs, or kits, it has a limiting effect; If it is only a doctor’s choice during medication, it may not be recognized.
2.2 Limitations of Use Should Be Clearly Defined

: The inventiveness of pharmaceutical patents almost entirely depends on indication innovation. When drafting claims for pharmaceutical use, the claim must specify the specific indication (disease name) and cannot be replaced solely by the mechanism of action.
 Common misspelling:
“Application of Compound A in the Preparation of EGFR Inhibitors”
 Correct Spelling:
“Application of Compound A in the Preparation of Drugs for Treating EGFR Exon 21 Mutant Non-Small Cell Lung Cancer”
Why can’t we just write about the mechanism? The mechanism of action alone cannot be applied to specific treatment scenarios. After reviewers find similar general research literature on similar targets, they will directly determine that the scheme lacks novelty.
The correct logic is: the claims must be implemented to clearly define the disease or disease subtype, and the mechanism should only be explained as a technical principle in the specification.

2.3 Secondary Pharmaceutical Uses: Preferably Lower-Level Sub-Diseases

When a drug already has known medical uses, if a new use is discovered (i.e., “secondary pharmaceutical use”), the scope of indications in the claims should be as specific as possible.
Core logic: If the prior art has already reported that a drug can treat a certain class of “higher-level diseases” (such as “tumors”), and now the inventor has discovered it can treat a specific subtype of that disease (such as “non-small cell lung cancer”), then the very limitation of this “subordinate concept” has the opportunity to give the claims novelty and creativity.
Key premise: The instructions must include sufficient experimental data to support the therapeutic effect of this specific subtype, rather than relying solely on known effects from higher-level diseases as analogies. For secondary medical uses, the indications should be written as specifically as possible. This not only avoids narrowing the scope of protection, but also helps maintain novelty and creativity during review, resulting in more stable authorization.

2.4 Segmented populations require supporting differentiated efficacy data

. If specific patient groups (drug-resistant populations, patients with liver or kidney dysfunction, pediatric patients) need to be limited, simply dividing the population is not enough; the package insert must provide animal/clinical comparative data specific to that populationIt demonstrates unexpected technical effects such as lower toxicity and higher remission rates compared to conventional populations. Without supporting data, simply dividing the population will be considered a routine clinical screening approach in this field and lacks creativity.

2.5 Special Strategies

for Dosing Regimen Claims As mentioned earlier, features like “10mg orally daily” are generally considered not limiting to the pharmaceutical process. But this does not mean that the administration regimen cannot appear in the claims entirely.
Strategy 1: Translate into constraints on the pharmaceutical process. If the characteristics of the administration regimen can be translated into the specifications or labels of the drug itself, it may be deemed to impose limitations on the pharmaceutical manufacturing process. For example: converting “10mg orally daily” to “each tablet contains 10mg of active ingredient, with packaging labeled ‘once daily’.” (This strategy can be tried in practice, but there is no direct case law supporting it; feasibility must be evaluated in case specifics.) )
Strategy 2: Adopt a dual-layer structure of “product + purpose.” It is written as a separate claim, such as: “A tablet for the treatment of hypertension, characterized in that the tablet contains X mg of the active ingredient, and the outer packaging of the tablet is marked with instructions for use, stating that the instructions for use should be taken orally once daily.” ”
Strategy 3: Only limited to the manual. If the administration regimen is not a core contribution of the invention, the most suitable regimen may be clearly stated in the specification without including the claims. This approach does not affect the smooth passage of the review and also plays a role in subsequent commercial use and infringement litigation.

3. Key to Supporting Specification Writing: Data is the Foundation

of Authorization. Whether claims can be granted and whether the procedure can be maintained in the process relies on experimental data from the specification for support. The following four types of data are the most important for reviewers:
(1) Essential basic data: in vitro cell experiments targeting inhibition, efficacy data of animal models for corresponding diseases. Existing technology drugs must be set as control groups to visually demonstrate “unexpected technical effects.”
(2) Supporting data for detailed indications: Each subtype of disease specified in the claims must correspond to independent efficacy embodiments. Mechanistic descriptions cannot replace in vivo activity data—in vitro experiments ≠ animal models are effective, and this is a key point for reviewers.
(3) Exclusive Combination Drug Comparison: The combination regimen must provide data comparing the effects of monotherapy and combination therapy to demonstrate synergistic or attenuated effects. Without comparative data, the “co-use” feature will not be recognized during review.

4. Conclusion

The drafting of claims for
pharmaceutical use essentially seeks a legal and effective path between the exclusion provisions of Article 25 of the Patent Law and the protection needs of the pharmaceutical industry.

Only by grasping the four dimensions—format, features, disease, and data—can claims withstand scrutiny and invalidity scrutiny. In practice, however, a single claim often struggles to provide effective protection. It is recommended to arrange four categories of independent claims around the same invention: compound, composition, dosage form, and pharmaceutical use, forming a complete patent protection portfolio.

Formal compliance is the threshold, characteristic specification is the core, disease specificity is key, and experimental data is the foundation. Only by strictly adhering to review rules and precisely controlling every detail of writing can a truly solid intellectual property barrier be provided for drug R&D results.

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