06/10/2025
When a “clarification” becomes a scope change: a Korean Supreme Court reminder
In Korea, you can seek a post-grant correction of claims. In practice, neither attorneys nor patentees want to do this unless necessary. Still, corrections are often used as a defense in invalidation actions, especially for medical use inventions (which in Korea are typically claimed as pharmaceutical compositions).
This is because challengers routinely not only raise invalidity grounds such as lack of novelty or inventive step, but also almost habitually argue that the claims are not sufficiently supported by the specification. As a result, patentees often have no choice but to respond through claim corrections. Corrections are also sometimes used to align MFDS (Korea’s FDA equivalent) product labeling with the claim wording when there is a mismatch after product approval.
In practice, whether a correction is allowable is often more a technical (factual) issue than a purely legal one. Therefore, it is unusual for the Supreme Court to overturn both the IP Trial Board (first instance) and the Patent Court (second instance), each of which had accepted the correction. But this year, that is exactly what happened.
The granted claim recited: 📌"a pharmaceutical composition for lowering blood pressure comprising 30 mg of fimasartan potassium or a hydrate thereof as an angiotensin II receptor blocker and 5 mg of amlodipine besylate as a calcium channel blocker."
The patentee attempted to correct it to: 📌"… 30 mg of fimasartan potassium or a hydrate thereof (as 30 mg of fimasartan potassium) as an angiotensin II receptor blocker and 5 mg of amlodipine besylate (as 5 mg of amlodipine) as a calcium channel blocker."
The Court specifically found that the correction of
🔔
“5 mg of amlodipine besylate as a calcium channel blocker”
to
🔔
“5 mg of amlodipine besylate (as 5 mg of amlodipine) as a calcium channel blocker”
was not allowable.
👉 The following analysis is my own professional commentary (not part of the judgment itself):
Amlodipine besylate is the salt form of amlodipine (the amlodipine base). Their molecular weights differ — amlodipine besylate ≈ 567.05; amlodipine (base) ≈ 408.9. Therefore, 5 mg of amlodipine besylate ≠ 5 mg of amlodipine (base). By inserting “as amlodipine 5 mg,” the correction could change the actual drug amount and thus the pharmacological effect. This illustrates why such a change can amount to a substantive change of claim scope, and thus be non-allowable.
✨Practical takeaways
✔Clarifications of dose or basis (salt vs. base, hydrate vs. anhydrate) require careful attention.
✔Draft claims and specs with the intended measurement basis clearly stated from the start.
✔Before pursuing MFDS listing or label alignment, audit your claims for basis consistency.
Bottom line: Avoid claim corrections if you can. If you must, proceed with extra care when dose basis is involved.
Amlodipine | C20H25ClN2O5 | CID 2162 - structure, chemical names, physical and chemical properties, classification, patents, literature, biological activities, safety/hazards/toxicity information, supplier lists, and more.
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