Sufficiency of Disclosure, Enablement and Clarity in Pharmaceutical Patent Applications in Vietnam

According to Decision No. 97/QĐ-SHTT dated 10 March 2026 of the Director General of the Intellectual Property Office of Vietnam on amendments and supplements to the Patent Examination Guidelines, the requirements of sufficiency of disclosure, enablement, and clarity are further clarified in relation to patent applications in the pharmaceutical and biotechnology fields. These requirements are particularly important in such fields because the claimed pharmacological or biological effects of a compound cannot always be predicted solely from its chemical structure. The specification must therefore provide sufficient technical information to enable a person skilled in the art to understand and carry out the claimed invention.

Several circumstances may give rise to deficiencies in these requirements.

1. Absence of pharmacological research results

Generally, based solely on the structure and name of a compound, pharmaceutical product, etc., it is very difficult to know whether the compound or pharmaceutical product can be used for one specific medical use. Accordingly, disclosure of dosage, administration, and formulation methods may not be sufficient where the specification contains no pharmacological research results.

For example, a claim relates to an antiemetic comprising known compound A as the active ingredient. Although the description discloses its dosage, administration, and formulation, it provides no pharmacological testing or results demonstrating antiemetic activity.

The disclosure is therefore insufficient to enable the skilled person to carry out the claimed invention. Supplementary experimental data cannot remedy the deficiency where the original specification contains no information concerning the relevant testing method or results, and the claimed effect cannot be inferred from common general knowledge at the filing date.

2. Pharmacological results without identification of the tested compound

A related problem arises where pharmacological results are provided but the specific compound tested is not clearly identified. If the compound is described only as “any one of several compounds,” the person skilled in the art cannot establish which compound produced the reported effect. The disclosure may therefore be regarded as insufficient and unclear, and the deficiency cannot necessarily be cured by post-filing data.

3. Functional definitions of prodrugs and metabolites

A claim covering a compound of formula [X], a pharmaceutically acceptable salt, a prodrug, or a metabolite thereof may lack clarity where the description provides no specific structures for the claimed prodrugs or metabolites.

Defining these compounds solely by their functional characteristics does not provide sufficient guidance to determine which derivatives fall within the claim. Without concrete chemical structures, the person skilled in the art cannot determine the scope of the claimed subject matter or carry out the invention across that scope.

4. AI-predicted activity without experimental support

A claim covers a compound identified using an AI-based molecular generation model trained to optimize binding affinity to human enzyme X. However, the description provides only computer-generated predictions and contains neither a synthesis method nor in vitro or in vivo experimental data demonstrating actual binding efficacy.

Such disclosure is insufficient because the person skilled in the art cannot carry out the synthesis based on the information provided, nor can the predicted biological effect be substantiated.

5. Broad functional claims beyond the disclosure

A claim covers any compound having receptor-R activating activity, while the description discloses structures, preparation methods, and experimental evidence only for compounds X, Y, and Z. Because receptor R is newly discovered and identifying other active compounds is not straightforward based on common general knowledge, there is no sufficient basis for extending the disclosure to an unlimited class of compounds defined solely by function.

The functional definition also creates a clarity problem because the person skilled in the art cannot determine the specific chemical structures falling within the scope of the claim.

6. Omission of essential technical features

A process claim covers reacting mixtures A and B for 5–15 minutes at 100°C, whereas the description states that at least 10 minutes is essential for completing the reaction and producing a compound.

The claim is therefore unclear and unsupported because it omits an essential technical feature expressly identified in the description. By covering reaction times shorter than 10 minutes, the claim encompasses embodiments in which the invention cannot be carried out and is consequently inconsistent with the description.

Conclusion

These circumstances illustrate the close relationship between sufficiency of disclosure, enablement, and clarity in pharmaceutical patent applications. Applicants should ensure that the specification provides adequate pharmacological evidence, clearly identifies tested compounds, contains sufficient information for synthesis and reproduction, and provides a technical basis for the full scope of the claims.

Caution is required for claims defined by functional characteristics, including prodrugs, metabolites, or results to be achieved. Where essential technical features are necessary to achieve the claimed result, those features should also be reflected consistently in the claims. Ultimately, the disclosure should enable the person skilled in the art, based on the information available at the filing date, to understand and carry out the invention within the scope claimed.